World Bank Document

Home , Dakatia River, Feni River, Ganges Barrage Project, Haora River, Rajshahi District

DOCUMENT OF INTERNATIONAL BANK FOR RECONSTRUCTION AND DEVELOPME,NT INTERNATIONAL DEVELOPMENT ASSOCIATION Not For Public Us_ PS-13 Public Disclosure Authorized VOL. 8

Report No. PS-13

BANGLADESH

LAND AND WATER RESOURCES SECTOR STUDY

Public Disclosure Authorized (in nine volumes)

VOLTTME VI!

WTATER

Technical Report No. 20 - Overall Water Resources Poteta Technical Report No. 21 - The Groundwater Potential Teclht,.icall Report N.NooInLT- - terr,ational Water Aspects Technical Report No. 23 - Rainfall Analyses Public Disclosure Authorized

TDLe embeLID 1r, 19a 72

Asia Projects Department Public Disclosure Authorized

This report was prepared for official use only by the Bank Group. It may not be published, quoted or cited without Bank Group authorization. The Bank GrouP does not accept responsibility for the .acPur:cyor comnpleteness of the report.

Note

"The Land and Water Resources Sector Study - Bangladesh" dated December 1, 1972 was prepared between May 1971 and the summer of 1972 under the general supervision of the Bank, by staff members of the Bank, and FAO, with substantial help from consultants. The UNDP and the Bank shared the cost of the consulting sernices. The study is made available on the understanding that it does not necessarily represent the official position of the Government of Bangladesh or of the Bank.

The study is based mostly on data collected prior to March 1971. Although some of the information contained in the study is out of date, the essence of it is vralid and it should be useful to the Government of Bangladesh and to other countries, agencies, and institutions interested in the development of Baneladesh.

LAND AND WATrER RESOURCES SECTOR STUD-Y

VOLUME VII

WATER

FOREWORD

i. Of the four separate Technical Reports that comprise this volume, the first (No. 20) presents the problem in Bangladesh as one of uneven water distribution in time and space - too much water over a major part of the country during the monsoon, and a limited amount available for irrigation in the dry season found mainly in the large rivers. Groundwater, which was given little emphasis in earlier studies, is presented as a vast untapped dry season water source for most of the country.

ii. The second report (No. 21) documents in more detail the magnitude of this important water source. Analysis of rainfall, runoff, and surface conditions, drawing together all available data, leads to the conclusion that - with the exception of limited areas near the western border and in the extreme south - recharge potential would be sufficient to sustain intensive irrigated agriculture from groundwater withdrawals over most of the country. ii. T,he great ri-vers, wmhich forIm1_ed the delta which comprises Bangladesh and which influence its destiny and development so profoundly, stem from far beyond the country's borders. ThLe activites upstreamL whch may affect ILand and water development efforts are analyzed in the third Technical Report in bL L V U±WIT10k PU . 4 J. iv. Rainfall and cropping patterns are intimately related. A detailed probability analysis of seasonal rainfall patterns is given in Technical Report No. 23. This analysis throws iight on the risk factors which underlie much of the agricultural activity of the region. Combined with the wealth of soils data described in Vol. II (Technical Report No. 2), and agronomic data currently being generated at IRRI, this analysis will provide a solid basis for regional irrigation development policy decisions. v. Technical Report No. 20 was prepared by Mr. E. Hunting using analysis provided by ACRES International (Overseas) Limited, General Consultants to EPWAPDA, except for the analysis of surface water potential done entirely by Mr. Hunting. Technical Report No. 21 was prepared by Mr. M. Maasland of ACRES International (Overseas) Ltd. The Report on Inter- national Water was written by Mr. W. R. Rangeley, Consultant. Statistical analysis of rainfall data presented in Technical Report No. 23 was prepared by Mr. Bernard Oury using probability analysis of weekly totals done by the National Climatic Center, U.S. Department of Commerce, and duration frequency analysis done by ACRES International (Overseas) Ltd.

RESTRICTED

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BANIGLADESH

LAND AND WATER RESOURCES SECTOR STUDY

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December 1, 1972

Asia Projects Department

BANGLADESH - SECTOR STUDY

VOLUME VII - WATER

TECHNICAL REPORT NO. 20

OVERALL WATER RESOURCES POTENTIAL!!

TABLE OF CONTENTS

SUMMARY AND CONCLUSIONS Page No.

I. INTRODUCTION

A. General Background ...... B. Earlier Reports on Water Resources ...... 2 C. Objectives and Scope of this Study ...... 3 D. Regional Aspects ...... 4

II. PRESENT lWATER REGIME AND CONSTRAINTS ON FUTURE DEVELOPMENT 6

A. Present Water Regime ...... 0...... 6 B. Upland River Discharges ...... 6 Ganges River ...... 6 Brahmaputra River ...... 7 Meghna River ...... 7 Annual Hydrographs ...... 7 Regime of Major Rivers ...... 10 C. Surface Water Increments Within Bangladesh ...... 11 Northwest Region ...... 12 Mymensingh and Sylhet Districts ...... 12 Dacca District ...... *.. ... *...... 12 Other Districts ...... 13 Example for Mymensingh and Sylhet Districts .. . 13 D. Dry-Season Rainfall and its Variation *...... 13 E. Groundwater Resources ...... 1 3 F. The Tides ...... 14 G. Salt Water Intrusion Into Coastal Estuaries ...... 16

Introduction ...... * * * *** *** .. * .* .* 16 Available Information and Current Knowledge ...... 16 Salinity Problem Areas ... .ee* .. * v v v .v ... 0. 1 7 Danger from Further Saline Water Intrusion ... 18 H. Prospects of Flow Reductions Due to Developments Outside Bangladesh .o...... 0 Introduction ...... 0.. ...a ...... 20 Potential Use of Drv-Season Flows of the Ganges ..* Potential Use of Dry-Season Flows of the Brahmaputra .. Total Possible Flow Reductions ...... I. Present Use of Dry-Season Water Resources ...... *..

1/ This report was prepared by Mr. E. Hunting using analysis provided by Acres International (Overseas) Limited, (formerly General Consultants to EPWAPDA) except for the analysis of surface water potential done entirely by Mr. Hunting. -2-

Page No.

III. FUTURE WATER REQUIREMENTS 23

A. Introduction ... *.. ... *...... 23 1AT_ -- 4 .._ , TY _ LCAY7 NMaVgator, and VO-ther Rura l US"O'esS U1 ofSua WaterT. 213 Fisheries ...... * ...... * .. 24 Munwicipal and Industrial Su-pplies ...... 24~ B. Water Requirements for Irrigation ...... 24 Evapoti-.nspiiation of Crops ...... 4 Effective Precipitation 9.0 ... .*...... 26 Ohner Factors Detenu.inThg Irrigation Requir-ents ... 27 Irrigation Water Requirements for Five Districts .... 29 'Water Losses Associated with Irrigation ...... 31 Area Served by a Single Two-Cusec Unit ...... 32

IV. POTENTIAL FOR LOCAL SURFACE WATER USE 34

A. Introduction and Summary ...... 34 B. Surface Wiater Available ...... 36 Data Sources ...... *...... 36 'water Utilization Criteria ...... 37 Water Available for Irrigation ...... 37 C. Irrigation Potential ...... *...... 40 Data Sources ...... * ...... 40 Criteria for Estimating the Irrigation Potential ... 141 Estimates of Full Potential for Surface Water Irrigation 42 Estimate of Present irrigation ... t.w ... *.. ... 34 Estimate of Potential for Expansion of Irrigation ... 44 D. Net Water Withdrawal from Rivers ...... D* 46 Dispersed Low-Lift Puap ...... 47 Closed Folders ... D...... * owe ... 49 Conclusions t.w *.. .*. *.. 999 ..* ...... 50 V. GROUNDWATER POTENTIAL 51

A. Introduction ...... we. ... .*0 ...... 51 B. Hydrogeology and Groundwater Quality s ... ..* ... 51 C. Availability of Groundwater for Irrigation ....oe o.. 53 Present Groundwater Regime **e 0e0 ...... 0 53 Potential Rainfall Recharge ...... * ...... 53 Acreages Irrigable by Groundwater ...... *.. ... 55 Detailed Water Balance Calculations for a Sample Area (Rangpur)...... 0. ... 56 Application of the Methodology of Detailed Water Balance Calculations to an Area with Possible Recharge Shortage (Rajshahi) ... . . *...... 61 D. Possible Effects of Groundwater Pumping on Surface Water Availability ...... oe *0 *.O 62 -3-

Page No.

VI. AREAS WITH SALINE GROUNDWATER AND/OR AFFECTED BY TIDES 65

A. Introduction ...... -...... 65 B. Present Coastal Embanklaent Program ...... 65 C. Expected Changes ... .., ... .., ... ,., ...... 65 D. Effects of Estuary Closures ...... 66 E. Monsoon Diversions from the rTanges River ...... 67 F. Gravity Diversions of Dry-Season Flows from the Ganges 67 rS. EbbH. and Flnood Volnraes . . . - 68~~~~----68 H. Benefits fron Estuary Closures ... . ,...... 69 T * Studi es Rui-ii rad ==9 J. Water Transfer and Diversion in the East Region ...... 69 K. Transfer of Brahmaputra Water+o Ganges River ... v** 70

VIIT WATER SqrTPPT. h fT'KIMTrTOMq 72

A. General *...., eo .** a ***.w** * * * zvv@...... 72 B. Irrigation Wlater Availability ...... O.. 73 The N-ortest ar.d- ental Reg4ons g F71 Southwest Region ...... 4...

C. Net River Withdrawals ...... 77 N Wa+er Requirements ...... 77 Net River Withdrawals ...... 77

D.**- W B a'anLce f or 99A9 090 . ... 78 ... River Water Withdrawals in Bangladesh Uhider TvT- -he|4 4cal T r-6-P. Devl- - ent ...... 78 Withdrawals in India ...... 78 River Water Balance Under the Hypothetical Development 79

TABTLE OF CONTENTS

T6Tr OF TALT,ES

1. Surface Water Inflow From India And Rainfall In Bangladesh 2. Mean Monthly Rainfall (In Inches) Period of Records: 1934-1969 3. Variation of Monthly Rainfall (In Inches) Period of Records: 1J4--1939 4. Average Monthly Discharge Of The Major Rivers 5. River Discharge Stations Used To Develop The Distribution Of Monthly Surface Water Supplies 6. Average Monthly Offtakes From The Ganges River 7. Discharge And Salinity At Stations In The Lower Meghna River 8. Mean Monthly Evapotranspiration Index 9. Half-Monthly Crop Factors 10. Estimated Monthly Evapotarnspiration For Non-Rice Winter Crops 11. Estimated Monthly Evapotranspiration For Rice 12 Estimated Seasonal Evapotranspiration For Different Rice Crops 13. Estimated Monthly Evapotranspiration For Jute lb. Estimated Monthly Evapotranspiration For Sugarcane 15. Estimated Monthly Effective Precipitation 16. Cropping Pattern With 90% Transplant-Boro Used To Calculate Regional Crop Water Requirements 17. Cropping Pattern With 15% Transplant-Boro Used to Calculate Regional Crop Water Requirements 18A. Calculation Of Average Irrigation Requirements For Transplanted Rice For Comilla District - Cropping Pattern - 90% Transplant Boro; Assumption A - Tnfiltration Loss of 3 Ihches/Month 18B. Calculation Of Average Irrigation Requirements For Transplanted Rice R:ice For Comilla District - Cropping Pattern - 90% Transplant Boro; Assumption B - Infiltration Loss of 5 Inches/Month 18C. Calculation of Average Irrigation Requirements For Transplanted Rice For Comilla District - Cropping Pattern - 90% Transplant Boro; Assumption C - 50% and 75% Field Efficiencies 18D. Calculation of Average Irrigation Requirements For Non-Rice Crop and Full-Cropping Pattern For Comilla District - Cropping Pattern - 90% Transplant Boro; Assumption C- 50% Field Efficiency For Rice And 75% Field Efficiency For Non-Rice Crop 19A. Calculation Of Average Irrigation Requirements For Transplanted Rice For Comilla District - Cropping Pattern - 15% Transplant Boro; Assumption A - Infiltration Loss of 3 Inches/Month 19B. Calculation of Average Irrigation Requirements For Transplanted Rice For Comilla District - Cropping Pattern - 15% Transplant Boro; Assumption B - Infiltration Loss Of 3 Inches/Month 19C. Calculation of Average Irrigation Requirements For Transplanted Rice For Comilla District - CroDping Pattern - 15% Transplant Bo'ro; Assumption C - 5u% and 75% Field Efficiencies 19D Calculation of Average Irrigation Requirements For Non-Rice Crop And For Full Cropping Pattern For Comilla District - Cropping Pattern - 15% Transplant Boro; AssumDtion C - 90% Field Efficiency For Rice And 75% Field Efficiency For Non-Rice Crop LIST OF TABLES

(CONT' D)

20. Irrigation Requirements For Transolanted Rice For 5 Districts Assumption A - Infiltration Loss of 3 Inches/MIonth 21. Irrigation Requirements For Transplanted Rice For 5 Districts Assumotion B - Infiltration Loss of 5 Inches/dater 22. Irrigation Requirements For Transolanted Rice For 5 Districts Assumption C - 50% Field Efficiency 23. Irrigation Requirements For Full Cropping Patterns For Five Districts - Assunption A - Infiltration Loss of 3 Inches/Aonth For Rice Crops and 75% Field Efficiency for Non-Rice Crops 24. Irrigation Requirements For Full Cropping ?atterns For Five Districts - AssumDtion C - 50% Field Efficiency For Rice Crops and 75% Field Efficiency For Non-Rice Crops 25. Calculation of' Average Irri7.ation Losses To Groundwater For Comilla District - Assumption A - Infiltration Loss of 3 Inches/ Month For Rice Crops and 75% Field Efficiency For Non-Rice Croos 26. Calculation of Average Irrigation Losses to Groundwater For Comilla District - Assumption C - 50% Field Efficiency For Rice Crops and 75% Field Efficiency For Non-Rice Crops 27. Calculation of Non-Beneficial Evaporation Losses From Anolied Irrigation For Comilla District - Assumption A - Infiltration Loss of 3 Inches/Month For Rice Crops and 75% Field Efficiency For Non-Rice Crops 28. Calculation of Non-Beneficial EvaDoration Losses From ADolied Irrigation For Comilla District - Assumption C - 50% Field Efficiency For Rice Crons and 75T Field FXficiency For Non-Rice Crops 29. Sinmarv of Monthly Irrigation rTssse to (roinndwatpr For ive Districts - Assumption A - Infiltration Loss of 3 Inches/ Month For RieP (Gronnq and 75% FilPI Rfficiency For Non-Rice Crops 30. :nmary of TMonthly Irrig,ation TLsses to Groundwater hior Fiive Districts - Assumotion C - 50% Field Efficiency Eor Rice Crops and 75%T eldI EffPriciency V^or Non-P4;, ceGr%nz 31. Summary of Monthly Non-Beneficial Evaporation Losses F'rom Aoolied Twv'- to For F~ivefl Dis+ric+s - Assi,d..ptio A =v* Ir^+ratior. Loss of 3 Inches/Month For Rice Crops and 75% Field Efficiency For NonRic-~C-rons 32. Summary of Monthly Non-Beneficial Evaooration Losses From Aoolied Tr-,igatio, Fo.rUj.-v Dtricts - t C - ' Av L dj.--I Efficiency For Rice CroDs and 75% Field Efficiency For Non-Rice Clrops 33. Number of Acres Irrigated By A 2-Cusec Unit For Varying Peak Recquirer,.entus andu Operating Hour-s_ 34. Data By Source and LDU For The Analysis of Irrigation Potential fl...... r.. D rln .n ,,L 21 fl .iX .. rrvu )ur-Lace rlows ariu liual BacKwatoel s 35. Estimated Irrigable Areas By LDU Above The Present Saline Limit using SIxty Percent of Lower Quartile Flows andu A-ia'Backwaters 36. Present Irrigation By Low-Lift Pumps From Surface Flows and Tidal Backwaters 37. Estimated Potential By LDU For Expansion of Irrigation Above The Present Saline Limit 38. Surface Water Withdrawals To Irrigate The Estimated Potential Above The Present Saline Limit T.Tc?r( n)~T

39. Sunnary of Potential Regional Groundwater Recharge By Districts 40. Net Potentia1 Recharge Available For The Bunded Areas, By Districts 41. Acreages Which Can Be Developed On The Basis of Groundwater Alone ar.d IT-ber ofP .bewells lossible 0.-' NeededU, 42. Rangpur Sample Calculation Alternative 1 - Rice Irrigation .U..L.cie>50 43. Rangpur Sample Calculation Alternative 2 - Rice Irrigation DFA.LciA.ecy 75;)/ 44. Irrigation Regime and Water Balances For Rajshahi Under Different Assu-wtions 45. Unit Monthly Net River Withdrawals For The 15% Transplant Boro Cropping Pattern In Tne Montns of March and April (Inches of water) 46. Unit Monthly Net River Withdrawals For The 15% Transplant Cropping Pattern In Tne Months or March and April (Cubic Feet Per Second) 47. Hypothetical Long-Range Water Development By Region 48. Net River Withdrawals In Critical Months For The Hypothetical Long- Range Development 49. Average River Water Balance After Hypothetical Long-Range Develop- ments in Bangladesh

__ ~~1/ LIST OF- PLATES -

TBITD - 10009 thru water Balance Study, Surface Water Supply, Average IBRD - 10020 Monthly Inflow, January through December IBRD - 10026 Water Balance Study, Surface Water, Lower Quartile IBRD - 10025 Inflow, March and April IBRD - 10030 Lines of Equal Salinity, November - May, 1968 IBR.D - 10031 Lines of Equal Salinity, June - October, 1968 IBRD - 10027 Major Hydrogeologic Regions IBRD - 10024 Tidal Volumes, Ebb and Flood - Springtides, February - March, 1965

Page No.

APPENDIX A GANGES DIVERSIONS ...... 1

Discussion ...... 1

List of Tables

la Project by Project Water Requirements, Month of April, Harvard Estimate lb April Flow in Ganges at Hardinge Brid.ges

1/ These plates appear at the end of this Volume. APPENDIX A GANGES DIVERSIONS (Cont'd)

List of Plates

Ala Southwest Area Project Locations Alb Northwest Area Project Locations

APPENDIX B THE GANGES AND BRAHMAPUTRA BARRAGES *-**** WITH LTNK CANAL

General ...... Major works and Cost Estimates ...... Area Benefited and Cost Per Aare ...... RATr.TT.AnV9W - qTrTP.T mTmy

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Situmm.ary and Conclusions i. This report reviews the overall water resource potential of nBvr1gladesh ar.di provides~ a factua~l basis fo a pv,rogram o'f w.nater co+vrtrl While the problem of drainage and flood control on the one hand, and the problem. of irrigva4 .4 on on the other, are aralyzed searael for£ planning purposes, it should be stressed that both aspects will need + AAaoA A 0 nrvnc. +. ^+ h A_ AtWO, r.h1s, ,o 1 ;o+ o 1 o+; nrce o _ 0aAS r, to V t OA tUS±¼.,e er n frJxflJ O>itok*=-V ^Lycln V UaJ.allt UJ L san ,g _o specific areas. ii. The emphasis in this report is on the technical analysis of w ateru r-g,JJMI e w.itbh Mespect IVo- the poteJIntiU5f al o-f tAhe Me rgion to -'J Metu fu turee water demands. Consequently, economic considerations are presented in

.Tehn_a I'ReJr U * 14 whic u,gst_A anec 4 0 mi. sqanc Sorwa..tQr investments. Chapter IIreviews the present water regimes and constraints on PUIJu..re Udevelopr,.ent . It -isU 4t a,,4 r.ual-basi more -a- enters Bangladesh than can ever be used effectively. Annual surface water

fu±LoW firo.. nudia iS some u87 million acre L4ee ki-r) dIiu the average annual rainfall is 203 MAF. On the consumption side, evaporation losses over the gross area are on the oruer olf _)U rinu wile crop cnupi by the 22 million acres of cultivated area is approximately 65 MAF net o' deep pe~rcolatiion 'losses, m,eanin toaU osumto of orH uabut 200 MAF, roughly 20% of the annual supply. iii. This overall picture, however, conceals the seasonal and spatial water shortages w.ich pre-valJ UU-.ULn,g thle werW Is IFIVIIL.I Ihe average rainfall amounts to only 2.5-4.5 inches during November through March which is irnsufficient to sustain crops. Moreo-ver, the flows in the river are significantly less during these winter months. Optimum a'L"'ocation oJ sca-rce -winit,er wtater a-moung variuus coui-±ictinig UIRUdeImUa forms the crux of the planning task associated with the "low flow" problemn. iv. Major constraints to irrigation development inciude the scarcity of surface water and low and irregular rainfall in the western par _ ' t' - con_- L-r __ _n _ - n - '" '_]a part of the country., saline groundwater in an area south of a still undetermined line stretching from Jessore to Comilla, and erratic grould- water supply where the geology is compiex in the eastern ana northern hill and piedmont areas. In addition, salt water intrusion in the delta estuaries has been a limiting factor to full agricultural development in the coastal areas. Future withdrawals of upstream water during the winter months for irrigation may cause further saline penetration. Finally, upstream uses, particularly major developments in India, will affect water availability. Winter water use is therefore an international Iproblem . v. Ch>apter HI di S -- c2S es- wa-terII rqi - I-em.e nts feor irgatlo-p- + n-n,+ tkn1 n into account requirements for other purposes such as: (a) navigation Wnd o+the,.r ruralu us.-t of surface water; (b) fi\s hleries; anrd (c)n\Mnica 0-1, domestic and industrial supplies. Irrigation water requirements for five-iA c ts, onePt f o omech-, h i. of- adesh, areM" + ulated for two different cropping patterns. For each cropping pattern, four assumnptions reg.ardin.g iJil 1 i--on ^.dA i o -- loseI- a.r+, m-- e. The effects on crop water requirements of assumptions regarding the cropping patterns, infiltration rate, field efficiencies, m,d the effective rainfall are brought out. Water requirements are highest during March

s I %,CtfW1UPPL116 HaUD t-,1110 .L 'J±~LUkJjJ.LI1~ 6.±± ~ U U .L g U:b Ilu P u:;I. b-U L - vi. Chapter Ivi-vestigates the pote,tial for the use of local surface water: the land areas which can be irrigated by single and rultiple stage pU-msping an,d the factors governirlng this t.ype of development in particular regions. The analysis indicates that a key factor in lu-ture i-r-gation UevelopmretIl will Ue inurteasiug thiez nlUiuter- Uohlurs of irrigation each day and that in this respect a large potential for exAp2uInuIo of )UW-LiL±U Hump ±-V-1Jg %U.tIx texsLtU -L aiUU±U±VonUL ttUe JpoUentiL aL remaining from unexploited sources of water. The effect would be a much larger supply of water a-vailable at the fields but, atthe same time, the analysis shows there wculd be a reduced requirement at the rivers in term-rs of LoVW ui-vertjALis. IU UUclVev UIiLs, thie efficiency UoL pmup use would not necessarily have to increase, but if utilization did improve, iL wuulu Mreai a luwer Uensity- of PulF-ps isU4l±leU aniu luWeL- unit irrigation costs. vii. Groundwater, which will probably become increasingly important for agricultural development in Bangladesh, is discussed Ln ChapterV, and more fully in Technical Report No. 21. Earlier estimates of water availability were generally made on the basis of river fiows without consideration of groundwater as a significant resource. In fact, the actual and potential groundwater recharges in Bangladesh during monsoon are very high and much of this water can be used during the dry season. Tubewells permit irrigation of lands which cannot be served by surface supplies because of the distances from perennial rivers. viii. Chapter VI discusses possible future development of areas with saline groundwater and areas subject to tidal erfects. The major aspects of this development include the pbldering of tidal lands, closure of estuaries and possible diversion of mainstream flows, especially of the Ganges. during both monsoon and dry seasons. - iii -

J-Z' o L&At; A.WJ %'.JJ..A1r J.L 4.LQ I.~JJ.1Z,JA tU C.L 4 a With,re'^- vel mlnor-- xcet4ns .+iga^ agi '-- e- .

%CZ . Ai.111. .. .L I.L-S A .IJ% U~.L'JL DJ ".L.L.5. UVZ.L &r .L.A,U..L UU± = J4 L .L four regions can be expanded from additional groundwater and surface water resor ces an(A. by i.uncreasng the periLods of operation from supplies available in each location;

(b) with full development of irrigation, total abstractions on an arnnual basis remairJnavir-tually nsignificant relative to availab]e resources; however, shortages in many locations and further penetration of saline water in the coastal areas would result fromn major diversions outside Bangladesh, highlighting the need for- an early accord with 'uI.uuw.L4u.a or- waUr r.LgLts

(cj ho de-velop lne Ui i.Llate potuertia.l .In Ulhe coasta.l area iL may be necessary to design and implement a major program of estuary closures.

BANGLADESH - SECTOR ST'UDY

VOLUME VII - WATER

TECHNICAL REPORT NO. 20

OVERALL WATER RESOURCES POTENTIAL

I. INTRODUCTION

A. General Background

1.01 The general objective of this study is to assess the agricultural ievelopme.nt po>+tena1 Of Bangladesh andA On the basiL OI This assessment, to devise a viable agricultural development strategy.

no 1amlAle the -ea is Iocated Lbetween 20°35'a-4and J AL-north latitudes, the climate is actually tropical because of the modifying effect of the Himalayanr Mount ains. Montl'y .e teperatures never fal belv- 60r°O and hence are favorable for crop growth 12 months of the year. Most of the soils have been developed on the -flood=pla n s ar. dtas of sar rivers and are above average in fertility for a tropical country.

1.03 Annual rainfall ranges from 50 inches in Rajshahi in the west to oe olvl nc e in 1'OIDA _ 4-All; no rt 4-- .4.A. -4 s rteast m;W- W__l ;%5s- OVVG LVV J.Ii GO £1fi~ UVUllk L,11G *VL)! s WGLilO0 d4LU DL)L,iL COUZ 1 . ±Lll IIi^JIILhIAJ distribution of this rainfall follows the usual pattern of monsoon Asia '.ith tLhe I=CaVJ radi. Lst-rtir,g in .Iay 4and endILr.g LI Vctouer.

L.0 L The groundwatetertable oVE most of the country is generally high ar.d is bbtween zero and 30 feet below ground surface depending on location and tim-e of year. The better aquifers are usually found between 60 and 350 feet.

1..05)) TrJ.tZL dL1 ilL 0±LII±UdU areas of.L VirI La-IU U. toJ b JeoIpr. uIpJ, so -.- creased production must come from land that is already being farmed. The wat'er regUImle inlIBang±ldaueshuI L Lsy±V ± Lcal LofUILI-.L10 W.iLLh r,,UonsUoLL UcirI ,a - there is either too much water or too little. Two of the largest rivers in lthe WoldU, the Ganges U D LuLpu.Lr, .LUW tIhroIu DBar.ILgUdeshI LIU IIadVta formed a large delta. In the monsoon seasoon, the great rivers rise to high level's causLi±g ac-Iu±iaLUIl Vo. ±VLocaLstormI waer and sor,,Ue o-vL-anLd fla-w of. river water. However, during the relatively long dry season (November-May), 1~~~~_ __ I 2 - -___n 2 - -32 I _ 3 4~~~~~~~~~~~~~~~~~~~~~~~~~~~~~..- tIhese rirvers cadrry very LtUle waLter. The CA.t: ,Ci!s ±11inudisharge ±WdU t'uo opposite probiems of irrigation and navigation during the winter or low-fLow months and drainage congestion and flooding during the summer or high-flow months.. In the dry months farmers have to adjust to extreme drought and Ln the monsoon periods to heavy rains augmented by flood waters from neighboring countries. - 2 -

1 lf0 TTnder tahecs aders,e, w.yar cr. -tionr-i+A or,nino. r ,A.r a'rnen 1 nu.I gm Irf' agricultural technology, present cropping intensities on the 22 million cultivated acres are subst-nti2ll h1bl-w those which climate would permit, and crop yields are only one-third to one forth of those in many other countries. T-.-o,-.,, a,+4 - nff?'~i^iil +ii,v3. Y%l iie-~ri+A gwt mv'o nn c )h1I w i 'hi v +h_I-ia.n _FIF..pota U ------ir prdutionae possible witLJ;n the p.-s-e- natural environment. However, the more basic problems of agriculture can only1 bsolv +-1,h wt conrol If thls i a n++ae,wn the wil also be an added incentive for the farmer to apply other inputs and so to further ir.crease agricultura-l prod-cti,ty.

'D. Ear"Lier Reports on Wf-ater Resources

1..06 Thr11e prL-1cL01Pi. LUYU.LLO. ha1Ve Ubee pV±e.Jly publJJ.ished conceLJ.Ung Bangladesh water development. They are:

(a) IECO/WAPDA - Master Plan of 1964;

(b) NEDECO/IWTA - Surveys of Inland Waterways and ports of 1967;

(c) Professor J. Th. Thysse's reports on the Hydrology of B&ngadesh arLd195 J. ( .0 ±anL 1 ~ -I~Lnl.u -3p±i-I ud±i V±JILi0L.4 d1.±'0 X/ . U Lil e s I b b rtu se p o s c o n a -I v Vouhu Ual' -m,n o u s ct aU;, aria ' > iz U z %: ; problems and development proposals, and provide valuable background material on thie wadAer resouarces of Bangladesh.

1.08 The 196u and L965 reports of Professor Thysse do not disagree witih the overall views of either NEDECO or IECO but they emphasize, correctly, the many uncertaunties at that tiJ-1e regarding the effects of the development proposals on the water levels and discharges in the major rivers the changes in their morphologlcal and hydraulic behaviour and the salt-water intrusion problems associated with the tides and decreased upland flows.

1.09 The IEC0-WAPDA Master Plan of 1964 was reviewed in a 1965 IBRD report. Thart report emphasizes development alternatives, especially agricultural inputs other than water; irrigation of non-flodded land and small- scale projects. It points out that water resources development is no more than an instrument for economic development.

1.10 The following reservations concerning the three principal documents now appear valid:

(a) water development projects were proposed without priority ranking.

(b) During the monsoon, the country was viewed as a large spill- basin for the major rivers. It is now known that the overland - 3 -

flow is relatively small as compared to the discharges carried by the rivers and that most flooding is caused by the accumulation of local rainwater and impeded drainage.

(c) Dry-season irrigation was discussed without regard to water-use efficiency even though serious surface water shortages exist in that season.

(d) The effect on rabi crops of inevitable waterlogging due to surface water irrigation was not considered.

(e) The extensive availability of groundwater was not taken into account in either the development program or in individual projects.

(f) The desirability of first using local water resources for irrigation was overlooked. As a result, government interest and implementation capacity was diverted to larg,e-scale projects.

C. Objectives and Scope of This Study

1.11 Any approach to the problem of water control will have to start with an analysis of water demands and supplies by region and season, leading to the identification of water shortages and surpluses. It appears that at this stage, the problems of irrigation on the one hand, and drainage and flood control on thei other hand, can to a large extent be analyzed seperately, since they occur in different seasons. Even at this analytical stage, however, there will be same interactions, for instance by the changes in cropping natterns and with these,water demands required with the introduction of 'drainage and for flood control. Tn the nroiect nlanning stage when phvsical installations for water control are planned for specific areas, both aspects will have to be considered together. since the same installations. such as maJor pumping stations, may serve both purposes.

1.12 The present report provides the factual basis for a program of water control. Water shortages and surpluses by malor regions and seasons are identified. It is suggested how the irrigation requirements can be met, and the consequences of irrigation on the water regime are assessed. Attention is given to the problems of the coastal areas.

1.13 The emphasis in this report is on the technical analysis of the wnt.pr regime. This imnliAq thnat. Prnnnmirf nonn'cidPrS%tinn. have hben larnlv left out, and these must be brought in at a later stage. For example, -ronpping patterns have hAAn treated an -ivPn- without analyzIng the trade_- off between gross returns per cropping pattern and its irrigation and f_lod contrnl costs. The order i n whi-h diff ront wvater nnpply alternatives are explored is based solely on physical potential. 1.1h Another limitation of the present report is that the empirical basis for the estimation of a number of important variables is still limited because basic data are not available. This is particularly true for future salt intrusion into the Lower Meghna Outlet, the problems associated with estuarine closures, and the aquifer characteristics in SyhLet and the southern portion of Bangladesh (the saline groundwater zone, Hydrogeologic Region I, defined in Chapter 1 of Technical Report No. 21).

1.15 Nevertheless in this volume a renewed attempt is made to come to grips with the major water control problems of Bangladesh.

1.16 This report is concerned with the meeting of water demands for various purposes. The current water regime in the low-flow season is described and probable future water withdrawals by neighboring states are discussed. Crop water requirements and irrigation requirements are determined taking into account the effective rainfall.

1.17 On the basis of available data it has been accepted that the quickest and most desirable way to meet irrigation demands is through the use of locally available surface water by single- or multi-stage low-lift pumping. The potential for this type of irrigation is analyzed in some detail as are the indirect consequences of withdrawal of local surface water on the water regime downstream.

1.18 The second extensive local source of irrigation water is groundwater. Suitable aquifers underlie large parts of Bangladesh. In order to assess the potential groundwater supply, an analysis of the annual recharge iF made. Again the implications of groundwater pumping for local and overall water regimes are discussed. Technical Report No. 21 discusses various aspects of groundwater use in detail.

1.19 It is shown that, for large parts of Bangladesh, irrigation requirements can be completely met from local surface and groundwater resources. However, a number of problem areas remain, mainly in the western part of the country where rainfall is relatively low and in the coastal area where the estuarine and groundwater are both saline. Possible solutions for these areas are discussed in the final chapter of this report.

D. Regional Aspects

1.20 For the purposes of development, the country has been divided into four regions - Northwest (NW), Central (C). East (E) and Southwest (SW) - separated primarily on hydrological considerations. The principle boundaries are une channels of the Brahrnaputra-Ja-UUun,, Ganges and MegLuha Ri-ver-s but te western boundary of the deeply flooded Syhlet basin constitutes the northern part of the boindary between the Central and East regi-ns. OnUhe bas s of land capabilities, these major regions have been further subdivided into a total of 49 Land Developments units (LDIUs). The locations of the developmLentl regions and LD''sare shown on Map VI - Land Development Unit of the Analytical Map Series.

1-21 Th-e hydrologic conditions ra-e th o land4.A ctic9 determine the agricultural potential of Bangladesh's cultivated area, i.e. th-ese conitins ete ire -whethercrps(sch as rice- -dJte rd,ln a.. A'.. - -W-A.LU.LMAAO - '±- --ILA~*Ik WM V LO± %''J. Jp kQLLAA.A1 6.0 4 .L~ U-, -O J U. U') V .4±*AlY.LO.±.U crops (such as sugercane, summer vegetables, bananas or other fruits) can be

C-,,tlLi%n +1., e mo: -0oareae.aoao..O., MVIA4 whvethr- ny.U.ie crops Caan, lbe 6-Mun. c-4- all.

1.22 In the context of the water demand and supply calculations it shoutld ber,ote ~ ta.t the maJorJdevelopr,,er.t reg-mes a L IrI- lr.ItFz 1r%gnUUJ W-Lul r-epetA to rainfall or climate. On the other hand, may LDU's differ little in this 4 woywvQ. * ±~a0jJ~.L. s;lv LU LeJx uUJ i ±s U W - uLE,Ill Ud;:i i LUill4 ' WUdut'Vl balance study1 ! For some aspects exact locations are important, (low-lift pu.ping, flod ing) and inf---- 4-o pe r " been1Du,.e

1.23 The districts-LIIZ: ofU_bL,'1U.l Chbitagong%ll_UutgLllg an,dtLIU ChittagonlgUi. uarUI6 JrvHill l. - LueTracts U. haveI riot been dealt with beacuse they do not belong to the main river basin.

1/ There are three to six districts per region. - 6 -

II. PRESENT WATER REGIME AND CONSTRAINTS 0F FIljuLRE DIVELOPMJENT

A. Present Water Regime

2.01 On an annual basis, more water enters Bangladesh than can ever be used effectively. The average annual surface water inflow from India into Bangladesh is 870 million acre-feet (MAF) and the average annual rainfall in Bangladesh is 203 MAF - a total of 1,073 MAF, (Table 1). The monthly rainfall for various frequencies are given in Tables 2 ana 3. with a gross area of some 35 million acres, the country receives annually about 30 feet of water per acre per year. The average annual evaporation is about Lv5 inches of 132 MAF over the gross area, Thus, 65% of the rain or only a little more than 12% of the total volume of water entering Bangladesh cannot be used for agriculture, and virtually all the rest flows off to the sea. About 20 inches of water are required for land preparation plus evapotranspiration for a boro rice crop and about 15 inches for non-rice winter crops during a five-month crop season. A boro rice crop on the cultivated area of 22 million acres would consume 22 x 10 x (20/12) = 37 MAF and non- rice winter crops would consume 28 MAF, both net of deep percolation- losses.

2.02 This annual picture conceals the important fluctuation in the course of the year. The average rainfall over most of Bangladesh amounts to only 2.5-h.5 inches during November through March (Table 2), which is insufficient to sustain crops. In addition, the flows in the rivers are also significantly reduced during the period of low rainfall. Water supplies are needed between November and May for agricultural, domestic and industrial purposes, for maintaining river depths to allow adequate navigation, to avoid damage to fisheries and to limit inland penetration of sea water. These are conflicting demands and optimal division of scarce winter water among them is the crux of the planning task associated with the "low-flow" problem. Upstream uses have an important effect on water availability and winter water use is therefore an international problem.

B. Upland River Discharges

Ganges River

2.03 The Ganges at Hardinge Bridge drains a catchment of about 360,000 square miles. The average discharge is 29b MAF per year (Table hi). The lowest recorded flow is 42,000 cusecs and the highest about 2.5 million cusecs. The average dry-season flow is about 80,000 cusecs. -7-

BEalmaputra River

2.0h The Brahmaputra drains an area of about 207,000 square miles, of which slightly more than half is in Tibet.

2.05 The average discharge at Bahadurabad is 501 MAF per year (Table 4). The minimum dis charge is 116,000 cusecs and the maximum 2.5 million cusecs. A typical dry-season discharge (January-April) is about 160.000 cusecs though it is frequently as low as 120,000-130,000 cusecs for prolonged periods. Table 4 shows the average monthly discharges in MAF.

Meghna River

2.06 The Meghna River drains the northeastern part of the country, principally the Districts of Syhlet, Mymensingh, Dacca and Comilla. The Meghna River is the smallest of the three great rivers and proportionately more of its cdrainage area is in Bangladesh. It collects water from numerous tributaries flowing from the hills of Assam and Tripura to the north, east and south. Principal tributaries from the right bank are the Kangsa, Someswari, Jadukata, Piyan and Sari-Gowain, Old Brahmaputra and Dhaleswari Rivers. Left bank tributaries of the Surma-Meghna include the Kusiyara, Karangi, Khawai, Sutang, Tista Tumti Rivers.

2.07 Average annual discharges of the Meghna at Bhairab Bazaar (about 75 miles upstream from junction with the Ganges-Padma) is 92 MAF per year (Table 4). This 75-m'ile reach formerly carried most of the Brahmaputra flows and is therefore oversize for the present Meghna discharges.

2.08 The Meghna River drains the Meghna depressions, which has the lowest relative surface elevation in Bangladesh. Consequently, it exhibits well-developed meander patterns and flows on very flat gradients At flood stages the slope of the Meghna downstream of Bhairab Bazaar is only about o.06 feet per mile, reflecting the influence of backwater from the Ganges-Padma.

Annual Hydrographs

2.09 The 1965 and 1966 hydrographs for the Ganges, Brahmaputra and Meghna Rivers are shown in Figures 1 and 2.

2.10 The smooth' lines in the figures represent confidence limits for the various river stages on record for'different times in the year. These curves indicate the minimum water levels at different dates which could be expected at roughly the frequency specified. Curves were determined from historic records at 90%, 50%, and 10% frequencies of exceedence. The 10% exceedence means that the water levels on that curve are exceeded by only 10% of the flows on record for each date indicated. The 10% and 90% lines provide an envelope of exnected water levels. The iagged line superimposed shows actual water level observations during 1965 (Figure 1) and 1966 (Figure 2). - 8 -

Figure 1: Actual waterlevel observations, 1965, and confidence limits from historic records.

52 Ganges River 1 1 48 StaIge Hydrograph l I I

44- F F 1-t7 t4 i9 F 401 1 - F 1-4A4Y' I 1 36 1F IL I' I 34I tI F I- JA I - I 4N

24t 4 - I 141 '[9__ 1~ F

1 J F M A M J J A S O N D HARDINGE BRIDGE 1965 6e[ Brhmnu,t;-a Rvel l r

|[StageHydrogra ph j | I0'/ }siAl 58 1 I I I44 ± P 1 1 1 62StI H rAozira%pI fI7 1 1 1 5461

42~~~V.~:Lj I 90%-T- I F I"4~ 50 1 ______I__ 501 38 { { I-1~ I A4J 4I I 1 1 K-0

J F M A M J J A S N D BAHADURABAD 1965 261 Meghna 1 I T 22|F Stage Hydrograph l l ] 1811 1 1- 1 zi4u2 Ip]

nt'll/I I 101 I I I I"N __

6 I4 I 1 I I I '<4>-

J F M A M J J A S O N D

BHAIRAB BAZAR 1965

Ref: EPIWTA/NEDECO Vol. III B, 1967

World Bank-6814 Figure 2: Actual vvater'evel observations, I'll, an' confience riu~ C. rbU VYtII CV U3 VOI IUa SuS utO ~ litU*,utf limits from historic records.

5 Ganges River f_ 1 _ 1 _ 1 1 1 St-Je Hydrog, aph

______~~~~V __ _ 241 -1/1 <

2i01 J_ 111_ F M A_ M t J_ J% A/~ S J~\O N _D HARDINGE 32IDG 16

2--...K, '11 1 1 1 1 17 J F M A M J J A S O N D HARDINGE BRIDGE 1966

66 Mehna River 2 Stage Hydrograph | i | _-__

8 1 1 1 541 1 loI IA'§J { -

~461 /Tl II

J F M A M J J A S 0 N D BAHADURABAD 1966 Meghna River 4L 1Y0 1 LV 1 90S 1 1`, __ Stage Hydrograph-4•-1_1--III N'.

11Fl__ , T o50%?ld 11 10 LL p~ ______I__I__I__K''v Ref__E!T___ T GO11ol] y!!v8,_1961

J F M A M J J A S 0 N D

BHAIHAB3 B3AZAR 966

Ref: EPIWdTA/NEPfEC.O Vo-l. III R, 19617

World Bank-eel5 - 10 -

RegiUe of M..a,or-. i.±Vers

2.11 Most of' the upland discharges follow the main river systems: Ganges and Brahmaputra flowing together into the Padma and Lower Neghna and tLhen into several branches towards tUhe estuaries.

2.12 Thei"-fl-uence of the major discharges is also felt outside the main river system. Overflows during high stages either inundate the land and are ca-ught in local drarnage rivers or dischaxged through the "disti-' butaries" - generally former branches of the main systems (e.g. the Old Brahmaputra, fhaleswari, Gorai, Arial Knan Rivers and many minor ones), which have silted up at their entrances and are active only during high stages. In some cases the water is fed back into a lower course of the main river system. Other distributaries have their own outlets towards the estuaries. It is noted that overland spills are always small compared to the main system discharges (FAO Flood Measurement Studies 1965-

2.13 Many local drainage rivers discharge into the main river system; among these are major streams (comparatively small when related to the main system) such as the Surama and Kusiyara Rivers, which flow together into the Upper Meghna and also the Tista and Gumti Rivers, all originating from adjoining indian territory. hnese "itributaries'i are obstructed in thelr discharges during high stages of the main river system because of backwater effects which, in several cases, are felt over considerable lengths, especially when, as is usually the case, the slopes along these tributaries are small. Bangladesh has small river slopes (0.3-0.6 feet per mile), and a level of 50 feet above sea level is reached at a few places only.

2.14 Rainfall in Bangladesh has a uniform seasonal character and since this is also true for the Indian catchment areas of the rivers, the discharges are always low in winter and high in summer. This phenomenon returns annually with surprising regularity (see Figure 3 showing the

| | 6 §2'¢ t2!l,-rk.C .,. I Figure 3 piV t.,* A A :civcrs. (The width of the linie gives the are; in which 809% of the hlvXdro-

1 I tt.'.''!.'.'2<;. * >x.Z "a:5Sgraphs durinq thie period

OI occur

v-i,;;lt| / , ,X,/>^Sa'' f Source: EPI-TA/N EADECO ! * 7~"So<1S. ga-v - X Vol. ljIB, 19C7

|V; | ' R /7A

Sti ;V;iRtss,lz J I .} I.1 !|¢in!e; ,) - 11 -

"average" hydrograph over the year and the deviations from this average). The Brah"m,ap, tra m,a=-.,m is nearly always ear'lier 4t- the G-r.ges,.althouh,, the difference is less than a month. The Surma River high precedes that of''the mai"n i;^^ver Q-yster,l.A U-:s-s 4to -b be ^ete--- ecause the Su--.a (-d also the Kusiyara) is a much shorter river and therefore more abrupt in its reaction to the initial st age oUf e rIiajY sesos. 2.15Ancuysisof blXeeffecbsofbhe-uplarddischargesisfacitated~~~~- ' s - s 0e " e c ~ L-J- AnL2"ISLLJ I UJ.jilc ~L1 u I UJ.L2J. UP.LdJ1U Ui uiiaRge1 .LS idUQ±1J(UcUU by their annuLal regularity as the latter makes statistical elaboration

C. Surface Water Increments Within Bangladesh

2 16 In addition to the inflows from India, there are important gails in river ±luw-s ocUcurg in Baniglaudei. A (dI'e.LUl analysis of discharge data from successive stations along the rivers shows that they all gain in a downstrean direction in both the wet and dry seasons. For the latter period this must be the result of regeneration from groundwater.

2.17 To arrive at the dry season gains by area, surface flows metered at selected key locations were combined to cepict total flow inputs to various areas of Bangladesh. Outputs were calculated similarly and compared to input. In this manner additions to flows were calculated by area. The key stations and number of years data available for these calculations are listed in Table 5. The Data was drawn from:

(a) Hydrology Data Complied for Master Plan Vol.I of VII - Climatology, Streamflow Data by I-CO, December 196h.

(b) H;ydrologic Yearbooks of East Pakistan by EPWAPDA for years: (ij 196h-1965 (ii) 1965-1966 (iii) 1966-1967 (iv) 1967-1968

2.18 Lower quartile flows were derived by ranking the mean monthly flows for each year and choosing the lower quartile value.

2.19 Only two years of data were available for five of the 33 key stations. Normally, the results over such a short period would be statistically unreliable. However, the rivers with short records were all virtually dry in the critical months of March and April and thus had no effect on the resulting pattern of surface supplies in these critical months. - 12 -

2.20 The average monthly discharges of the major rivers are su_ma- rized in Table 14and the average monthly inflows to the Gorai and Arial Khan at the ofttakes from the Ganges-Padma River as well as the discharge from the Meglna outlet are given in Table 6.

2.21 The results of the computations for all the months are shown on the attached Plates 1 through 12. Using the same procedure, additional calculations were then carried out to define lower quartile surface flows for March and April, the critical dry months for irrigation supplies. These are presented on Plates 13 and 14 and represent the low-flow conditions occurring annroximately once in four years.

2.22 Tn the following sections emnhasis is on the drv period November to April (occasionally May if the monsoon arrives late) when detailed know1peI-Pe of murfqen flnows i qe_n__(_(

2=2 rThe att2ehd plates for- the period November thrrmch An-ri reveal that during the dry season major inflows from India occur only via the Gan-es and Brahmaputra channels= Minor inflows enter via the Tista, Dhudkumar and Dharla Rivers in the northwest, via the Mohananda in the west and via the urmna-Kushyara channels in the northeast All o+her dry-season inflows are statistically insignificant.

2.24 The incremental streamflows are combined for three major areas - the total northwest region, the combnned districts of WrTmensingh and Sylhet and the district of Dacca. The incremental discharges in the other

_i_.-Mil _niioa l.,if'f'-i - n rl-i movre..asouthenr Fis vri_ h+h_v_. no b. p+C.TfMi" hC. i_ r- _ charge data are available. Monthly groundwater runoff was computed as follows.

Northu,res-t RPei-on

2.25~~IT . e wLreTater lwthe no_h;wres. region south oh Tista River and east of the Mohananda River are effluent into the Jamuna via the Fr-s3gai R-ier and a sm- '1-river to the nn--I-,. n-ce this a receives very little input from India during the dry season, the total flo,-w o-f 4these 4wo river 4s gr--uA-4-- reenraio. le flow f'rom the11se two rivers, which drain about 85% of the area of the northwest region, was

Ude4terminel U -LILL1u. d.LIU.and 4then-U11iI LL£d.TU.------e byUy d3kUOL4.abou_1--1 _L 4toU1,0 ereen 1. localLLJOdt- LLLLLV1runoff- ±for iL the entire northwest region.

Mymensingh and Sylhet Districts

2.26 Groundwater discharge in the combined area of Mymensingh and Sy-lhet has been Ump-uted as the difLerL-nUe be+ween ±irlowa and outflows: inflows coning from India and the Old Brahmaputra, and outflows passing into 3acca LLstrict iL theUleghVa 7Lverat bnanLra DbaLaar, iin the Old Brahmaputra and Lahkya Rivers and in the Bansi River to the west.

Dacca District

2.27 Available flow records are inadequate to determine groundwater discharge in the Dacca District. However, groundwater discharge for this - 13 -

a±suric± is puuuauiy higher t'nan in bthr drier nortnwesu region andL less than in the wetter and more hilly regions of Mymensingh and Sylhet Dis- tricts. Accordingly, groundwater discnarge for Dacca District nas been estimated by applying a monthly unit discharge per square mile of con- tributary area wnich was between the computed values for the nortnwest region and Mymensingh-Sylhet Districts.

Other Districts

2.28 Groundwater discharge in the other more southerly districts will be lower because groundwater fluctuations decrease nearer to the Bay of Bengal. Since computed values of the northern areas are already small during the driest months of March, April and May, it was not considered necessary to compute values for the other districts.

Example for Mymensingh and Sylhet Districts

2.29 Average monthly inflow in November in this area is shown on Plate 12 as b.,000 cusecs through the Old Brahmaputra plus 5,000 plus iL,o0o plus 5,000 plus 5,000 cusecs across the Indian border. Total inflow is therefore 25,000 cusecs. The outflow is 101,000 cusecs at Bhairab Bazaar and 13,000 cusecs through the Old Brahmaputra, Lahkya and Bansi Rivers. Total outflow is therefore 114,000 cusecs. The difference, 114,000 minus 25,000 equals 89,000 cusecs, represents the average gain in surface flow in November within Mymensingh and Sylhet Districts, and is mainly supplied by discharge from the groundwater reservoir.

D. Dry-Season Rainfall and Its Variation

2.30 For the driest months (November through March) there is generally no significant rain in most years. For March, and for some districts also in April, the median (Table 3) is much lower than the average (Table 2), indicating that the rainfall is very irregular and that the farmer cannot depend on it. When considering the variation in rainfall, the need for drv-season irrigation is therefore even more evident than when considering the averages.

E. Groundwater Resources

2.31 Over most of Bangladesh, there are groundwater aquifers which are suitable for pumping (see Chapter 1 and Plate 1 of T.R. 21). There are two major exceptions: the area south of a still undetermined line stretching from Jessore to Comilla towns, where the groundwater is saline, and the eastern and northern hill areas together with closely adjacent piedmont and floodplain land where available evidence indicates that significant groundwater resources are available but their distribution - 14 -

L~j.LL, U4~ * .L11 u UII UVJ ~L4. Ucdlkjlu dAjuiLL.L ~~_ IAiV_Lu L ± L Ly LO eratcU-L l dphtsuabeq.fers appears to -var-y regionall-1y; in general it is less in the north and west than in central, eastern and southernn areas. Groundwater quality is generally satisfacto-y for lrri- gation north of the approximate Jessore-Comilla line, with the possible exceptlon ofLUI Uhe as yeu unLdetemLined effect ofJ 'loca±L±ly high. iron cont,entus on sensitive crops.

2.32 At present, the groundwater reservoir is in dynamic equilibrium on anl annrcual basis, the groum-nwater level reaches or approximates the surface towards the end of the monsoon season. The water table declines in the dxy season on the average by 12 feet to be recharged again during the next monsoon. Rainfall is the principal source of recharge. The annual groundwater depletion is the result of a combination of beneficial evapotranspiration, non-beneficial evaporation and river regeneration. Present data are inadequate for a complete analysis of these components.

2.33 Detailed information on the geology, aquifer characteristics, groundwater quality and annual groundwater recharge is given in Technical Rwoort TJo. 21. F. Tne Tides

2.34 The tides are important in that tidal levels regulate river discharges through the estuaries along the coast, cause saline inundation of the coastal areas during the high tide period of the day, and enable land drainage during the low tide period.

2.35 The tide along the coast originates from the Indian Ocean. It travels very fast through the deep Bay of Bengal and arrives at Hiran Point (also called Jefford Point) and at Cox's Bazaar at the same moment. The line between these two stations is roughly the ten-fathom contour which thus demarcates the end of the deep part of the Bay.

2.36 Particularly in the extensive shallow area in the northeastern corner of the Bay, the tidal range increases due to partial reflections. Further distortion of the tide takes place due to friction (Figure 4). The rising branch of the graph becomes steeper and under some circumstances tidal bores occur.

2.37 The friction forces increase in rivers, resulting finally in the tide dying out. This process may be accelerated by the upland flow. The tidal graphs of Khulna and Chandpur (roughly the same distance to Hiran Point and Sandwip respectively) show clearly the difference between the combined effect of depth and upland flow along the Rupsa/Pusur and Lower Meghna Rivers.

2.38 The tide is predominantly semi-diurnal and only a small daily inequality can be observed. Investigations over a longer period than a day show also a fortnightly and yearly variation. 18 101/ \f, SAND WIP I

6 / \ j||I St ~~~~~~~~~~~1/6\ ct,,OP'UR I j 14 j

1. A /g~ A A Al V \\ / \ r Nj1

2V 7 V / I 21.7 /\ ISLY 2j1Dl \ i \/ 9|w2J1 \ ii?

P.Ao k.0

r.wv:oj ~j ,.SH h'V! ______\______1 3!JF I- \. /4\JR-zTME+9\SP. -~41-1 eej-\je1 -\ G I IW Cqjjj T(JM HJ.RAN P.MKT -

SLW SAhVWY!P XPPisL.N J -;f'

F:igure 4 Examples of tidal curves; springtide March 8, 1966. Reference: NEDECO/EPIWTA Vol. IIIB, 1967

All of theEse observations of the tide's character are consistent with ti2AA theoz-yl/.

S/NEMZEC-0, wth the -z4s+var-- of 4the NeSvherl.an^ Hy.-au liv

Laboratory, has made a harmonic analysis of tidal levels L-n B---.gade-sh.. UaT+er levels of the id. -4 viers h-ave been calculated in relation to reference levels at Hiran POle ndn a CWtagorev. Tla,e res 'sC o- tbALI Vol. axe compiled in a Waterlevel Atlas, NEDECO/EPIWTA, Vol. IIIA, 1967. - 16 -

G. Salt Water Intrusion into Coastal Estuaries

Introduction

2.39 The effects of salt water intrusion have long been recognized as a limiting factor to full development of agriculture in the southern regions of Bangladesh. For the present the Coastal Embankment Program has been undertaken to reduce saline inundation of agricultural lands by direct tidal flooding.

2.40 Future expansion of agriculture requires irrigation development but withdrawals upstream may cause fuirther saline penetration in the coastal estuaries. To study this problem, FAO, among others, have collected salinity and tidal data in the southwest region where the present inland salinity penetration is greatest. However, a more serious situation may develop in the Lower Nleghna where consistent data have not yet been collected.

Available Information and Current Knowledge

2.41 The basic sources of present information on the saline intrusion problem are:

(a) EPWAPDA/IECO Master Plan - Supplement A - Climate and Hydrology, containing limited salinity data collected in 1)bl;

(b) Leedshill DeLeuw - Coastal Embankment Project, Vol. 1, and Office Report on Salinity Study in Coastal Embank- ment Project Area, containing salinity data collected from 1966 to 1968;

(c) Letter report by Haig Zinn and Associates dated May 17, 1967 - giving results of salinity samples at Hajimara drainage regulator site for the Chandpur Project from August 1966 to February 1967;

(d) Unpublished results of observations by the EPWAPDA Hydrology Directorate with initial assistance o,f FAO - containing salinity data collected since 1966-./;

(e) Report on the Analysis of Hydrological Data in the Ganges Tidal Cell, 1968, by T.R.E. Chidley, Raikes and Partners, Consulting Engineers containing a report prepared for FAO using FAO-gathered salinity data. The principal conclusion drawn in this report is that existing data are not sufficiently complete to derive statistical relationships to describe the flows and salinities in the complex channel network;

4/ FAO have prepared a 19-volume report giving results of their initia.1 effnrts whinb has not been nuhliqhed. Onz draft c onv of this set is held by EPWAPDA. Harvard University has a xerox copy of selected data from the set. - 17 -

(f) EPIWTA Survey of Inland Waterways and Ports, July 1967. by NEDECO - which present information on tides, currents and channel depths;

(g) EPWAPDA Data Status Report, Vol. 1, 1970, by Acres International (Overseas) Limited - which describes salinity sampling procedures used by Leedshill DeLeuw and the FAO/FPWAPDA Hvdrolopv Directorate.

2.h2 Data in these reports led to the following findings:

(a)'~ For~ agriculture pu,n.annnn,ose +he .,sal4ne li,ndlf+ it. w defed in relation to the maximum tolerance of rice crops. Tn terms Of thle concentration of dissolvred sollids this was assumed to be a maximum of about 1,300 parts per ,n.11 ona, c to a -r-.amcv,+of4 '2,000 -- ~-I1 - - %.. .I..A .bJJLA, -LA CL AILfCL0"A%a'.- -U JJ micromhos electrical conductivity.

(b) Reported limits of saline intrusion are shown as lines

of± ecq.ualJ s'-.U14ty on map of the coastal. -1- a- see-- Plates 15 and 16.

(d) The limit moves inland as monsoon flood levels recede and is located farthest inland in May/June.

(e) Between April and June, salinity varies with the tidal levels, maximum at high tide, minimum at low tide. This inclicates a relationship of the saline limit to the energy gradient and the importance in this respect of the tidal levels as well as the magnitudes of river discharge.

(f) A clearly defined salt wedge has never been reported. At the coast, salinity near channel bottom may be twice that at-the surface, but at 25 to 30 miles inland, mixing is such that surface and bottom salinities are about the same.

Salinity Problem Areas

2.43 There are three areas with distinct problems:

(a) the Khulna Region;

(b) the Comilla-Noakhali Region or southern portion of the east region; and

2.4h In the first two of these areas, the problems are independent of the magnitude of the discharges in the mnin rivers Tn the third area, the problem is directly related to the combined discharges of the Ganges, BramAnutra. and Mepghna Rivers and to develonments outside BRangladesh whinh may reduce dry season flow in any of them.

2.45 Khulna Region. In the Khulna District, saline penetration with a r-oncentration of 1000 nnm Axtends annroximqtelv 85 milePs inland from the coast. The salinity is somewhat opposed by the fresh water flow in the (1orai_/Madhnmati River and by local inflows via the Kobadak and Nabnnganga Rivers. Depletion of the low flow of the Ganges will have no effect on this arepa herasnse it is not infThen-ed byvriationhv in Ganges discharge at present. The slight movements that do take place in its salinity margins are associated with local runoff nnd monsoon rainfall.

2.1A6 Comnlla-Noaklhali Region.n Tn the Comnlla-NoakhalRegii nr the Bara Khal/Noakhali Khal, the Little Feni River and some other small drainage outletsare subjec+ +o +tril influiences ar.d cslt intrusion. Tn Tt+tIa Feni now has tidal sluices which should be of assistance in keeping saline water oultt of the areao This coastal area is presently inder study bh IECOr

2.147 Barisal District and the Lower.. ehna River. In Barisal District salinity of 1,000 ppm penetrates only about 2- miles inland from the coast. Sanline intrusion is apparently limited by fresh wa+r Tn,inlr frnm. the Lower Meghna via the Bishkhali, Buriswar and Patna- ralochipa distributaries and partly from. the Ga.nges via the Gorai-nkTnaumnti anrd A.4ral Khian distributaries.

Danger from Further Saline Water Intrusion

2.48 Movement of the saline limit during the year in relation to the ang6e in river dischargesv in-dicates- that in- the estuaries A -lnet - s sc' ne water may penetrate further inland if current dry season discharges are reduced signilf4cMnt+ly .and+hne energy gradient Js subst-+nn-4 y lowered. Wiith respect to the latter, however, energy levels in the backwaters of the

4L&da±1 es L,uar ieU i4G11 sn J UGOVI1 GA D ± V6L UI L,J U4.CiS L V'S .U- "onse quently, change in the dry season location of the saline limit is likely to be subs antia on--y as th-IIeresult- ofL major upstrean water wtdaas

. 47 The riost aiVU.Jerab area to fLL Urlter sa0LU iLIItLu.oLvilsL thiIe Lower Meghna outlet and this has not received sufficient attention. A major red-uction iniUute coumbined Udy--ason lo-w of Lhe andraiuiap-u-radle Rivers could have an important effect on the position of the saline wedge in the estuary proper. Also, reduced flows in 'LIe Goral/'iia-un-u-l -i Arial Khan distributaries may contribute to the problem south of Khulna. 2.50 The Lower Meghna itself divides into three principal outlet channels, TentuJa, ShmobbzpuJand H-latia (see Plates 15 n,d 16). Salinity measurements in the Lower Meghna are sparse. However, a n,,m.ber orf monthly obSerTcrationS wrer ta+kLe by conosultnts f,or the Coastal Embankments Project between February 1966 and June 1967 at - 19 -

the locations shown on Plate 186 Table 7 presents values of discharge and salinity from December 1966 to Maay 1967. From the table it is evident that the saline water comes up the Hatia and Shahbazpur channels, which join and progress up the Lower M4eghna River. The Tentulia channel remains relatively salt free. It is not at present known why the salinity at C2 exceeded that at B21 and B22.

'.f1 Th,nI +the d- Jr of Hrch ndi April the onlvy1r C. turi-5a D .. ,*-, .- mnths,-,,. .*-- -_.. - -J-_ - OignJf9nt'2fl fresh-water flow in western Barisal is about 3,000 cfs in the Gorai/

n;raudF.n ui. .*&nce~ thisais a msr r.al fo a;lyi.taa..n is probably near its limit. However, for future development it would appear prudent 4 4 | ba, 4 4n 4-rmo r c+-'tm-,+ ;+tnt," +Qtr Ar +. nt+ VV %-,OI1nSi VW fl.w iWL t orai t.W, M.. Aa _- a t C a limit. Future irrigation from the Gorai may have to be accompanied by 4 specialfaci1444- (A-_-_vesin str ,tu-e aronel i r v--t----r- 4or fltflpit .1A.CL.,.L4.L.LVl.LUOl %%" 4.0.~.AVI OQUL 'VXIA l. t.~- , - - -l,,.IIV.a*.~*i. .a stations) which would increase dry-season flows to more than 3,000 ofs, 4 according 'U0 a rI,ain discharg4 - - frAo4 the a--ai, flows straight into the Bay of Bengal through the Haringhata and other estuarie~s 4.- 4.1_ ___4 or AU _: UU WRlI tl v, vl I M11 UVW ..L.

2.52 It is apparent, however, that the salinity level in the Tentulia channel infltinnre the salinity throughout all the cha-nels south of Barisal since they draw from the Tentulia channel.

2.53 During February and March 1967, when the Lower Meghna discharges, at Chandprlr were near average lo flaw (aut+ 250,000 cfs) 14a 44 viit"inlev of salinity for irrigation equal to 1,200 ppm (or about 1,800 microhoms conductivrity) occ red beta+ ee B 2 &A DB1 4 a. t1he l1 r4. -itof ab e a ,. - t LSS . lS. llA. 4)'.- OJ.A ldn-., 4 UhU~ 4-4-JILt Li W.1 ".oLJ.. V- u.a occurred five to ten miles downstream of the major cross-connection between the Lower I n Ri er -Am M-4-14TeuIa (Table 7).

2 .5h A substantial reduction in low fl4" in the lIgha could cause the limit of salinity to move northward. Change of as much as about 25 miles could result in thle saiiato f the ^tlllengthn of theL Tentulia 1Rivrer and all channels south of the city of Barisal because the tidal inflow in t1hae 4egAha.una could be f--lusheA U .ack.t te-o - -s-v -t-hs- c e . 1~r ,- 1ma.l -0 4 4-A.~a*0A- -- 0I4 0 11-10 -44 -±d n o11D 41W -PI-. 4 2.55 Available data do n.ot perrt estimation of the mIIn.1-,.,. flow in the Lower M4eghna required to prevent salt water penetration into the Tentulia oh- I r - rwD -4 -w ,,1 nl;s+-a ;-4 I n4:A_,_v .a_- 9;ljWa.LL0a 0.. LJ. .I.LJ. UJ. t"l .4.1i X e L-±u±ie 1010.IIL.L-1i fl0O for conJtro± o.0± sa.LL1 intrusion are also dependent on the closure of selected channels. However,

4L LI 4-. %J1 V 10 _L'-V ULIJd.1 d.I~ ±IIVVJLJ I.,dLI. L-UUUULVOJ.A U±Ll..110 II3LI LILLUIL ±-LVW LI-WiL .LLID present level of 250,000 cfs will cause significant saline intrusion problems. A 4full . u - Uttve assess.,ent of U410 L.i.Lt1n Udischge is hLowe-ver not possible at this time. Collection of data which can be used to explain the .3-4.0Wflow COUgLLrLtU.LdL±1crira-n L ar.d sa1saiity "LLLL11 -U±L.LZ±-LUU.LnLVIdisributior. ±1Jn t,LIts U(L1"JJLjJhrll L)ULW~tsulewe UlllupI)I±hnp and Bay of Bengal during a period of minimum flow is therefore a high priority reqU-rem|ent. Detai'led know'ledge of the prototype is required to develop the necessary predictive models. Water consumption in Bangladesh - 20 -

which would decrease the minimrum discharge in the future is discussed in the subsequent sections of this report. Probable withdrawals by Iudla Eue discussed below.

H. Prospects of Flow Reductions due to Developments Outside Bangladesh

Introduction

2.56 WJater withdrawals upstream lead to problems of water shortage and possibly further saline intrusion downstream. This holds true for withdrawals outside Bangladesh as well as for those in the country itself. The Bangladesh withdrawals are discussed extensively in subsequent chapters and must be considered against the background of changes in upland river flows which are, in principle, beyond the control of Bangladesh. For practical purposes, these upland diversions will be influenced by only one countrys India. Both the quantity and the quality of the river flows may change. In trying to assess these changes, it is important not only to consider the short- to medium-term future (say, 1980 or 1985) but also the longer term prospects (say 2000 and beyond). Any water development strategy for Bangladesh must take this factor into account.

Potential Use of Dry-Season Flows of the Ganges

2.57 The Gangetic plains are so vast that India can eventually use all Ganges water profitably for irrigation. This would require several storage reservoirs and is, theretore, a long-term consideration. IIoreover, resulting dry-season flows downstrean might not decrease under those circumstances to the same extent since minimuT return flows from irrigated areas must be allowed so as to maintain a reasonable salt balance within projects. This implies that, in the longer term, Bangladesh will have to seek protection against return flows bearing toxic salts and other chemicals.

2.58 In addition to the use for irrigation, India intends to divert water from the Ganges into the Bhagirathi-Hoogli at the Farraka Barrange to control sllt deposition. This is a prospect for the near future. It is doubtful if this would represent optimuLm use of scarce dry-season water. Nevertheless, irrigation development may be used instead by India to justify a net Ganges withdrawal of L,,000 cfs froa present flows. In the longer term, India can withiout doubt use the full dry-season flow of the Ganges for irrigation and for Farraka diversions. A decision in this regard is, therefore, a matter of policy rather than of technical feasibility. If India were to withdraw the full dry-season flow, there would be two consequences for Bangladesh. In the first place withdrawals from the Ganges above the confluence with the Jamuna would no longer be possible. In the second place, it is likely that salt intrusion in the lower Meghna would increase. If India were to withdraw only part of the water flows, Bangladesh would still have a choice between upstream withdrawal for surface irrigation or use of the water to limit saline intrusion in the lower :Ieghna and along the coast. - 21 -

Potential Use of Dry-Season Flows of the Brahmaputra

2.59 The minimum observed discharge of the Brahmaputra is 116,000 cusiecs 4 (F{o7sebsrur 10 190 atn+ ohr,v,-o^ sho+1-r .-- ~ iO%iA[f_ / *o A~,ron mr+n flows are given in Table 4. The average minimum flow is some 125,000 cfs.

2.60 Assam has a cultivable area of 7.7 million acres of which some 1.5 11pesen'; r -e rigatd. Te po ent-ialy earigb a is stated to be some 4.2 million acres or 2.7 million acres more than at present. VWith the present program, the rate of expansion is only abo-ut 20,000 to 30,_)00 -acres per year but sorae acceleration can be expected because Assam is pressing the Goveimrnment of India for de-velopment f-unds.

2.61 T-he potental for irrigation in Assam is limited by the extent ol suitable land. Furthermore, demand for irrigation is less pressing than in most parts of the subcontinent because tne rainfall is generally favorable for wet-season crop production. In the short term it is unlikely, therefore, that the rate of growtn in irrigation will have a serious effect on the fiows in the main river, but ultimately a net demand of some 40,000 cusecs for drcy- season irrigation might be abstracted in India and this would represent abclut one-third of the present average low flow in the dry season. In the nearer future, it is reasonabie to expect a withdrawal of some 20,000 cusecs.

Tota-l Possib.le F-low Reductions

2.62 From the above discussion, it appears that the ultimate potential for withdrawals by India is around 120,000 cusecs (80,000 from the Ganges and O,000 from the Brahmaputra) or nearly half the flow in the Lower Meghna during the lowest-flow months of February and Miarch. It follows that a settlement with India is needed on the disposition of the dry-season flows of both the Ganges and Brahmaputra. Even with such a settlement, it is to be expected that part of the present river flows into Bangladesh will be withdrawn, but it is impc'ssible to predict how much. Given India's capability to use the scarce winter water advantageously, tnere is little reason to assume that, in the long run, India will stop short of full utilization of the potential. The question then remains how quickly the water would be withdrawn. The capability to divert most of the low-flow Ganges water already exists in India, and the Ganges dry-season inflows can therefore be decreased significantly at this time. The withdrawals from the Brahmaputra would, on the other hand, take several decades to reach their full potential.

I. Present Use of Dry-Season Wgater Resources

2.63 Until the late 1950's irrigation in the area was extremely limited due to lack of efficient methods for lifting water to the fields. The winter season irrigation by traditional methods was limited to low-lying haor areas which are deeply flooded during the monsoon, and are planted as the flood water recedes. The dry season water requirements were met by raising water a few feet only. The area irrigated by these methods amounted to about one million acres located primarily in the Itnyensingh-Sylhet region.

I/ Government of India, 1965 and 1970. - 22 -

2.64 Since 1956 there has been a gradual buildup in mechanical pumping of surface water, primarily by low-lift pumps of two cusec capacity. By 1971, use of these pumps was fully accepted by the farmers, although on the average they were severely underutilized (see Tecnnicai Report No. 18). Very short pumping hours in most cases and the lack of phased operation at many sites resulted in using only a portion of tne available water. However, low-lift pumrp irrigation could expand substantially with gradual improvement of pump use (see Chapter 1V).

2.65 Present installations drawing from surface water include nearly 24,000 low-lift pumps with an an average capacity of two cusecs, the Ganges- Kobadak Project (Kushtia Phases I and !I) with a pumping plant of 3,900 cusecs and the DND project with a pumping capacity of about 300 cusecs. A pumping capacity of l,i35 cusecs has been proposed for the Chandpur project.

2.66 Groundwater developments include one tubewell project in Thakurgaon (364 wells with an average capacity of about 3.5 cusecs), a fairly concentrated development in the Comilla area, and hundreds of ADC irrigation wells scattered over the country. Other tubewell projects are under construction and being prepared.

2.67 The effect on streamflows of surface and groundwater pumping are evaluated in Chapter IV of this report. - 23 -

1 TI . _UTU±RE viATER RWUIR1 IJT1T

A. Introduction

3.01 water supplies and controls are required for the following purposes:

(1) Agriculture (2) Control of salt-water intrusion from Bay of Bengal (3) Navigation and other rural uses of surface water (4) Fisheries (5) Municipal, domestic and industrial supplies

3.02 Large volumes of water are required for the irrigation of crops in the non-monsoon season and for control of salt-water intrusion. Requirements for navigation are maintenance of minimum water depths and widths in streams used for that purpose. The requiremients for flEheries and municipal, domestic and industrial supplies, while significant, are smaller and less concentrated by area than for either irrigation or control of salt-water intrusion.

3.03 The aggregate demands for the various purposes must be met over time and space from rainfall, surface water or groundwater. The time distribution of rainfall and surface water poses problems because of the huge excess of water during the monsoon and lack of rainfall and surface water during winte- and spring. Surface storage potentials are virtually nil. The only significant storage reservoir is the groundater aquifer which is thus far virtually untapped.

3.04 This chapter deals principally with irrigation water requirements. The control of salt-water intrusion is treated in Chapter VI of this report. Navigation, domestic and industrial uses are discussed briefly below.

Navigation and Other Rural Uses of Surface Water

3.05 Maximum withdrawal of water for irrigation will only occur during the months of March and April. Moreover, pumping from any river will not affect the river equally over its whole length; the adverse effects being experienced only in the downstream reaches while the upstream sections will remain relatively unaffected. Also, even in the months with peak requirements, pumping does not take place 24 hours per day. In lieu of a detailed survey of current and future demands for surface water, it has been assumed that up to a maximum of 60% of the lower quartile flow may be pumped from the rivers without adverse effects on navigation and other rural uses of surface water. The net withdrawal will actually be less as a certain amount of water will inevitably return to the river as surface runoff and through groundwater regeneration. Furthermore, the 60% restriction is important only in the small perennial rivers and the water levels in the major rivers will not be affected sianificantly by the low- lift pumping from minor streams. - 24 -

Fisheries

3.06 The most pronounced effects of low-lift pumping on river water levels and flows will occur in the small perennial rivers. Migratory movements of fish between spawning grounds and the major river and the environment in which the fish spawn are likely to be adversely affected only by major water schemes. The environmental effects of major schemes should be investigated case by ease in terms of the tvTne of structures proposed, the location and nature of the waterways, and the proposed pro- visionns for a11eviatina dietrimental efeets of the nronosed works.

Mnni oninl and Tnrlns1+-rinI Sinnl i sq

3=07 At present these reqmirements are generallv met hv grouindwater pumping and numerous tubewells are already supplying these needs. 1/ Water spmply nrohlems cio eiist. however, nartirnilarlv in the-coastal areas where fresh water generally occurs both at very shallow depths -- up to 70 to 80 feet. (so-calledl (rhvhPn TebPr7.g lehPsra - which mnakes nqf of high-nnnrcitv tubewells impossible and at great depth -- below 700 feet. In this connection it is of interest, to note that T.WApDA consqi dered inst-.1ing 2, desain- ization plant at Khulna for municipal and industrial supply. Requirements of fut1ure indHstri21 development should he carefullv acountedl for in nlanning allocations of the surface and groundwater resources.

B. Water Requirements for Irrigation

3.08 Irrigation requirements,of a crop are deterrnined by the following

4 4 (1 \ o,Jrnn+rn on rn -In;n o f r . rnnc (2) effective precipitation (3) preplanting requ7irem.ents and soil moisture depletion (a) efficiency of the irrigation system

(1) is determined both by the climate and the crop; (2) depends on rainfall, infl1tra-tion ratlue ofL soil andd bun'd heUlght;U (3 ees nco ndsi LLIJJ~L~.U~ ]. S±. UJJiJJJ~L .L1' UUIN.LiJA.~,lU~ \) I ~ Jc,I'A OIl 0].-UU[ 0AUQU±± moisture conditions, and (4) is determined by evaporation and soil losses

.L ii eUi1 .LL U].rJALLULJIIJ 0-I1O.LUIUL'JD 0.11'] U,) U 0~A,O _L VU' WCL U'z:] CLP1 CdU1OLI.

IlUi llD U 1dA t O iVl U] 01 UU: 3.9Evapotranspirationof Crrp sclcitd ymutplsn

) .O7 L£vaotransd~piratiLon I0±0 Ui1J P~ _LZ ~.UCL.LU-L0.UZU VY L1Ui_U_LJI Y ILIg a a potential evaporation index by a crop growth stage factor. Mean monthly evaporat i on 4lndi4ces were ea'lulated 1- 4the -olf4ieP enn method- -4.U_1 fo. - number of representative stations in Bangladesh.

1/ See inset map on distribution of tubewells and low-lift pumps by district on Map III - TTyuiuogy of the Anal-ybcal Map- Series. - 25 -

3.10 For the purpose of this study the results have been compared with the figures calculated according to the U.S. Weather Bureau (USWITB) method as presented inthe Harvard Progress Report of 1968. This comparison shows that the modified Penman formula results in consistently higher figures for crop consumptive use.

3.11 Evaporation indices calculated according to USWB method are available for three stations (Dacca, Pabna and Rangnur). On the basis of the consistently lower figures obtained by the USWB method it was decided to use the higher evaporation indices but with a reduction of 15 (Table 8), 1/

3.12 The evapotranspiration of crops can be calculated bv multiplying the potential evaporation indices of the growing season by appropriate crop growth stage factors (Table 9).

3.13 Evapotranspiration has been calculated for all crops. As is to be expected,, the evapotranspiration for the various types of rice in one particular month does not differ much. The same is true for the non-rice winter crops. Therefore, they have been grouped together. The evapotran- sDiration for both non-rice and rice croDs is nresented in Tables 10 through 14. 3.14 Table 10 gives the evapotranspiration of non-rice winter crops. The lo-w evapotranspiration renuirements for non-rice winter crops are reflected in the results obtained at the Amla experimental farm of the Ganges-Kohadak projeet. There the henefits for irrigation, 13nder prevailirng methods and waterlogged conditions, are often negative.

3.15 Table 11, giving the evapotranspiration of rice, is useful for the calculation of rire water recuirements in regions and districts. However, the table does not give any information about the evapotranspiration of a snecific rice cron. The total evapotranspiration of average boro. aus and aman crops has, therefore, been included as Table 12.

3.16 Tables 13 and 1 give the monthly evapotranspiration of jute and sugarcane, resnectivel-y.

1/ For a better understanding of the figures of Table 8 it is noted that the Penman evanoration index repnreents th-e ev2noration of a hypothetical infinitely thin, layer of water of unlimited extent. This equals approx- imatplv th. evanotransniration of short mit crnsR, vieorn1olv growing nnri well supplied with water. In the modified Penman formula a number of emnirical constants are used which generally have heehn determined in temperate regions. The USW^B and the US Geological Survey (USGS) have determined these ePmniric-l c-onqtantsz in field stdies at TLake Hefner and Lake Mead and developed equations for calculating "Shallow Lake Evaporation." in-ifferences these ncnstants car ily lead to an over-estimat'in of 15,. Comparison with the USWB method suggests that this is the case and hence a flat reduction of 15/ has been a-plied. Effective Precipitation

3.17 To calculate the net crop-water requirements, effective precipitation has to be deducted from the evapotranspiration. A reliable estimate of effective precipitation can only be made on the basis of a soil moisture balance study, for specific areas, taking into consideration daily rainfall and evapotranspiration, soil moisture retention for non-rice fields, infiltration capacity and field storage for rice fields. Such a study would divide the rainfall into surface runoff, evapotranspiration and deep percolation to goundwater. This type of study also should account for the different durations and intensities of rainfall at selected frequencies and at different times of the year. Different rates of runoff, groundwater recharge, and effective rainfall should be determined for each month or two- week period.

3.18 In the absence of such a soil moisture balance study the following criteria will be used for surface runoff from agricultural lands:

(1) In the months of May through October the minimum surface runoff is 20% of the rainfall, i.e., 80% of the monthly rainfall is available for monthly consumptive use plus infiltration losses from bunded plots with transplanted paddy.

(2) In the months of November through April no surface runoff occurs.

3.19 The irrigation requirements and infiltration can be calculated on the basis of these assumptions. Except for minor interception, this nart of the rainfall can be 100% effected for ponded rice fields on soils with an infiltration rate over 0.01 inches per hour in areas with a groundwater table below land surface.

3 20 The rates of effective precipitation selected above are based on estimates of probable runoff and recharge for Jessore and Bogra made at Harvsrd in 1968 and on insoftion ofre x year ofr daily rainfall fdrom nine other stations. The 1968 estimates are based on a synthetic daily rainfall distribution construnted from informntion pnublilhed in the TEGO/ WAPDA Master Plan 1964. The accuracy of that information is limited by the short period of daily records avala2ble. The criteria were selected taking into consideration, to the extent possible, the effect from occasional high intensity rainfti on,d storage efentpss of bu,ingnearound the fields. In general, with bunding, lower loss percentages occur, particularly for low rainfals.Q Thp ePff+ctivP nrecpint+.a.n in ;ing +.hp abnovp +.trw crit+.pria is griven in Table 15 for average monthly rainfall amounts. 1/

1/ The average rainfall figures used for this analysis are from the Draft Guideline, Rainfall Analysis, East Pakistan, by ACRES International (Overseas), Limited, in association with H.G. Acres, Limited, Interna- tional Land Development Consultants, N.V., and Booz, Allen and Hamilton International, Inc., February 1971. These are included in Technical Report No. 23 in addition to the rainfall probability analysis of weekly totals. The 35 years of daily rainfall records for nine stations in Bangladesh, which were used in the detailed probability analysis of weekly totals, were only available subsequent to the work in this section. - 27 -

3.21 For non-ponded irrigated fields, an effective precipitation of only OU6 is used for calc-ulating Err±gaU±on r-eq-uiree. ThWere -I-iL- 4l-±ys be fields which have been irrigated just before a storm and where part of the effective precipitation percolates to the groundwater and another part is lost by non-beneficial evapotranspiration. Therefore, the assumption is made that only 60% oI the precipitation is avaiiabie for meeting tne evapotranspiration requirements of other crops than rice.

3.22 The above assumptions regarding effective precipitation provide a basis for calculating average irrigation requirements and for water balance calculations. Average rainfall figures are used for the water balance. For design purposes, lower quartile rainfall conditions could be considered.

Other Factors Determining Irrigation Requirements

3.23 TWater is required for preplanting, some of which can be recovered from soil moisture at the end of the preceding cropping season.

3.24 water losses occur throughout the whole irrigation system and it is convenient to group them into three categories:

- water losses on the field (or farm); - water losses in the field channels (generally serving 50 to 100 acres); - water losses in the main conveyance system.

Preplan-ting Requirements and Soil Moisture Depletion

3.25 Prenlanting water is required to bring the soil to suitable moisture condition for seedbed preparation or for transplanting of rice. Preplanting water is required some two to three weeks before transplanting.

3.26 For crops other than rice a prewatering of three inches is required. For transplanted rice, more water is needed and this requirement may well constitute the peak water requirement. Taking into consideration that not all fields will be absolutely dry and that fields will be nroperly levelled in the future, preplanting requirements are estimated to be five inches.

3.27 Thie preplanting water applied at the beginning of the growing season can be depleted at the end of the growing season if allowance is made for some losses during the preplanting period. Therefore, some two inches for other crops than rice and some four inches for rice may be deducted from the evapotranspiration requirements in the last month of the growing season. - 2b -

Water Losses on Rice Fields

3.28 For transplanted rice with ponded field plots a continuous infiltration loss must be taken into consideration. Present field methods for transplanted rice are very different from those for broadcast rice and crops other than rice.

3.29 Infiltration losses from paddy fields with ponded water depend mainly on the infiltration rate of the soil. These losses occur throughout the cropping season in tubewell projects. However, in polder-type nrniects the Prcundwater table mav reach land surface earlv in the irrigation season. Field infiltration losses are then determined by the groundwater drainage characteristics of the area and the losses will be low.

3=30 With water table levels helow ground surface and even with low infiltration rates (say five to seven inches per month) the total loss to infilt.rat.inn amouints. tn a ;ignificant amount. of water These losses lead to high volumes of pumped water per crop if paddy fields are ponded permanently. In the case of tubewell irrigation the water table is kept below ground surface and pumping costs can become very high because the water volume pumped is determined by the infiltration rate rather than cron water reouirements. For that reason it will be assumed that paddy fields will have only inter- mittent ponding, allowing soil mnoistire depletion between irrigation annlica- tions, on all, lands with infiltration rates exceeding five inches per month. For these soils. irrigation losses are taken into account in the field efficiency which is taken to be 50% for rice. The latter is a rather low fimrp anri caqn 'h nnhipvpd wit.h -rPlat.iuPlv poorT ir-rgiat.ion mqnamn. practices.

Field Losses on Da-landCpields

3.31 Field losses for dry-land crop fields are taken into account by di_iin ne r iituse hir +bhe, fieldirrigation efficiency. Most dry-land crops will be growTn in small basins and a rather high field efficiency may be expected; therefore, the *ultimate field efficiency has been estimated at 75%.

3.32 Initially, due to lack of irrigation experience, field efficiency

VV4...L.L;11J beVUS -lessWtS03 -- perlFED a Ml(Os 0C 1Tow|LV; Jt W0V| 6 Unq ThQ_ a.vSCaVQS-4--o kitWis tSZAtSV UtS _t+Ot;^r;V1t LULSA1 1.L S.t UA use of irrigation waterin the initial period are accounted for inthe ,rield pr,ojections and a slo,rs expansion rate of t-he irrigated acreaAge.

3.a 'A lo,Tler aield effi ci ency 4.ehia 'iia stages of irrigation development can be taken care of by using a high number of operating hours for the pu.A.Ips .

I^T_4t__ Tosses Jn Fie-ld Channlels I . U. O ALL I LL .LUQO

3 9L~ AL.I J.rrigatLIon wateIr I 3lAUJi UimLI Ue U UIIhe 11head.L o lt field cAhar,el (which equal the requirements at a tubewelle or low-lift pump) are calculated uy adding losses inlthe field channel to the fIeld requirl-ents. - 29 -

3.35 Losses in the field channels depend on soil type and to some extent on the depth of the groundwater table. An allowance for operational waste is generally added but this amount will be low with tubewells and low-lift pumps because the service area is very small and the equipment can be shut down immediately if there is no demand. Total losses in field channels are estimated at 10% in areas with a high groundwater table and at 15% in areas with a low groundwater table. These figures apply for average soil conditions. However, taking into account the relatively small amounts of water involved, and the inaccuracies in other assumptions, a flat rate of 15% field channel losses is used.

Irrigation Water Requirements for Five Districts

Assumptions

3.36 For the purpose of calculating irrigation water requirements two different cropping patterns have been selecteds one 90% transplant boro 10% transplant aus (Table 16); the other 15% transplant boro, 60% transplant aus (Table 17). An effort was made to maintain a high level of land utilization and to maintain a high rice content (190% and 165% crop intensity. respectivelv). On the basis of the crop water reauirements and assumptions regarding losses, discussed above, irrigation requirements were nrenared for each cropping pattern for each of the five distrints of!

romilla East Region Khulna Southwest Region Mvmensingh. flentral 1ReFion Rangpur, Northwest Region Sylhet3 East Region

Requirements for riGe ernps were dterminpfi undieor +h. hre ±.o-nat.iv assumptions below:

A - an infiltration loss from paddy fields of three inches per month

B - a. infiiltration loss from paddy fields of five inches per month

C - an irrigation loss from paddy fields of CUn(l-r 9Kal n f' hoi Pi nl Ai , ;

Di scussc Sionr of Re sults

3.3-47 Minn cluai n9are - ilnusre, for- Csl-la n 4itich1s- e of Tables 18 and 19; series number 18 corresponding to the 90% transplant borno cropp--ng patterr., s-Meris r.ur.ber '190----coresondr. 4to 4the 15% 4transplar.t boro pattern. Calculations of water requirements for the rice portion of th_e Cropping patterns, ea-1culae- epratl; u.der-- 4the 4hre ss,___on 511 .. .iF9jJ.SL F ~ LUJM , _L .LQ.L,UU VC1 VL. U±IUU.L- I.,ii U.ivt0 d.00UIAPdU_LU"i~ above are shown in Tables 18A, 18B, 18C, 19A, 19B and 19C. Note that in the C tables the effective rainfall is taken to be 60% of the a-verage. Requirements for the non-rice areas under each cropping pattern were determined as shown in Tables 18 D and lyv, and trhe aggregate requirements for the complete cropping patterns are shown at the bottom of the same tables. - 30 -

3.38 The requirements for all five districts under each assumption

for eachIIc pp±1i6ngJ±r1o paa4t.te± 04.aare g-iVeV.Un in T0.ables. 230A throuS 11 4. Ta0ls 20 through 22 show requirements for the rice crops only, Tables 23 and 24

sults shows the effects on irrigation requirements of the cropping pat-

different locations.

3.39 The peak water requirements occur always in March in these cropping patterns and are highest for the pattern -with 90% boro. Comlparing the alternative calculations for rice, the requirements are lowest with lthe luwesUt Ihult l .U1L,LUoss VI lthree Linchets:6 pr Uday- (IalUe 2U) culu Lthe highest peak occurs with a field efficiency of 50% (11.6 inches in March for the Khuln-a Dilstrict, Table 22) . However, the aninual requirement is highest with an infiltration loss of 5 inches per day (53.5 inches per year again for the K'ulna DistricCt, Table 21). Comnparisonl wk Taules 20 ald 21 shows the strong effect of the infiltration rate on both mcnthly and annual rice water requirernents. In fact with infiltrabion rates of five or more inches per month the water requirements are dominated by the infiltration rate rather than crop water requirements. This leads to Lhe conclusion that, as soil permeabilities increase, it becomes expensive to maintain permanent ponds on paddy fields unless hne groundwater level is kept at the surface. It will still be possible, however, to grow rice economically on these soils if the rice is irrigated like any other crop allowing soil moisture depletion between irrigation intervals. This is technically quite feasible and is done in many areas (e.g. Japan, the Philippines and Louisiana).

3.140U The effect of rainfall is reflected in the differences between Districts (low requirements for Sylhet and high ones for Khulna, for both the peaks in March and the annual totals) and also between the March and April requirements, there being more rain in April. The April requirements for 15% boro are higher than for 90% boro because transplant aus is high (60%) in the latter cropping pattern.

3.41 The water requirements for the total cropping patterns, for rice plus non-rice crops, are given in Tables 23 and 24. The winter requirements are significantly lower for the 15% boro cropping pattern but the March requirements are still substantial for the latter because 20% of the commanded area already has a growing aus crop. 30% of the area is being prepared for aus, and jute is growing on 20%. The March peakc is again highest with the assumed field efficiency for rice of 50% (11.6 inches in the Khulna District. Table 24).

3.42 All these calculations imply a substantial amount of groundwater recharge which in the case of tubewell irrigation is merely recirculation of pumped water. These and other irrigation losses are dealt with in the following paragraphs. Water Losses Associated with Irrigation

3.43 Crop water and irrigation requirements are set out in the preceding section. These requirements incl-ude losses duue to non-beneficia evapotranspiration, operation waste and deep percolation. However, some of this water will reappear as return flow in thte naUUrUil rdrinage Lichannels and rivers when low-lift pumps are used for irrigation, or as recirculated water in the case of tubewells. Both the potential retuurn flow anu recirculated water are quantified below.

Assumptions and Calculations

3.44 The- irrigation water requirements at the head of the field ILILaevls are Jsu1TUrrs1ri;au in TbLues 2u tlhruugn 44. Tne cropping patterns on which these calculations are based imply high intensities for rice. The following luosse have been ±included in thIne calculations.

- an infiltration loss from paddy fields of three inches per month or alternatively, a field efficiency of 50% is used of whicn

20% is non-beneficial evapotranspiration 60% is groundwater recharge 20% is not allocated l/

- a farm irrigation loss from non-paddy fields of 25% of the field diversion of which:

20% is non-beneficial evapotranspiration 20% is surface runoff 60% is percolation loss

- field channel losses amounting to 15% of the field channel diversion of which

30% is non-beneficial evapotranspiration 70% is seepage losses

3.45 Losses to groundwater are the principal source of return flow to the rivers with low-lift pumps and of recirculation in the case of tubewells. Surface runoff of irrigation water is comparatively very small and is therefore excluded from the calculations.

3.46 Calculations of losses to groundwater for the Comilla District are shown in Tables 25 and 26 and the results for the five districts are summarized in Tables 29 and 30, with paddy fields having a monthly infiltration loss of three inches or a field efficiency of 50% respectively.

1/ Elsewhere in this report this amount has been allocated to surface runcff. This is not valid for large contiguous blocks of irrigated rice. In addition, the distribution of the irrigation losses between groundwater recharge and non-beneficial evaporation is not constant. With the above assumptions it follows that a recharge of either 1.8 or 2.4 inches can result from three inches of infiltration. - 32 -

1. '7 Tb _'n- ,-wj L*4 T he ~non=beneficlale -N -&1n nr' -,n+ i I f'v'-jr n ~~ Ii ori ~i -' mn +A r water are calculated for the Comilla District in Tables 27 and 28 and the result4s for t-he Iflvet Jst.riict s are sjm-Iumized in Tables 31 and 32, L -- l ing a monthly infiltration loss of three inches and a field efficiency of

Cvra. cos u 'I a- e-t- T Se

Tabl 29 shows 4tlt4 4the 'osse to gonwtragefmalow 9 .L4U 3.l8~~~~~~~14.d.J - 7 O.l1W ULU uU11 ll ~ O~.0L0!V. A-- ~. ±44 110 of 24% of the monthly application, or 1.1 inches of water in February and 0.1Lf,4 1, 0±a high5ld)14Q ofor0.e 1.67.1- .1 -nches.. 17 I~ of04. waterW0l11 4n±1 A---ilL. in C,4il'at11L)LL.L. wit-41,±UI±20 borof1_L0 and assuming a constant infiltration loss of three inches from irrigated r4ice fields. LIor 90a b-oro 4these losses var-y fror, a low of 31Ic; or 2.4. 4.±U 4±Lt.1..L 104 ;7U0,0 001 U1~I~i V.4zy 4.111 _L0 01 J/0 c1-.L inches in February and a high of 52% or 1.24 inches in April, again both in ComllIa. IlThICLrLi II.ibU0hlLgt i0no peiueI talgel -"I rinJ1U± re lecL Utll effect of increased rainfall in that month -- it is implicit in the calcula- 4. Z ..... 4r. 4-- L1 2Z. Z I2 A4. .2 - 1…L - .. 4..L 4... 2 _...... 4.2 UtLlons Uthat ith iniltratioUnUI losses arC dL,I...U0-ea U,rjd0IUCle oi-)iIgd on ratULer than to combined irrigation application plus rainfall. The results given 4,...-. 'T,m..t.~ .. j j - r~ -, j D 2 _.2 - - - .1 r -0jc I, - l- .. 4. - -. 2 _ _ _ -.. -- ,- TabLe±. 3AC Wit14h a fleld efL±ficiencly of 5)U' LeadUs to a iiaXL-TiUIfL grounLdwauter water loss of 36% of the monthly irrigation application, a percentage which occ -rs frequently in the 90) boro pattern*. The lowesbt value is 22_ in February in Corilla for the 15% boro pattern.

3.h9 Tables 31 and 32 show that the calculated losses to non-beneficial evaporation -vary between 9 and _-1±Y,-eO aniu- betwen 1.4, I~~~~1, to - 0.55-x r'I~ inches, per month. The variations in percentage are again related to rainfall occurrence and monthly pump raquirem3nt.

3.50 These numbers will be discussed ferther in subsequent sections.

Area Served by a Singie Two-Cusec Unit

3.51 For both tubewelis and low-lift pumps a standard capacity of two-cusecs has been accepted for the purpose of this study. The area to be irrigated by a pump depends then only on the peak requirements and the daily operating hours during the peak demand period.

3.52 The effect of the daily operating hours on the area served is shown in Table 33 which has been prepared on the following basis:

2 cusecs = 2 acre inches per hour = 2 t acre inches per day = 60 t acre inches per month where t = daily operating hours

3.53 The area served is 60 t/D acres if the monthly peak requirement at the pumping unit is D acre inch per acre of the area served. - 33 -

3.54 Table 33 illustrates, for instance., that for a tubewell having a peak requirement of twelve inches per month and an irrigated area of 80 acres, an average daily operating time of 16 hours is required. For a low-lift pump serving 50 acres with a peak requirement of ten inches per month, an average daily operating time of approximately eight hours is required. Longer operating hours would enable larger areas to be served by each unit. - 34 -

IV. POTENTIAL FOR SURFACE WATER USE

A . Tn+roduc+ti non awnd Suma-mary

4.01 The lt4 +ate scope for irrigetione from. surface resou^rces is determined by the fraction of the critical flows which can be abstracted for agr culture pI the - - of hours the f------is abstracted to the fields, and the amount of suitable land which can be

*aoo*~~~~~~~~~~~~~A _ the ;+ffi ,ol a,w,mol_w4A was-- - ahal^y.v -v - - -w w- - ~t4>_-vvv^_v ; .,__v 9te atT 1r9P - 4 abstraction future irrigation development will be increasing the period4 of and,ar.d +W>t+kn+ 4,,4r. +1-,4tfls. r"n- _pe_t - sin..if_n..t,,4-,..4 4'4 a+ poter. l fry epnio-- r-, ~rPoft,+w+ 1-l--lift ^wLTl 4 P+ irrigation exists in addition to the potential remaining from unexploited sources ofPI-_a t e r an, n fl fl 7,0 fl- e e

4.o2c£4 .U~ PotentEa.UE J /LL I.LC6.L. .J.-.LrJ.i|4gabe L A .areas O.UJVVabv- %ALV FL9I i1u4prse.t salir.eLO.LLUL J.LJJIJ.J14-.t,- Includ-LA AW, ing areas presently irrigated from rivers and tidal backwaters, assuming 60% of the lower quartile flows available for irrigation, are shown below for various periods of abstraction for the four regions:

(i) Under Small-scale Schemes: (Restricted to suitable land within only 9,^0%j le17.- of availa-b-le -LVIer f-lows zr.dfres SUidal4, baclzters )

n7v.'J1j.ull~ U.J IV .LL-1 .ly J.L LL.L-/JIW- 1J-L ± LLI-/ 4 f- III .

Regiorl~~~~~~~~~~~~~~~- /J Qp 1-A_-A 1A Xol. _. TOOO AC) (000 A0AAjc) c (000

Northwest 60 85 100 110

East 470 840 900 945 -otws 905l 1,40 1,800_ 1,990'

m _ Ltk L v n IorRZArZ- rr, n I onr Totdal l,e26) 2o 3,l)1U ,)4v:

(ii) 'Under Schemes with Major 'works: (Restricted to suitable land within 5,000 acres per mile of available flows and fresh tidal waters and including the land estimated for small-scale schemes.

A ., n_. . . . . I Region o nr/aay 1Z nr/aa lo nrr/laay eLrl CaLy (000 (000 Ac) |000 Ac)

Northwest 375 395 425 445 Central 840 905 980 1,030 East 1,275 1,540 1,685 1,820 Southwest 1,925 2,015 2,080 2,130

Total 4,415 4,855 5,170 5,425

4.03 At present, the pump group average period of irrigation is about 6 hours per day 1/. Longer periods of abstraction would not necessarily require greater efficiency of pump use, but could be achieved simply by

1/ EPADC, Evaluation of the Thana Irrigation Program in East Pakistan (1968-69). PARD, November 1969. sagered _e:ra+ion of seeral 'mns draving fwrhm +!h, cza sun'r l-w And hy

rotating duty for single units (see Technical Report No. 18). The effect ^ould1be a much 1-5a-e slppyw5 of wate available at _he fiedaa1 nd, at the same time, the analysis shows a reduced requirement at the rivers in te_Ms of cu.bic feet per se.cdA A4.,n+aAe (- T.^nf+%tf -he ef4'4 e% eof puMp use also increases it would result in a lower density of pumps installed ar. d 3 L .Ldi'L .L LA per acreVUoL U %riOvo

4. x'iI. of-. 41.-. -44.o. for 4at r.4 -e 4 orosn 4i..the SvC,.4-hwes+ 94 * w14 .A.JJtilt YJ. L AO P IJ=1AV L .L V.IL _.LJ. A. L LL%'JU Wi CA~4L.L,JA LAL ULAV "JJ "Uxa&w v Region is qualified by the possibility that saline water may intrude further -?-'I r d as the resu't-9 of Ji-4 lga-9- i-n d veo5^nt upS-r,.^dicse below, the change in the dry season location of the limit as the result of

A ._ iJgaiJ LIU..Ld.Wd.Ls ls'deer d'WIWlg no MZ2JV± diver-siosUg.lanO, ut-- side of the country, probably would not exceed the maximum seasonal movement resu.liting ± rom bthUe eextUreMe v4-r-ia"OL n El1.ver U.cULMrgei dUUandn.L-gy gradient between monsoon flooding and low dry season flows. The new location *_- LL _ 2__ _'______-. na 4___-__ _L._*1_**_L_eT _L_L .LI iUne DUriLUd.L a drEd WUU.LU fJJJt .Ly- Ut Iljdr rUL U4flIG.L±x* b15U v V. DcAl'.d.s I J I7._U. LV the locations would change little The potential for expansion of surface A~~~ -A-___ ...... J . wate-r ir -rigatvion and the alffuct of increased witLdrawals onvthe potUeia.Ul( expansion in the Southwest Region are estimated in the sections which follow. 4.05 Irrigation from surface water in Bangladesh is limited by flow inI the critical dry months of March and April and part of the IlDow must be reserved for other purposes: navigation, domestic use and, ultimately, containing furtner saline water intrusion in the coastal estuaries. Never- theless, assuming roughly 60% available for agriculture, the supply in total would be enougn to irrigate boro rice on nearly half the agriculture land in the country and is more than could be distributed effectively. 4.o6 Water in the critical months is supplied from perennial flows, regeneration from groundwater, and residual floodwaters in undrained basins, and is found in rivers, tidal channels and the static basins of the Bils and Haors. The static supply could not be assessed from information available for this report and, consequently, only potential irrigation from surface f-lows and tidal backwaters is estimated below. However, a large portion oif the static bodiies are in the Haors areas where irrigation practices have tie longest histor:y and power pump irrigation expanded most rapidly. Therefore, the scope for irrigation from Bils and other static water bodies may already have been substantially achieved. Although these resources could not be assessed here, however, they should be included in future government surveys.

4h0 7 The study reported here draws on the estimate of available surface water in Annex 9 of the 1968/69 Bank Report on the EPADC Low Lift Pump Program (see report Ps-2a, Vol.III) and on topographic and land capability information in the FAQ Reconnaissance Soil Survey (see Technical Report No 2). It makes the same assumptions as the earlier Bank report regarding the fraction of the supply available for agriculture (60%) and regarding, for small-scale schemes, the abstraction rate per mile of channel (no more than 10 cusecs capacity installed at the fields per mile of channel bank -- equivalent to five 2-cusec pumps per mile. These assumptions are in lieu of information which is not available; the values are conservative, particularly the limitation of 10 cusecs per mile, with the aim for planning purposes to underestimate, rather than overestimate, the potential for small- scale irrigat:Lon. - 36 -

the full potential possible under improved utilization of the available water nppI. ThP%e anrlier A eport >i,h asi >n a onl fiv4 we 50=ar.e si+ a pner vnl of bank, implied a maximum period of abstraction of only about 8 hours per 4 4 4 djAn.r and3,n"v.A ir4,. e0 ' n-+t, ,.44,+4a.i ti.. - ' ^"Iiw-ofl. ano-+h4A -_ - .a+ -_J.o^l' the4-ho-JA&%J ,.y.+a . ncnvo avail-nn41 able for irrigation. This study for purposes of future planning assumes, Iaorg 4W "1 -- P 4------A 4 . -,- ai.,;ga+404 ance A grea+er- ian+0 use, a somewhat larger average distance (9A10 mile; the earlier Bank report

--sAe 3~,./_ ,ML" ml)-4 .L J.V LOUe-% VUWVAL e. 4ALVh A ,h.reLaMU b^-sar.W-ALLX%U -J41-A +'keW .- 1imi+sJ.JSLL U ofP~ L+1e VJUL~ s.-lscle kDC type of irrigation scheme 1/. This limitation only constrains those ,si-'---es fPor over about hurs of4bstacuon (dependir. on 4-be proportion 3s.7~uJ.u. v .'. L J QLJVIULt1.4" 1 LI¶Vurs ofU. abst, IJ±Q;U.LVi1 IL~V~J.LLJ UIA~ Fp J.LkJWLJU.LJ1 of the land within the limit which is suitable for irrigation -- 14 hours corresponds to T% of theU .LlLnU sU_L e);j Wthe 3R/4 m1il ;imitXLU woudA UbUVecoL a cULo- straint over about 12 hours abstraction. Finally, this analysis assumes a some- -whsat lar-ger- area in the Southwest Region would be accessible to tidal back-aters than the 1968/69 analysis. The earlier analysis assumed 1,150 miles of tidal channlel after reducing th e meas-ured Imileage by about 50% wo exclude cIhaInel extremities. Also, it assumed the saline limit to be farther inland than _~~~~__ ___ 1 z____ _1_ I ______-- J rs _ _ t __- nz OL L n_ _ - rt _ - . L- _ L reported from stuudies completUe vecemwbr 1YUU uy~_ lte WCoastl FLlriUcientLU project consultants and the UN Hydrologic Survey Team. The FAO Soil Survey reported tLat in mar,aareas n thiS region wer-e addition.al nme-ous small channels which could be used for distribution, using small closures and some multiple lifting as done elsewhere unlder the ADC program. For these reasons this analysis assumed the equivalent of about 1,690 miles of channel in fresh water areas in the Southwest Region, iiUcLUudng abo&ut 130 .Iles for Bhola island and roughly 650 miles south of the older saline limit delineation. Since water supply in the tidal areas is in effect umlimited, this assumption mainly affects the estimates governed by limited hours of pumping and by the arbitrary limit on the rate of abstraction per mile for the small-scale schemes.

B. Surface Water Available

Data Sources

4.09 Critical river discharges used in this study, as in the 1968/69 Bank report, are based on data available from three sources:

a) EPWAPDA, Water Supply Paper No. 313;

b) EPWAPDA, Hydrologic Year Books of East Pakistan;

c) International Engineering Co., (for EPWAPDA) Master Plan- Climatology, December 1964.

4.10 Low-flow data is lacking for many small and intermediate-size streams that may or may not be perennial, and the data available is not necessarily reliable due to the short duration of the records. Most records

1/ ADC schemes are believed to have provided irrigation on the average between 1½ and 1 mile from channel banks. The schemes employed 1, 2, 3 and 5 cusec pump units and sometimes involved multiple-stage lifts. The costs of small-scale irrigation schemes used for indicative planning in this report are based on the average costs of the EPADC program. - 37 -

extend, at most, to only 12 years. The data in may instances is sporadic and not in sufficient number to submit to normal methods of data analysis for establishing reliable frequencies of occurrence. This study uses, where possible, flows in the lowest quartile on record in contrast to the 1968/69 analysis which generally used the lowest flows on record. The differences are not substantial.

Water Utilization Criteria 4.11 The, following criteria have been used to govern the estimates of surface water available for irrigation: a) The period of eritical smrface water flow. on the basis of monthly crop requirements, evaporation losses, effective rainfall, and low river di-seharoes- is in March and April (see Chapter III).

b) Lower quartile flows are used. These were derived by ranking the mean mont.hly flows-for eanh year and hoosng t+he largest value in the lower quartile. Average flows would not be a basis with adequate reliability for +hp farm.e%rs on the o+her hand, more severe criteria, such as the 90% dry year, are considered +ood, pessi4is+- for' t~he ypw,oe of +hi report.

c) Irriaio- awmwpl is rest t t An of the lower qtartile flows to maintain established water use such as inland navigation, domestic requ4rements and fisheries (see Chapter III). T'>" assumption is possibly conservative; accurate information in +h4o+>4 v--regar a-" ^o-nr ,..vTry V~--eo+ ,1+_n4 vnAe n-f+~-" detailedA -.2f4 1 gA suo+viAlr ,^ff1rn ,¶,g and projected water use on each stream.

d) The current limit of saline intrusion in the coastal estuaries (see Chapter II) is assumed and the estimates obtained for specific localities are qualified by the ±likr e±±ullhood of lurther intruLionw-usl- wll cuulUd resbL-Lu fruor increased withdrawals upstream. The relationship between the magnitude of upstream withdrawals and inland movement of the saline limit in the dry season has not been determined and is a priority study requiremenc. Estimates based on the above assumption enable testing the sensitivity to different assumptions regarding the effect of major water withdrawals.

Water Available for Irrigation

4.12 The critical dry season supply, as indicated in the summary below, is concentrated in major rivers while only a smaii part oI the total is available in the numerous minor rivers which are more accessible to large areas of agricultural land. The critical flows are summarized below: - 38 -

Cubic Feet per Second li March April

Minor Rivers by Region

Northwest 11,600 12,000 Central 5,700 13,000 East 8.hoo 10.000 Southwest 3,900 3;900

Total 29,600 38,900

Major Rivers

Brahmaputra 136,000 207,000

_an-__s 68.;no 61;000 Meghna 18,000 28,ooo

Total 222,000 296,000

4.13 Because of the uneven distribution indicated above, irrigation sppl7 mnest. be assAeAsd snparatAlv fnr Peach Infale vith a fiiffArAnit river source. This study has drawn on the water balance analysis described in Chanter TT (seP also nlatesq 13 and i4) to account for 211 river inflow from India and groundwater recharge to the river channels. Below is tabulated availahility in +he varions stireamq and rivers ThAe quanti+ies are in+end- ed not to duplicate tributary and distributary flows and to represent to the extent possible +he en+ire +1 eanr flevu in+t +IrnT"r. anrd out of +he area. ;14 Vn-+.hwr*Q+. Parcie-n-

T-4. 4 -41 Anct A -4-1nlO f,-P Lo0wer -artlev4n% Avilbl for---- Flow (cfs) Irrigation (cfs) River March 4pil M.arch ApAI'

Dudhkumar_~~~~~~~~~~~~1 ., 5n 2,600)n \ - ,1 1 .WAno Dharla 2,200 ) 10,000 1,300) 6,000 Tista 4,000 ) 2 ,h- )\ Mohananda 2,000 2.000 1,200 1,200 Internal runoff from groundwater 1,000 1 ,000 600 600

Totals 7,100 7,800

1/ Figures given are in the lower quartile of flow rates on record.

2/ Includes inflow from the minor rivers and regeneration from groundwater. - 39 - b) Central Region:

Lower Quartile ou6 Available for Flow (cfs) Irrigation (cis) River March April March Apri

Bhogai-Kangsa 50U 1 .750 300 1,050 Someswari 250 250 150 150 Old Brahmaputra Nil 1 ,000 Nil 600 Dhaleswari-Kalinganga 4,820 8,500 2,890 5,100 Ghior Nil 500 Nil 300 Bangsi 150 600 90 360 Turag 21C 400 120 240 Internal runoff from groundwater 7,000 7,000 4,200 4,200

Totals 7,750 12,000 c) Eastern Region:

Lower Quartile 60% Available for Flow (cfs) Irrigation (cfs) River March April March April

Jadukata 200 700 120 420 Pijan 400 650 240 390 Sari-Gowain 200 700 120 420 Surma 150 1,500 90 2,700 Kushiyara 1,300 1,500 780 900 Sonai-Bardal 250 700 150 420 Juri 50 200 30 120 Manu 200 300 120 180 Dhalai 100 100 60 60 Khowai 170 300 100 180 Sutang Nil 100 Nil 60 Howra 60 100 h0 60 Gumti 240 200 110 120 Internal runoff from groundwater 9,f000 10,000 52i40 6,ooo

Totals 7,390 12,030 - 40 -

rd) qniithw_qt. PpRignA

Lower Quartile 60% Avilnable For Flow (cf Irrigation (cfs) R?i ve MrhMr Anr.iI Ma rch Anri

Goraif i n 92,5009 1 Roo 1 c°nc Arial Khan 500 1,000 300 600 Kobadakr 1/ 71' c5 50c5 Mathabanga - 330 330 200 200

Totals 2,350 2,350

L4l.14~ * J..L. ±111~Ml .V".LIh JU qurtlU" -4weU.L..L~_ -1 .LLJFVows- a .Lt.An th4U,II- UO.L,6K,aG.-ges .LI.in Bangladesh~i0 are atu present 70,000 cfs in March and 62,000 cfs in April. Some 3,000 cfs fl ow from the Ganges to the Bay of Bengal through the Gorai River. The resultant total ]ower quartile discharge through the Lower Meghna River is 220,000 cfs i n March and 296,000 cs 2 / in April. Regional withdrawals under full development would reduce the main river discharge to about 190 ,000 cfs in March and 265, 000 fs in Apl.

).15 >7-e to the posiblit -are4psrem-4--rwl- of -ate *4 .AJL~j u 4.. VIL--- U Y4Jk.LJ..4.J4 L.LO. ' p)F/.C.F-4- 1..UJ.±UW.. . ncxu'~.3. from the river system by India, together with the danger of further saline J-nts -n-none-- of4t+he*1o flv" innlAthe Gange,6-e except th,at i n t hera distributary, is considered in this analysis available for irrigation. m1l"' som po AeAn_-4a- de e_ opmnt nA_ _LDajsali _ ga_-n _v_.__ _ __v.._ ____A . ILA. , v F,J.0..L,Il-LU-II U V -LjIF-IIL U -LII.LF..[ L r.u.LiO. nULJ. IJ> CFILU CL.l..LALU .Ul is not included in the estimates.

C. Irrigation Potential

4.16 Data available is not adequate to support accurate analysis of irrigation potential Ior the country and the estimates below are intended to provide a basis for medium and long-term planning. This analysis should not preclude detailed appraisal of the water supply, lanc suitability, and feasibility of distribution in the locations indicated or other locations where surface water irrigation may appear possible.

Data Sources

4.i7 Suitability of land in different locations is based on the Land Capability Classifications of the FAO Reconnaissance Soil Survey (see

1/ Taken from Annex 9 of IBRP/IDA Report of Miay 1969. 7/ Calculated as follows (in cfs):

March April Meghna/Tnrm-n 15774,0 2n57,Tfn Ganges 70.000 62,000 Groun+o,' r,vf'Crnnnl 1 1 c5nn 225,000 295.500 Less Gorai- ' nno 2:mon Net 222,000 296,000 cfs - 4' -

Technic1 Report No 2). For this reason the analysis is presented in terms of the 58 Land Development Units (LDU) into which the Soil Survey v,iideti Bnnoladesh_ Tnble 3Ih gives the base information for the analysis for each LDU.

4.18 The number of miles of channel bank directly exposed to dry season flows is hbed: onymeaqnrements derived from the aerial photographs and maps made avialable by WAPDA for the 1968/69 Bank report on the low- 1;ft+raympr nm.^,Th Msnaeic pri n+ts,cl c one inth to the mil e. of aerial photographs taken in 1952 were available for the major rivers. Comparison of these photographs with photographs of a later date (1962) of parts of the Brahmaputra indicated that the 1952 set was generally representative for the prose of this type of analysis. Topographic manps a-t. the sc ale 1:b0,000 were available for the rivers and drainage channels in the tidal areas.

4.19 "LLLe J.L,U± OJr tdl ers i s 'vase' on -UoI,Laion obta .LL1eu from wAPDA and IWTA. The present limits of saline intrusion in the coastal estuarles ari the it -igAtor_ r-_---reamen' - for f.r.±exren -c,o a;. discussed in Chapters II and III. Criteria for Estimating the Irrigation Potential h.20 In addition to the criteria for water utilization above, the following criteria govern the estimntes:

(a) The range of Histrihutinn Ji resz_tir4fc1te

4) unlder small-sc21e schemes to within a grovs area of 600 acres per mile of cut bank, equivalent to an ave7rage of _hral+. Q/1C, mile: fr-m +ho ]h:nlr

4i) under chom.es with major works to within a gross area of 5,000 acres per mile of cut bank or a distance of about 8 miles

The definitions for these two categories is intended to distdin guiSh the potential for small-scale schemes of the type under the EPADC LowT Lift Program and larger schemes w1hich could be achieved With a primary pump plant, channel controls and other improvements. Th- range for the smal-scale schiemes is buasedU on perLori-iiarice under the ADC program on which the cost estimates for the indLicative program mare basedl/l The range for the lar-ge schees, in one category, is quite arbitrary and the estimates, therefore, provide ag i of' 4the Onl ."'Y ndiu-'U-1L1 cati~on .LUlm Pu.,I1pot enti-:a"lU_ '.JJof thiULdL±b-A typbype: UviLI ±LrrlgcELu±UJ1.ir- igab,oi The range is based on estimates made in connection with the feasibility sudies for Chandpur and the Dacca Southwest projects. (b) Irrigation potential is limited to the suitable agriculture land i-thin tAhe gross range Of diStriDUtiOn; peak irrigation requirement is for March/April for improved rice varieties (see Chapter III).

1/ See footnote 1 to para. 14.08. (c) The rate of abstraction under small-scale schemes is limited for estimating purposes to 10 cfs per mile of cut bank where water is available (20 cfs per mile of channel where both banks can be used) or to the available flow rate where it is less than 10 cfs. This restriction is equivalent to a maximum of only 5 pump groups per mile of cut bank which arbitrarily restricts the potential for irrigation where pumping operation is less than about 18 hours per day.

Estimates of Full Potential for Surface Water Irrigation

4.21 The full potential for irrigation, including present irrigation from rivers and tidal channels, is estimated for the two scales of investment, the small-scale schemes and larger schemes with major works, defined above. Since the static supply in the Bils and Hoars could not be assessed, the estimates do not include this potential. Separate estimates are made for each water supply in each of the 49 Land Development Units (LIXJ). The totals for each LDU are given in Table 35. In cases where the water supply could only be used in one of several LDIJUs, the estimated potential is allocated, often arbitrarily, to only one of the alternatives, The other alternatives for each source of water are shown in Table 34 which also gives the data on water supply, irrigation requirements, and land characteristics from which the estimates were made.

4.22 In each location, the estimates are determined under the criteria for water availability and two ranges of distribution defined above, using the available flow rate, the designated periods of abstration and the average irrigation requirement for the area. For small-scale schemes, the amount of available water is determined, at the rate of 10 cfs per mile of cut bank, from the lengths of bank available in each location. The irrigable area in each case is limited to suitable land within the range of distribution as estimated from the proportion of suitable land in each Land Development Unit in the Soil Survev. Tvpical neak irrigation reouirement. at the numps; is about 9 inches per month, but the requirements for different regions vary from 7 to 11 inches (see Table X1 ). h.23 Estimates are made for f'oinr periods of abstraction- R hours, 12 hours, 18 hours, and the full 24 hours per day, to illustrate the full range of the note.nti al- An average daily per:iod of 8 hours, under a peav reqirement of 10 inches in the critical month, would enable a 2 cusec pump to servT/50 acres, sliaghth re+r tan+ +t.e recn0t average u+vilizatior re_rte hyAC-. As seen in Table 35, for longer periods the potential does not increase pro- nor+. onae1vy hbecause +:he various Cr4+csr4;n +th.e est4ntesa+ diA4ffern4t points. For different LDUs, different criteria govern, depending on the cAnditio-rns mAur'nft. to thfe supplies.

/I DAnl reportd 4-n 1 040ar. a Irage 40 ac.re per onoan nr.p and a erage daily operating period of 6.3 hours. - 43 -

4.24 In the Northwest Region, major parts of the Central Region and other relatively elevated areas which are outside the limit of tidal influence, available water and the maximum rate of abstraction is limited to the flow rate in the rivers. within the tidal limit, the supply is available in hydraulic backwaters which are regulated by the ocean tides. In each tidal channel the supply is a function of the total river inflow to the estuary- systems, the tidal level, and the hydraulics of the network. The supply in each case is more than could be used locally and, therefore in these areas irrigation abstractions are generally limited only in total to the combined discharge into the channel system, net of upstream abstractions and other allowances. The boundary of the tidal areas was taken as the recorded limits of tidal influence in the river channels, covering about the southern half of the Southwest Region, large parts of Comilla and Noakhali Districts, and extending inland along the Meghna Depression into Sylhet and Mymensinah Districts l/. The LDUs with tidal supply are indicated in Table 34.

4.25 Estimates of irrigation potential are made for areas inland from the present saline limit (see Chapter II) and each is qualified by the likelihood of further saline intrusion which might result from increased withdrawls upstrieam. In this way, sensitivity to different assunptions regarding the effect and location of future major upstream withdrawals can be tested.

4.26 The location of the saline limit, as discussed in Chapter II, is a function of the hydraulics of the estuary system. The relationship between the limit of intrusion. river discharge. and enerov oradient is not fully understood, but the curve of the saline line indicates that its loeation is not related simply to the int;vidtal flow rates in different channels. The unliform seasonal movement of the line indicates that the location is related to the comhined discharae and to the Aneror gradiant in the whole estuary system. The extreme variation in discharge between the Monsoon and the f'rv seasnsq indicnates that the rhqnnge in t.he irh seasonn location of the limit as the result of irrigation withdrawals inside Banp"ladesh nrobablv would not exceed the max-imum seasonal movement. Assuming no major diversions upstream, irrigation withdrawals in Bangladesh would not exceed 10 O00O ciuec-s epven inmder fll developernnt with multn1rpnose schemes. Furthermore, variation in the energy gradient as the result of irrigation withdrawanls wn l1 he mhuch less +han that as aresult of +he mons.n' flonnnng. Consequently, the new location in the Barisal area would likely be near Patuakhali, and records of the seaso.nal m.ovement indicate that very little change would occtr west of Barisal District (see plates 15 and 16). The consequent reduc+ion i.n poe+ntial for expa.nsionr is esi+ma+ed below (see para . 'A31).

Rst;.n+ae of Presern+ Tt.4rPat,4

4.27 RP of^c! ATl( distribution of low-lift purpe b7- district in 1969/70 and records of WAPDA installation were used to estimate the are-f-s presently+1 Jr4_- te-+ f,P nA "4we%" fI l ^4-a Or +4AM* 1o t4ya_ +Uh_ -' -v_ ; - -- 6wDZ~ 'Wffz *_A wwwvz*_w _ vsW-- Ws purpose of determining the potential for expansion of surface water irrigation.

1/ See 1tp III - Hydrology in the Analytic Map Series. - 44 -

Since present irrigation from river flows and tidal backwaters was not explicitly recorded, it was necessary to estimate from the records for each district the portion of irrigation from static supplies and from the rivers and tidal waters, using information from the FAO Soil Survey and tne best judgement of experts with experience in the various localities. The estimates do not include area under the Ganges-Kobadak project since it diverts water from the Ganges and since that area is not included in estimates of the irrigation potential. The estimates are given by LLU- in Table 36 and are summarized below for the four regions:

Region All Low-Lift Pump LLP Irrig. From LLP Irrig. From Irrigation Static Supplies River Flows and Tidal Waters

------______(toOO Ac)------

Northwest 104 52 52 Central 135 83 52 East 305 149 156 Southwest 109 14 95

Total 653 298 355

4.28 The data from which these estimates were made, available on a district basis, had to be broken down for the respective LDUs. Where possible, the overall totals were maintained as closely as possible. The results for specific LDUs are only very approximate and the estimates are indicative for aggregate planning purposes only.

Estimate of Potential for Expansion of Irrigation

4.29 The potential for expansion of irrigation under the two scales of investment defined above is determined for each location by subtracting from the above estimates of full potential the estimates of present irrigation supplies from rivers and tidal packwaters. These estimates are indicative only since broad assumptions underly the estimates of potential and present irrigation. T¶e estimates for each LDU are shown in Table 37.

4.3 0 Small-Scale Schemes. The estimates for expansion of small-scale schemes under the ADC type of program, above the present saline limit, are summarized below for the four regions:

Region 8 hr./day 12 hr./day 18 hr./day 2 hr./day (000 Ac.) (000 Ac.) (000 Ac.) (000 Ac.)

Northwest 8 33 h8 58 Central 138 228 298 338 East 314 684 744 789 Southwest 810 1,305 1,705 1,895

Total 1,270 2,250 2,795 3,o80 - 45 -

4.31 Some of the potential for irrigation wxpansion in the Southwest Region is qualified by the possibility that saline intrusion further inland as the result of irrigation developments upstream would contaminate the water supply for areas nearest the present location of the limit. As discussed in the section above and in Chapter I1, change in the dry season location of the limit as the result of maximum irrigation withdrawals upstream, which would not exceed 100,000 cusecs assuming no major river diversions in India, is likely to be less than the maximum movement of the line between the annual floods and the dry season. The maximum movement would result in a new location of the limit roughly near Patuakhali in Barisal District. At most, the following areas would be affected:

LDU 8 hr./day 12 hr./day lb hr.jday 24 hr.jda (000 Ac.) (000 Ac.) (000 Ac.) (000 Ac.) SW4 20 34 53 71 Sw6 77 130 170 170 SW7 54 99 139 139 SW8 8 13 15 15 Total 159 276 377 395

Likely movement wrould result in less than half these areas being affected. The potential for expansion in that case would be as follows:

Region 8 hr./day 12 hr./day 18 hr./day 24 hr./day (000 Ac.) (000 Ac.) (000 Ac.) (000 Ac.)

Northwest 8 33 48 58 Central 138 228 298 338 East 314 684 744 789 Southwest 730 1,175 1,515 11880 Total 1,190 2,120 2,605 3,o65 4.32 In summary, the irrigation potential stated involves full utilization of the water available on streams tributary to main rivers, except along the Tista, Dharla and Dudhkmnar Rivers in the northwest region, the Ganges River and some other rivers in the Central Region where adverse soil and topographic considerations limit this type of development. Low-lift pump development along the main rivers is limited by geographic conditions and existing embankments and in the coastal areas by potential saline intrusion. 4.33 Multiple Stage Pump Irrigation Potential. Irrigation from Low- Lift pump development could be considerably expanded by multiple lift pumping. Primary pumping stations and regulatory structures located on perennial streams could lift water into other natural water channels for controlled transfer and distribution. Low-Lift pumps would pump the water onto the fields. Such schemes can be successful provided the following conditions are met:

-- the slope of the land is minimal;

-- there are suitable natural distribution and drainage channels; - )46 -

-- there is a suitable location for a primary pumping station.

4.34 It would appear that the last mentioned condition is the most rest,VA~~. Lc:v.T.e ,U V I J.&AJ riverJ.LV± bCanrusLJ4Z.UI.L of lGheLL Ja,-raaeJ.ILLLLLC6 CL so ~ur.Lstale-uJ -IJ eL~~LJ. '-uatbL4 const~c to uctLLL..O"Oiucln of permanent primary pumping stations along them is not technically feasible.

hLe i-Lis.tall ti ofJL uj. %.L_(J IoxL.iUr PIGlluay ptWalp' clUlug w&Ue ma4Jiu r.ivers is a possibility that would require careful consideration.

4.35 The feasible locations for primary pumping stations are to be found at or near the coifl-uences o uthe major rivers where backwater assures a permanent water supply.

4.36 Such tributaries are:

-- the Hurasagar River in the Northwest Region from which water could be lifted into Lw's 5 and i0;

- - the Dnaleswari-Kalinganga and Lahknya Rivers in the Central Region from which water could be lifted into LWUs 8A, 8B, 9, 11 and 13;

-- the tidal channels in LDW 6 of the Eastern Region from which most of this unit can possibly be irrigated;

- - the Gumti and Dakatia Rivers in the Eastern Region from which water could be conveyed into LDW 4 and 5.

4.37 Diversion and pumping from the Middle Meghna as far upstream as Bnairab Bazar is also feasible and could supply water to LDUs 3D (Central) and additional water to LDUs 4 and 5 (Eastern).

4.38 Similarly, water deficiencies in the northern part of the Southwest Region could be alleviated by diversion of water from the Ganges/Brahmaputra confluence into the Faridpur district and into the Gorai River by a canal (Chapter VI, Section F).

h.39 The water supply at any one of the tributaries mentioned above is unlimited compared to the available irrigable lands. Additional projects in the Faridpur-Sureswar area are possible under major water diversion schemes. Most of these projects would cover areas where initial irrigation by low-lift pumps is envisaged.

h.4o Constraints other than availability of land for multi-lift numning may be binding. Considerations at each site will be the cobt of works such as sluice structures, pumping stations, dykes and channel improvements necessary to increase backwater flows into the tributaries. The effect on surface flows downstream, and thus indirectly on saline intumsion, is another factor which will be dealt with in the final section of this report. In order to do this, however, the net effect of surface irrigation on flows in the main rivers is estimated below.

Dn= Net Wator Withdrawal from Rivers

4.41 Th.e resIlts nf the analvsis above indicate that eross irrigation abstractions from the rivers under small-scale schemes could be less than 50,000 cusecs and under lar-ge schem,es, iclusive, could be less than, 85,0oo - 47 -

4.- len 000 ------1 / 4if perod of irr_a+.-io>. rniv averatge as wich as IR hours %"' .LS, .S .. oW .. ta, .. ------per day. As the table belo^w shows, greater abstractions are required if irriga- :v~~~~- 4sp'4ddo hr^ An4l-v peAwiosnA nsaejte198/9Rn report on the EPADC Low-Lift Pump Program, assuming a pump duty of about 8 hours 4 and a seri-- -"r'a of' 50 s-cs, pl4±edwithdraw'1' of asemnch as RCLOoo cnsAcs under the Thana Irrigation Program.

4.42 Gross abstractions from the rivers to develop the full potentials de1fined abvo v.e are -.4-- 1.- TDTT 4- Mn'kle 38. '1'h^g araen amma"i-zA bhalnw for the four regions: (i) Under Small-scale Schemes (see para 4.02)

Region 8 hr/day 12 hr/day 18 hr/day 24 hr/day (000 cfs5 (000 cfs) T(Ooo cfs (000 cfs)

Northwest 2.3 2.2 1.8 1.14 Central 6.8 5.7 4.9 4.5 East 18.8 17.8 12.5 10.0 Southwest 36.3 35.14 30.4 25.0

Total 644.2 61.1 49.6 ho.9

(ii) Under Schemes with Major Works (see para 4.02)

Region 8 hr/daa 12 hr/day 18 hr/day 24 hr/day (000 (000 cfs T(

Northwest 15.1 10 1, 73 5.9 Central 35.5 22.1 15.9 12.1 East -50.7 33.3 2), 1 1 9.6 Southwest 78.6 50.8 35.1 26.8 Total 179.9 116.6 82.4 64.4

4.43 With irrigation, some of the groundwater recharge will reappear as return flow in the channels and rivers. This return flow is quantified and the influence of irrigation on the total river flow is evaluated below for the critical low-flow months.

4.44 The irrigation water requirements at the pump are given in Tables 20 through 24. The losses included in these requirements are given in Tables 29 through 32 and are discussed in paras. 3.43 through 3.47.

Dispersed Low-Lift Pump

4.45 The present groundwater flow to the rivers has been discussed earlier. In the wet season both river and groundwater levels increase significantly. As the rains stop, river levels recede quickly and a

1/ Assuming full development with large multi-purpose projects not included in the analvsis above. For these proiects, however, abstractions commonlv would be made over 24-hour periods. Assuming an average irrigation re- auirement at the pumDs of 8 inches per month. l50.000 cusecs. with 18 hour periods, would irrigate about 10 million acres, half the cultivable land in Bangladesh. With 2h-hour neriods; 115q.000 cusecs woul d be snffi ruient - 48 - hydraulic gradient develops towards the river ieading to groundwater regeneration in the rivers. The source of this regeneration is virtually confined to bank storage within one or one-and-a-half miles of the river. Generally low- lift pump irrigation will take place exactly in these areas. The present quantities of regeneration are given in Plates 1 through i2.

4.L6 If on this existing regime, surface irrigation is superimposed, the water table immediately below the irrigated plots will be kept at a higher level, and it may even come to, or remain at, the surtace. However, evaporation from the irrigated plots themselves cannot increase beyond the crop evaporation already included in the calculations. If, however, the percentage of plots irrigated in a certain area is small, there will be a significant border effect in the form of a non-beneficial evaporation from groundwater if the water table is near the surface under these lands. If the water table is deep the non-beneficial evaporation loss will be low. Notwithstanding these losses the groundwater level in the irrigation area will increase (as compared to the original situation) as the dry season progresses. Thus, the hydraulic gradient towards the river will also increase, leading to additional groundwater flow toward the river. How much of this will ever show up in the form of river flows depends again on three factors: The distance from the river, the transmissibility of the subsoil, and the extent to which streams have deeply-incised, steep banks. In the case of wide flood channels a significant portion of the inflow may evaporate before it reaches the actual stream.

4.47 The higher the percentage of irrigated plots in a certain area, the lower the local losses will be, and the larger the relative increase of the groundwater table, leading to increased river regeneration. In many cases groundwater levels will remain at the surface and required irrigation applications will then decrease (or, if the same amounts are applied, the surplus will simply return to the river).

4.48 From the above discussion it thus appears that the following factors will determine the amount of return flow to the river:

-- the percentage of land irrigated in the area;

-- the groundwater level at the end of the wet season;

-- the transmissibility of the subsoil:

-- the distance from the river;

-- the character of the river banks.

4.49 Tt is ce1ar that the number of nossible combinationq Of these factors is very large. To make the problem manageable, distances from the ri>nzr :lrinul::o>rnap t-rmnnmicc:z;hi1iiv r-qt-,c:: bnup nnt, 'hpn vunripti Non-r-npc nf the water table to the surface is assumed to be related to the percentage of land irrigatedr - 49 -

4.50 The assumptions for the remaining variables are then as follows:

Loca:L losses: with low irrigation intensity: allocate non- allocated item (Para. 3.44to non-beneficial evaporation. With high irrigation intensity: allocate this item to groundwater recharge.

Groundwater streams towards river: Assume that 75% of the groundwater recharge in the critical month (March) reaches the river bank in that month.

Evaporation losses from river banks: assume 10% losses for deeply incised rivers, against 50% for rivers with wide banks.

These assumDtions lead to four different percentage returns of irrigation water to the rivers, depending on the assumptions made. The results are given below, for a weighted irrigation efficiencv of 55< Resiults for the case in which losses of three inches per month have been assumed are not very different.

Returns of Total Surface Irrigation Annlication to Rivers in Perrentage

Deeply Rivers with incised Rivers flat banks

High percentage of land irrigated 28 22

Low percentage of land irrigated 15 12

4.51 Detailed knowledge of local conditions is required to distinguish between cases. This cannot be done with information at hand. It is therefore assum..ed here tha.t return -I S 4 Mrc-ain amount to anL average olfU O .of the March pumping requirements.

C-losed' Po'lders

4.)L IrLrgaLioUn WiLLLI Jw-lLft puIUps supported by primlary pumps is particularly suitable for certain polder-type projects, many of which are interianced with natural drainage channels (khals) having a depth of some eight feet or less. Irrigation in that kind of project is more concentrated than with dispersed single-stage low-lift pumps. Such areas constitute a "iclosed" system, in which operational waste and losses to groundwater will return to the natural drainage channels from which low-lift pumps will re- pump to the fields. - 50 -

4,53~ If- th1e groundwater level is at land surface = as will b-e the case 4~ 53 ii1 LLie LUt L .W-Lt -L~ -L ~L.LLI ~u .L W-L-La -L U LI L cI with. intensive irrigation over large contiguous areas such as polder systems - CarmI losses are determilned ma-inly by the inera ---surfac daiag 1_iL _LIU ~b d UJ LLL U -LLdii-L L). L IJ LtL,JLiW.J. ZLIUULA Lauce Uka -Iitiage characteristics of the polder. Neither farm efficiency nor infiltration

rates are tihen deterLmini in[g -actors. In1 LthI 5Le case wLLere only rl.ce iLs grown with groundwater levels at land surface and water levels in khals below the land, the water can disappear frOm the syseLL LnlY b-y evapULLolas- piration and evaporation, and losses to groundwater must flow back into the khals. Non-beneficial evapotranspiration will take place from the free water surfaces in the channels and from uncultivated lands. In other words, the NBE is determined mainly by the intensity of cultivation. With high intensities, surface runoff is not a factor because the water can only flow to neighboring lands or khals. Under these conditions rice water requirements are the evapotranspiration minus the effective rain fall plus a minor loss factor of, say, 20 to 30%; the increment accounting for NBE from uncultivated lands and some regional subsurface outflow due to the higher water levels within the polder as compared to the water levels outside. For the 50% rice irrigation efficiency case, this is equivalent to assuming that 41% of total pumping requirement calculated inPara. 3.0u returns to the river.

Conclusions

4.54 The result of the discussions in the two above subsections is that, to arrive at net surface withdrawals, the gross pumping requirements in the critical month March, as given in Tables 23 and 24 must be decreased by 20% in the case of dispersed low-lift pumps. In the case of closed polders, this percentage is roughly 40% for the 50% rice-irrigation efficiency case (Table 24). - 51 -

V. GROUNDwATER POTENTIAL

A. Introductian

5.01 Groundwater, being an additional source of water beyond the flow in streams, will nrobablv bcpnm increasinglv imnortint for arri- cultural development in Bangladesh. One of the main advantages of greniwater use is the flexrihlitv of spinnIv sine-- with properly nlnn- ned well fields, groundwater can meet cropping needs during the dry season when -su-rf-ace flows are at a minimum and irrigation requirements high. Tubewells also permit the irrigation of lands which otherwise wnild be denied irrigation- water hbeaiisa of +haiv location bhamnd the reach of surface water supplies or at elevations too high to be served frnm canals. The grourndwater potential is established inl76chnical Report No. 21 and is very great indeed.

5.02 Previous estimates of water availability have generally been made onn the hb-ais of river floiw wi+.mi+.+ t-on.QiAaerAi n of eit+.hera'roiind- water as a resource or integrated surface and groundwater development. Recer.t stvudies hav.e shown^ t-hat much more wintter wanter is avazila-bl'e ths-n has been assumed so far because the actual and potential groundwater recharges from monsoon r"Tns n-e very high arA m.u,h of t4h1,s a r-+acan be used during the dry season.

5.03 At present some of the groundwater already returns to the

r a-u -s . " U bj.T AP.L,r-o( , .A-A 4J, HaIIA, V LA (1.J/ / , Tsc I-'AICALIV.A, %A.L / and Acres have established that regeneration of groundwater is an import- nt com po en_A of r+uA_nthe d~ryeao IAw of th -4._-,, 4-,|AA -.A:_i V ^ _ VsFVa%VS w. VW a)-S7VCIJU V .L *A J i V UIG JJV .LV VIIL JA%,.a.LtA.A.AI UWIV major rivers. Peterson showed that most streams to Bangladesh gain ir. 4ah.rge 4.-- a direction.t44re4a..o - - i t-he aquife .A.& L4JULLI-A. .J.LAX 0. U'Afl1LQ VJ.L VC0 U.LLL . U.LA I 11CL4 V04%A %ALA.LJ.VVL ULit;C;ULL . characteristics from the dry-season recession curves for 12 rivers. Tscharr.erl fomr.d that th-.here m.-as a sig-nificyan+v C-r +4otla n. Detva4en. the amount of monsoon rainfall in Gauhati in Assam arnd the volume of winter 4 fl r rn,sma 'n .a_A .-,4. f .AlnhA, ,A f sv: 4-h.-,4- -- ,,,. -1n e.E4-,-.v 4-1 -, 4,. - downstream direction in the whole river system during the dry season ha,vr bar. quar.i-4fed ar.-PDlates 1 h -1h..o' -2o4-V,- -4 In T.R. 21 it is shown that the potential rainfall recharge is suf- fica ,ie to m.^ crop cons,. pu.v.e sa 4 inafe4-ra Aendr o 4s A. -A,J1Len +'- meetJIio '.~J~J V.A. V LOV A~ .L V%IULLLL =UIVI0I UOO A.A.L hdlix LAL Y 00 O %JLA A.LL most fresh groundwater areas of Bangladesh.

Ai LI).ydo0Iology Ul. an.d GUound-a4er Quality

5.04 Most of Bangladesh is underlain by permeable sediments. TLILV0.-LUVA..al U Q.L O typcUdepJ.osi-ts j. range Lror.,s-IILts andOJAtUo cl ays sands. Over much of the area, silts and clays predominate in the top 50 to 80 feet, wi-th sanlds forming the m,ajor part> of the deposits at greater depth. - 52 -

These changes in vertical distribution are associated with changes in stream flow and the types of sediment transported during the glacial and pobt-glacial period. Gravels or mixtures of sand and gravel are found at only a few localities, mainly in the northern areas.

5.05 Indications from the many hundreds of wells that have been drilled, together with other evidence, are that nearly the entire area of Bangladesh is underlain by a groundwater reservoir. The water table depth ranges from zero to about 30 feet, depending on location and season. The total volume of groundwater in storage is enormous, since the alluvial strata in which the water occurs have been shown by deep drillings to have a thickness of 3,000 feet or more. Of course, only a part of this stored water is available for irrigation use since the cost of pumping limits the depth at which wells can be operated. For most areas in the province the depth of wells has generally been limited to 300 to 400 feet, with turbine pumrps which are set at leps than 100 feet.

5.o6 WAPDA, ADC and the Directorate of Public Health Engineering have compiled data on wells drilled for irrigation, municipal and domestic supply which indicate that large quantities of groundwater can be developed in extensive areas, On the basis of this evidence, it is assumed in this Report that everywhere, except for some geologically comolex areas along the Eastern border, groundwater can be pumped.

5.07 Large-scale groundwater development projects and programs have been proposed mainly for irrigation. In order that development may be as efficient and beneficial as possible, prior and continuing studies should be made at project sites. Also, in order that projeclt areas can be properly evaluated, the geologic and hydrologic setting not only of project areas, but of the countrv as a whole should be analyzed further. Additional studies are therefore essential.

5.o8 As far as groundwater quality is concerned, the groundwater is generally too saline for irrigation in the area south of a still undefined line stretching from Jessore to Comilla towns. North of this line, the water quality is generally satisfactory. possibly with the exception of the as yet undetermined effe.t of locally high iron content on sensitive crops.

R',° 'IThe hydrogeological and water quiality aspects of the groundwater resource are discussed in detail in T.R.21 r3ections 1, 3 and 4.. The conclusions are shown in Plate 17. Except for the coastal area VI) where the groundwater is generally saline, all of Bangladesh appears to be well suited for groundwater development. - 53 -

C. Availabilitv of GCroundwater for Irrigatinn

Present Groundwater Regime

5.10 An important factor in the operation of a well field is the rechrge of gr---chater extracted diw.mng a penwod of -,ng -e. Pumping results in a lowering of the water table and an accompanying increase in the p.p lift and pumping cost. Unless the pm+ped wt is periodically recharged this expense can become prohibitive and event1uall +h. -ell fjeld be^orM.e valueleas.

; 11 1h.S.re is abur.dar.t evidence uhtAu even, now, wi;1L%tAou si.ificar.t pumping, groindwater levels fluctuate in the course of the year. Observa- 4tions4f* wrater table ir. povU-e U- .. ,JYG U 4%L U~-_ .Jlevels 4 LLIUJLhurd-u A-.- VLAs L J.Wwf-ells .LJ 4throughoutVI"J LJUWJU U 4hIL1 'V.JJ JV .LJV.., n 6 show that the water table rises everywhere during the rainy season and recedvAs .4- - 4_: _-|1- - -4. A -- -_4 A.4.U - A A ___A_4_1;_ LAtA.LA. 1U16 aIIi I. U.LY VO.O.AA, .UVL "116 C 1IJU-.LIIWU 4Lk tIW GLU of the dry period.-

3'.J2 TheoreticaSlJ, groundiwater recharge can occur from a number of sources. A careful aralysis ho-we-ver reveals that deep percolation of rainfall is the principal recharge mechanism in Bangladesh. The emapiri±lU evidence indiuaue3 uriau even in areas wiun less permeable soils groundwater recharge is substantial (See T. R. 21).

Potential Rainfall Recharge

5.13 Conditions for groundwater recharge from rainfall are generally favourable. nThepractice of subdividing the rice areas into paddies or terraces by the construction of low dikes or bunds increases infiltration, since these buLnds are of such a height that they store some six inches of water which remain until infiltrated or evaporated. The character of the monsoon rains, in whicnh large quantities of rain fall within a four to six-month period, also aids infiltration, as the soil seldom becomes dr-y during this periud adiu there is thus little requirement for waater to replenish soil moisture. On the other hand, concentrated rainfall in the form of big st,orms wiil generally increase the runoff. b.14 If, in future, irrigation is to be based on groundwater, tne groundwater availability for pumping has to be estimated for the future situation (with irrigation) rather than for the present one. Moreover, it is the future potential recharge.which has to be assessed as well as the new dynamic equilibrium in which both recharge and depletion are again in balance.

1/ FAO, Groundwater Investigations, Final Report, 1966, and WAPDA Water Supply Papers and Hydrological Yearbooks. 5.15 Total precipitation can always be divided between rnoff, evapotranspiration and recharge. The proportions will depend on the foll)ming factors:

(1) - total rainfall and its distribution over time

(2) - land use and vegetative cover

(3) - extent of bunding around the fields

(4) - infiltration characteristics of the top soil

(5) - permeability anci storage capacity of subsoil layers

(6) - water table depth below land surface.

5.16 These factors are cdiscussed in detail in T.C. 21, Chapter :I, Section D. It is concluded that:

- the water table depth plays little role if the potential recharge is considered;

- soil infiltration and permeability will generally not be a binding constraint given the general magnitude of pumping needs;

- bunding is important, but is necessary in any case for irrigation;

- land use and vegetative cover, ab determinect by the cro;c- ping pattern, are important in that they determine the consumptive use during the wet months and therefore the degree to which soils dry up without irrigation;

- total rainfall and its distribution over time are the mcst important determining factors of rainfall recharge, because the percentage surface runoff increases with the rainfa]l intensitv. Runoff rates have been bracketed by assumingl a minimum of lC0 and maximum of 30% for bunded cultivated lands.

5.17 The rpsiilts of thp notenti1 reeha)rgP calcul, ations are nresented in Tables 39 and 40.

5.18 In assessing the recharge figures, both the maximum and minimium potential recharge for 5yl-h-et are verv hiogh and exceed any future evapotranspiration requirement. Due to the very high rainfall., the ruinoff fantor manv hp snmewhnt higher thnn for the other areas. Lo effort was made to improve the analysis because the monthly rainfall in bylhet exceeic the PvAnotr-nncznirntinn rPeqi rPm4zn+. r-inrina' the rpe,rinod MarGh - 55 - through October and is insufficient only during four months of the year (November through Febru.nv). Even if the effective rainfall were only 60% of the average, the monthly rainfall in Sylhet would still be adqut dng-- +the-pr,-od April4 1I u Octoe r to m transpiration requirements if the rainfall distribution is reasonably ur or-.ii. (,.e latter p4-.tA U r tur U. US r sO W.J .. J1In A.4ythe) - UIAAVAt the irrigation requirements are so low (see ChapterII) that recharge poV1toentJ'J~&.L0..L 'a-^ __1WA.L±L 110s VULs U_UoV 0.LL-- 4LOOQUIU - O-o 'r-L.A. ' U.U LLIi;UAUUJ. _.LJ..Ar L AJU..L.LVS% , .LO4-s, QS-iJs "VCLUV'4, l for installation of irrigation wells, all irrigation requirements in

S yLhLe c U.L'U 'Lle .,iiet Ljy groundUwatdter P.,UL.IIgs,.

v ..197 T I J.YJLIIJ.O.L1A61AsI 0.LIU A.J±IdJpCrj)U.RLIUr ReLg)ions h av a.lso. La.L1 potential recharge. The rainfall intensity is lower in these areas ar inylet,U and e --- r r relst The full recharge potential will however probably not be needed, even Unuerl- rrgigaU.LUII.

5 .rLnally, it appears frun these caLcuLations that the recharge in Rajshahi District in the Northwest and in the fresh groundwater areas in the Southwest (parts of the districts of Kushtia, and possibly Jessore) recharge will be insufficient to support full development from groundwater. However, before such a conclusion can be drawn, fulther detailed studies are necessary (see Paras. 5.23-44 below).

Acreages Irrigable by Groundwater

5.Z1 To arrive at acreages that can be irrigated by groundwater without inducing recharge from the rivers, tne net requirements per irrigated acre must be compared to the potential recharge. For this comparison integrated surface and groundwater use has been ignored at this time. On the basis of arguments given in T.R. 21, it has been considered that minimum runoff will occur in regions where the rainfall is so small that the potential recharge constrains the irrigation poten tial.

5.;ee The number of acres that can be irrigated is dependent on the water requirement per acre, which in tur depends on the cropping pattern on one hand, and climatic factors on the other. Both influences are dealt with in Chapter IlI.It appears that the variations caused bv climatic factors are limited. For the purpose of a first approximation they can be ignored. The water-intensive cropping pattern developed in Chapter III-with emphasis on boro rice - requires, as an average over the lrovince, a net irrigation (net of additional recharge) of about 2O inches per acre. The less water-intensive cropping pattern requires approximately 15 inches. On the basis of these rough estimates of irrigation requirements per acre, and totaL quantities of water available by districts (Tlable hO), the total area that could theoretically be developed on the basis of grountcLwater alone (assuming that all the recharge is available for irrigation) is calculated in Table 4l. The results show that, except for an area on both sides of the Ganges (the Rajshahi, and - 56 -

Kushtia districts) recharge will be sufficient to fully irrigate all bunied areas from groundwater alone, even if the water-intensive cropping pattern is used. The total area that could be irrigated from groundwater (ignoring economics, flooding and alternative sources of water supply) is approximately 16.5 miMllion acre of a total bunded. area with fresh groundwater of about 17.5 million acres.

Detailed Water Balance Calculations for a Sample Area (Rangpur)

5.23 The calculations described in Chapter III provide a convenient frame- work to come to grips with the demand and supply of irrigation water and to calculate recharge. The following is the detailed analysis of the water balance for Rangpur to check the consistency of the various assumptions made both in Chapter III and T.R.21. This is done because a number of assumptions are on the conservative side and this may accumulate and lead to biased results.

5.24 For most areas, a conservative bias will not influence the conclusions on groundwater availability since the recharge is ample. For the marginal areas however, this may be different. In the following paragraphs a description is given of a detailed simulation which was made of the ultimate water regime in the Rangpur arca under one of the basic croppirg patterns. Results are given in Tables 42 and 43 and illustrated in Fig.5.

Cropping Pattern

5.25 The basic 15% Transplant boro cropping pattern, which has a cropping intensity of 250,' has been chosen (Table 17). Some of the cropping seESons given in the Table may be somewhat on the short side for this Northern area. The periods of land occupation (including preparation) taken for the sinmlation study were as follows:

Rabi crops and T-an 3.5 - 4 mLonths T-boro, T-aus and jute 4.5 - 5 months

For each 5% of the cultivated area, the exact sequence of crops was established. After this, each of the crop 'areds was studLed separateLy and at the end they were combined to provide the overall picture.

Gross and Net Rainfall

5.26 The average rainfall has been taken from Table 2. Direct losses are of two kinds: interception and runoff.

5.27 interception is significant only in periods with sparse rainfall. Taking into consideration that even in those periods rainfall tends to be concentrated in a few storms, the following schedule has been assumed for interception losses: Figure 5 Wateir Riegime in Rangpiur bascGd on Groundwater Pumping i(inches of water) Cropping Patterrn: Low T- Boro (Tcible 16) Rice Field irrigation elficih3ncy 50%

DRY F'ERIOD ( Novernber to April) MIONSOON PERIOD (May to October)

Non-Benelficial '0 R Evaporalicon 2-7ti-j -::,---; . Inter ception -7 ,c. . . - . : -- ' | Irrigationj

Run- Off 1-8 : n.. - t 5 :R y C'

r rri a|on hr jin of Fielt

TOTAI wA TE R APPLiCA7;0W TO SOI L 91~4

Net ;'3rotero .r :: _ _ I I | WVler Pupifng 2

Channel Loss to ( I Grouindwater, 2-3 Tc I l I7,A:-) ,

Ge'r e..,1ssGto}Lpw d>.r ---.--,

K ~~~~~~~~~~~~~~~~~3.9

- ^ 1 ~~~~~~~~~~~FieldF'ercolotion - Vfto Groundwater-1, \]/ - 58 -

0 inch to .3 inch per month: all intercepted .3 inch to .7 inch per month: .2 inch " .7 inch to 1.0 incn per month: .1 inch

'.20 The rain runoff calculations are based on theoretical considerations, and on a detailed rain simulation study for Rangpur. It has been assumed that rainfall runoff depends on two main factors: the size and sequence of individual storms, and the speed at which the water can evaporate and percolate. To stim- ulate this, rainfall runoff has been derived in two steps as follows:

(1) instant runoff first 5 inches per month : O,b 5 inches to 15 inches : 1M; 15 inches to 20 inches : 200

(2) runoff through cumulation (overtopping of bunds etc.): deduct evaporation from the residual after applying (1) and then apply a second schedule:

first 5 inches per month : b 5 iniches to 15 inches :20 15 inches to 20 inches :40o

Application of these scheaules leads to results which conform closely to those obtained in the simulation study. The runoff percentage is about 11, or about equal to the runoff obtained if the deep percolation rate of the soil is .01 inch per hour and the bund height 9 inches (or alternatively if the deep percolation rate is .015 inch per hour, and the bund height 6 inches). Probably these assumptions are still conservative.

Gross and Net Irrigation

5.29 The net irrigation requirement is obtained as the residual between the crop and preplanting requirements, minus the net contribution by rain, taking into account irrigation losses (see below). The net contribution by rain is equal to the one calculated above, except in April, when rain is significant enough to lead to "overlap" losses with irrigation, if it rains just after a plot has been irrigated. Losses of more than 20% of the rain are however improbable, and this percentage has therefore been deducted.

5.30 The losses, which form the margin between the gross and the net irrigation requirement consist of non-beneficial evaporation, irrigation runoff and percolation from channels and fields. The assumptions stated earlier in this Report have been retained for these items. They are as follows: - 59 -

Non-beneficial evaporation is 3u0 of channel losses (which in turn are 15% of total gross irrigation), plus 20% of field losses (which, for the two alternatives, are 50% and 25% respectively, of gross field requirement for rice and 25% for other crops).

Irrigation runoff is equal to the second component of the non-beneficial evaporation.

Deep percolation from channels is 70% of channel losses which in turn are 15% of gross irrigation. Percolation from fields is 50% of the field losses. Total Effective Moisture Applicatian to the Land and Its Use 5.31 By totalling the net rainfall and the gross irrigation application minus conveyance losses, the amount of water that is effectively applied to the land is derived. This water either evaporates or percolates into the soil.

5.32 Part of the evaporation is still non-beneficial because cultivated land can be temporarily fallow. For these periods evaporation has been assumed at 100% of the evaporation index (Table 8) in the first month after harvest; thereafter at 75% of this index until 311 soil moisture has been exhausted; thereafter at 50% of this index. Crop evaporation for the different crops has been taken fram Tables 10, l; 12, 13 and l4.

5.33 The water percolating into the soil can add moisture to the top soil, or it can percolate downward to the water table. The latter will occur after the top soil has reached field capacity.

5.34 Between irrigations or rainstorms, evapotranspiration depletes the moisture in the top soil, to be replaced by new moisture at the next irrigation or rainfall. However, soil moisture depletion is allowed to occur for about a month before harvest. The resulting changes in the moisture of the top soil have been estimated. Deep percolation is the balancing item. In the monsoon season this deep percolation is attributed to rain; otherwise it is the result of irrigation. It should be understood that the deep percolation thus derived is a potential one; if the water table reaches the surface before all the potential recharge is accoimmodated the rest will show up as runoff. However, for the purpose of the assessment of the groundwater availability, it is the potential recharge which is relevant.

Results

5.35 The results for the case of 50% field efficiency for rice are summarized in Table 42 and Figure 5 (those for the other case, which mav become relevant in the futnre. are summarized in Table i)ibut will not be dibcussed here). - 6o -

5.36 Over the whole year, crop consumptive requirements came tc 44.5 inches. In addition, 5.6 inches will evaporate from temporarily fallow soils. The total requirement thus comes to approximately 50 inches.

5.37 Two seasons can be distinguished clearly, the wet and the dry. During the wet season, total evapotranspiration as defined above is 33 inches or nearly two-thirds of the totaL. In addition, 0.8 inches of soil moisture which is depleted at the end of the dry season, is replaced by rain, for a total of 33.8 inches.

5.3b In the same period total rainfall amount to 80.1 inches, of which 9.1 is lost as runoff and 71 reaches the field. The balance between this amount and the evapotranspiration plus top soil moisture addition cames to 71 - 33.8 = 37.2 inches and is potential deep percolation.

5.39 In the dry season, total evapotranspiration from crops amounts to 15.4 inches and evaporation from fallow land is 1.7 inches for a total of 17.1 inches. Of this, .8 is provided by depletion o: soil moisture so that only 16.3 inches is added to the soil.

5.40 Of this amount, 5.2 inches are provided by rain 15.9 inchas gross minus 10.7 inches interception. On a net basis therefore, onLy 10.3 - 5.2 = 11.1 inches, or less than a foot, has to be provided by irrigation.

5.41 However, irrigation is a ratner inerficient process. Los:3es to non-beneficial evaporation and runoff amount to 4.5 inches, increasing the irrigation requirement to 15.6 inches. In addition, 6.4 inches of irrigation water percolate downwards to the water, table. Thus, the total irrigation requirement comes to 22 inches_/ However, the net withdrawal from groundwater is only 15.6 inches. If this is compared to the wet season recharge of 37.2 inches, there indeed appears to be hardly any problem with regaroa to the availability of recharge.

5.4a- The total Dumping requirement of 22 inches can be comparei to the one obtained earlier for Rangpur for the same cropping pattern and efficiency assumptions, which comes to 30.9 inches. The fairly

a/ This is slightly less than twice the net irrigation recuirement of 11.1 inches. Thus, the overall efficiency of irrigation is slightly better than 50. At first sight this arnears to be inconsistent with the assumption of 15% channel loss plus 50% field loss over the remainder. making for an overall efficiencv of h2.5-L. Howepver. the overall process is somewhat more efficient because part of the effetivye eAvanoration leafns to 80-il moisture depnletion. whih is later replaced by the irrigation losses, rather than by net irrigationn This is nen. of the cases .he t+.h. c n on of t.he whole system gives results which are different from calculaticns based on partial a.nalysis. - 61 -

substantial difference must be attributed partly to less conservative assumptions and that the latter figure, therefore, includes some water that is being recirculated.

>.4_j The estimate of the rainfall ecnarge comes out much closer. Frnm T.R. 21, Tahle- Il -tapnrnit thnt iinder the mvni mnvm rechnrve assumptions, total recharge in Rangpur would ccme to 32.5 inches, and t.hna. in nraiition h4 inrhp 1 moiture wrnluli ha :riorit Tf in fnt-+. only .8 soil rnoisture is to be replaced, recharge will amount to 35.7 inc.hes , wh.ch i9 relatiAvely close t.o the recharge of 37._ ~clculated above. The difference is due to the fact that the runoff assumptions on Whith T_R. 21. Table 11 is based appear somewnat conservative, evein for the favourable alternative. For the rainfall Dattern prevailing in Rangpur, the maorm,.m-rrnoff ass .pt'ions of T.R. 21. Table 11 certainly appear to be imrealistically pessimistic.

5.44 Finally, the total net water withdrawn from ground water (or inliirm. recharge requi-red) com.tes to 15 .6 inches, ",^.ch is~ qite near to the lower number used in the calculations to derive acreages

A^plicatlon o. thAX Lue 4odoloA-1 o Detile w--1ate a&c UJ UAW WWSlL..l4JT JJ. "VVC"J -~,%A.LLJ IDU.L .L5.)6LilA.. Calcuations -o an Area with Possible Recharge bhortage (P.a7 -%_I I

) .4) ±~~1Ale net1UULLU±IjYD UWQ%.L.JL.LJ L11. l.LLD .LI.L DrU.L1Jr iJ4L rJ4JL uc also be applied to areas where the recharge may be too low to support .L-ull UL.LL± deeo^ltVUDV .LVLAIiDi.L,____4r . TheILIC 1IIJIJV.L- SLLI..1Asuch CUIZLarea, ±UL%A:4ItJ.L.±CUidniie 44.1nPar<-- _-2_ is the Rajshahi District.

5.46 On the basis of the same assumptions as were usea for Rangpur, the first colum-n of Table 44 gi-ves the results for Rajshari. T-he rainfall recharge in the wet season (which is shorter and less intensive than in £Ld4uIgr).LJ %.orilluo Vor.Ly tU aboUUt L6 h.Ls.LIZ * As ag&in thLiLs, U4ith W±11- arawal of irrigation water from the aquifer necessary to sustain the a s sum inie ru Ulg pO t t e.r-I Wi I Ue UUULbut...) ±LxCt:be * I ILa; rLu1j±p"i .id1 on the basis of these figures alone, about 64% of the area could be 1eveLope-d f-uiy froiI grIour,dwater. IIITh UUi1PdXUC tU 2%U ±liPtU .in Table 4l(using relatively favourable recharge as well as irrigation req remlent ass uMLpt ons). ±ILLs rather siL e.n re -l Lu UuisotaindU because according to the more detailea calculations reported here, both the recharge aia the re.uIremlents are s-ubsanLtially Ihigher than, was as-uzuIeu earlier.

*-47 The Qevelopment potential is however not necessarily limitea to 64A6. In the first place, more recharge may also occ-ur in the non- bundea and uncultivated areas, which together form about 22% of the total lana area or .j0- of the bunded area ( mT.R. 21, T'De 5). The extent to which rain falling on these areas will percolate downwara will depend partly on the way in which the population will husband its water resources. Probably, although these areas do not sustain crops, runoff will be so much hipher that recharge may not surpass 10 inches. Even such a modest recharge would however increase the development potential to about 7$<. This still nssrmps that no rnnoff from these nrp-q runs on to an irrigated or cultivated field, to percolate there.

~5.40 Of course, if -w-ater husbandry can be improvea, this may apply n the first place to irrigation itself. If t-he iriga--iel tion efficiency for rice woulQ reach the level assumea for the other ropsQ' {7-O,hs the +total net wal A A^T +> 71 7 4 rr.h o (see the seconQ column of Table 44) permitting 75% of the area to be servea with grounawater (S8O4 if' the recanb,.-ge on *.bu.e a 10 inches).

5 .49 Finally, all these calculations are based on a cropping pal;- te,, in <.hi r. eA is preponuverarnt ir.the sprng as +WSe summer. If the emphabis on rice in the spring is removea, the net groundwater withdrawal is reduced +t 16 7 inc.hes (last colM.) of Tabe ii) virtually balancing it with recharge on bunaed areas.

5.50 Any recharge from unbunaed areas proviaes a cushion to account for ciforcs=encir nct.c-.

.L L-he.LA. bbe rt-u-sson 4 of± the... above appear to that

4-...)- I1A5 %LJ.1L%, JLU..L'J1L UJ. .'115 dLUkvS UJ.L0.~'..I 0.LIJ11 0..kJiJSaJ UV L iu44 14110$. even in the low rainfall areas on both sides of the Ganges full aeveLop- ment4- based -- groundwater alone r,.ay be p4ossbl,n al g -c-ra v451.ULOU..JSU. '4.1 ± %AVYUW LISI. . lL 1IL0Y 4.4 YvQ0ULL..LS , 0L.4. L,1ILUU L.~,t .5 V40.1.11 restrictions on the cropping pattern will probably have to be acceptea. MThe -4n J.4. I.150retitons U J. .L4.U-14± baseJ41%QU%05L 'AI -erW0 4 balnce-UO..LCO.ll4. %.b4IIQconsid-rations±UU5± CLU.LVLIO zre,04.5 , however,LIULWU Ver,- no more severe than those generally imposea by soil characteri;tics. Aht th115epresent' st0at.e of4 knLowLe5uge, there.LS Ls Liu inuee to4U adooWl.t that0.1 important surface water inputs must be proviaea to the Rajshahi vUv;v" tWs- -Lt U .

D. Possible Effects of Groundwater Pumping on b-urface water Availability

5.52 Ultimately, if most of the fresh grounawater areas in Banjla- d es h are to be irr'igateu from grounuwater, the net withorawal from the aquifer (after recycling) may be in the order of 100,000 cusecs Quring tne critical month (iv miiiion acres at an average of 4.8 incnes/ monthl/ = 6 million acre/feet per month = 100,000 cusecs). The question

1/ This number is basea on the 15% T-boro cropping pattern given in Table 17. That pattern appears a reasonable one on wnich to base the average water requirements for Bangladesh since they are lower than for the 90% T-boro pattern ana, on the other hand, can be reouced further by changing, for example from high aus rice (Table 17) to a higher portion of jute (Table 44). The average net requirement can be calculatec from Tables 24 to 30. From these tables the average gross requirement for March is 6.8 inches (excluaing Khulna) while the return to groundwJater is 1.9 incheE, or a net requirement of 4.9 inches. - 63 - arises whether this substantial weithdrawal will affect surface water streems adiu if so, Uy how riiuchi.

- ,,I In .- con4xt-li 4to ~)._5 J.UI ~IJ_L UUiiLe.A.U, theAULIU ruehLt1L1,uIU.ILOILUO r rerelate L.Ld vU u uJ ' surfaceCL% -A-~Irrigat-ion ~' - - water- - returns to the rivers are relevant (paras. 4.43 - 4.53). In that case, additional deep percolation to the gro-uuLdwater wILas ser-,1osed in tIe exist-4-e regime. In the case of tubemells, 7he opposite occurs, in that withdrawals are superimposeud on Lae present rerginiel-. effectsIU1-a truThe eic: opposite.

5.54 In discussing the possible result of groundwater withdrawals, it is useful to consider the fo Lowing facutour-;

- the percentage of land irrizated in the area;

- the groundwater level at the end of the wet season;

- the transmissibility of the sub-soil;

- the distance from the river;

- the character of the river banks.

In the present case, and contrary to the case of lowlift pumps, the distance to the river does no; play a major role. inere is nc particular reason why tubewells should be located near to surface water sources, and as long as the wells are more than one-ana-a half miles away from them. the effect will be nealigible. due to the low hydraulic gradients involved, and the short pumping period of six months annually.

5.56 For areas near to the rivers, the effect of a lower water table will first be to lower the hyvrnulic gradienit towards the river- This will lead to lower groundwater regeneration. However, over the whole of Bangladesh beyond the tidal inffl uence , total groundw.1ater regeneration in March is only about 5,000 cusecs (Plate 3). If the groundwater table is drawn down to the same level as that of t.he water in the streams, total losses in the rivers will therefore probably not surpass this amount which is a mere 5% of total ti1hewell water pumping.

5.7 However, if the water table is drawn down beyond this level, an inverse hydlraulic gradient will develop and ddititonal losses from

4/ It should be pointed out here, however, that after each wet seabon the initial water table level may w-ell be higher due to the increased percolation as a result of a higher percentage of bunded fielos. - 64 - the rivers will occur if at least they have not yet fallen dry. However, it may be expected that such a situatian will develop only if tubewell fields are placed right next to the river bank. Even in that case, the effect on surface streams will, however, probably remair small since at least a part of the current pumping will be withdrawn from the aquifer itself and another part will be compensated by decreaeed river bank evaporation.

Without detailed study, it is not possible to quantify the effects of tubewell fields near rivers. Assuming evenly spaced wells over the whole strip of one-and-a-half mile width along a river, the effect on surface streams would probably not be more than 15 to 20% of the net pumping requirement (after recycling). VI. AREAS WITH SALINE GROUNDWATER AND/OR AFFECTED BY TIDES

A. Introduction

6.01 The preceding sections have dealt with water requirements, surface and groundwater availability, and the potential for lowlift pumps and multi- lift pumping. The areas that have not been dealt with are those with saline groundwater and those experiencing significant tidal effects. The development of these areas will be discussed in this chanter.

B. Present Coastal Embankment Program

6.02 The tidal effects and associated saline intrusion along the Bangladesh coast have been described in ChaDter II. WAPDA initiated an extensive coastal embankment program by which some 2 million acres of land will be protected against inundation by saline water. The embankment program is well under way but the area requires early introduction of irrigation and improved drainage inside the polders. Pilot schemes for water managemaent programs have been prepared for 3 typical polders with the assistance of 1DA. Polder lands can be irrigated presently from the following sources:

- excess rainfall accumulated in the internal drainage system;

- fresh water brought into certain polders at high tide through existine drainage sluices: and

- river water brought into certain nolders by means of pnumning plants at suitable points along the levees.

C. Exnected Changes

6.03 At present, the embanknents are constructed around comparatively small island<. avoiding closure of even small creeks. No vaterwavs of amnr importance are included in present polders; only systems of minor drainage and irrigation oanals.. oweverr the r.ut.tmrsvg between tihe nolAers will gradually be included so as to diminish the lengths of embankments (and their mAintenancet;. to give better r-ontro1 of' water levels nd sunpplies inside and between polders and to provide fresh water for irrigation. The' nattern of tidal movements will thius he tehanoRd.

6.04, Tn the ultimnte stage, n more or less nontinliuous chmain of Pmbank- ments will be created along the seacoast and only a small number of the lrarer est_n-rieA woul i he1 eflt noen- This c.hnin of embanlm.ents 'ull vetua&l' - 66 - be connected to embankments on the southern banks of the Ganes-Padma-Mghna. Navigation to and from the Southwest Region will be concentrated in a few inlet- and outlet-channels instead of the present numerous large excellent natural channels in the coastal area. Provision must then be made for internal transportation within poller areas (at present usually by countr;T- boats). The water transport system in the small channels will be replaced by road transport and shiplocks must be provided in the channel closures to maintain navieation on the larger streams. 6.05 Other problems arise when areas are embanked. Modifications in agricultural routines are required and farmers are willing to accept such changes only graduallv, even when they are improvements. This has been one of the principal justifications for keeping the sizes of the embanked areas to a minimum even if future enlargements will nullify the future usefulness of part of the initial embankments. 6.06 As tidal volumes are reduced, salinity penetration will recede tnwnrd8 the sea; and local drainAge flows and unpland discharges can be directed and used to replenish freshwater basins. The process of closing: estuarIesinevitably leads to controlled river offtakes as well. nrainare discharges from polders will be based on gravity flow to the extent possible but drainage numning will be neeassarv in several cases.

6.07 Fort.nnAtel.v_ the develorments mentioned above will not nal beecime urgent in the next 10 years. However, several decisions will have to be taken dtiring this period for whiYch a thormwh knaoledoe in required of t_dAl volumes, local drainage and irrigation requirements, upland discharges arLd theAir snills nnd salinity; ns well as their changes9 over th_e venrs.

D. Effects of Estuary Closures

6.08 Freshw"ater lsupplies D-e id sele-tir estuary closures can be used to create freshwater basins in which water ean be7 stor|w-A -P^ - e , jnc ai v _ ' rl vr wyz- t*j_ X _ _ _b gates and locks, large channels can be closed and more fresh water retailed in the coastal a-.ea Closure of chajnjels Of a width of 400 feeto would be a new feature in the coastal embankment program and appears cos-;ly. T* .. st- Ibe- kp r4.d&A*-, h-v r tbt theseO clos 8 4'1 res0.t U a shlort-= ening of the total length of required levees aroundpol.iers and a lowerinZ of ups4tre&I---ILJ UkW.LVU .J.W.UU0 -eesLi'..koL. WAof .~ WAAA.1IA-which wo-d L4'JkL6A ter.dUAj.k -LLA.0 toUVW reduce4L to+-JL V .. .L. %,WOIi.Vcot.-+ £IFO..L^a,t-fo.+ V ..-.1 111L the cost aspect, however, there are very substantial benefits to be gained from the creMatior. ofP freshAwma-ter lbasins adceseAA-----n r.eed fo dpepend- ence on the major rivers during the period of low river flow. The net e:-fect o-L c.lose etU 4 WUU U'd to -crease GILhe usabL)e wmte. uJpp]..Ls dur4JJ, With period of low river flow with a minimum of upstream river regulation and to eXtenAnationA thetJrea period t. LAonL" du-.Ag JAL -4-1In4.1.0AJLoJL w"aterv %dvluetcarU.&r kAUUL1U coLhI. L inre -wWsL hout'Uk* .Ul;r r- national treaty on the uses of water from the major rivers. - 67 -

E. Monsoon Diversions From The Ganges River

6.09 No Ganees monsoon water reaches the Khulna-Sundarban Region because the Ganges offtakes of the Kumar and Kaliganga Rivers have both been closed and their channels are now decavine due to silt deaosition and water hyacinths. Their capacities are small in any case and their points of' discharge into tnh estnaries are unfavorablv located. The latt,er tan be changed by dredging. New channels such as the Halifax Gut and the Bil Rnolte have hben rhirAdoiqd ffnr nnvi antiAon nvani qAvern1 naiantion rhonnnr1 fran the Padma River through the center of the Region are being maintained by d?rAeiJ?IftY.l /

6.10 Upon reopening of the Kumar and Kaliganga offtakes bv provision of controlled inlets from the Ganges, monsoon water from the Ganges could be discharged into the coastal region to imnrove freshwater availabilitv. These improved channels can also provide drainage relief to the north- western reaa of' JeAsore and Kushtia.

F. Gravity Diversions Of Dry-Season Flows From The Ganges

6.11 Several proposals an.d s+uie_s are available regazd_g a barage on the Ganges River. In connection with this barrage, large-scale diversions -ae envisaged to irriga4 e=v+a,nSiae anas 4in +hp q,,11+liijaa+t aer4^, ,,A for" .Al._-b t ex fl a.,. We_S 0 a -_, 80u. W&fl. _~5 _.S O A _ lesser areas in the northwest region. With estuary closures in the southern n.~~ y+Ovi ,n A,.,+a A ae v,a+4v% +)ha .+a . - ",,+ n 4' +ha an., +I,.n + ~ pt- t 5- Wf-.AV- de_lok.entVr thAe v oV t-.-- JflIl- rLonf.,8 the total water demand from the Ganges will be greatly reduced (Appendix A.).

6.12 Present dry-season flows in the Gorai River are often decreased by

s.dba s a thatIM. V l4.'Vderelop 'J.Uk atmwV 4VheVJ41 %#J6SAf5rl--A-.e V offtJ. 4 be. Wivh--riA.UAW%LW QCUWAJC6&s.ba UL-CPhemu4,s £lLLLA.LAILW&Li discharge varies historically between 10,000 to 18,000 cfs, but with the

VS"AS 1f" S 4. O'. OA f.w- A '. AS .^~ S4C:^-P 4 bA Aa&J sndba thze discc6zrg h^6d decreased to 5 cfs 4- ,ba~ ..c&&y A 0 of 15 2,900 cfs in January 1952, and to 500 cfs in May 1954. However, the effect ofP.L. s-A.darsI'LOAMA £ U~c-o_J LLA.ALOd bU el:14-4.-a'du_~L.LJI1J1.&LLU%1A UJ. %.LLd- edg:gULLrJ..h18 OLL'A-- A 0L- SUJLLLJJUIAAU1-r - .A.&a'.,LA0±L_'% LJ.Lo-:u, OwJU_-ago 15,000 cfs could be assured under present circumstances.

6.13 With increased Ganges depletions in India it may become necessar2y

ACAs4A _A4-_- _ 4_U -_; D -_ -P -- 1 re r 4 L~ ~OL.Ae.L r,.L-tV.LUq ULVW.L_O.LW&1 44LLLVA ULML O'JAUW..ZW LP L=6J.VL %Ji1LjpOa, I.1J % LUV 25,000 cfs from a point near the Ganges-Brahmaputra confluence.

6.14 The possibility of dredging a link canal from the confluence to somfe suitable poiLt V-on theUo-aX River should Lbe 1VestLUUU* W'a-U'L improvements may be necessary on Gorai to increase the flow to the south. FOu11 ev a uation of this diversion requires detailed iaiowledge of the topography and cross section of the Ganges up to the confluence, and of the

1/ NEDECO-EPTIITA, June 1967. - 68 -

k_ToraiGora Ri'verLi- . andd.I U otheUilul. irivers ivU O to--voL -'-,ieth4 ^west. The- cos+t ofof' anl malntepn anc dredging must also be determined. However, any diversion of this kird Twould be achileved at iLMI costUa UU11-Iree to zny barrage on tU -a o rivers.

LI G. 1L4U')1,Ebb and h U. Flood0-L IU'U ITl1--sl/U JW.

6.15 The sum of ebb and flood volumes is often used to indicate the ,,agntud of aLctia Irive orLIua est;I ULL-

6.l' Tidl v u±WIlesli Ct a(i ce_rtaln locat.Ulo Calir I'CaL.ClateU Uby ilUteg.LatUJ4In, (over the ebb period and the flood period, respectively) the momentary

product of velocity andu area of thl'iecross-section. The difference Ee ween the ebb and flood volumes (taking into account storage as a result of

u I I It~ll.t1lU b L.d..L daiiu CUL Lt:± VCtz -, J i L,IUlt~ VU±LWfIC U I LIt C UidAYLcIlL, UJL5L idL-tC UUJJI-lr a tidal cycle (Plate 18).

6.17 At springtide and low upland discharge the following approximate sums of ebb arL flood volumes can be giv-ij our t 2des:

Sums of Ebb and Flood Volumes For Selected Estuaries

?IJ.II-T ll-ion1ivf. Cubic Meters

Entrance Pusur River 2,200 Entrance .Iaringhata River l,40U Entrance Tetulia River 1/,4hoo Entrance Sha7~bazpur River- 5,500 Hatia Rivcrl 12,200 , 21 ~~~~~~~~~~~~~~~~~I --- Sand.wip Channel- 6, LJIoU

6.18 Comparison of these data Twith estuaries where closure is conmpleted or under construction shows:

Million Cubic Meters Rance (French tidal hydroelectric project; closure completed in 1963) 180

Oosterscneldt (Largest closure of Netherlands Delta Plan; completion expected in 1978) 2,000

1/ NEDECO-EPIUTA, Volume IIIB, June 1967. 2/ Prinrcipal Meg1hna CItll-q - 69 -

6.19 These numbers are large but Plate 18 shows that sums of ebb and f"nood volumes dme-rta A rnnidly itlnnd and closures thAn become smaller and easier to construct.

6.20 The following list of benefits suggests the desirability of further inverstigation.

H. Benefits From Estuary Closures

6.21 ((1 CZ1t+. watrn;i kept otn+. of the+.hf+. erhn nne.. anlr wSh rh the freshwater system;

(2) High tidal levels will no longer affect river levels awn so +a-t.a+.ulpstre&Mm em,b,-an, lent he-ighnts canan ba reduced or eliminated;

(3) Temporary storage in the new freshwater basins will reduce the dependence thetr. scarce flOwS 4in Mvr.ch -nA April;

(4) Upland flows will discharge through a lesser number of

=4-1l4t-JU L'.L IJ AALUt.V4-4o 4-h-UIAJ 1D-- %I.L-Or 1YOUL4O. 4BengWIAt .LLL 4,-skep-goU'J0 a minimum the volume of dry-season water required to contr.ol sa't intrJ4 sion.

6.22~ ObbJulysVV.LJLJV_.4 oa f, ->heLD-L cok-st 'an b=enefit-S of clu-suresL needL1t to4.WiLL-L±.Lj041,0A- ue qUu.tified LiLLtU Preliminary studies, using available data could be started on return to Dacca.

1. Su-udLies Required

6.23 Studies required include analyses of tides and their effect on stL,-iatler ULLJ7Lii@L1g .LI aFcuVuuLLs uJre1,.WL L.LoWs, U1'U.Ua6agd 0UbL-tiU, estimation of storage volumes in tidal channels, net water availability for Lu--y -season uase, ant.icJ+Uw:: -ru'Ja cun1Lges af'umv kclVUs.-u" (k.c&;l-udrg ZsL'>- ation) and evaluation of decreased dependence on river supplies in the low- flow_ onTh. ev_ -lopmn o eL y md w .ilb1e _t_ X____ f lVW 1VIItlbX1. VlUVt.VALt14 IW t:U Uc-U- U.U1UUt.Z WA-. lI 11t::SEd55J-

J. Water Transfer and Diversion in the East Region

6.24 Most of the southern portion of the East Region is now under study by IECO. A special study is being made of the possibility of supplying water to tne Muhuri Project Dy transferring Meghna water through a link canal from the Dakatia River. The IEC0/EPT.APDA Master Plan of 1964 mentions the - 70 -

possibility of a dam across the Meghna River at Bhairab Bazar and that this scher,e 'w^as the subJect of a feasibtWity study .n 1961. .Le vz.bV14; F.4 the dam is questioned in the Master Plan primarily because too much laad -wouldWOU±Lu bLI-U- LI 'JU;U.de upou-pt-4>..=ev-IJ.reaII. LLU VW . Lj it-V r-iz U 1-o,-JeV. VYW..L A'±LVVi.l.J.4.LV'e toLAD 0 I/l.U.LJA. 4tu-Uthi alternative possibility of providing a diversion weir on the Meghan Rirer near Bhairab Baza_- to dvert -water- to the souther p-4 -oft,,e E -- Region.

6.25 Additional surface water input is certainly required for the sou-,thern portioun of the aster-n1 Region,, an.d it is desirable toU rvestijate alternative sites for the point of offtake from the Meghna. In the soath IB is L5 Vi.f-u (ULW5Cr 81s0l a reqL-LJ.±'1tLLLU.LO Lf1orchatreL UJclos-U.E_Ure UVtLULrU.L salt water intrusion and inundation of lands by saline water which shoild be stuLdied in conJunLction Wwith the water sUpp.ly requirements.

6.26 Dubeweli irrigati±on is certaIL'Ly possiule in Lne midBiLe Mrgxlva reach of the Eastern Region. However, comparative costs for surface water development or integrated surface and grouncwater or groundwater alone are not yet available. Such studies are particularly useful for regions w:iere provision of additional surface water is required in any case [or tISe southern portion.

6.27 In this connection it should be noted that the Terms of Reference of tne consultant now working in the southeast are exclusively project oriented even though the regional requirements, problems and prioritie3 have not yet been resolved. Also the boundary of the Northeast Region, as defined in the Terms of Reference of SOGREAH, does not coincide with the boundary of the area under study by the consultant responsible for the Southeast.

K. T'ransfer of Brahmaputra water to uanges River

6.28 Appendix B describes a scheme for transferring Brahmaputra water from a point near Bahadurabad to the Ganges River near Hardinge Bridge. This scheme was originally conceived to ensure an adequate supply of sn-face water to irrigate the Southwest Region and part of the Northwest Regio:' as it was believed that these areas could not be irrigated unless large quantities of surface water were diverted into them.

6.29 The present study has established that between locally available surface and groundwater all of the Northwest Region and the northern h lf of the Southwest Region can be supplied by means of low-lift pumps and tubewells.

6.30 Supply of water is not the only requirement for the coastal aLrea. To attain full irrigation development in the southern half of the Southwest Region it is also necessary to control salt-water intrusion which can be achieved either by closing selected channels and estuaries or using va;st - 71 -

volumes of scarce dry-season flows. The closures would eliminate tidal fluetuAtions in the selected channels whieh can then serve as frenhwater storage basins from which polders can be irrigated (see Section D.).

6.31 It is emphasized that control of salt-water intrusion in the estuarine a:reas in the qonthwest Region and in the M?P4hnsi outlet is a necessity for full development of these saline areas and the Appendix B transfrer qchpeme w-ould be Of no une for this piurpose,

6 32 The following e-nne1ueinins may be dran:

1. ArIPhmn+. 1 onr.l sr-fa-e nd grnfimA +eAr 0delWreare available to irrigate the whole Northwest Region and +ite northern half of the m4+h.yest ,eon. 4 2 AdAitionv1 a+t.e -,m,+ca 4,+ r +ho C +oo4+ evn ,mitn be obtained by dredging chranels with controlled off-

taims from the C- near'geSI/-P_sd or down.stream of the Ganges/Brahmaputra confluence (Section F.).

3. The water transfer scheme without estuary closures

%Z.OfV V VJ.A * 0.h/%V U .1 WA..L.& v A|V, V U JVC. VJ LAJO 6 ~.jIV_ U0j 0.! 0 - 72 -

VII. WATER SUPPLY CONDITIONS

A. General

7.01 The hvdrologic conditions in Bangladesh rather than soil and land characteristics are the primary determinate of agricul-tural potential, that is the former conditions govern whether crops such as rice and jiute or iry- land crops such as sugarcane, summer vegetables, bananas or other fruits can be grown in the m-onsoon seasonn or even whether anv summer crons can be grown at alQ/.

7.02 Tables 3 and 4 of T.R. 21 give the acreages of prevailing land types and present and future area conditions for the districts under study.

7.03 E-t-Amntes deriveri from soil sqrvey recorrds indicate the land areas in selected flood-depth classes, are given in Tables 1 through 7 of T.R. 4-- Annex 2--anrd shown on Plates 1 through )iof that report. These floodr-epnth classes indicate, in a broad manner, the area of land best suited for aus, transplanted aman nnd iilte (one foot and one to three feet floodin).- They also indicate the acreage that would benefit from drainage wherever this is practical.* The main purpose of drainage ianrio Bangladesh conditions is to increase the area suitable for transplanted rice production in the monsoon

7 0), an fnor nQ irr; c,n+;nn ron+.on+.; nl i czroiin+.hr rronrorned - fo-r tiihp- well irrigation is readily available in most areas that would benefit from irigation. There are two major exceptions: the aren soith of a stJll undetermined line stretching from Jessore to Comilla towns, where the groundwater is saline, and the eastern and northern hill areas together with closely adjacent piedmont and floodplain land where available evidence indicates that eroundwaterresources are available but u7nevenly distri7buted. The depth to suitable aquifers appears to vary regionally; in general, it is less in the north and wpst than in central - as.tern anri southii-trn areas. Groundwater quality is generally satisfactory for irrigation north of the approximate .essore-Comilla line, with the possible exception of +e as -t undetermined effect of locally high iron contents on sensitive crops (Ghapter v and T.R. 21).

7 .05 The prospects for irrilgation ifrom local s-Urface water So-urcet art discussed, in Chapter IV. In brief, surface water supplies now used fcr low- lift p ulmp lrrigatlon are deri-ved mainl-y fromll bils, hoars and minor sGreams. Additional supplies in other rivers and in the tidal channels could prcvide for s-b tUantial exp_ausOi oi ufsarfac waterU .r.uigaU-on. now ewver, the cc nsider- able flow in the major rivers is difficult to exploit because of their shift- ing channels and the fact that most of the immediately adjoining iand is raw alluvium suited for irrigatimn. This supply nevertheless can be tapped downstream wnere it is dispersed and tzemporarily storea in the tidala .ack- waters.

1/ FAOn 1971. - 73 -

7.n00 Con,sequently, a relativelyr 1arg r-ain-ng -ov1-re o-f' exploltbl river water exists in the freshwater tidal zone of Barisal and Patuakhali (LDU S:J6) and in thne rldlI Meghna River (E6). UTT1+lat-e dv -,en'd' result after some estuaries are closed.

7.07 Salt water intrusion was discussed in Chapter VI where it was poifnted out t-hat there are th"ree areas W4tl4stntprbes

7.08 Tt is noted that impending development will reduce the low flow

e _ _XIf. _ _ __ n - .1 -> l_ _ _ _ *L__n__. ;:>[diversions,n Ull dloU,e irrigationrlflUD'11-b~ VUdU developmentt:: |1 i Wl"t inUt::VtdilU India 11UtJ:nand, W ato 1s a UUr%'Lillesser F t[uarLtlkaa extent, P luarragthe s Lingle andu multui-stuage l-ow--lift pumapLing and ubwl Udeve~Luloomts1Lt inside~l Bangladesh. Existing data do not permit estimation of the minimum upland flow in the Lo_w-r Negnula required to prevrent salt-water penetration into the Tetulia Channel and Bakerganj District. Required minimum flows for control of salt intrusion are also dependent on the rate at which selected channels can be closed. Required river withdrawals for full irrigation development of the saline areas are given in a subsequent section.

H. Irrigation water Availability

7.09 The rajor conclusion that emerges from the preceding sections is that irrigation water is available, either from the groundwater reservoir by tubewells, or from surface sources by low-lift pumps, to irrigate most of the cultivated area in Bangladesh. This would include multi-lift pumping to provide water for low-lift pumps or gravity distribution but no major structures.

7.10 The only locations where irrigation water availability has not been introduced to a major part of the cultivated area are south of a still undetermined line stretchnig from Jessore to Comilla towns where the groundwater is saline. Furthermore, the estuarine water in the area west of the Goral River and in the rivers of the lower part of the Eastern Region are also saline. This poses water supply problems in each of these areas. Adequate irrigation water may be made available even for these regions after provision of estuary closures by relatively modest link canals requiring mainly excavea- tion and dredging of existing waterways and some control structures. Navi- gation links already exist between the Padma and the southwest part of the Southwest Region through its central parts. A study for water transfer to the southern part of the Eastern Region is under way. - 74 -

The Northwest and Central Regions 7.11 These regions have no major water supply problems to be overcome. The whole cultivated area can be irrigated from tubewells and low-lift pumps. Full development of the latter will undoubtedly demand some minor diversions and multiple-lift schemes which reauire consideration of the water man2-gement and conservation potentials within the regions. It is noted, however, that some minor diversions from the malor rivers mav well be found economicclly more attractive than full depletion of the internal water resources. Southwest Region

7.12 The northern portion of this region has sufficient ground an,l sr"face water fo-r f-Ull irringtlon deve1onmpnt. Tt comnrises the areas designated C and D on Plate 17 showing the major hydro-geologic region3, which are north o+f +he as yet poorly-defJned; -onuthward-buhging line between the town of Jessore and the Padma-Meghna confluence. The area -;c.4S4 +1,a whole A; Q+trict P+f IKS snAi +hO -nnr+ahrn +.wn-t.hMrec of J11 _LA vvA vs"II Wve,vs9 _ -^z_ .. _ -._ -. _ _ . ._-.-- -_, _-,-_ each of the districts of Jessore and Faridpur.

7.13 The southern portion of this region has generally saline groindwater and co t nrlaoa acdeslgnated T on Plate 17. It includes ths districts of Khulna, Barisal and Patuakhali and the southern one-thirl of +the Ad+isric+v o-f TJesore7o and 1aritnr-

7.14 The hyvdrogeolog4cn reg_onsnc D and T are the igher rlne WLInnrd- plain, Lower Ganges Floodplain and Coastal Area, respectively, which awe described ;i 'r. 1 qr_ios problems a--,;St with sa t 4t.asior. 4_ thei- many interconnecting tidal channels, particularly in the district of Knilna (see Ghapter II).

7 1 l 'his4 s +a+ - a 4r. +;rethea te Regioncope gross and cultivated areas of 5.5 and 5.3 million acres, respectively,

%'.V4.V 4.'.A.J 00 4. .L4..J J ItO

diviOde asQ .o'oL.s West of Gorai (in 1,000 acres)

Khuilna 1,700 1,600 South Jessore (33%) 540 510

,UstofJ GoUrd. South Faridnur (3TIW 57° 54. Barisal/Patuakhali 2,710 2,630 Sub-total 3,280 3,54 Mf,%nA T- r-n'IL) vL .LJ 5,520J ,264 = =~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - 75 -

7.16 To develoD the ultimate agricultural potential it will be necessary to close several of the estuaries and to bring fresh water into the area. This possibility is discussed in Chapter VI and Appendix A.

7.17 The water requirements to be used are those for closed polders plus an allowance for conveyance losses in the channel system. The water requirements for closed Dolders are those given in Table 2h minus LNC (para. 4.52) and are given below: Water Reauirements for Closed Polders in the Khulna District

(in inches of water)

Cropping Pattern1i 90% Transplant Boro 15% Transplant Boro

January 3.9 1.4 Februarv )1.0 3.1 March 7.0 5.2 Arnril 3.7 May 0.5 3.5 June July Au _ut,_ 0n,2 September 0.3 October 1.4 1.t November 3.2 2.0 December 3.8.

Annual Requirement 27.8 24.5

The annual requirements of 27.8 and 24.5 inches are not significantly different but the requirements for the low Transplant boro pattern during the low-flow months of February, March and April are much more favorably distributed with respect to r:iver flows.

7.18 To irrigate e + ed area of the whole saline zone n the Southwest Region (including Barisal/Patuakhali which has extensive tidal chMnnel's witI, frehWte) a *vr5Dr. of (2/12)) 5v261l = 10n.6 .n;'IlirA acre- ~~WV-f~~L. UJ . A.J..L DAA vvw~.V / - '.~'. .J W %L.4, 'rL/ .)% SW *'wJ 1 L%LL~J4d'. ~.S 4 ~' feet (MAF) is required for the 15% transplant boro pattern and the months of Felbruary,'J.L .40.LJ,L.'LLL 14March~ C.LJALarA .1.jLApril .LJ- .Lrequire 1 1.4,)0 4, C-*_ ~Ii"an-- A C-L£2.4 1- MAV±t.L' .L , VU-% VU.Lj* MIpetiel.L.AL_h necessary allowance for incremental conveyance losses in the river channel

teiz 2 'bD OJUcLlJ. ..Un is es SJI U-[AaVeAU 1b 1 0% SS* 1.L.0 ulivw1U IIIUL ja Ue added to the figures given above to arrive at diversion requirements. The order 'J.aof-L J.J'LJ. magnituade Jr~IiLULS.A~ S.Lof' thesVAVO J-~ll4A~ LIAV.4UO J-0 -eurmrtQ1A%AL-- I 4suchVL41CLLUWat '&..LJdierio -V.L O.L¶.AL- IjAct LJVI,.yb practical. However, saline area irrigation will be costly and intensification

'.1/1. W..± U~J~J.l, l jJu±V.Ll1. W±J...L A1LLL.LC"L__L" LJ, 11tV.L_t d. U U.L-at, U.L V

1/ See Tables 16 and 17. - 76 -

7.19 The largest remaining source of riverwater to be exoloited exists in the fresh water tidal zone of Barisal and Patuakhali (LDU SW16). Few areas in SW6 are more than half a mile from a tidal creek and the soiLs are almost all suitable for irrigated rice cultivation. The factors limi;ing full development of low-lift Drinf irrigation in this area nre (1) the pos.i- bility of major water diversions outside Bangladesh from the Ganges-Brahml.putra- Maghna system which would draw the salinity limit further upstream in the Meghna estuary and (2) the lesser risk that heavy water extraction within the Barisal/PatiakhP1i area will al1so draw the sq1inity limit upwards. Ultiml.te exploitation would not be possible without estuary closures.

Eastern Region

7.20 The northern part of the Eastern Region includes the Sylhet Basin which is deepnl-v flooded and for which the develonment potential is as yet undefined. The middle section comprises the district of Comilla and incl2des the minor river basins of the Titas; rGumti and BunRi which all drain into the Meghna. In the lower section are the Dakatia, Barakhal, Noakhali, Khal aid t.hne Tittle Feni andi Mhmiri Rivers which disc-harge into the Bay of Eeng"m

721 The middle vMieghna River (between the to.ns of Baab Bazar and Chandpur) is mildly tidal in the dry season. Full development of lo-li-ft pTump irrigation in the adjonining area (TTu V) is restricted by earlyIg flo of the low-lying areas suitable for boro rice cultivation. Construction Df lnw embankments to protpet +.he land until after theboro harvesT+ might be practical along this non-erosive river. Alternatively, major works to divert the water for use in the adjoining Tn 's rqG8a, and a p rnr f1. ea+e value LDU El includes the Comilla-Noakhali and Little Feni project areas now unier studyi~ forv? irrigatio~n frinm +he Ms>.hnn P1Rive.

7299 The saline 2roundwater area in the lower Eastern Region comprises gross and cultivated areas of 1.4 and 1.3 million acres respectively, Ai-vi AAdnS fWnl1mTs:

Gross Area Cultivated Area

C.omi ll n (1 5%) 0.250 0.225 Noakhali 1.190 1.090

TOTAL 1.440 1.315

Net irrigation requirements for the low Transplant boro cropping pattern will not exceed (24/12) x 1.3 = 2.6 MAF per year for the lower Eastern regaon and the total diversion reQuirement for the saline area will be about 2.9 MAF per year. Gravity diversion into this saline area is di^ri,.ssed in Chapter VI. Section J. Again, the order of magnitude of the requirement is such that diversion appears practical. However, in±ensific(tion of cropning unstream mav be more attractive. - 77 -

C. Net River Withdrawals

Net Water Re2uirements

7.23 It was stated in Chapter IV, Section D that the net withdrawals from rivers may be calculated as follows:

Use pumping requirements given in Table 24 minus 20% for dispersed low-lift pumps and Table 24 pumping requirements minus 4(W for closed polders.

7.2L With reQmnet to tuhevalle two factorR munt bAeonni HTr-dA! (1) net withdrawal. of water from the aquifer, and (2) effect of groundwater pumping on river regeneration. The net withdrawal from the aquifer amoun+_ts to crop evapotranspiration minus the effective rainfall + non-beneficial evaporat'Lon losses. The calculated numping reanhiraments are agiven in atble 23 asimrhi a monthly infiltration loss of three inches and in Table 24 assuming a field efficiencv of q01. For the nA.uA of A mnnthl infiltrntinn lnqeq of th.rAa inches, the monthly irrigation losses to groundwater are given in Table 29 and the non-bPeneP4firLal Ava-ratin-n losses in Table 31 For a farm effic4ency of 50% the monthly losses are given in Tables 30 and 32 respectively. AIJL qsmpnt±ons innde for i1nlmil at4n rmwminei renhnirementsa .04inzn ir.hw+_,4;v% TTT and it is recalled that the field losses had three components (a) losses to groundwater (h0%), (b) nen-b-nefici-a evaportn^A. (20%) nd c) a lo.:s of 20% not yet allocated to either groundwater or non-beneficial evaporation. Regardless of soil pe^.eability "ater~ i¶e~ ,.A, be h4,.hlw efiie. "th44 v: wells -- if -the soil has zero permeability all irrigation water is used for cros evapot:ransvpi -4-1ion and wiYh a .ery higwh permeabl1sv ^1 "ater excep)t that consumed by evapotranspiration plus some non-beneficial evaporation will

-ecoa baol to the g,-w^4^aflter~.0.. is ghrfrAIt.L~J corclde -t, net aquifer with(drawals will not exceed the monthly pumping requirements given 4 n Tbe2 1 4f" -S1f TTn -,- oi - t_*-4.J+U-4A --- - .J LA. ~ --+A+W O & 'tJ4uL& RA. j.AI UL5" W.I 1. AAL LOIJ,. .LAA UOU V .L .Lr1._KL.L ULLMA water with tubewells equals that of closed polders. The effect of graowd- *s.,+nv, pmp,ngnirn-, on riv fls w be niw.al on as the net onwifo withdrawals renain within the limits of rainfall recharge and will not be more than 5_ ofVhe total tube-we'll pumping. (See Chapte V.)

Ne, R1.Lver- WitsL Wa-caLZl

,7 eir m_Tl-_ .. 41A__,.'..41- -. r 4. I o L) 1 *=tlubu"1% 1W IJ L. J V v- N SJ V.LviiU.a LD N 'L' ' ViLU. L a.1 ".l.Ojaaym L ., low-lift pumps (Table 24 figures minus 20%); closed polders cause a net riLver witXhrU-awal equi-valent to the TLlable 2J4 f-et milus 4C ad tube-wells cau;e net river withdrawals equivalent to: (the Table 24 figures minus 40%) times 5S ISItJ e,rtphasized tha "tve lautte- i90 t^u ifL Wit ave,-age; warn-,a nt, aquifer with(rawal is less than the average annual rainfall recharge. The average net rL-ver withawals for- the 15% T.rnsplant boro cropping pattern and for the rnonths of March and April are given in Table 45 in inches of rater, I- / ,,.±~~~~~~~~~~~~.~~m t- . .L .1._1- - -- I 1 1 anud in Table 4/ in cusecs per IL L.LiI UdVe VjJte U acrLes. Thesl Utb.Le WiL be used in the next section to develop a typical water balance for Bangladeshl D. Water Balance For Bangladesh

7.26 The present water regime is dealt with in Chapter II of this

report. Detailed water bhalan- for the diotricts orvf P--" RA are given in Paragraphs 5.23 through 5.51. The water supply requirements

nforthle snut4llern sal4rne zones -reghiven T rah 7 120 mn-, 7 0') The basis for calculating river withdrawals is given in the preceding section. ThIle overall water b-allar.ce fo4r 1Qaglladeshn as preseted elr the basis of a long-range hypothetical water development program. River rl. ws fro0m1 TLa.d, %u.-l0vvo 1' tVIJO se.A.VjA,.L£11on.et for 4. UL in Bangladesh, and Indian diversions must all be taken into account.

River Water Withdrawals in Bangladesh Under Hypothetical Long-Range DevelVo p-1Ien1t1 I

'7.2)7 For the proeofP this -nlys-is themaniud of rivrwa;

withdrawals are constructed on the basis of the hypothetical long-rang B

J~~~~~~~~~~4 m-1-1 1._A7 IvT _ .4|L_. f.L___ ueSvt:eopiLenti l ; i Iis Lv! IGC% c: 4 rf V: 1YsQW.n v Lanc XL.;: _LV.L 1-iCL W I U AA sfty L- cu - calculated using the unit monthly net withdrawals under the 15% TranspLant

004.0- U4L-.0kJi)Lt1 YC0. U 1,0111 00~- 4.I0.0.1. Li. / .LL0WW1 4..L 1.LJJL0~ 142_ 0 1414.£11. 4-110 ii_u river withdrawals for the hypothetical development is presented in Table 48.

7.28 It follows that with this magnitude of development, irrigatiDn ofL 8.2 miL±L..Lion acres, CLILa1. nWC riverVe 1iU.h-VVC.LV olLLyVo. 3L,joo cUsecs in March and 30,000 cusecs in April. Calculation of net river withdra>ials for altern,ative developmertJI-I prograls -ispossi;ULe Using TablesUd0.Z4J anu 'i, in the same manner. The net river withdrawals may be compared with th3 presernt ri-verI f-lows shvwii onj Plateso I through1 14, 1thesurfLa:c water.L LIn,lVWb from India given in Table 1, the average monthly discharge of the majo:^ ri-ver-s gi-ven inl Table 4 nIU W± aVetrge 1muiuy- outL.flWs gi-ven in TaU.L U6.

Withdruawals in India

7.29 The net witrnoawals calculated beDluw for Bang.ladesn for tne 3.2 million acre irrigation development are quite moderate compared to the possible withdrawals in India (see Chapter II, Section H).

7.30 The following figures for diversions in India could easily a;?ply by the year 2003 (for March and April):

(Cubic Feet (Million Acre- Per Second) Feet )

Farakka Barrage Diversions 30,000 1.o Irrigation Expansion in: Ganges Plains 30,000 1.8 Brahmaputra Plains 20,000 1.2

TOTAL 80,000 4.8 - 79 -

7.31 Withdrawals of this magnitude would increase salt intrusion in the Lower Meghna Outlet and in other estuaries aLong the coast, and would pose serious problems for irrigation development in Bangladesh.

River Water Balance Under The Hypothetical Development

7.32 The river flows in March and April under long-range development are presented in Table 49. It is clear that the developments inside Bangla- desh pose no insurmountable water supply problems. However, any withdrawals or diversions in India, considering the vast area available in India that can potentially be developed for irrigation would seriously affect the agriculture potential in Bangladesh.

TABLE 1

BANGLADESH - SECTOR STUDY

SURFACE WATER INFLOW FROM INDIA AND HAINFALL 1N BANGLALESH

Av. Mrionitly

uanuary 302 18.71

Flehrua--v 254 1 .72

April 331 19.88

MMay CG83 42 .34

June 1482 88.92

July 2405 132. 46

,yus-L 319/ 195.49

Stc'iriher 2760 _ in

Oc.ob1ie r ,.1f .. 9] .o3

Novembe-r 643 38.58

December 398 24.65

8C;9.85 lA,l

say .70 PlhF

203 MAF

TOTAL THROUG IJHPUT 1073 MAP

Sourcc-: EFAPDA WL)i Wter Suprl! PaPE,r , EPTiAPDA Hv.reOlPAic2 al Yearbooks, _rCTE-EP.;'LPDA )1I\ister Plan Datpa, 1964, and. Acre, I / Fe'Tbruar\. C971. (See-eTable 6) BANGLADESH - SECTOR STIDY

MAN MONTHLY RAINFALL (in Inches 1- PERIOD, OF RECORDS: 1937 199

Station Jan |Feb Mar Apr M7ay June July Aug Sept Oct Nov Dec Arnual |

-______- -- p- - --- 1 -K -- - - t Barisal 0.58 0.59 1.49 3.2 7 7.62 16.86 16.95 16.82 L1.65 I 8.57 1.20 C. 20

Boara 0.30 0.48 0.996 2 20 7.06 13.041 13.6 1]3.48 9. 66 6.76_ C).366 .07 6 8.25 Chittagong 0. 43 0(.77 2.17 4.48 10.14 22.29 25.35 22.72 12.5 8378 1.45 10.57 11173

Comilla 0.37i 1.25 1.74 6.33 11,.25 20.94 19.32 6.07 1l.96 9.23 1.71 0.17 1100.34

Dacca 0.43 1 0.84 1.80 4.68 9.46 13.83 12.84 1.3.58 1 .32 5.74 0.94 0. 7 3._5

Khulna 0.56 0.54 1.25 3.11 6.30 13. 48 14.03 12.1,3 8.93 6.02 1.02 0.10 67 .4'7

.wmens nc h 0.45 0.64 1.83 4.46 1.1].68 17. 97 15.292 1.74 12 .-39 6.77 0.54 0.ca PY 5

Rangplut 0.57 0.53 1.11 3.40 | 12.14 19.41 | 17.69 j13. 24 'L1.03 6.'7: | ) .23 0 04 86 1

Rajshahi 0.516 0.51 1 0.91 1.37 | 4.72 1i.06, 12.06 1]0.02 8 .02 4.92 C0.39 | 0.08 53.68

______- __ I _ ,______1__Jv_L_____L______,______. __

3 i v £ a L c .1 -- I - S , ; r iLy1 U d Vr; _ I

Ij P'0 co a,C, C' aY~~~~~sl U~~~~C (C~ a 'IVa-I'a aC' C. a a~.

aC> r, D e 0C; ~C;C;afo o a nzC . CC- a C CC, 00 -0 -, C0 CC 0-DC, 0000 * cC C. 04 0 a-----,~~ ~ ~~~~~~~~~~~~--- -- C I . CO-a, Iafl'n'a''- a a, -a a--ar--an0 a r1-0 - a --. ar-O aa~~~~ a - ~~~~~~a-o a o~~~~~~~~r-~~~a --a~~~o-Ca C -. I-- a -a af a tasj' 0 a Ica a Lea'-n, a CI-PC; a a~ 0C0Ce-~0-~'0--'t a 000--aC C~-Ze-aC~ I O0O-aarl a o~.0.-a.fl O0C,Ca~a CaCc-ZC;a CaC;CIaC, I I -4 I --a aI I a ~ ~~ ~ ~ ~ ~~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~~~------a C-..aa-aO~~a'a~-la 0-C.'- I r-a-----a--c', a -U 0Jl C ,a- a -an--r-o.4 a N -~. a In a~a4.r-1 .- l,4a,~

a I -~~~a'a-4 a r- ia na -an] a r, ca a a;- o.a a O ao .-aa - a '----n------a------a ~ J .an .~ --a -~~--- a------a------aa a a~a a a C).a. . . . a .a,. . .Ina a .. ,.

a a .... a .. . a . . a . . a . . I . . a .~~~~~~~~~~~~~~~~~~~~~~~~~~C.aa -

a a no -4--r a a'a-'ao----r-- a ~ --aI-I'.fl a,.-ar-.rr a.2 a------a------a -a--a---:D onir-- a a . . a ...... a~~~---- . a . . a . . I ...... a---

rLq In, I In In I ----- ~~~~~~~~~~~~~~~~~~~~~~~-----a -"a- -.-.-- a.a ~ -- N ElS. a a~~~~~--.C-- ].-a------L- - a ~ --- --. aa a- a C-. Iaa-.0 0 a!'C'a-C-a- a a-a r-aaa a'a - - . a ----- a------ONa a N 0'n a ]Q aat cac I 0al -aa a -O a aa-aC C a .aj-JAOC a 'aI1at a -- r- E- c a . . a . .coa .,a oa . . .I . . a .7, co . a ~ . . a .. a .. IDC,

a-,.. a a Nai~~~~c~C.r-- a;c, a .. C,aa'' Q a'- a naar r- 4aIcnr- c a .C- -fa Ia co- ata a C -C,'-0 .a

a --~~~~a-,------a ------a ---- a---a - - - a--- - - a --- - - a-- a. a..a ... .. a .a-Ca-a-a-C-a `0Ca,a-aa-aaa a'IV aIa'-'- In an a a-J-C,a r ~ - aJa a ~ nna. a I

a a-i-~~~a---r---a a cu-a C a ant~~------a------a------~.l -- -a ------

ca~~~ 0~~~I a C O.... > ao O ' c- C5 . . O a Q C , .1 ar C . CO . C; , . a C C; O

- .--- ~~~~~~~~~~-.4- a. --- ..a …………~~~~~~~~~~~~~~~~~------……-S -- --- ……------

a . a .co r el . a .

a Ca O -NaC; a aflC;COaatOC; -a-C,a c I c,C O I O 0a a-I c-. I a ; 4 C a------C----a -aa------a --- a a---~'a --- ca a' o cal * . a - ---- C --

aa-, - a~~~~~~~~~~~~~~~~~~~~~~~~~~- ... a a a, a, aC 00cC-la ~ a coo-.~ a 000a--In 00 Cc- G Coa o o o ~ - a 0 Ca .1- . a.--…-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ P---

I.- a~~~~~~~a

Pia .-a - 11N aq-.I 0) a 0) w tn a CI, a 0)N - an N an CI a a -- '- -aa a --a a -a a a-a a~~~~~~~~~~~~~------

------a ------a--a a-. ------a a-C------~ a a-. TART.1i. L

BANG.T.AnE.SH - SECTOR STUMY

AVERAGE MONTHLY DISCHARGE OF THE MAJOR RIVERS- (million acre feet)

Ri-ver Ganges Braniaputra Meghu' L______- (Hardi;-)ge B3riage) (Bahadurabad) (BhaLi-atra1bazar

January 6.76 11.28 1.29

b"x -U'a y 00 A,4 r. Q7i

14iarchl 5.02 1u.23 1.38

April 4.32 14.34 1.97 i;lay 4.26 34.41 4.20

June 9.06 68.28 8.03

>uSly 38.81 95.73 16.97

Auc.lfrust 81 .5/ 97.'96 17 98

|C c-, rp tcIl>e4Cc e -7 0 7 00 1 7 072°

October 37.45 47.68 L3.55

November 14.94 22.02 6.4-i

Decenmb_er 9.11 14.03 2.15

Annual 294.31 501.27 92.24 MAP

____ _ .. ,. . _ .____._ . 88 . .____ ... 1 Taken ii from Plates 1 titrougih 12. TABLE 5

BANGLADESH - SECTOR STUDY rPage I RIVER DISCHARGE STATIONS USED TO DEVELOP THE DISTRIBUTION OF MONTHLY SURFACE WATER SUPPLIES

Contributor,,,y S tation |No of Yc-ars - T |j n r-A -f I 7o-I 4S.a |

A Indiarl Border Nortli of Tista 291 6 Rangour Dharla 76 .3 Northwst of |Dudhkumar 81

B J Nort.hest o' Rajshahi Mohananda I 211 1.2

C Ganges at Hardinge | Ganges 90 | 3 Bridge

Di I Gorai near Kushtia Gorai 99 18

E Jamuna at Bahadurabad -|Jamuna 47 1

F Iindian Border nort-h of Bhogai-Kangsa 36 1|4 Mymenei.riq,h| Someswari. 263 6

G OOld B3raThnv1-ut-ra near Old 10 aI1 a , r a,ID.uU L 1. 2,

- I- Indiam border north of Jadukata J.31 2 Sylhet Piyan | 234 2 Sari-Gowain | 251 9

|~, TInd3ian Border east of Surmc 266 2 Cyl'I &u7shiyara '3

K Indian Border south of Sonai-Bardal 265 | 15 I Sa,/1helSy:1| het | ~~~ ~ ~ ~~~~~~~~|I .353 I ~~ 6 ~~~~~~Juri Manu 201 1|5

Lungla 192 6 Iiarangj i3I Khowai 153 5 Sutang 2 v9 5

| I No-tihvzcst of Dacca frcx,|i _Dhaleswaii 68.5 4 I'he | Jam;;ria | ~Kaliganq,a 1 79 ,a t a -_ -______J ______I______o______i _ _ _ __9_ _ _ __2_ TAELE 5 Page 2

BANGLADESH - SECTOR STUDY

I' j Contributory Stat ion 1,o of .-]L, r Index Combined In'low At ;ivers No of Data

Is I nr-i ! nf TŽ;,rrc, fr nrt I -lnnr. I 144 MIymensingh D.istrict T'Lurag | 301

N Northeast of Dacca at S u rTia-Le ghnla | 273 | Bhairab Bazaar Old Bralhmaautra 228 13

P TIian Por-'er east of Howrah 123'3 Comilla | Bumti 110 20

R Arial KThan east of Arial Khan 4A 2 II i-aripur

| S| l9eghna River at Me,ghna | o Z [ G'landc,ur | (1

0 fojS < 'L1 ts U I| ; l l I ~~~~IIZi; fe

iQots:rs1S i tle nn,e o£years of. data availa'ble for this a!nalysis. Aaatona aat 1Savailable witn LrwArPDA. TABLE S

BANGLADESH - SECTOR STUDY

AVERAGE MONTHLY OFFTAKES FROM THE GANGES RIVER (million acre feet)

Month River Corai Arial Khan Meghna (Ra l,way DBr Aq-e (Pda- - OFfte.ke1 COUt]e

January 0U74 0.09 18.87

February 0.50 0.06 14.46

March 0.43 0.08 16.33

April 0.30 0.0 20.56

May 0.43 0.27 43.19

Trunn 1tl4 7.06 86 48

Iz. r n __-r ' n -r 'I r% f I LJLULy J e u z 17 0 .OJ d v L

August 8.52 3.49 192.00

September 8.04 3.76 164.70

October 5.52 1.64 94.45

November 1.98 0.42 42.47

December 1.05 0.17 25.21

Annua1 ,3,67 13,0R 869 63

(say) _47 870 vAF 917/

NOTE: These are measured discharges. Other offtakes from the utajor systemn exist but are llot accounted for. Locall1 cienerated surface runoff in Southwest Region is also not taken into account.

BANGLADESH - SECTOR STUDY

DI[SCHARGE AND SAL:rNITY AT STATIONS INq TIE.E LOIGR IIEGI-DA RIVER-

FMonth-I DischarLe - Est4mated18 CONDUCTIVITY OF WATER. SAMPLE3S TI MICTRC)MNOS at Discharge at Bhagya:kul Chandpur _ St:ation No. cfs cfS _ C3 B24 B23 B22 C2 B21 B19 B]18

DeC 6(56 288,000 320,000 22,000 3,500 1,550 :250 455 2O0 200 193

Jan 67 215,0Q233,000 0 2/K 2/ 3/ 3/ 8,000+ r 2 15 220

Feb 67 224,000 245,000 2/ 2/ 8,000+ 2, 300 5, 000 260 3/ 3/

Mar 67 239,000 265, 000 2/t 2/ 8,,O00 2,425 1,100 540 370 30(

AlPr 6 7323,000 360,000 2/ 2/ 8P,,000+ 2, 100 3/ 430 440 3:30

May 67 422,000 500,000 2/ 2/ 2 , 800 :240 1, 300 150 2/ 3/

1/ Discharge at BhagyaLkul Station 93.5 on Padma River augmented by inflow in the Upper Meghna estimated from average monthly data 2/ Sta.tion dropped from further stuidy 3/Sample not taken during month

Source: Information on conductivity obtained from "Operation and Maintenance Manual for the Coast.al Ernba.nkment" by Leedshil-I-DeLeuw Enqincers.

L1 BANGLADESH - SECTOR STIDY MEAN MONTHLY EVAPOTRANSPIRATION INIEX (inches of water)

Static In,' Month Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec Total

Rangp-ur 1.3 2.3 - 3.7 4.9 5.0 4.3 4.5 4>5 4.0 3.' 2.4 1.7 4 2.6

Bogra 2.0 2.7 4.r 4 .9 5.C 3.9 3.9 33 3. 6 3 .4 1 2.5 2 .0 41.77

Rajshahi 2.0 2.7 4.1 5.1 6.0 4.7 4.2 4.1 3.3 3.6 2.5 1.9 44.7

Khulna 2.2 2.8 4.5 5.1 5.5 4.6 4.6 4. ! 3*9 3. 7 2.7 2.2 46.2

Sylhet 2.2 2.9 3.9 4.4 4.3 3.6 3.9 3.5 3.2 3 .3 2.7 2.1 40.0

Dacca 2.1 2.7 4.3 5.4 5.5 4.1 4.3 4.2 3.7 3-5 2.6 2.0 44.$

Comihlla 2-0 2.7 4.2 4r9 5.3 4r4 4.6 4.2 3.9 3,7 2.6 2.0 44.5

Barisal 2.2 2r7 4.2 4.9 5.1 4.2 4.0 3.9 3.7 3.3 2-6 2.1 43.4 BANGLADESH - SECTOR STUDY 1/ HALF -MONMMY CRO:P FACTORS'

| ge n Months | i | 2 3 | -1 " ______- I _ __ II itII KI I:i~~i xx ~~I 21TICii __-______

Rice (A;a) L.20 1.25 1.25 1.30 1.Lo 1. ' . 1. _ _- _ _ _ _ .Rice LA^s() 1.20 1.245 1.25 1.30i,.LO 1KI;_ 1 | _ _ -_ _ _ _ Rice (Boro) 1.20 1.25 1.25 1.30 1.35 1,, ij 2 .50 1.30 ______J te 0.50 0.65 0.90 1.15 1.0O 1 kL 1.L' 190 - ______W'eat o.5c ,.'0 C.$5 0.70 o.8, 2. GO I 2 1.20 l.0O _ ^ntEe0.ff0 O.,'' C.15 -140> _ _ _ _ - ',10 1,;0 1.:1') rl c,>) _O I 0__ _ _ .(50 0.55 0.75 1.05 1.10 _2 _ _2 i.,9~ ______MUngs bewls 0.50 0. 55 0.-75 1. 05 1.10 095c -. - - - -- Oilseeds 0.50.5 0.65 0.95 1.10D I _ i .2S______|

C-rotindnut '.5 0,50 .55 0.60 0.7' 0,-' 1.1' 1O1. 1.' C 1.1C O.6o _ _ _ _ | _ p.toe 0.50 0. 5 0.65 1.05 1.20 1 : 1.20 0. 3 _ .. -

1": r,gar-x 1 30.50 0.5,0 0.5, 0.60' 0 .S707 O.O.,.10 13.2 . ,3C . 13 1 .20,i^ 0.2 5

Mh*3tgrd * Col-a LLns eed

1/' Source: Work4i !g Papers on Indus TEasinr Study of Harza Enicg. Cc.

\0 BjNWGLDESH - SECTOR STUDY

&SIMATED MONTHLY EVA]OTRANSPIRATION FOR NON-]UCE WINrER C"ROPS (Inches

'Staationa. o-

iaonth Oct -2/ Dec Jan EriarF0.' - i-anci-ur 1. 7 1. 2 L. 2 1. 8 2.5 2.2

.Boqra 1.7 1., 2.2,4 2.8 2.4

F'a.jshah i 1. 8 1 1., 2.0 2. 3 ,2, 4

K.huina 1. 8 I . 6 2. 3 .0 2.6 Svhhe-t 1.3 . ,1 _ 2.1 3. 2.3

Dacca 1.3 1. 4 _4 2.0 2. 8 >6

C'omrrlI 11 a 1. S .Q 1.4 2.0 3.. Q.5 Barisal 1.3 1. 4 1, 5 2.1 J.0 2.5

1/ CaiculEit-ea usirg TL&_s ain:i 9 2/ Lan(d pre-parat.ir.& taie; PL.ace in CcTL,oer 3/ v_> fo½!t- ia1r th.all ri`em-dtr

0 BANGLADEISH - SECTOR STUDY

ESTIMATED MONTH.Y EVAPOTRANSPIRATION FPORRICE (Ench4is)le/

St,)tion/l 21 1 I 1 1 K Month en Mar Ap rM JI ' uuly A- uC S c LDt. Otc No 4'2~ T.rotal

iRnlaCpUr 2 . 2 29 4. 3 6 3 6 .; 6IL 5 5.5 5.1 3 2.'J i6.S

Boura 2 . 4 . 5. 0 6.4 6. . 2 5.2 .l 4. 8' 5. 0 3 .5. _2 .4 54. 3

F.a-i shahi G . 4 3,. 0 5.1 6 .6 8. V . 5. 6 5.3 5 . 5. 2 3. 5, 2 3 53 . 2

Khulna 2. 8 3.4 5.6 6.6 7. e 6 1 6.2 5.9 5.2 5*3 39 2.6 61 0

S 'L 2 . 8 3 . 6 ,0 5.6 6. U) '-3 4 .7 4 .4 4 .9 3. 2 5 53.5

Dacca 2. 6 3 . 4 5 .4 7 .0 7 .4 ! 4 5 .7 5. 5 5S O 5 .L 3 .7 2.44

Comnil.la .2.4 3.4 5.2 6.3 7. 2 6 0 65.2 .. 5 5.2 5 3 3. 2. ;8.6

B_risaL 2.8 3.4 5.2 6.3 6 . G 5.4 5 5 5 3.5 2.. 5_.

1/ Calculated usingc Tables 8 and :9

2/ Presentl1 irrigeLtion only in second ba 'f of aon-r1th

3/ P-resently water requi red o)nl7 ' fo: t landl '.l..T) 1t: flI.rn 4 r

BANGLP UiWSH - SECTOiR ST'u'DY

ESTIMATED SEASONAL EVAPOTRANSPIRATION FOR DIFFERENT RICE CROPS (Inche )1L/

C BLo ro k u /L')',D | 18t 3 22 |Z 21ua

I~~~~~~~~~~~~~~~~~~oqr~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Rajshahi 13 24 20

Khu1.na 21 24 21 j

|.. yl1het j 19 20 |1'3

I I -; ' I 2-;IC I

2~~2

J/ .Vi-oni Tac-Ble 1-1, takri;^z3 into accouvnt plantin-r dates;. -orenlantira recruiremc'1: of 5 inch-es ajnd -a sFoil moisture depletion of 7 inches. BANCGMADESH -- SECTOR STUDY

ESTIMATED MONTHLY EVAPOTRANS'PIRLTION FOft JUTE (:[nches)'s

Station I 2 .H;DnthIFe]b _J Mar -Aor May June July

Pangpur 1.2 2.0 3.,8 4.9 5.6 G.4

Bogra 1.4 2.2 4.0 4.9 5.0 5.4

Ra.jshah:i 1.4 2.2 4.0 5.9 5.9 5.8

Khulna 1.4 2.4 4.0O 5.7 5.8 6.4

Sy lhet 1.5 2 . S) 3 4.3 4.5 5.4

Dacca 1.4 2.4 4.2 5.4 5.2 6.0

Coniila 1.4 2.2 3.8 5.2 5.6 654

' arisal 1. 4 2.2 3.8 4.9 5.2 5.4

1/ From Tables 8. ar.d 9 g! Land preparat:ion takes place in February BANGLADESH - SECTOR STUDY

IESTMATED MONTHLY EVAPOTRANSPIRATION FOR SUGARCANInches)/

Sta1 ion/ Month Jan Feb Mar _pr May June __uy Pg Sept Oct Nov Dec Tota.L

Rangpur 2.2 :3.G2.4 4.6 5.3 532 5.9 5. , 5.3 4.5 2.9 2,2 492,3

Bogra 2.4 2.5 3.2 4.7 5.3 4.7 5.0 4.9 4.6 4.4 2.9 2.5 A7.1

Rajshahi 2.4 2 5 3.3 4 .3 6.3 5.6 5.4 5. 3 4.9 4.6 2.9 2.4 5,04

.KhuLne 2 2.7 3.6 4.8 5.8 5.5 5.9 5.8 3.1 4.8 2.2 2. 9 53.0

Syvllet 2.7 2.8 3. 2 4.2 4.6 4.3 5.0 4.6 4.3 4 . 3,2 2.7 45.9

Dacca 2.5 2.7 3.6 5.0 5.3 4.3 5 . 51.5 4.8 4.5 3,.2 2.7 50,7

Comr:lla. 2.4 2.7 3.4 4.6 5.5 '5.3 5.9 5.5 5 1 4.9 3.1 2.5 50.C9

Barisal 2.7 2.7 3.4 4.6 5.4 5,1 5.1 4.8 4 .9 3.,2 2.7 49..6

:y Erom. Tables 8 and 9 BAN'GLAD3ESH - SECTOR STUDY

ESTIMIATED MONTHLY EFFEC'TIVE PRECIPITATIlDNj(Inches)

Gc.141i ng C2o d Jan Eb Mar Ar u~Jl c e. Ot N~aN ov

Ra'nap'r A 0.,57 C.53 1.11 3.40 12. !.4, 12. 1::17.6 l 2 3.24 21I. 07 6.71 0. 28. 0 .0O4 8C6.1 Dina1pur B~~~ Ofl5 0 53 1-.11 3.40 97" Dinaipur~~'.w~~~~~~~~ ~~~~~ ±.~~~± 3.40 9.71 ~~~~~~~~.33 :4. 15S 1,0.5-9 8.82 5 3 i 0.23 0.104 70. IC C 0.34 0.3 2 O-67 2.0a4 -7. 116 06 .4 66 .3 0.7 0C 16

&vCjir a. A 0. 50 0.48 0_96 ~2.2C1 7.0O6i n.4, 1 3 .68 13.48 9.66 65.76 0,.36 0.07 8~. 2 5 p~ba E 0.50. 0.8 .9 22 5.5 04 10. 94 10.78 71.73 ).41 0.3 0.0" 55.31 C 0 30 0_2 9 0.58 1.32 4,2, .2, 3.21 0.309 5.80 406. 0.2 .6 4.3

7. hi A O.5G 9.31 0.91 1.37/ .7 1.j. 5 2.zu 160. 02 8.0 4 .Si2, 0~., 9 Z. 0 .56 u3.5 1 0.91 1 .37 .. *3.705 91 9.35 a3.02 6.46 .94 0.39 0 .0 43.. C 0.3t 0 .311 0.55 0.3'I'2 2.5 6 0~ 7.24 6.01 4.0.5 2.95 0.23 0.-05 32.2 2

4Iymensinerh A. 0.51 0 .70 2.01 4. 91 128 2 9.7,:z7 16 .52 17.31 1 3 .653 .435 0.9 0 .09" C.64' O0. 51 0.'70 2.01 4. 92. 10 .2S 1.5 I:3 .4 G 13 . 8 1.C 90 593 0. 5 3.,09 708 C 0.31 0 .4 2 1. .21 2.95 7.7 1 -25Il 1.0 0.. 39 8 . 18 4. 47; 0. 3 0 O~ 573

Sylhet A. 0.A4O 1 30 4.40. I 'L 9C /23 2 ' C,C 2 .00 24 30 2 0.20C 1 0 .60 1 .40 0, ).1 033 -71- E 0.40 330 4.4 0 11. 90 1 8 2 4 20.80 19 AI16 .16 8.48 1.40 0.- 10 12 91 C O-2 0 0 . 3 2.64 7J _3 a"71~ 1, C2 15.6El0 14. 13S12 .12 6 .36 0 .84 0.06 942 i

ca D A 0 A 3 0 84 1.30 ' rc 4A s L2 .84 13 58 93 5.74 0. 94 0;.09 0.4 4.0 ~1.27C 0 'i .46- .59 0.94 0.09 6 9

A 2omilla ~~~ ~~~~~~~0.313'("0 107 () -u.i 91 -~ Q'2 2- i.5 7 1. 0.S09.CC 574 I' S .T@ . .- i ' Ttv ¢5 ' - :2 tH z tU,''. v da FA3@;d' ->(' '; _- l- _-{tf > ;C7:1 _t; q Il)TT g'D 3-s>8 J T - rv'2zS& 7,/ -D jt ,-r)^i3t _-- ? -S l: :*_(l2tlC.

L)° 4-ib-r. _ ,L ''-12D >-'

C~~~~~~ 0 ~~~~~~~~A ; x;tK-.7 _ 7 -I ~~~(-+2,A (''I

C' 'T I' r ) ~ C ; ; ;' ~C ( 1 , ,[ , ,¢ C E 3 Jw * ,W 0 . L ;1.eL l.;iJ_v' ' -L 2 L r. t C; a r r t71T .7.' '3' bi,--)° '9'

C,' T7 , . O ) t g 6i5 _I 8 Oo _ . 3 8B 5 C,I8 9 Z c)1S. , 0 3Z O

1 1' 75.1 -st j1 S,T v1 , 9! dL , T8 9 ' ,i O' , 7C

5l '-C | ; C; '° 'r 6 () 7 i'6 c xT 98 2T < : E7'6 c]9't 3§3 L ftO o r -. p

is'| 9 0' Ti7O ' 19 l7 () 1 9 £ 9 tSSi8 ZLLT Fv T n ) o " c ,

E Z .|OI-Z'..,8L 67 [ L OS Z 6 * S I7,_L1 I 8 £ 8 9 ,T7 C 'C I ,

617 |9 C 0 -TC9 () .9 9 17 S 8 Z'L ZA C )Xt ,*t LS * T S L 0- Z£ 0 0

0 T C _ 0 __ x ; ' Ti7C,7 t' 1L L 0D 9 T cL 5*.S.;-. Z ,CIT T 7t S fi S O 9 S O

6 Z t. | '9 C O ',- 2C)S- 3 T7 LC 9 t, L ' i c, co ; . ot C i !.'8 £-I7rJ o £ () Fj * r 5 1 'L Z ' L 9 16 - . .'£ L. 'I r( S '. O (3 W-'

S~~~~~ 93 0- C tr o 6 of8()£ Z O r- 0 c S ()t' -*T/IXj7lsOVwTrl r )'C

1~~ ~~~ :807 0: L § O S -} T 5E -rrLr4 1 C -li -adE 1T;, 7U r +x O, E i;D

L I S 0 C- I.1'7 T9 0 S 77 D- i

_,~~~~~ ._ . El .__ _. . _ _ .______, _:...... T T_. T_.___6

o a -I q C3 S A':EDEL rL r '2IXj [J7 C'l,Tj BANGDLDES1[ - SECTOR SIIUDY

CRIDPPIING PA'TTERN WITH 590% TRADJSPLADIT-BCIR0 USED TO cALcu1TLATE RIEGIOW1I7CROP_ WATh REQUIREMENT'S

'.'s,\t'-. 1 JulyeJune .uu, eet t c . . -.-,

*, T--iboroD 70) 3i) tUSJ t I T-Aiu ! 10, v7 1 0 A 20 1 60 90 5 0 0 unde3'r Pepara.:2Jon 30C wRf e iJ--i<. ,,D 27 | 30 ajir L§-- iPercen~r;ar Paddy 90 90 .0 0 55 1i0 70 910 0 90 90 I ~~~ i~~rea ad 0 r I0

ier,- .. ec_ ze~ .lc r >Pren araticm \%c ea -tnir

T-i- nt-er Crops Area 10 ' 3 .° Area unlde.+r Prep 3rat -n Ar-ea urxder S1DP 10j

I Per--enta- A Jrea 1Cio 100 00 100 5 5 10 70 3( 9 0 10C, II

'ho cryp;:in'z oattectrn is bu ilt up as follouws (-n ez ce--t CcrnrnanC7td a!a)f

Su',)- t o t a 1. ;: intern Cr)ps 10

)./,MD S,i i o::Suwn 7 leio D r tnon)- r-i-C .) i

BANGLADESH - SECTOR STUiDY

CROPPING PATTERN WITH 15% TRANSPLANT-BORO Lt,ED TO C9M iL REC,IOISAL CROP WA R EQ -*7,%of cultivated land)

Borr 1 T- s 213 6 6 0 25 !'~|28mtan ' 513 90 6 0 20 jd dc.ies-. urndwr Prenar-ationo20 30 (O) 50 4 D Mr eaun(r SM'e 2/-,)/ 35 25 -; 4 0 2 F-nddy. Land 15 :35 65 75 70 (60 75 9t0 Q0 90 500 3

u t e r ea I~~~~~~~~~~~~~~2.03 20 0 ca uncer Preparation I 20 1P.rea under SMn'i J 2/ _ 220

71npter Crops A.,rea 45 :L5 - 5 0 Avrea under P ZEpara:n 1¢0 30 25 i ,a.re, undel SMI 20 30 15

c r__rer,>il* rea ccUed ___ 0 _ 100 -9 (J030 9 90 13 102j5

Th.,e cropping patltrr is built up as i.ollowsc1- (in ci?nt of Comoranded Area)

TP-Boro A.

1.-Au s ' 9

17 er.- Crops 'p,

l/ Niimber In brackets ro,- 4'v-o 1.e Co.:nt:.c. n area nerc<- cl s.

-- SoilDerŽietK;.c: J~1cis~x~ra (:u13x10i.:m 4 iioic~':.~ ror J c~ and 2 irx.cne -L 21 nnITl-rice.).., 1) r te

]3ANG]ADESH - SECTOR SrUDY CALC'ULAI'ION OF AVERAGE IMRIGLTION REQUIREMENTS FORI TRA,NSPLANTED RICE EhOR COMILLA DISTRICT - CRC)PPING PATTERN TlNSPLANT BORO; ALSSU-PTION A - INFILTRATICIN LOSS OF 3 INCHEiUS/MCNTH (Inc:hes of Water) KMoth Jan Feb ar IAP May June J'uly Aug Sepl Oct jov r Dec

Boro Area (Fraction) _ 0.70 0.90 (.90 O.45 D.30 T-Aus Akrea (Fraction) Table 16 0.10 0.10 0.10 T-Aman Areat (Fraction) o .60 O.9S0 O.90 0 .60 0.20

Area Under Preparation 0.20 (.10 o.60 0.30 0.30 0.40 Area W:ith Growing FPaddy Table 16 0.70 0.90 ).90 0.35 0.10 0.10 o.60 0.90 0.6CI 0.20 0.30 Area Under Depletion 0.45 0.4.5 0.10 0.3C0 0.1.0 0.20 Total Rice Area 0.90 0 .90 l .00 1.00 0.55 0.10 0 . 70 0.90 0.90 0. 9C0 0.90 0.90

Evapotranspiration(Table 11) 2.4 3.4 !5.2 6.3 7.2 6 .0 6.2 5.5 5 .2 5.3 3.5 2.4 Evapotranspiration + 3" Infiltration Loss 5.4 8.4 8.2 9.3 10.2 9.0 9. 2 8.5 8. 2 8.3 6.5 5.4 Effective Preci-pitaLtion (Ta'ble 15) 0.3 1.1 1.6 5.7 8.1 15.1 13.9 11.6 8.c6 6.7 1.5 0.2 Preplanting ReCUirement 5 .0 5.0 C.0 5.0 5.0 5.0

A 7.4 7.5 6.8 7.5 A x Preparation Areia 1.5 0.8 2 0 3.0

B3 5.1 7.3 6.6 3.6 2.1 1.6 5 .0 5.2 B x Growing Area 3.6 6.6 5.9 2.0 0.2 1.0 1.0 1.6

C C x Depletion Area

Total Field Requirement - FR 5.1 6.6 6.7 2.0 0.2 1.0 3.0 4.6 Total Pump Requirement - FR/O.85 1 / 6.o 7.8 7.9 2.h 0.2 1.2 3.5 5.1

A = 1/2(Evapotranspiration + 3") + 5" - Effective Precipitation B = Evapotranspiration + 3" - Effective Precipitation 1/ Diversion Efficiency is o57, (D BANGLADESIi - SECMTOR STUDY CALMULATION OF AVERAGE IRRIGATION REQUIREMENTS FOR TRANSPIAMTED RICE FOR COMIlLA DISTRICT - CROPPING PATTERN riRNSPLAW BORO; - SSU!PTION B - INFILTRTION LOSS of 5 INCHES/MONTH (Inches of Water) Month Jan Feb Mar Apr May June July Aug Sep Oct blov Dec

Bo:ro Area (Fraction) O.70 O.90 O .90 O. 45 0.30 T-Aus Area (FraLction) Tab:le 16S 0.10 0.10 0.10 T-Aman Area (Fraction) 0.60 O.90 0.90 t).60 0.20

Area Under Preparation 0.20 0.10 0.60 0.30 C).30 0.h0 Area W:ith Growing Paddy Tabler 16 0.70 0.90 'D.90 0.55 0.10 0.10 c.60 O.gO o.60 0.20 0.30 Area Under Depleticor O.h5O 0.15 0.10 0.30). 0Jo 0.20

To-tal Rice Area 0.90 0.90 1.00 1.00 0.55 0.10 (.70 0.90 0.90 0.9( ).g90 0.90

Evapotranspiration (Table 11) 2.4 3.4 .5.2 6.3 7.2 6.0 6.2 5 5 5.2 5.3 3.5 2.4 Evapotranspiration + 5"1 Irnfi:Ltration Loss 7.4 8.4 10.2 11 ,3 12.2 11.0 1:L.2 lo0.5 10.2 ILO.3 8 .5 7.4 Effective Precipitation (Talble 15) 0.3 1.1 .1.6 5.7 8.1 15.1 1:3.9 la.6 8.6 6.7 1.5 0.2 Prieplanuingr Req 1 uirement 5.0 5. 0 5 .0 5 .O 5.0 5.0

A 8.4 8 .5 7.8 8.5 A x Preparation Area 1.7 0D.9 2'.3 3.4

B 7.1 7.3 5.6 5.6 4.1 1.6 3.6 7.0 7.2 B x Growing Area 5.0 6.6 7 .7 3.1 O.4~ 1.4 2.2 1.4 2 .2

C x Depletion Area

Total Field Requirement = 11 6.7 6.6 8.6 3.-1 0.4 1.E4 2.2 3 . 7 5.6 Total Pump Requirement FR/0.851/ 7.9 7.8 10.1 3.6 0.5 1. 6 2.4 4.4 6.6

A: 1/2(Evapotranspiration + 5f) +5') - Effective Preocip:Ltati-on B = Evapotranspiration F 5" - Emf,eL,V :mrrv±it.t 1/ Diversion Efficiency is 85%

co. BANGLkDESH - 'BECTOR STUDY CALCUIATION OF AVERAGE IRR:[GATION REQUIREN4NTS FOR T'RANSPLANTED RICE FORt COP[ULA DISrRI C -ltOPPING PATTERN - 90% TRANSPIANTED BORO; ASSUPTION C - 50,E and 75% FIELD EFFICIENC:IES (Inches of Whater) lMonth Jar eb Mar I ADr I May _ Jiune July _ _l Oct Nov Dec Boro Area (Franction) 0.70O 0.90 0.90 oi4s5 0.30 T-Aus Area (Fraction) Table 16 0.10 0.10 0.10 T-Aman Area (Fraction) O.60 0.90 0.90 0,60 O0.20

Area Under Preparation 0.20 0.10 o.60 0.30 0.,30 o.Lo Area With Growing Paddy Table 16 0.i70 0.90 0.90 0.'55 0.10 0.10 o.60 0.90 O.60 0.20 0.30 Area Under ])epletion *) 0.45 0.45 0.10 0.30 0.140 0.20 Total Rice Alrea 0.590 0.90 1.00 1.00 0.55 0.10 0.70 0.90 0.90 0.90 0,90 0.90

Evapotransp:iration (Table 11) 2.14 3.4 5.2 6.:3 7.2 6.o 6.2 56-5 5.2 5.3 3.5 2.1b 60% Effective Precipitation 0.2 0.7 0.9 3.14 6.1 11.3 10.4 8.7 6.5 5.0 0,9 0.1 (Table 15) Preplanting ReqLtirement 5.0 5.0 5so 5.0 5.o 5.0

A 2.2 2.7 4.3 2.9 1.1 0.3 2,6 2.3 Ax (1/2 Prep. Area+Growing Area) v NFR 1.8 2.4 4.1 1.6 0.1 0D.2 0.9 1.2

B =;Field Req. = NFR/'0.51 3. 5 4.8 8.2 3.2 0.2 0.4 1.8 2. t 2 C = Field Req. = NFR/0.75 ' 2.14 3.2 5.5 2.1 0.1 0.3 1.2 1. 6

D -- 5 7- r- ~ - ~ ~~-.y~ ~ ~~-57-- tT7r~ 6.T- E (Prep. Area) x 1) 1.2 0.7 1.8 2. l F = Total Field Req (TFR) (B+E) 4. 8 4.8 8.9 3.2 0.2 0.4 3.6 4.8 G = Total Field Req. (TFR) (C+E) 3.1S 3.2 6.2 2.1 0.1 0.3 3 0 4.0 Total Pump Requirement ' I - F/O.85J/ 5.6 5.6 10.5 3.8 0.2 0.5 .2 5.6 II = G/0.85Y 14.2 3.8 7.3 2.5. 0.1 _ 0.4 3.5 _4. A = Evapotranspiration --Eff'ective Precipitation (60%) D = 1/2 Evapotranspiration + 5 - Effective Precipitation (60%)

1/ Using a Fie:Ld Efficiency of' 50% 1/ Using a Fie:Ld Efficiency of 75% _/ Diversion Efficiency is 85% BANGLADESH - SE'TOR STUDY CALCULATION OF AVERAGE IRFLIGATION REQUIREM43NTS FORNON-RICE CROP AND FULL-CROPPING P'ATTERN FOR COMILLA DISTR]:CT - CROPPING PATTERN - 90% TRANSPLACr BOFLO, ASSUMPTION C - 50'% FIELD EFFICIENC'Y FOEL RICE ANDW% FIELD EFFICIENCY FOR NON-RICE CRLOP

Month Jan Feb Mar Apr May June July Aug Sep Oct NoDv Dec_

60% Effective Precipitation (Table 15) 0.2 0.7 C.9 3.4 6.1 11.3 lO.4 8.7 6.5 5.o 0.9 0.1

Other Rabi Crop Area (Fraction)o lable O.L0O 0.10 0.10 Area Under Preparation 16 0.10 Evapotranspiration (Table 10) 2.0(D 1.8 1.L4 lA. Preplanting Requirement 3.0

II - A (Preparation Area) B 1.8 0.5 1.3 II - B (crop Area) 0."? 0.1 0.1

Net Field Requirementl/ 0.2 0.1 0.1

Requirement at Field Heacd. 073 O.l 0.715

Req. at Head of Fiel1d haLnnel (Ass. A) Non-Transplanted Rice- 0.3 0.2 0.2 Transplanted Rice (3" Inf'. Loss)-, 6.o 7.8 7.9 2.L4 0.2 1.2 3.5 5.-4

Total Requirement at Head of . 7. _ _ 0_. Field Chaanrel (Assumption A) 6.3 7.8 7.*9 2 . 0.2 1.2 3.7 5.6

Pump Req. for Rice (Assumpticon C)_/ 5.6 5.6 1c.5 3.8 0.2 0.5 4.2 5 .6

Total Pump Requirement (Assumption C) 5.6 10.5 3.8 0.2 0.5 5.85

_ .. _…_ _. _ In Inches of Water A = Preplanting Requirement + 1/2 mon-Lh evapotranspiration- 60g Effective F'recipitation P = 7vAQnnf.r1nni ratinn - Anl.ffpptiv 11- n+-cn l/ Net Requirement to be met by Irrigation 2/ Net Field Requirement /0.75 7/ Requiremient at Fi-eld Head /0.85 Ti/Last line of Table 18A for TranspLanted RiLce '/ Field Efficiency for Transplanted Rice = 5()%; Diversion Efficiency = 85% (second last line of Table 18C) BANGLADESH - SECTOR STtJDY

CAL(ULATICN OF AVERAGE IRRIGATIONI REQUIREMENTS FOR TRANSPLANTED RICE FOR COMILLA DIlSTRICT - CROPPING PATTERN - 1lRANSPLANT BORO; ASSUMPTICIN A -- INILTRATIO!N LOSS OF 3 INCEEN9m0TH (I[nches of' Water)

Month Jan | Feb I Mar Apr May June | u; Aug Sept Oct ]Nov Dec

Borc' Area (Fraction) } 0.15 0.15 0.15 0.15 0.10 T-Aus Area (Fraction') j Table 17 0.20 0.60 o.60 0.60 0.25 T-Arnan Area (Fraction) 0.5(0 O.90 0.90 0.60 0.20

Area. Under Preparation ) 0.20 0.30 (0.10)2 0.50 O.O4 0.15 Area With Growing Paddy Table 17 0.-15 0.15 0.35 0.70 o.60 C0.25 O.5C c).go o.60 0.20 Area Under Depletion J 0.05 0.10C C'.35 0.25 0.30 O0 40 0.20

Total Rice A:rea 0.15 0.35 o.65 0 . 75 0.70 0.60 0 .75 O.9C) 0.0go 0.0go 0.60 o. 35

Evapotranspi:ration (Table 11) 2.4 3.4 5.2 15.3 7.2 6. O 6.2 5.5 5,.2 5.3 3.5 2. It Evapotranspiration + 31? Infiltration Loss 5.4 8.4 8.2 9.3 10.2 51.0 9.2 8.5 8.2 8.3 6S.5 5.4 Effective Precip:itation (Table 15) 0.3 1.1 1.6 5.7 8.1 15.1 13.9 -1.6 8.6 6.7 L.5 0.2 Preplant:ing lRequ:irement 5.0 5.0 5.0 5.0D 5.0 5.o

A 8.1 7.5 4.0 7.5 A x Preparat:ion Airea 1.6 2.3 0.2 1. ].

B 5.1 7.3 6.6 .3.6 2.1 1.6 5.0 B x Growing Area 0.8 1.1 2.3 :2.3 1.3 1.0 IL.0 C C x Depletion Area

Total Fieald Requirement = FR 0.8 2.7 4.6 2 .5 1.3 1.0 1.0 1.1 8 Total Pwnp Requirement = FR/0. 5' 0.9 3.2 5.4 :2.9 1.5 1.2 'L.2 1. 3

A = 1/2 (Eva]?otranspiration + 3") + 5", - Effective Precipitation n Ly - O J. _ ._ U_ ._ A_- .4 ._.6._ OtJ- V. - 13 -4 -LkJ4-4 AJA_4- lJ Diversion Eff'icieincy is 85% g/ Number in brackets not to be counted iLn area perce;ntages BANGLADESH - SECTOR STUD'Y

CALCULATION OF' AVERAGE IRRIGATION REQUIREMENTS FCR TRANSPLkNTE) RICE F(DR C(IILUL D[STRICT CROPPING PATTEBRN -1 TRANSPLANT BORO; ASSUMPTION B - INFILTRATION LOSS OF 3 :[NCIUMNTH (Inche s of Water) Month J'an Feb Mar Apr May June July Aug Sept Oct Nov Dec

Boro Area (Fraction) ) C .15 0.15 0.15 0.15 0.10 T-Aus Area (Fraction) ) Table 10 0.20 0.60 0.60 0.60 0.25 T-krian Area (Fraction) ) 0.50 0.90 0.,90 0.60 0.20

Ai-ea Under Preparation ) 0.20 0.30 (0.10) 0.t50 0.140 0C.15 Area With Growing Paddy ) Table 17 0C.15 0.15 0.35 0.70 0.60 0.25 0.50 0.90 0.,60 0.2,0 Area UJnder Depletion ) 0.05 0.10 0.35 0.25 0.,30 0.140 0.20

Total Rice Area C0.15 0.35 o.65 0.75 0.70 0.60 0.75 0.90 (.90 0.,90 0.60 C0.35

Evapotranspiration (TTable 11) 2.14 3.14 5.2 6.3 7.2 6 .0 6.2 5 . 5.2 5. 3 3.c 2.4 Erapotranspirratiorn + 5j1 Inf iLltratiori Loss 7'.14 8.14 10.2 11.3 12.2 11.0 11.2 10.!5 10.2 103 8.5 7 .4 Iffective Precipitation (Table 15 '> 0.3 1.1 1.6 5.7 8.1 15.1 13.9 11.t6 8.6 6,7 1.5 C0.2 Preplzntirig Requirement 5.0 5.0 5.0 5.0 5.( 5.0

A 8.1 8.5 5.0 8 .5 A x Preparation Area 1.6 2.6 0.3 1.3 B 7.1 7.3 8.6 5.6 14.1 L.6 3..6 7 .0 B x Growing Area 1.1 1.1 3.0 3.6 2.5 1L.4 2.2 1.4

C x Depletion Area

Total Field Requirement = FR 1.1 2.7 5.6 3.9 2.5 L.4 2.,2 1.4 1.3

Total Pump) Requirement = FIo.8a" 1.3 3.2 6.6 4.6 2.9 L.6 2.6 1.6 1.5

A = 1/2(E'vapotranEpiration + 5tf) + 5tt - Effective Precipitation B - Evapotranspiration + 5" - Effective Precipitation , ' Diversion Efficiency i.s 65% NuLmber in brackets not be counted in area percentages

I-i EANGLADEMH - SECTOR STUDY

CALCULATION OF AVEBLAGE IRRIGATON ,UIREMENTS FOR TRANSPLANT-ED RICE FOR COMILLA DISTRICT- CROPPING PATTEMRN- 15RANSPLANT BOCLROASSUMPTION C - NAND 75FILD EFIFICIMNCIES (Ircheh8 of Water)

~:or,

r. \rtea (Fr.acc:t-ion ` C. 1.5 0.1 5 l5 . 1.5 0 c h S ep | T1&''('?.( -A;;. 1 ^c-:ll) Tra"bic 17 U O6t O.6 1'i G 2J - i. .rea T? ac t ion, -., . 0.,. 9 Li 0. 610 (. 2

.' t:-:-nSrRJ ar PrtDara' ior~ ' 0 . 20 . O 0 (O 10)5 0. 50 0. 0C17 Ar :a 1%UiLh CGrox'TJn QPaCd>y Tal-ble- 17 0. j 0.15 0.3* 0.7;, 0. i 0.25 .50 0.90 C. 50 0.2'.- IcaL UrJ.".er TDe>letioa .G ij 1 O s.35 0. 2 5 0.30 I. 4;0 0,1 '2tOta 1 ,Ri Ce Area 0.15 0.35 O. 65 U. 75 0.70 0,6f; 0.'75 (1.90 0. O.050 ° (. C,.6 (I - 3 …_ _- _- _--.__ _.__ _ I -a , t ran ; 'i*:a t i on (Tabl e 1 L) 2.4 3.4 5. 6 . 3 7.. 6.0 f.2 5. 5 5. 2 5.3 3.5 2. Z,

I E17fet .'r :i tatio e Tab ]5) 0. 2 G, 7 0 )4 . 4 15.1 11. 3 10. 4 3.7 6e6. 5 , . ;.x Ptnopiaist.t; L *\no J;it em.en t 5. C;0 | r . 5.0c 5.O

A 2.2 2.7 ..231 9 1 .3.. 2. A'l x1 {1!' O) ^P-x. krea -' 'roxwiiig Arca) = R, Q.70.9 2-2 2.1 0.7 0.2 0.5 2 -…_ _.~ .-. _- _- ___ _ 7 __2__ _ . _ _ TL11.; /.C)ri 5'L/ ¢ 6 K,>r.- -. . | ' .

C - 'iel Req. = NFF/0.75' 0.4 0.9 2 . 2.3 ID.9 0. 0C, 7 C.

0.0 'n.7 4.8 (Prop. Ar2a) x D 1e2 2 . 0.1 . ' 1 -ri-.: ' tn':i ex' Rec.±. (rr'R)=m-E{5G4.+C t. ( 2,2.6 6.4. 4 .. 1.4.0.6 1.;C ,

r,= r.<,. '' Fi.e7d Req. (TFR)~(C~-( @ 0..4o 2.12..9 4 ,1.7 2.9z .9 0.3IJ 0.7 f.$

0- 3=5 -J ''0.0 0.7 5.1 S.5 35.1 1.6.t 07.5 1.2 i.J. , ,;1 . , 5 2Z 3*; 4 0.6:. _0. . s < . . 0 2 0. C;

,A, '-r'-zLv4--r7.D atiur; - ('EI ect±vn P.:c.i;it.aici '.60'',

DTafl&irat3rL = ii. .)co + 5 -piie 2c.tpit::i.-. (60%)

J FField (.dai',F...Icien .- ' J.- 50%/ sfj.ng- a Fi,-.d :;>;ticiecv ^ 75%

;Js'-,tU ir. ickr: ntist: e cc'iintr.4 .flni. s ?rce eflcact:. BNGLADESF1 - SECTOR STUDY

CAlLCULTICK OF AVERAGE IRRIGATION REQU]EMENTS FOR NON-RICE; CROP AND FOR FULL CROPPING :PATTERN FOR (,OMIILA I)ISTRICT CROP'PING?PING- 15 T I T BOTR. 90TFI EFFICIENCY FOR UCE AN'D 75MEELD EFFICIENCY FOR NON-RICE CROP (]:-nchE'S of' W`atei; ______.______nce _f~tr ______- Munth… _ Jan Feb Mar Apr Ma June July Aug Se t , Oct Nov Dec

60% Effective Precipi-'ation (Table 1i) 0.2 0.7 0.9 3.4 6.1 11.3 10 4 8.7 6,.5 ).O 0.9 0.1 Jute Area (Fraction) 1-7 0Tale0.20 0.20 0.20 0. 20 Area Under Preparation J T 0.20 Evapotranspiration (rable 13) 1.4 2.2 3.8 5.2 5.6 Frep_lPrep:Lanting Requirement _. 3.0 ______A ~~~~~~~~~~~~~3.0 r - A (Preparation Area) o.6 ]B 1.3 0.4 II - B (Jute Area) 0.3 0.1 Net Field Requirement 1 /O.6 0 .3 0.1 Otheir Rabi Crop Area (Fraction)S. 0.T15 0.15 0.30 O.42o Area Under Preparation Table .7 0.10 0,30 0.25, Evapotranspiration (T.-ble 10) 2.0 3.0 1.8 1.,4 1.4 ]PrepLanting Requirement 3.0 3,O0 lA- - , ______. . _ 22.8 3.6 :[ - A (Preparation Area) o.,8 o.9 13 1.8 2.3 o.,5 1.3 :[I - B (Crop Area) O.8 0.3 0.,1 0.5 Net Fielcl Recluirementi 0.8 0.3 O.,9 _ _4 Total Net Field Requirement _ 0.8 0.9 0.3 0.1 o.4 1.4j Requ:irement ait Field He&ac, 1.1 1.2 O.?4 0.1 0.5 1.9 Requirement at Head of Fi-eld Channel Non-Transplanted Rice 2/ 1.3 1.4 0.5 0.2 o.,6 2.2 Transplanted Rice (3" Inf'. Loss) 4/ 0.9 3.2 5.4 2.9 1.5 1.2 1, 2 1.3 Total at Head of Field ChannelAss tion_ 2.2 4.6 5.9 3.1 1.5 _ 1.2 1,8 ___ F%r Req. for Rice (Assumptior C) 0.7 3.1 7.5 5.1 1.6 0.5 1.2 1.1

Tiotal Ptp ReqEirenerrt(C 2.0 4.5 8.0 5.3 1.6 _ _ __ . _ 0.5 1.8 3.3

= rP~n nMnc Ppmini rpmrnt.: 1/9 monfnh Pvanotrnnsnirat,ion - 60c Effective PreciDitation H B = Evapotranspiration - 60% Effective Precipitation 1/J Swun of Net Field RequLirenLents N 2,/ Total Net; Field Requirement /0.75 " 3 Requirement a.t Field Hea. /0.85 I Last line of Table 1"A for Transplanted Rice Field Efficiency for Transplanted Rice = 50%; Diversion Efficienc.y = 85% i(second Last line of Table 15C) BANGLADESH - SECTOR STUDY

-IRRIGATIIKLREQURMMNTS FOR TRANSPLANTEED RICE FOR 5 DIST'RICTS ASSUMPTICI A - INFILTRATICN LOSS OF' 3 INOH7cINTH

MONT'H _ Jan Feb Mar APL- May Jue _ July Ag SepEP )ct Nov Dec Total

CROPPING; PATTERN _ 90% T R A N S P L A N T B D R 0 (see Table 16)

(I nches o.; Water)

Comilla (Table 18 A) 6.0 7.8 7.9 2.4 0.2 :L.2 3.5 5.4 34.4 Khulna 6.0 G,2 8.7 4.2 0.6 1.2 2.5 4.:1 5.6 39.1 Mymensingh 6.0 5.3 7.6 2.7 L.4 4.1: 5.5 32.6 Rangpiur 5.4 5.8 8,0 3.8 i. 9 4.:2 5.3 34.4 Sylhec 6.2 .5.6 4.4 3.o 5.8 26.8

… CROPPING PATTERNI _ l;7% T R A N S P L A N T B 0 R 0 (see Table 17)

--- (Inches of Water) --- Comilla (Table iL9 A! 009 :3.2 5.4 2.9 1.5 1. 1.2 1.3 17,6 Khulna 0.9 2.8 5.9 .5.3 3.8 1. 2 2. 5 1. 4 -1.4 25.2 Mymensingh 0 2, 7 4.9 3.4 1.4 1.4 1. 4 16.1 Rangpur 0.8 :2. 7 5. 4 4.8 2. 8 1. 4 l.3 19.2 Sylhet 0.9 2.9 3.6 1.3 1.4 10.i

BANGAIIE;SH - SWCTOR STUDY

IRRIGA'kION REQIREME?NTS F(' TRANSPIMNTED R:CE FO DISTRICTS ASSUI'TIO& B - INF31TRATICN LCSS CF' FIVE INCHESCTH

''Jan Mar A.. .y *_e JebJuly Aug Sept )Oct No; v De. Total

(7Cr? TNC PATTRNy - 90% TRANSFIT BORG (See Table 16)

-- r.lc.hes o .Xe)-

CorLi -.l I (Table 18B) 7.9 7.8 10.1 3 . (, .5 1.6 2.L 4.4 6.6 44.9 3Wilu.a 7.9 8.4 10.9 5.5 ;. i.'} 3.3 3.9 4.9 6.8 53.5 7.9 8.0 9.4 4C0 2.2. 2.8 4.9 6.7 43.8

,F 7._ 7.9 1 _5i ! A A 3. 3. 5.1 6.5 S-ct 1.; 18.178 r1.6 0.9 4.6 8.5 6. 5

.*-pyt,raz-i;[_ 5 ;-. tzv& - ~15%T'ISPLANT 13ORG (See Table 17)

(Table 19B) 1. 3 6. 5 .C . 1 . 6 2.6 1.6 1.5 23.9 1,3 3.I = 7.1 6. ' 2 .1 33 3. 9 i.9 1. 5 . 5. 7 '. y.sirg .4.. 1.9 1.5 22,8 R-- 1 Co 23 s -~~~~~~~ J * =6 > tr-! 31.:'57<>te>r*8ta^rNi/5~~~~~~~~~~.3 1 1 ,52 7 .

1/.,Th. . _ rei 4C. O. t . 3 : 3. _tI r ' , , _ . .. _ _.____ ...... ___ _ ...... _ ._ _ ___ . __ _ __._ . _ _ ...... __ ... _ . _ __ _ _ ...... _ _ __ .___ j hF^esic ...... 3 iZ..A,l)eio ;t.tp--e'rt. ;.-.l.SeflT~s (1-.,::vs-;'t;-...... _ri,-.- e BlNGLADES - SECTOR STUD

IEGATION EQUIEMENTS FOR TRkNSP:LAnTE1 DRICE FOR IlVE DISTICCTS ASS1JNPTrON IC - '13FIEUD EFMICIKCY

' oN'-il! Jar. l'_o ML: Apir Mayt i.n Jily Au:, et &Z t Ncv '!ec

CROPPING PATTERN - 90% TRANSPLANT BORt) (see Table 16)

*(lnchels c.9';f ' )

('0ille (Table 18c) .5.C. 5 i0. 5 3.23 2 C).

Khu1t-.l1T< 6.1 6.6 1:L.6 6.1 C.;4 Q.,5.1./+ '.14 ' A.0.5 0 ,7lv3eSl eT; Si i1 f)9 / {Ib i li) ) . 4 . I. . i . 6 R .

,$mew5S. s- IsI h ? 4,>6. 0 ?.X 5. F)).O 3 . -.

'jy Lt;('t 6- . /+ ) . o ~ ~~~~~~iQ. 0 4 .,5 . _. 3't.f 6 4 . 6 . 4,, .

CROPPING PATTERN - 15% TRAUNSPLANT BOR) (see Table 17)

- (>'.ch>;^ ¢,r >,lC er)-

Conilla (Table 19o; 0.7 3.9 7.5 5.1 .,2 i 0.' .] 2i.

1uLluina, 0.9 :3.4 3.J1 8. ,._J .1/ .12 s.

'yii'ensingh 0, 7 3.2 15.7 5. 0).7 1 .'6 1'.5 .

Rangpur 0). 7 :3.1 7.3 7 . 1.6 1.4 1.5 23.2

1ZIe t C. 9 3. 1 4.6 1. .5. 1..

i/ :1heor4tica11y needle LG ncmet preplanting requirernceants, cut m n oraybe Cc i-. pract.c-.| Y 1c e.~~~~~~~~~~~~~~~~~~~~~~~~~~~~~' BEAKOADS - SECTOR STUDY

IRRIGATION FMUIREMEXTS FOR FM CROPPIJNI PA'rM MROS FVE _DISTRICTS' ASSUIMPTION A - INFLTRTIW0ELOSES I=CHS73THjOR RCE ICROPlS A-IfF TI-ES EFMIECNIC FOR MON RICE CROPS

?MONTU JAN FEB nMAR A9P. M -t JUNE JUTLY AUG SEPT OCT NOV DEC TCOAL

CRCIPPINIG PATTEARN - 90% TRANSPLAINT BORO (see Table 16S)

of Wqater)---

,omilla 6.3 7.8 7.9 2. 4 0.2 1.2 3.7 5.6 35.1

Khulna 6.3 6.2' a.7 4. 2 C.- 1.2L/ 2.5 4.3 .5.9 39.,9

Nyivensingh 6. 3 5.3 7.6 2. 7 1.4 4. 3 5. 7 33. 3

Rangpur 5.8 5.8 8.0 3.R 1.9 4.4 5.5 33. 2

Svilet 6.5 . 6- 4.4 4.1 7.L1 ?

CROPPTNIG PATTERN - 15% TRlNSPLANT B)RO (see Tab:Le 1?) -(Inches of Water)--- Coaii1-a 2.2 4.6 5.9 3. ' 1.2 1.8 3.5 23,

KhuThtr.a 2.3 4.5 6.4 5,9 '.' 1.2 2.5 3.1 3.8 34.1

sAvnUle--s irigb 2.2 4,4 5,2 3. i,4 3.1. 23,7

~.zangnu. 1. 4.3, 5.9 5.4 2.8 3.1 3.5 26 19

,,9?1het 2.3 4.3 3,. 1 3.8 *,

14 4 ...... :!s;'.-.he !etrl.. . y-.r! >-4..ns nr1.n s9t,-,>, r e . i li.. BANGULDESH - "SECTOR STIUDY

IIRRIOATIO)N RIQUIRLENMETS FOR FTULL CROPPING PA'TTERNS FOR FI'VE DISTRICTS ASSUMPTION_C5?5 E TKM=1%7ffET~ CROrS- -AN! 7 W ELD EFFICIENCY FOR NION-RICE. CROPS

CROPPING PATTERN - 90% TRLANSP'LANT BOBO (siee TAble 16)

c.~ ~~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~~~~~~~~

CROPPING PATrTERN :L%1 TRANSPLANT BORO (see Table 17)

2, (, - - .- , T,

iv r ~z-, ~~ ~ ~ ~ ~ ~ ,~j '4Vs, I * .

8 L.; - ~16 32.i 3.7

j*-.1-" A ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~1~~~~~~~~~~~~~~~~~~~~~~~~3~~~~~~~~~~~~~~, 3 -.

T.-teoretica`to 1,1-et iv -.2 d -P. -r.-actice.- BANGLADESH - SECTOR STUIY

-CLUMLATION O:F AVERAGE IRRIGATION LOSSES TO GROUNDATER FOR COMILTA IlSTELCT ASSUMPTION A - :MFILTRATION LOSS OF 3 19CHE,SNETH FOR 'RICE CROPS AND 7 FIfLfl EFICIE FOR ON CE CROPS

CROPPING PATTERN: 90% TranspLant Boro 15% Transplant Bloro ___Talble 6 5see Table i17 MDNTH: FPeb Mlar Apr Feb Mar Apr ---- (Inches of Water)---- Rice Field Loss T7 re-aratin + Growing Area C'.90 0.95 0,595 0.25 0.50 0073 (Fraction) PGA X L. 8 1.62 1. 7. O..9 0.45 0M0 1.32

Non Rice Field Loss =eLd l7=d =equirement J 1,2 0.4 O; FHR X 015o 1 0.18 0,06 0,02

Field Channel Loss Ts-

Tot,. Irr. Losses to Groundwater 2.44 2.54 1 24 1.11 1.58 1.67

Percent Loss of TctalInput 31 32 52 24 27 54

1/ Tables 18A artd 159A _ZA1/2 _ ejratlon+ Gw3iRLce 1 X_ LX_16 3/ Table l9I) _%f% of Field Head - Rernit.- 15% o i 5/ I'able,s 18D arLd 159D o/ 70% of 15, of- ToiAl Pump Reqiiremrent -l.5% of TPR. BA]NGLADESH - SECTOR STIJ1D

CALcuLATION OF AVERAGE IRRIGATION LOSSES TO GROUNDIATER, FOR01COMLA DISTRICT A 5[s 2 S 1 = C 5 1 w E!i=l) EFfICIENC! F NON-RICE CROPS

CROPPING PATTERNs 90% TrasLant Boro 1%Tramsplant Boro (8et3 Table L6) see Tabl.e17F DNrTH: I. e&

---- (Inlches of Water)---

TFR 2K '2,. 144 2.: 0,4L422 A9.J

r. ic r ie .Lo,0s- '

Fil 0 .13 JC'~

FleiS ;h 1/ -1 e s .Los S ail^e,en-3(-1; -^-2 jl S z ,. -. ' CJ,7 cl I eul4. RFeq]rement 5 4, _-R._._ ,. .1 _,_ _ _ .... 0_59 .

Tot , Ir ._ io sess to . . 3 9 . ,. . .. . ci

*e rcec-.7, lo:rs o; TiotaL 3hu'36 4

J/ Tablets 180e and 1os0 -/60% cif 50% of' F'eld Req. of' FR .30% 3/ lables 19D H Wd b0% of 25%, ot Mleild hieaCa keq. = >7 r 5/ Tables 18D and 159D / 70'%of 15% of Total Pi.uip Requirement = lCI.5% of TPR ]BANGLADESH - SECTOR S y¶JDY

CALCULIATICN OF NON-BENEFICtAL EVAPORATI[O LOSSES FROWM .APPLUED IRIGrATICN FOCR CCI4ILLA DISTRICT ASSUMPTIM A - IDFILTRATION LOSSC, INCRI5!I FCIR RI CE CROPS AIND 75% YIFELD EYKICIENtY Ji'OR N[ON-EITCE CROP'S

Ci<0? PlUG PATTERNs 9 traplant Boro i;% TpaMdant, 3Boro (iFl1e-e e Tabble_1 1; .N-TI1N. F E13 a; -LE;'-' ;'

L/2 eo.naratiort + Growing Area 1/ 090 5 .9' 0,5 -50 0.'3

FGA X 0.0.6 / 0.:5 0.5 3.3 C,344

Vor. R FieldPi:e Loss !-: ed -Head R.o:iire.nent 3/ 1O. 0.5 0.1

'I ie:id C;hanel .c.p s Total Pum.nk Requirement W 7 8.9 7. 2 4.6 3.:i T2fl> X 0).045 6/ 0.35 .11 0.21C 0.:27 0.:14

T'ot. Non-Ben. Evaooration 0. 89 .- 93 0.14, U.l2: 0.59 C, 59

'ercent'Loss of Total I.iput I1 ,2 9 10 19

3./ Tables 1BA and 19A g/ (1/2 Prepaatioe + awving RLoe Area)l I 3I 0.2 3/ Table 19D 14/ 20% or 25% or Field Head Requireument - 5y. of FHR %/ Tables 18D ard 19D 6/ 30% of 15% o.f Thtal Pwmp Requaireuent - 4.,5% of TR ]BANGLADESH - SECT'OR 'iTUDY

CALCULATION OF NON-BEIEFICIAL E3VAPORATION LOSSES FROM APPLUED IRRIGATION FOR COMILLA DISTRICT ASSMJPTIIDN C 5(% [ELD EFF:ECIEIICY FOR RICE CROP'S AND 75 FIELD EFIFICINCY FOR NON--RICE CROPS

CROPPING PATTERN: j0%jITransplant Boro 15% MLans2int Boro

MONTHU D .Feb A

T ' :<.:.. A:. .F . .;t / 4.i8* .L ,, ,.. ~'~-:2/ ( : ' ? 2

Ncon P1c ei.edT oss

~i~d ''?~U~rFc~ meric3/ ~*. ~ *4

_F,.. _ .-Ce_'.:!'; .'_ _-_..-'- - .' ?~~~u D. C.~

TcL.i iu:w. r6 5.6 I.Xi i - .: , '5

C.; ) ' ; ' i e.)- C-C,;;., i, I), u.'

7't.c•c n .Li ; o' Thtr71 Ii'kXi: 13 12' ? JO): L

-1/ Tables 18C and 19C. 20% of 50% of Field Req. - 10% of FR V/ Table 19D §/ Tables 18D and 19D 6/ 30% of 15% of Total Pump Requirement = ,4.5% of TPR. RANGLADESH - SECTrOR ISTUDY

]MYIARY OF MONT[LY IRRIGATICON LOSSES TO GROUINDWATER FOR FIVE DISTRICTS AS'SMTION A -- INFILTRATION LOSS )F3 INC1IS!ONTH FOR RICE CROPS AND 7 FIELD EFFICIENCY FOR NON-RICE CROPS

(ROPPING PATrERN: 90% BransiolantBoro (see Table 16) 15% Transplant Eboro (see Table 17)

IONTEI:

A B A B A B A B A I A B

,Comilla 42.4 3-1 2. 54 32 1.2"2 52 1.1.1 24. 1.5 S 2 1. ID7 5/4

.Khulna 2.27 37 2.62 30 1.43 34 i.. 2rJ 1.63 25 202 34

Mymens inmh 2.1l 4:L 251 .33 1.27 47 1.14 26 1.5() 29. 1. 72 48

KRa-gpur 2.23 38 2.55 32 1,39 37 1.10 26 1. 58 27 1. 97 3i

Sylhet 2.21 39y 2.17 49 1. 03 25 1,283 36

A. = lnches of Water

B = F'er cent of monthly pump requirement

1\0 BANGLADESH -- SECTOR STUIDY

SDIMARKY OF MONTLMY IRRIGATION LOSSES TCOGRC1NDWATER FOR FIVE DISTRICTS ASS'TICN C - 5FIELD EFFICrENCl' FOR RICE CROPS AND - 75%F

CROPIPINGC PATrE: 2Tranapr1t Boro (see Table 9Q 15% Trm=pl:ant BDr-C (lse Table 17)

MONTH: c _ icirci; ___A rM

_ S Ai B' B A B A B

2,-1-,.:)3 36 3.,5 334 1h 35 1.15 22 , .222 28 1.84

Kt~_i:na 2r 3h 36 3.97 34 . 36 1.25 25 2.40 28 3./7 3-:

I I :l.nsin~h 2.20 36 3.13 3 4 36 1. i6 24 1. 93 28 1. °4 34

7arr;iFur 1.93 36 3.39 34 203 36 1.11 24 .14 27 2.30 34

Sitlet ,, , 36 . 01 4 1.07 244 . 20 2 6

A = Inches of wv.tcr

B = Per cent of monthily pump requircment.

IC) BANG,LADE:SH - SECTOR STUIIY

SUMMARY OF KONISLY NON-BENEFICIAL EVAPORATION LOSSES FROM APPLIED IRRICATI(N FOR FIVE DISTRICTS ASSUMPTlCN A - INTIRTATION I,OSS OF 3 INCHIES,/4ONrH FOR RI:CE CROPS AND75FELD EFFICIENCY IFR NRN-EICE CRPMS

CROPPING PATTERN: 2 Transplant Boro (see Table 16) 125LTransplant Boro (see Tab]Le U

II)NTH: Fieb Mar ch Apr Feb March Apr A B A B A B A B A B A B

Comilla 0.89 31 0).93 12 0.44 18 0.42 ° 0.59 10 0.59 19

Khulna 0.81 13 0.96 1I 0.52 12 0.43 10 0.61 10 0.74 1 3

Mynmensingh (1.78 1.5 0.91 12 0. 45 17 0 .43 10 0. 55 11 0.61 17

Rangpur 0.830 14 0M93 12 0.50 13 0.41 1i 0.59; 10 0.71 13

Sylhet 0.79 14 0.77 13 0.40 9 0.46 13

A = Ineches of wator

B = Per cent o-. monthly pump requiremeint BANGrLADESH -. SECTOR STUDY

SUMKARY OF MONIILY NON-BENEFICIAL EVAPORATION LOSSES FRCIK APPLIED IRRI(zATION FOR FIVE ])ISTRICTS

ASSWNPTION C - M TFIELD EFFICIENCY FORt RICE CRtOPS AND 7 FIELD EFFICIENCY FOR NON-RICE CROPS3

CROPPN PA.TEEXl 9C nransplant Boro (isse 'abl¢ 16 L 1-5% rran:plt bDro (see Table 17) MON I: Feb Morch Apr Feb Mdrch Av'r A A B A B A B A A BE

Cor.i11 tI G0.73 13 1.29 12 0.49 1 0'.,3 9 0.32 10 Q. 66 12

Rhulna 0.86 13 1.44 Iz' 0.79 13 0. 45 C.39 1i) 1.11 12

M rrier ^sir g5 0.7 9 13 o ,13 12 Q52 13 0.41 9 Q.72 1Q 0.70 12

Ran~purt<,? 0.70 13 ,231 12 0.73 13 0.4 2 9 0.79 10 1.02 12

Syli'het 0. 7. 13 0Q73 12 0..½ 0 0.4 i 0

A = 'Inches cf votcr

. = ?Per icent oF nonlhlv puvp reuiArement

Iti' TA^BLE 33

BANGLADESH - SECTR STUDY NUMBIR OF ACRES IRRIGATED BY A 2-SEC UNIT FOR VARYING PEAK ARZTnIVESKTQ ATiWP A 'T,. u av

.w .a.s1. . -a Lw . s. ~ p tr

|Peak Requirem:,nts, in D ; tAcre cmcjllt.hc,i-r (D) I 2? 1l

l!(Acres! Acres l (AcresDlAcres) 6 40 I8 1,0 1,'0 8 ~~~~30 60 90 1-0 !I & 3iO 1 eMn I ()t) I l

1( 24 1 4L• 72 96

i12 1 20 4 0 I 308

14 [17 -' I 1 6 !

1]6 ! 15, 1 JO 1 45 ! 60 I , i l

BANGLADESH - SECTOR STUDY

DATA BY SOURCE ANI) LDU FOR THE ANALYSIS OF 'IRRIGATION POTENTIAL FROM SURFACE FLOWS AND TIDAL BACKWATERS NORTHWEST GROSS SUI'TABLE AREA IRRIGATION RIDER SOURCE OTHER ARBEAS ErE RNAL CONSTSRAINTS 1L/ 2/ 3/ FLEGION iREAUA FOrL IRRIGATION RSQUIRMENT NAME LOW FL3r ACCE3SSIBIL

LDU (000 Ac! (000 Ac) (IN./__O.) _ (cfs.) LDU ____

NW1 212 175 10 I)ahuk 20 Yaratoya lOOr NW2 858 660 10 TLangan 170 Dhepa 250 Atrai 150 NW 3, 6, 7, 8 a NW3 1,507 1,160 9 Dudhkumar 2,600 NW hsa D)harla 2,200 N'Wlg a Tista 4,000 NW 4a NW4a 480 35:5 9 See Ni3 B3rahmaputra 146,000 See note 5 NW4b 201 160 9 Little Jamuna 0 NW5 645 470 9 Karatoya-Bangali-Hurasagar 125m l\NW3, 4a, 10 Brahmaputra 146,000 See note 5 Backwater into mouth of

NW6 79 55 10 'Atrai lOOm NWJ2, 3, 7, 8 a Hrasagar NW7 39 25 10 See NW6 NW8a 210 160 10 Atrai 140m NW 2, 3, 6, 7 t,umani 0 NW8b 34 20 10 Purnababa 0 NW9 941 7CIO 10 M4ahananda 2,000 NW 13, I4 Ganges 55,ooo See note 5 Subject to reduction by daevelopment in India. NWIO 359 300 10 Atrai--Hurasagar 140m NW 2, 3, 5, 6, 7, 8a Brahmaputra 46,000 See note 5 B3ackwater into mouth of Hurasagar Ganges 55,000 See note 5 Subject to reduction lDy development in India NW]Lla 4°40 65 10 S;ee NW 4a NII1IID 234 85 10 Ganges 55,000 See note 5 Subject to reduction by development in India NW12 206 175 9 -- __H NW13 1,4h58 1,030 9 _o NW1L4 180 35 9 _ _ 7 76047 5,b7 Brahmaputra l7705005 See Footnotes cn Page 5. Ganges 55,000 Others 11,615 BANG]LADAStl - SECTOR STUDY

DATA BY SOURCE AND LDU FOR THE ANALYSIS OF IRRIGATION POTEN'TIAL FROM SURFACE FLOWS ANT) TIDAL BACKWATERS

CENTRAL GROSS SUITABLE AREA IRRIGATION __RIVER SOURCE _ OT'ER AREAS EXTE!''AL CO.STR.AD.TS - ~ ~~~~~~~l/ 2/ 3/V-_____ REGI(UI AREA FOR IRRIGATION REQUIREI23NfT NAME LOW FLC7.,r ACCESSIBL3

LDU (000 Ac) (000 Ac) (IN./MO. ) (-c-s.- LDt7

C1 494 125 7 Brahmaputra 146, 000 See note 5 C2 201. 170 7 Bhugai 0 C3a 696 560 7 N.eglna Tidal See note 5 Bhugai-Kangsa 500 C 2, 6, E 3 C3b 266 220 7 Bralbaputra 146, 000 See note 5 Backwater into Old Brahmaputra cutoff. C3c 312' 250 7 Banar, Mahari, Sutia 0 Meghna Tidal See note 5 C3d 137 110 8 Lakhya Tidal See note 5 C4 13 2 105 7 C5 182 130 7 Old Brahmaputira 0 C6 191. 150 7 SomeswariL 250 E3 C7 3859 320 7 Old BrahxRaputra 0 Barimi 0 Meglma, Mogra TidRI See note 5 C8a 158 120 9 Lakhya Tidal See note 5 C8b 81 65 9 Dha-Leswari Tidal See note 5 C9 72 3 560 9 Brahln3putra 146,ooo See note 5 Dhaleswari-Kaliganga 4,800 Cl, 1( Bansi 150 C13 Dhaleswari-Burigang7a Tidal See note 5 C10 1i2 115 9 See C9 Cl 3 3 25 9 P adcma Tidal See note 5 C12 61 25 9 See Cll - C13 1, 018 710 9 Turag 210 IJ 9 Lakhya T'idal See note 5 C14 36 10 9 --

TOTAL 5, 218 3,770 Brahmiaputra 146, 000 Others 5,660 Tidal _. See Footnotes on t'Lge D. '4:- BANGLADESH - SECTOR STUDY

DATA BY SOURCE AND LDU FOR THE ANALYSIS OF IRRIGATION POTENTIAL -FROM SURFACE FLOWS AND TIDAL BACKWATERS

EAST GROSS SUITAB3LE AREA IRRIGATION RIVER SOURCE OTHER ARE,AS 'E:7TiFiAL CG.ONSTR^IITNTS _ 1/ *_-/…- _3/- RF:GION AREA ;FOR IRRIGATION REQUIRE.MENT NAME LOW' FKaZ ACCESSIBI.F;

LDU *22 C2 .- L00 A.L (11N./MO.) (cfs.) LDU

El 304 150 7 Minor streams 0 E2 1,181 750 7 Surma 150 E3, 7 Kushiyara 1,300 E3, 7 Sonai, Juri, Manu, Dhalai 600 E3, 7 Piyain 4OG E3, 7 E3 1,219 775 7 Som,eswari-Jadukata 200 El, C6 Surma-Dhanu-Baulai 150 E2, 7 E4 1,411 1,000 8 Gurnti 240 E5 Subject to reduction by de-velopmnent in India Channels east of Maghna Tidal See note 5 E5 300 195 8 Guir[ti Tidal Using channeLs of Little Feni an(' Gumti E6 300 215 8 Channels N. of Padma & "E. Tidal See note 5 of Meghna E7 269 190 7 Manu 50 E2, 3 Khowai, Sutang 170 E3, 4 E8 871 635 8 Matamuhuri, Sangu 300 Ellb Karnafuli-Halda 5,000 Ellb Also, Karnaf:li-Ssngu water transfer under consideration E9 64 0 8 -- -- E10 810 0 8 -- -- Ella 5L4 145 8 Minor rivers -- E2, 3, 4, 5, 7 Ellb 3,644 130 8 Karnafuli and tributaries -- E8

TOTAL 10,917 4,185 Rivers 8.,410 Tidal --

Ss r

See Footnotes on nPage 'i. BANGLADESH - SECTOR STUDY

EDATA BY SOURCE AND LDIJ FOR THE ANALYSIS OF IRRIGATION POTENTIAL FROM SURFACE FLOWS AND TIDAL BACKWATERS

SOUTHWEST GROSS SUITABLE AREA IRRIGATION _RIVER SOURCE OTHZR ARZAS EXTERThAL CCU1ST.R41.72S I/ - ~- 2/~ ~ ~ ~ ~ ~ ~ V3 t/ REGION AREA FOR IRRIGATION REQUIREIENT NAMS LOGi FLOGf ACCESSIBLE

LDU (OOO hc) (000 Ac) (IN./MQ.) (cfs.) LDU_

SW1 280 55 9 Ganges 55,000 See note 5 Padmna Tidal See note 5 sW2 242 130 9 Joyanti, Hizla, Tetulia and Tidal See note 5 others sW3 2,231 1,830 10 Mathabhanga 330 Kobadak 75 SW4 1,599 1,2Li0 9 Gorai-Madhumati 3,000 5;W3 Arial Khan 500 Madhumati., Arial Khan and Tidal See note 5 others SwC, 562 280 9 Minor Rivers Tilial See note 5 sWI, 929 720 9 Minor Rivers Tidal See note 5 sW7 1,456 160 9 Minor channels Tidal See note 5 Suitable area is outside present saline limit (April) SW8 317 2L0 9 Tetulia Tidal See note 5 SW9 28e 0 9 ID Off shore island, fresh surface water negl'Lgible SWIO _1,450 0 9

TOTAL 9,354 4, 6 55 Ganges 55, D00 Others 3,905 Tidal

See Footnotes on Page 5. BANGLADE'SH - SECTOR STUDY

DATA BY SOURCE AND LDU FOR THE ANALYSIS OF IRRIGATION POTENTIAL FROM SURFACE FLOWS AND TIDAL BACKWATERS

FOOTNOTES

I/ Estimated on the basis of land capability classifications of the ]FAO Soil Survey project. (See Volume II, Technical Report No. 2).

2/ Estimated using March-April consumptive use requirements, effective precipitation, and efficiencies of application and distribution discassed in Chapter III.

3/ Flow rates are lower quartile value:s for March-April, except where minimum flow is indicated (m) because lower quartile estimate unavailable, or where water is available from fresh tidal backwaters (indicated tidal). Where available water is from river flows,6QZ of the low flow value has been used to estimate the irrigation potential. Areas dependent on withdrawals from the Ganges have, not been included i.n the estimate (except along the' Gorai distributary).

4/ The irrigation potential has been allocaited in some cases arbitrarily between Land Development Units competing for t'he sarne river flow.

5/ Flow in the channels of the Brahmaputra, the Ganges, the Padna, the Meghna, and water available in tidal channels in each case exceeds the requirements of Land Development Units within connand from the channel. However, any withdrawals affect the total availability of water as well as the limit of incursion of saline tides. These constraints govern overall irrigation potential and enforce selection of irrigable lancd using economic criteria. Withdrawals from the Brahmaputra would 'be used in the North-- west in Land Development Units 3, La, 5, 10, and lla; in the Central region in LDUs 1, 3b, 4, 8b, 9, 10, 11, and 12. With- drawals from the Ganges would be used in the Northwest in LDUs 9, llb, and 14; in the Central region from the Padma in LDUs 10, 11, and 12; and in the Southwest in LDUs 1, 3, 4, and 5. Withdrawals from tidal channels would be used in the Central region in LDUs 3a, 3c, 3d, 7, 8a, 8b, 9, 1., 11, 12 and 13; in the East in LDfUs 4, 5, 6, 8, and 10; in the Southwest in LDUs 1, 2, 4, 5, 6, 7, and 8.

BANGLADESH - SECTOR STUD=

ESTIMATED IRRIGABLE AREAS BY LDU ABOVE T1h PRESENNT SALINE LIMIT USING SIXTIC

PERCENT OF LOWER QUARTILE FLOWS AN]) TIEAL BACKWATERS

'1'OF'T^

8 ___ x _ Bb. 12JL~ 31 S 18: hz/dhr/da3 3/_

Sm1l 7 , hi Snl / 4 Small- Large/ Small h4 soale4± Larlge- Seale- Large- scale L Large- scale Large -

_LDU (OOO Ac) (OOO L (OC0 Ac) (000 Ac) ) 0O Ac) __ CO Ac) (000 Ac) (000 A. )

NW1 0 0 0 ID 0 0 I) 0 NM.2 10 0 0 ID 0 0 ID 0 Y.W3 13 (120) 20 (120) 27 (120) 27 (120) ; , Technical NW4a 13 C 60) 20 ( 60) 25 ( 60) 25 1 60) ,1 Technical NY!b 0 0 0 O 0 0 0 0 NWJ5 24 70 35 81D 36 80 38 80 NW6 2 2 3 3 4 4 5 NW7 0 0 0 0D 0 0 0D 0 NW8a 0 45 ) 0 ( 45) 0 ( 45C) D 145) ( , Technical NW8b 0 0 0 0 0 0 o 0 NW9 5 30 7 410 10 65 1:3 85 NWH1O O 50 0 51 0 50 0D 50 iNWt1a 0 0 0 0D 0 0 0D 0 ]Nl1111D0 0 0 ID 0 0 0D 0 NW112 0 0 0 0D 0 0 0D 0 NWl3 0 0 0 0 0 0 0 0 :NW14 0 0 0 ID 0 0 0D 0

TOTAL 60 150 85 170 100 200 110 220 (225) (22'7) (225) (225)

OEM rUO'1NITo N rPAUEUr . o~w Ht BANGLADESH - SECTOR STJDY

ESTIMATED IRRIGABLIE AREAS BY LDU ABOVE THE PRESENT SALINE LIlIT USING SIXITY

PERCENT OF LOWER QUARTILE FLOWS AND 'rIDAI BACKWATERS

:1/ CENAL ESTIIMATED FULL POTENTIAL EXT=RNAL COLS T7.

OEQION lFrom river flows and fresh tidal backwaters

8hri'daJr hr/daj 3/ 12 :8 24 hr/cay/ Small- nSmall - Smal-- Small- scale-Large sle e 4/ Large s ale Large 4/ scale Large 4 LDU (OO) Ac) Ac) ¢0 (000 Ac (000) Ac) ( 000 Ac) (000) Ac)

C1 17 17 17 17 17 17 17 L7 C2 0 0 0 0 0 0 0 0 C3a 7 7(53) 15 15(53) 23 23(53) 30 :30(53) ( ) Techn:ical C3b 0 0 0 0 0 0 0 C3c 0 0(52) 0 0(52) 0 0(52) 0 0(52) ( ) Technical C3d 10 75 15 75 720 75 20 75 C4 0 0 0 0 0 0 0 C5 0 0 0 0 0 0 0 0 c6 5 5 10 10 1O 10 15 15 C7 0 55 (32) 0 55(3:2) 0 55(32) 0 55 (32) ( ) Techn:lical C8a 10 120 15 120 ;20 120 20 120 C8b 1 5 5 5 55 5 55 5 55 C9 50 215 85 260 120 315 :150 3220 Dredging for part,. C1o 0 7 5 0 75 0 75 0 75 CilL25 25' 25 25 25 25 25 425 C12 20 20 20 20 2 0 20 20 20 C13 25 80 40 80 ',0 85 50 0O C14 0 0 0 0 0 0 0 0

TOTAL 190 700) 280 765 350 840 390 8c0 (14(E) (EO14) (140) (PGLO)

S3EE FOCTN;OTES ON PAGE 5. - BANGLADESH - SECI'OR STUDY

;ESTI4ATE) IRRIGABILE AR1EAS BY LDU ABOVE, THE PRESENT SALINE :LnT TUSING SIXTY

PERCENT OF LOWER QUJARTILE FLOWS' AND TIDAL BACKWATERS'

1/ EAS T - ESTIMATED 'iULL PoTrNTIAiL _EXTE2AL CO1TS T?IjAT

REGrION From river flows and fresh tidal backwaters

8 hr/day -/ 12 hr/c1ay 18 hr/day 24 hr/ilay Shall- 4/ Small- Small-4/ 4/ scale 4W L-rge ~ scale 4! Large 4/' scale Large - scale - Large I; _ O c (000 AcA) 000 AC) 00 Ac) (00 Ac.) (000 Ac) (000 ) 0D0 Ac

El OCOA O OAc O E2 40 40 75 75 110 110 130 150 FLash floods on part E3 140 ]L40 240 310 245 3 35 245 350 E4 155 655 285 655 290 660 295 665 E5 0 (140) 0 (140) 0 (1410) 0 (140) ( ) Technical E6 120 215 215 215 215 215 215 215 E7 5 5 .5 5 10 10 15 15 E8 10 80 20 140 30 210 45 290 E9 o O O 0 a ID a O E:10 o o 1o o O O O 0 ElLa 0 °0 I 0 0 0 0 E'LLb o O ° 0 °o °0

TOTAL 470 1, 135 840 1,,400 900 :1, gL 945 1, 680 (1141.0) (140) (140) (140)

O EW .'R* SE FOCTNOTES ON PAGE C. BANGLADESH - SECTOR STUDY

ESTIMATED IRRIGABLE AREAS BY LDU ABOVE THE PRESENT SALINE LIYI,IT USING SIXTY

PERCENT OF LOWER QUARTILE FLOWS AND TIDAL BACKWATERS

1/ 2/ i(jJTHjIS T _ ESTMATED IqULL POTIITIAL _ EZ iTAL COM7ST?UAIi!T

FEGION From river flows and fresh tidal backwaters 8 hr/day 3! 12 hr/day3 / 18 hr/day 3/ 24 hr/day3Y Small- 4/ Small- Smal:l- Small- scalei large k/ scale Large 4/ scale 4/ Large / saLe 4/ Large4/

LDU_ (00O Ac) (000 AC 000 Ac) 000 AO OAc (CC (000 Ac) (OCO Ac)

Slql1 5 5 5' 5 10 10 10 10 90 130 130 130 :L30 130 130 130 Sl J,W 5 1C 10 15 1.5 15 15 Salinity SWAL 230 650 36C) 680 550 730 730 770, SW,,,' 120 260 16C) 260 :L60 260 160 260 SW6 350 7:20 56C) 720 '720 720 720 720 SIlg 75 160 12C) 160 :L60 160 160 160 Sw8 30 30 5C) 50 60 60 60 60 S119 o0 0 C) 0 0 0 0 0 SWLOn rO 0 C) 0 0 0 0 0 vwi _-_ , . - - - , __ _-

TOTCAL 905 1,925 1,400) 2,015 1,800 2,080 1,990 2,,130

w .O.C's {:V,,-m1Tf>IT"T C' {oT T~ p,rT r AJt.A,hJ ± irs j. _IJJ ¼~1~ ± r 4 j A _ BANGLADESH SEC TOR STUDY

ESTIMATED IRRIGABLE AREAS BY LDU ABOVE THE P]PESENT SALIME LIMIT USING SIXTY

PERCENT OF LOWER QUARTILF FLOWGS A'ND T:IDAL BACKWATERS

FOO INOTES

1/ Values are numbiers of acres of net agricultural land. These estimates do not include the area potentially irrigable by means of major engineering schemes such as the Ganges-PKobadak Project in the Southwest Region, the proposed water transfer scheme in the East Region, or the Pabna-Belkuchi Project proposed for the Northwest. However, some of' the areas that wouild become part of these projects have been included in this estimate according to the criteria used. ( See note 6 below.)

2/ External constraints must be aprlied before including areas in the estimated potential. Bracketed figures have nct been included in the t,otals. Technical constraint, indicates that technical feasibility must be eval- uat,ed in order to assess the relative magnitude of the cost. Salinit,y constraint indicates that the limit of saline tides in March-April may encompass all or part of the area as fresh water withdrawals are made upstream. Areas that could be irrigated from the Ganges, whose low flow is subject to significant reduction by India, have ncot been included in the estimates.

.3/ Average number of hours of wrater withdrawal each day. The estimates for 8 hours withdrawal represernt area that cou]Ld be irrigated with efficierncy of 50acres per 2-cfs pumlp unit.

J~/ These categories represent the sumall-scale schemes and t]he schemes wlich imight require ma,jor works as def'inedL in paragraph 4.20. The estimates.wrere restricted by the following criteria:

1all-scale - minimum, agricultural area (1) within 600 acres per mile of estinated cut, river bank, or (2) using maximum of 1.0 cf's. per mile of e!stilrated. cut bank, cr (3) using available water. Lare - minimum agricultural area which could be commanded (]. wi.thin roughly 5,000 acres per mile of' estimated cut b'ank, or (2) using availabl.e water.

BANGLIDES1 - SECTOR STUDY

PREsENT IRREGAT:EON BY DOW-LIFT FUWPS FRlOM SJTtFACE FLOWS AND TIDAL BACKWATERS

Nortliwest All lbow-Lift Pup"-/ Portion From Portion From Region Irrigation Stxtic Supplieis River Flows and Tidal Backwaters 0 A-c)-- Ac 700W A T

NW1l 0D 0 0 NW42 10 0 0 NW53 04 4 NWUa 0 2 2 NW4b .3 0 3 NW 10 :24 24 NWS ID 2 2 NW7 3 0 3 NW3a 25 0 25 NWBb 6 0 6 NW? 11 10 21 NWiO 0 10 10 NWI a 0 0 0 NWl 1b ID 0 0 NWdi 2 0 0 0 NWI3 U 0 4 NWI 4 10 0 0

To tal 5;2 52 104

! Estimated from EPADC riecords by districut of pu'nps fielded in 1 969/70.

CDi

"CT' BANGLADESH - SECTOR STUDY

PRESENT IRMIGATION BY DOW-LIFT PUMPS FROM SURFACE FLOWS AND TIDAL EIACKWATEiRS

Central All WLow-LLift Pump-/ Portion From Portion Fromn Region Irrigation Static Supplies River Flows and Tidal Backwaters U.(0-00 -Ac)0 AcT - 00 A

cl 1 4 5 C2 0It0 4 C3a 6D 4 10 C31D I8 0 8 C3c 7 0 7 C3d 10 8 8 C4 1 0 I c5 :3 0 3 C6 7 0 7 C7 8 0 8 C8,31 1 2 3 C8b) :2 1 3 C9 5 17 22 C1() 3 0 8 C11 6 0 6 C1 0lO 1 1 C1:3 16 15 31 ClI1 0 -0 0

Total 83 52 135

/ Estimated from EPADC records by district of pumps fielded in 1969/70.

(D CY\ iBANGLADESH - SECTOR STUDY

PRESENT IRRIGATION BY LOW-LIFT PUMPS FROM SURFACE FLOWS AND TIDAL BACKWATERS

East All Low-Lift PwupL Portion From Portion From Region Trrigation Static Surpplies River Flows and Tidal Backwaters

- (000 Ac Ac7 77)OOO 0 7

El 4 0 4 0 31 31 E:3 84 46 130 FJ4 0 50 50 E, 12 0 12 13S 0 18 18 E'7 0 1 1 EB 249 10 59 E9 0 0 0 ElO 0 0 0 El1a 0 0 0 El1b 0 0 O

Total 149 156 305

!/ Estimated from EPADC records by district of pumps fielded in 1969/70.

iw t ., BANGLADESH - SECIOR STUMY

PRESENT IRRIGATION BY LOW-LIFT PUMPS FROM SURFACE FLOWS AND TIDAL BACKWATERS

Southwest All Low-Lift Pum.pJ/ FPrtion From Portion From Region Irrigation Static Supplies Ftiver Flcws aLnd Tidal Backwaters (000 Ac AcT T LF

5,'11 0 0 0 SW2 0 5 5 SW3 7 2 9 sw,4 6 22 28 sw5 1 3 4 swS 0 42 42 SW7 0 21 21 SW3 0 0 0 SW9 0 0 0 SW10 0 0 0

Total 14 95 109

1/ Estimated from EPADC records by district cf pumps fielded in 1969/70.

UQ td

tDWI r6l OC1 BANGLADESH - SECTOR STUDY

ESTIMATED POTENTIAL BY LDU /FOR EUANSION OF IERIGATION ABOVE THE PiRSEN[T SALINE LIfIT"

NORTHWEST ESTIMATED POTENMIAL _ _ _ EX1lMAL CONSTRAINT

REGION Fromna riirer flows and fresh tidal backwaters

8 hr/day 12 h:r_y 14 hrd _ _ 18 hr/da

Small- Small- Snmall- scale Large scale Large scale Large scale Large LDU __00_(000 Ac) (J AL) 0 Ac) (000 Ac) (COO Ac) (000 Ac) (000 Ac (00 Ac)

NW1 C) 0 0 0 0 0 0 I0 I1*12 C)0 0 0 0 0 0 0 1Th73 91 (116) 16 (116) 18 (116) 23 (116) ( ) Techral M;FtWa 11. (58) 18 (58) 20 (58) 23 (58) ( ) Techical I!iTb C) 0 0 0 0 0 0 10 mWS C) 46 11 56 11 56 1.2 516 MK:6 C) 0 1 1 1 1 2 .2 1-;17 OC) 0 0 0 0 0 0 0 NW:8a C) (45) 0 (45) 0 (45) 0 (45) ( )!rechnical I'E.-8b C) 0 0 0 0 0 0 03 YFO9 C) 20 0 30 0 38 0 55 C) 40 0 40 0 40 0 40 N>'Tla C) 0 0 0 0 0 0 0 NWlIb, C) 0 0 0 0 0 0 ID N,Wl 2 C) 0 0 0 0 0 0 0 NWl 3 C 0 0 0 0 0 0 0D M414 C) 0 0 0_ 0 0 0

TlOTAL NIW 20 106 46 127 50 135 60 153 (219) (219) (;219) (219)

Ca~~~~Ss

1/ ThLe potential shoira for each T.TT may not hbe. entrel1 4ndi-at-ve ofswpossIble :u sn1eeeai^r. then es tJ.p-'t for water supply available to more than one LDU but not suffi ient for all were allocated arbitrarily between the ccmpeting LDUs. Thie alternatives are inldicELted in Table 34. 2/ Estim-ated using figures shown in Tables 35 and 36. See also footnotes to Table 35. BANGLADESH *- SECTOR STUDY

ESTIMATED POTENlIAL BY' LDUI-/FOR ECPANSION OF IRRIGA.TION ABO'VE THE PRESE:NT SALINE LIMIT

GENTRA:L ]ESTII4ATEI) POTENTIALY EXTERNAL CONSTPLINT

REGION From river flows ancd fresh tidal backwaters

8 hr/d hr/daL _1_ 14 hr/dy 18 hr/day

Sma:11- Small- Uall.- Small.- scale Large scale Large Scale Large scale Large LDUJ (00 Ac)__0( Ac) (000 Ac) (000 Akc) (000 Ac) (000 Ac) (000 Ac) (000 Ac)

Cl 13 13 13 13 13 13 13 13 C2 0 0 0 0 0 0 C3a :3 3 (49) L. 11 (49) L4 L4 (49) :19 19 (49) ( ) Techniicall C3b 0)0 0 0 0 0 0 ( ) Technical C3e ) O (52) 0 0 (52) 0 0 (52) 0 0 (52) C3d 2 67 7 67 9 67 L2 67 C4 00 0 0 0 0 0 0 C5 00 0 0 0 0 0 C6 5 5 1( 10 10 10 :1O 1, C7 0 55 (32) .0 55 (32) 0 55 (32) 0 55 (32) C8a 8 118 1:3 118 15 118 :18 118 ( ) Technical C8b 0 54 14 54 14 54 4 54 C09 33 198 68 243 80 261 103 298 C10 0 75 0 75 0 75 0 75 C1l 25> 25 2!5 25 25 25 :25 25 C12 19R 19 19 19 19 19 L9 19 C13 10 65 2!5 65 28 67 .35 70 C014 0 0 () 0 0 0

TOTAL C 118 697 195 755 217 778 2>58 823 (133) (133) (133) (133) rot

1/ The potential shown for each LIX may not be entirely indicative of possible :future expansion since the estimates for water supply avrailtble to more than one LDU but not sufficient for all were allocatedi arbitrarily between the co:mpet:ing LDUs., The alternatives are indicaLted in Table 34. 2/ Est-imated using figures shown in Tables 35 -and 36. See also footnotes tD Table :35. BANGLADESH - SECTOR STUDY

ESTIMATEI) POTENTIAL BY IDU-IFO)R1 E1CANSION OF IRRIGATIOiN ABOVE TrHE PRESENT SALINE LI;IT

Eastern ESTIMATED POTENTIAI2Y EXTERNAL CONSTRAINT

REGION From river flows and fresh tidal backwatlers

8 hr/day 12 hr/dy 14lhr/day 18 hr/day

Small- Small- Small- c l.1- scale Large scale Large scale Large scale Large LDU _ (000 Ac) A'000 (00(000 Ac) (000 Ac) (000 Ac) (000 Ac) (000 Ac'

El 0 0 0 0 0 0 0 0 E2 9 9 44 44 56 516 79 79 FE3 94 94 194 264 196 272 199 289 ( ) Techrkical E4 105 605 235 605 237 6o5 240 605 ( ) Technical E5 0 0 (1,O) 0 00(I40) 0 0(14() 0 o(i4() E6 1102 197 1197 197 1957 197 197 197 E7 4 4 4 4 6 is 9 9 E8 0 70 10 130 13 153 20 200 ( ) Technical E9 0 0 0 0 0 0 0 0 El0 0 0 0 0 0 O 0 0 El la 0 0 0 0 0 0 0 0 Ellb 0 0 0 0 0 10 0 0

TOTAL 314 979(140) 684 1,244(140) 705 1,289(140) 744 1,379(140)

C D

41~ ~ ~~ ~ ~~ ~ ~~~~~~~

.L4 k.L j A± JA UJ 4.iU U en-1± ~ ~ iLU..LJ.~JO~~.~~J~ A JYL U V ' L ~J0. .V .L% U. ULL.L JAU V Lv Vo UJJili Uv= for water supply available to :more than one LDU but; not sufficient for atll Were allocated arbitrarily between the compelting LDUs. The alternatives are indicated in Table 34. 2/ Estimated usinig fi.gures shown in Tables 35 and 36. See also footnotes to TaLble 35. BANGLADESH - SECTOR STUDY

]ESTIMATEI) POTENTIAL BY LDUIlFOR EXPANSION OF IRRIGATION ABOVE THE PRESENT SALINE LIMET

Southwest ESTIMATID POTENTIAL! EXTERNAL CONSTRAINT

REGION From river flows and fresh tidal backwaters

8 hr,/dy 12 hr/day 14 hr/day l_8 hr/day

Small- Small- Small- Small- scale Large scale Large scale Large scale Large LDU (00C Ac) (OOCA' (000 Ac) (000 Ac) (:000 Ac) (000 Ac) ( A00A,c) (000 Ac)

SW 5 5 5 5 7 7 1C) 10 SN2 85 125 25 125 125 12' 125 SW3 3 3 8 8 10 10 1 1 3 ( ) TechmicaLl SW4 208 628 :338 658 4(1 675 528 708 ( ) Technical SW5 117 257 157 257 157 257 1 57 257 SW6 308 678 ',18 678 5r71 678 678 678 SW7 54 1 39 99 139 139 139 139 1 39 SW8 30 30 50 50 53 53 60 60 1 ) Technical SW9 0 0 0 0 0 0 C) 0 SWi 0 0 0 0 0 0 C) 0

TOTAL 810 1,865 1 ,300 1,920 1,I 63 1,944 1,71() 1,990

1/ The potential shown for each L,W may not be entireLy indicative! of possible future expansion since the estimaites for water supply available to more than one LDU but nolt sufficient for all lwere allocated arbitrarily betbween the c:ompeting LDUs. 'fhe altetnatives are indicated in Table 34. 2/' Estimnated using figures shown in Tables 35 and 36. See also footnotes to Table 35. BANGLADESH - SECTOR STU2D

SURFACE WATER WITHDRAWALSi TO IRRItTATE THE ESTI24ATED PO)TENTIAL ABOVE THE PRESENT SALINE LIMIT-

1/ ESTIMATED ;SURFACE WATER WITH{DRAWALS FOR IRRIGATION 4/ NORTHWEST FROI; RIVER FLaiS AND FRESH TIDAL BACKWATERS EXTERNAL CONSTRAINT

REGION 8 hr/day _/ 12 hr/day2/ :18 hr/day 2i/. hr/day-- ' ,arr iErII-i rna- SCfSlB 3/ Iarge scale_3/ Large scale 3/ Iarge 3/ scale:'3 Large LDU (000 CfS) (000 cfs) (000 Cfs) (000 cfs) (OO Cf.S) (O)O cffS) (OO c.fs) (000 cfs)

NWI 0.0 0.0 0 °0 0.0 0.0 0.0 0.0 0. NW2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 NW3 .5 (4.8) .5 (3.0) .5 (2.01) .3 (1.5) ( ) Technical NWha .5 (2.4) .5 (1-5) .4 (1.0) .3 ( .8) ( ) Technical NW4b 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 NW5 1.0 2.8 .9 2.0 .6 1.3 .5 1.( NW6 .1 .1 .1 .1 .1 .1 .1 .1 NW7 0.0 0.0 0.0 0.0 0.0 0.0 0.0 O.( NWT8a 0.0 (1.8) 0.0 (1.3) 0.0 ( .8) 0.0 ( *6) ( ) Technical NW8b 0.0 0.0 0.0 0.0 0.0°.* 0.0 0.0 Nm9 .2 1.2 .2 1.2 .2 1.2 .2 1.2 NWl10 0.0 2.0 0.0 1.4 0.0 .9 0.0 7 NWlla 0.0 0.0 0.0 0.0 0.0 0.0 0.0 .0( NWllb 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 NW12 0.0 0.0 0.-0 0.0 0.0 0.0 0.0 0. NW1.3 0.0 0.0 0.0 0.0 0.0 0.0 0.0 O.() NM14 0.0 0.0 0.0 0.0 0.0 0.0 0.0 O.(

TOTAL 2.3 6.1 2.2 4.6 1.8 3.5 1.4 3.t) (9.0) (5.8) (3.8) (2.9)

SEE FOOTNOTES ON PAGE 5. BANGLADESH -- SECTOR STUDY

SURFACE WATER WITHDRAWALS TO IRTIGATE THE ESTIMATED POTENTIAL ABOVE THE PRESENT SALINE LIMIT-/

CENTakL FROM RIVER FLOTJS AN'D FRESH TIDAL BACKWATERS Er [AL CONSTRAINT

2/ 2/ 2/ 2/ REGION / 18 hr/_/ Small- i7 37 Sma'u.. :~ smll-73 3/ Small-3/ S7 scale Large sca-le La:rge scale Larg3e scale Large LDU (000 cfs;) (ooo0 cfs) (000D cfls) (000 cfs;) (000 cfs) ((000 cfs) (00 cl's) (ooo cl's)

C1 .7 .7 .3 .3 .2 .2 .2 .2 C2 0.0 0.0 D.0 ().0 0.0 0.( 0.0 0.0 C3a .3 .3(2.1) .3 .3(1.0) .3 . 3(.7) .3 . 3(.5) ( ) Technical C3b (.0 .o0 0.0 0.0 0.0 0.0 0.0 0.0 C3c (.0 C0.0(2.1) 0.0 ( .0(1.. 0) 0.0 0-0(-7) O.; 0.0(.5) ( ) Technical C3d .4 3.0 .3 1.7 .3 1 .1 .1 .8 C4 0.0 Cl.0 0C.0 ().0 0.0 0.(D 0.0 0.0 C5 0.0 0.0 0.0 (.0 0.0 0.03 0.0 0.0 C6 .2 .2 .2 .2 .2 .2 .2 .2 C7 0.0 2.2(1.3) 0.0 1.1(.6) 0.0 .7( .4) 0.0 .5(.3) ( ) Technical C8a .4 4.8 .4 3.0 .3 2.0 .3 1.5 C8b 0.0 2.2 .1 1.4 .1 .9 .1 .7 C9 2.0 8.6 2.0 6.5 2.0 5 3 2.0 4.0 Dredging flor part. C1o 10.0 3.0 0.0 1.9 0.0 1.3 0.0 .9 C1l 1.0 1. 0 .6 .6 .4 .4 .3 .3 C12 .8 .8 .5 .5 .3 .. 3 .3 C13 'L.0 3.2 1.0 2.0 .8 1.4 .6 1.1 C14 (.0 C0.0 0.0 (.0 0.0 0.0D 0.0 0.0

TOPAT. R irn n 1Q) h.- 10.8 m0t (5.5) (2.6) (1.8) (1.3)

**-~tSEE FOOTNOTES ON PAGE 5. BANGLADESH - SECTOR STUIY

SURFACE WATER WITHDRAWALS TO IRRIGAT:E THE ESTIMATED P'OTENTIAL ABO'VE

TIEM PRESENT SAL:NE lIMIT-i

EAST FROM RIVEPR FLCWS AND FRESH TIDAL BACKWATERS EXIERNAL CONSTRAINTi

REtGION 8 hr/da -Z 2 PEGICN8- hrs _12 hr/day 18 hr/day 24 hr/clay 317 '>mall77 _ SmauL-3/ 7 scale Large scale 'Large scale Large scale Dirge CLDU (OOO000s)(()OO c:fs) (000 cl's) (000 cfs) (OOO cf's) (000 cfs) (0(0 cf's) (COO cfs)

El1 0.0 O.() 0.0 0.0 0.0 O0.0 0.0 0.0 E2 1..6 1.6 1.5 1.5 1.4 1.4 1.3 1.5 Flash floods on part. E3 5.6 5.6 4.7 6.1 3.2 4.4 2.4 3.4 E4 6.,2 26.2 6.4 14.7 4.3 9.9 3.3 7.4 E5 °0.0 (5.6) 0.0 (3.1) 0.0 (2.1) 0.0 (1.6) ( Technical E6 4.8 8.4 4.7 4.7 3.1 3.1 2.4 2.4 E7 .2 .2 .1 .1 .1 .1 .1 .1 ES .1 3.1 .4 3.1 .4 3.1 .5 3.2 E9 0.O O.O 0.0 O.0 0.0 0.0 0.0 0.0 EJO 0.0 0.0 0.0 O.( 0.0 0.0 0.0 0.0 Ella 0.0 O.(0 0.0 O.0 0.0 0.0 0.0 0.0 0.0 Ellb 0.0 0. 0.0 0.0 0.0 0.0 0.0

TOTAL 18.8 45.1 17.8 30.2 12.5 22.0 1O.0 18.0 (5.6) (3.1) (2.1) (1.6)

;D t *u SEE FOOTNOTES ON PAGE 5. ' l BANGLA.DESH - SECTOR STlJDY

SURFACE WA'ER WITHRAWILLS TO IERIGATE THE ESTTM?TED POTENTIAL ABOVE

THE PRESENT SALINE LIM:T1/

SOUTHWEST FROM RIVERT FLCWS AND FRESH TIDAL BACKWATERS EXTE:NAL CONSTRAINT

2/ 2/ 2// 2/ REGION 8 hr/da 12 hr/daay 18 hr/day 24 hr/da ajL3/1-_ 37 Smna l- 3/7 Small- 37 37 Small- 3/ scale Large scale Large scale Large scale Large LDU (0()0 cf's) (000 cfs) (000 cfs) (000 cf's) (000 cfs) (000 cfs) (000 cfs) (000 cf3s)

SWl .2 .2 .2 .2 .2 .2 .1 .1 SW2 3.6 5.2 3.3 3.3 2.2 2.2 1.6 1.6 SW3 .2 .2 .3 .3 .3 .3 .2 .2 Salinity SWL4 9.2 26.0 9.2 17.1 9.2 12.2 9.2 9*-7 Salinity S'w5 4.8 10.4 4.o 6.5 2.7 4.4 2.0 3.3 Salinity SW6 140. 29.0 14.1 18.1 12.1 12.1 91.1 9.1 Salinity SW7 3.0 6.4 3.0 4.0 2.7 2.7 2.0 ,2.0 Sailinity SWt8 1.3 1.2 1.3 1.3 1.0 1.0 .8 .8 Salinity SW59 0.0 0.0 0.0 0.0 0.0 0.0 C0. 0 0.0 SW.O 0.0 0.00 0.0 0 0.0 0.0Cl.0 .0

TOTAL 36.3 78.6 35.4 O.8 30.4 35.1 25.0 26.8

u*~& SEE FOOTNOT'ES C'N PAGE 5.

CDig BANGLADESH - SECTOR STUDY

STRFACE WATER 'WITHDRAWALS TO IRRIGATE THE ESTIMATED POTENTIAL ABOVE

THE PRESENT SALINE LDITTl

FDOTNOTES

1/ Divers:Lons in cubic feet pegr sieconid which would be necessary to irrigate the areas shown :Ln Table 34. (see paras 4.02, 4.11, 4.20 and 4.41). 2/ See note 3/ for Table 34. 3/ See note 4/ for Table 34.

4 See note 2/ for Table ,34.

1" cIo

BANCrLADEISH -- SECTOR STUDY

SUMNARY OF POTENTIAI REGIONAL GROUNDWATER RICHARGE BY DISTRI]CTS

Potential Recharge Gross Area Less Pot. Recharge 1' 1/ Open Waiter Max:- Mir- Max Min Max 1v5in District (inches) (feet) (milliona acres) (MAFZ2 Dinajpur, Rangpur 32.54 16.80 2.71. 1.40 3.98 :LO. 79 .5.57 Bogra, Pabna 20.44 9.52 1. 70 0.79 2.08 3.514 :1.64 Rajshahi 9.4B 1.65 0.79 0- 14 2.:25 1.78 0.32 Mymens ingh 38.39' 21.34 :.20 1.78 3.91 12.51 65. 96 Sylhlet 80.2:1 55.15 6.68 4.60 2.65 1L7.70 122.19 Dacca 19.74 8.46 L.65 0.70 1.78 2.94 1.25 Comilla, Noakhal'Ji 26.46 12.05 2.20 1.00 2.58 5.68 :2.58E KushtiaL 10.30 2.28 (.86 0.1'9 0.86 0.74 0 .16 Jes sore3/ 16.84 6.71 1.40 0.56 1.60 2.24 0.90 Faridpuc3/ 18.7 7 7. 8 1 .56 0.66 6 1.63 2.54 1L . 08

. ______TOTAL 60.46 32.65 1/ From Tables .11 through 20. :2/ Million Acre Feet.

3,/ Onlyv fro.h crcmn9wat1-r area considered

/ -- ____~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~1 BANGLADESH - SMTOR STUJDY

NE'T POTENTIAL RECHARGE AVAILAI3LE FOR THE, BUNDED AREAS) BY DISTRtICT

Future Non-Berifl i cial1 Nion-I-rrigjated Evaporation from Evaporation from Plotenatial Rechar'ge A,creage Non-IrrigatedL Areas Non-Irrigated Avai'lable L,ess OpeniWte! Less Open Wae2/Arae/ f'or B3unded A.creage District (mill, acres) In-ches Feet (MAF) Max. - Min.- Max.2/ Min./' (MAF) -(f:eet/acre)

(1) ~~~~~(2) (3) ()(5) (6) (7) () (9) Dinajpur, RaLngpur 0.77 12.6 1.05 1L.81 9.98 4 .76 -3.11 1.48 Pogra, PabDna 0.51 13.6 1.13 0.58 2.96 1.06 1.89 0.68 Rajshaihi 0.151 :13.7 1.14 0.58 1.20) o .69 - Mymensingh 0.88 .13.7 1.14 1.00 1.1.51 5.96 -3.80 1.97 sylhet. Less Hills 0.158 13.7 1.14 0.66 17.04 11.53 8.23 5.57 Dacca 0.46 .14.3 1.19 0.55 2.39 0.70 1.81 0.53 Comilla, Noakhali 0.79 13.8 1.15 0,91 4.77 1.67 2.66 0.93 Kushtia 0.223 13.7 1.14 0.26 0.48 - 1.76 - Jessore 0.47 .14.2 1.18 0.55 1.69) 0.35 1.50 0.31 Faridpur 0.51 14.0 1.17 0,60 1.914 1.48 1.73 04

1/From Tab.Le 4i (T.R. 21) (Future Unbanded .+Unaultivatedi Areas + HomesteadIs) 2/ Evaporation Index (Table 8) time 0.75 for period November-April 3/Evaporation from nc'n-bunded acreage! (Cc). 4) times non--irrigated acreaLge (col. 2) &/Obtained by subtracting non-beneficial evalporation, from potential recharge gie nTable 21, T.R.21. 5/ Cols. 6 aind 7 divided by Fu-ture Bunded AcreBage (Table 4-. TR. 21)

t-. BANGLADESH - SECTOR STUDY

ACREAGES WHICH CAN BE DE'VELO:PED ON THE B.ASIS OF GROUNDWATER ALONE* AJ1D NIJMBERS O]F TUBEWE:LLS POSSIBLE OR NEEDED

Future Max. Pot. Recharge Bunded Avail' able fo Areas- Bunded Area Acreage for Groundwater Numbe r of 2 Cuse. (million (.xRF) Development9/ Tubewe l/s Posss:i.ble or Districlt acres) Max. (million acres) NEqaded_/ at 20C"/acre at 15'sacre

(1) 1(2) (3) 1(4) (5) (6)

Dinajpur,Rangpur 3.21 9.98 3.21 3 .21 24,700 Pogra., Pabna 1.57 2.96 1.57 1.57 12,100 Rajshahi 1.74 1.20 0.72 0.96 5,500 Mymensiingh 3.03 11.5:L 3.03 3.03 23,300 Sylhet Less Hills 2.07 17.04 2.07 2.07 15,900 Dacca 1.32 2.39 1.32 1.32 10,200 Comilla, Noakhali 1.79 4.77 1.79 1.79 13,800 K;ushtia 0.63 0.413 0.29 0.38 2,200 J'essore 1.13 1.693 1.01 1.13 7,800 Faridpur 1.12 1.94 1.12 1.12 8.600

TOTAL ]17.61 1L6.13 16.58 124,100

/ From Table 4, T.R.21 2/ From Table 22, T.R.21 I/ Underlined.: development constrained by ground.Vater availability 4 'This implies one tu]bewell per 130 net acres and approximately 170 gross acres -'i+hrm. onisnqieration of flooding. cost and other water sDources. RIAGLADESH - SBXTOR STDY

RANGRR SUAPLE GALCULATION ALTERNATIVE 1 _CE IRRIGATION EFFICIECY =T __

Jan E'eb Mar Apr May June July Aug Sept Oct Nlov Dec Total

Rain 1 Total Rain .6 .5 1.1 3.4 12.1 19.4 17.7 13.2 11.0 6.7 .3 0 86.0 2 Interception .2 .2 .3 .7 3 Rain Runoff .8 3.7 2.7 1.1 .6 .2 9.1 4 Net Rain on Cultivated Area .4 .3 1.1 3.4 11.3 15.7 15.0 12.1 10.4 6.5 .( 0 76.2

Irr ic;ation 5 Total Irriga_ion 1.2 4.1 6.5 6.3 2.2 1.,7 22. 0 6 ucon--.aeneCicial evaporaticn .,1 .5 .8 .8 .3 .2 2.7 7 Irrigation Run-ff. .. .5 .5 .2 .2 1.8 8 Deep percolation from channels .1 .4 .7 .7 .2 .2 2.3 9 Net irrigation on C;ultivated Area .9 2.9 4.5 4.3 1.5 1.1 15.2

'Net n.ater Ust 10 Total ie. Walter on Cultivated Area 1.3 3.2 5.6 7.7 11.3 15.7 15.C0 12.1 10.4 6.5 1.5 1 1 91.4 11 Evaporation from Lnnd Temporarily Fallow .2 .3 .3 .3 .7 .9 .9 .8 .4 .2 .3 ,3 5.6 12 Crop Evatoratlor, 1.5 2.1 3.5 5.3 5.3 4.6 4.9 4.9 5.0 4.4 1.'9 1.1 44.5 13 Net Added to Soi:L -,4 .8 1.8 2.1 5.3 10.2 9.2 6.4 5.0 1.8 -. 7 -. 3 41.3 14 Deep Percolation: trom raLin 4.5 10.2 9.2 6.4 5.0 1.9 37.2 :: tirom irrigation .2 .6 1.1 1.4 .6 .2 4.1 16 Moisture Addition to Top Soil -.6 .2 .7 .7 .8 -1.:3 -.5 0

Sum.marv, 17 Total Water Input (l)+(5) 1.8 4.6 7.6 9.7 12.1 13.4 17.7 13.2 11.0 6.7 2.r5 1.7 108.0 18 Non-beneficial Evag. (2)4(6)+(11) .5 'L.0 1.1 1.1 .7 .9 .9 .8 .4 .2 .9 ,5 9.0 19 Runoff (13)+(7) .1 .3 .5 .5 .8 3.7 2.7 1.1 .6 .2 .:2 2 10l.9 20 Deep Percolation (8)i-(14)+(15) .3 1.0 1.8 2.1 4.5 13.2 9.2 6.4 5.,0 1.9 .8 .4 43.6 21 Crop Evaporation (12) 1.5 2.1 3.5 5.3 5.3 4.6 4.9 4.9 5.0 4.4 1.93 1 1 44.5 22 Total Water lIse (12)+-(19)+(20)+(21) 2.4 4.4 6.9 9.0 11.3 19.4 17.7 13.2 11.0 6.7 3.13 2.2 108.0 23 1M'oisture Addition to Top Soil (16) -.6 .2 .7 .7 .8 -1.:3 -.5 0 BANGLADESH - SBCTOR STUIY

ANGP1R SMUPLE CA.LCULATION ALTFNATIVE 2 -_RICE IR_RIGATION FEFICIENCY 75%

Jan iFeb Mar Apr MaLv June Ju-v Auq ;Sept Oct. Nov Dec Total

Total Rain .6 .5 1.1 3. 4 12.1 19.4 17.7 13.2 11.0 6.7 .3 0 86.0 2 Interception .2 .2 .3 .7 3 Runoff .8 3. 7 2.7 1.1 .6 .2 9.1 4 Net Rain on Cultivated Area .4 .3 1.1 3.4 11.3 15.7 15.0 12.1 'L0.4 6.5 0 0 76.2

Irrigation 5 Total Irrigation 1.0 3.6 5.0 4.5 1.9 1.6 17.6 6 Non-beneficial Evaporation .1 .3 .4 .4 .2 .1 1.5 7 Irrigation Run-off .2 .2 .2 .1 .1 .8 8 Deep Percolation from Channels .1 .4 .5 .5 .2 .1 1.8 9 Net Irrigaitiorn on Cultivated Area .8 2.7 3.9 3.4 1.4 1.3 13.5

iqet Water Use 10 Total Net Wat,er on. Cultivated Area 1.2 3.0 5.0 6.8 11.3 15.7 15.0 12.1 LO.4 6.5 1.4 1.3 89.7 Evaporation from Land Temporar:ily Fallow .2 .3 -. 3 .3 .7 .9 .9 .8 .4 2 .3 .3 5.6 12 Crop Evapcration 1.5 2.1 3.5 5.3 5.3 4.6 4.9 4. 9 5.0 4.4 1.Si 1.1 44.5 13 Net added to Soil -.5 .6 1.2 1.2 5.3 10.2 9.2 6.4 5.0 1.8 -.8 -.1 39.6 14 Deep Percolation: from rain 4.5 10.2 9.2 6.4 5.0 1.9S 37.2 : from irrigation .1 .4 .6 .6; .4 .3 2.4 116 Moisture addition to top soil -. 6 .2 .6 .6 .8 -1.2 -.4 0

Summary 17 Total Water Input !1)+(5) 1.6 4.1 6.1 7.9 12.1 19.4 17.7 13.2 11.0 6.7 2.2 1.6 103.6 18 Non-beneficial evap. (2)±(6)+(.11) .5 .8 .7 .17 .7 .9 .9 .8 .4 .2 .8 .4 7.8 19 Runn-off (3)+(7) .2 .2 .2 .8 3.7 2.7 1.1 .6 .2 .1 .1 9.9 20 Deep Percolation (E)+(14)+(15) .2 .8 1.1 1.1 4.5 10.2 9.2 6.4 5.0 1.9 .6 .4 41.4 21 C:rop Evaporation (].2) 1.5 2.1 3.5 5.3 5.3 4.6 4.9 4 .9 5.0 4.4 1.9 1.1 44.5 22 Total Water Use (18)+(19)+(20) -(21) 2.2 3.9 5.5 7.3 11.3 19.4 17.7 13.2 11.0 6.7 3 .4 2.0 103.6 23 Moisture Addition to Top Soil (16) -.6 .2 .6 .6 .8 -1.2 -.4 0 BANGLADESH - SECTOR STUDY TABL.2. WI

TDDTI-2mTCn1J DVrCTMP ~ITfl1 ,mr' PAT ANTrPcq Vn' TLTAUTT IRRIGCATION PT-GI- AND WATER BAJ.L-4-S O ETHH UNDER DIFFERENT ASSUMPTIONS (inches of water)

Cropping pattern: 15% Transplant-/

I. 50% field effi- II.75% field effi- III.As II, but with ciency for rice, ciency for all adjusted srop-/ 75% for other crops ping pat-tern crops

Wet season (June-Oct) Rain 45.1 45.1I.1 45 Rain runoff 2.3 2.3 2.3 Net rain 2.8 42.8 42A

Crop evaporation 233.5 23.5 23.4 Fallow evaporation 3.1 3.1 3.1 Total evapoLation 2b. b 26.6 2b. b

Rain recharge from cropped areas 16.2 16.2 16.3

Dry season (Nov - May) Crop evaporation 23.1 23.1 18.9 Fallow evaporation 2.7 2.7 2.7 Total evaporation 25.8 25.8 21.6

Rain 8.6 8.6 8.6 Rain intercepctin . . . Net rain 7.8 7.8 7.8

Net irrigation requirement 18.0 18.0 13.8 SourfLace 'losses fLrom 7.3 3.7 2.9 irrigation ioaLnet withdrawal from groundwater 25.3 21.7 16.7

Groundwater losses from 10.4 6.8 5.2 irrigation Gross irrigation 35.7 28.5 21.9 requirement -

1/ See table 17. 27 Ise------roppingintensity fcr T-Aus and 20% for jute, this cropping pattern includes 10 T-Aus and 70% jute (or another crop with

cohiiparadle water reqa -u-i-- nt). BANGLADESH - SECTOR STUDY TABLE 45

UNII' MONTHLY NET RIVER WITHDRAWALS FOR THE 15% TRANSPLANT BORO CROPPING PATTERN IN THE MONTHS OF MARCH AND APRIL (Inches of Water)

Gross Closed., 4I Thiri D.TPnJ Polders /I_iih.wpll I., *~~~~~~p iD 1~~c A _:InI March I_April March IAniAprlMac MrhIArL Comilla 8.0 5.3 6.4 4.2 4.8 3.2 0.24 o.615 Khulna 8.6 9.0 6.9 7.2 5.2 5.4 0.26 0.27 Mymensingh 7.0 5.7 5.6 4.6 *4.2 3.4 0.21 0.17 Rangpur 7.8 8.2 6.3 6.6 4.7 4.9 0.24 o.25

Sylhet 4.6 - 3.7 - 2.8 - o.i11 -

2 Figures taker. from Table 24 Dispersed lowlift pumps: Table 24 figures mivw:: >2Of.

Closed Polders: Table 294 figures minus 40%; these figures also r-present the net aquifer withdrawal for tubeweli pumping. / Tubewells: Figures for Closed Poliers times 0.05. TABLE 46

BANGLADESH - SECTOR STUDY

UNIT MONTHLY NET RIVER WITHDRAWALS FOR THE 15% TRANSPLANT CROPPING PATTERN IN THE MONTHS OF MARCH AND APRIL-'

(Cubic Feet Per Second Per Million Development Acres)

DLLP- Closed Polders Tubewells March April March April March April

Comilla 8,900 5,800 6,700 4,400 330 220

Khulna 9,600 10,000 7,200 7,500 360 375

Mymensingh 7,800 6,hoo 5,800 b,700 290 235

Rangpur 8,800 9,200 6,500 6,800 330 350

Sylhet 5,100 - 3,900 _ 190 _

1/ To obtain cusecs per million acres multiply monithly withdrawals in inches given in Tnble )tLby 106/720 = 1;390.

2/ Disnersed low-lift numns. TA3LE 47 BANGLADESH SFXTOR STUDY

HYPOTHETICAL LONG-RANGE WATER DEVELOPMENT BY REGION

Ir-ri ate Arcas - ml io ar'-rec4n

Low Lift Region Pumps Tubewells Polders Total

Northwest 0.13 2.21 0.13 2.47

CentraL 0.25 1.15 0.25 1.65

East 0.40 0.27 0.98 1.65

Southwest 1.02 0.39 1.0Ot±' 2.41

Total 1.80 4.02 2.36 8.18

Say 1.8 4.0 2.4 8.2

Z'Includes 500,000 acres Coastal Embankment Project and 300,000 acres Ganqes - Kobadak Project BANGLADESH - SBJTOR STUDY 40

NE1T RI-VsM WLTHDRVAWALS IN CRITICAL MONTHS FuA THE HYtPOTHETICAL LONG-RANGuE DEVELOPMENT-V Low Lift Region~ ~ Pumsn-- ubewel Is no ld e rs Total Mar. Apr. Mar. Apr. Mar Apr. Mar. Apr. Northwest 1,144 1,i96 729 773 845 814 2,718 2,853

Central 1,950 1,600 334 207 1,450 1,175 3,734 2,982

East 3,560 2,320 89 59 6,566 4,312 10,215 6,691

Southwest 9,792 10,200 140 146 7,200 7,500 17,132 17,846

TOTAL 33,799 30,372

/ See Table 43 TABLE: h9 BANGLADESH - SBOT0R STUDY

AVERAGE RIVER WATER BALANCE AFTER trtnt%,ll,,mrt h 7flT f flY * %T. 1, rl r,lTl%V t\f,AlmyTl UWtT n . ~.Tnr T.flf"I T HYPLIuin.m C±Lu ivlu~-nIulium LjzvnjuvriwI JN DIU1JUJjflWZ0f

March April

Ganges (Wiilion Acre-Feet)

Average Inflow from India1/ 5.02 4.32 Net Withdrawal (Southwest) i.02 1.07

Remaining Flow 4.00 3.25

Brahmaputra

Average Inflow from India l/ 10.23 14.34 Net Withdrawal (Northwest)Z' 0.16 0.17

Remaining Flow 10.07 14.17

Meghna

Average Inflow from Upper Basin-/ 1.38 1.97 Net W-ithdrawal (Central & East)'/ 0.84 0.58

Remaining Flow 0.54 1.39

TOTAL REMAINING FLOW 14.61 18.81

Discharge into Sea Historic_/ 16.84 20.86 Total Net Withdrawals 2.03 1.82

FUTURE DISCHARGE INTO SEA 14.81 19.04

Y From Table 4 _/' From Table 46

31 Fro Tabl- OJJJI

APPENTTX A Page 1

BANGLADESH

LAND AND WATER RESOURCES SECTOR STUDY

VOLUME VII

WATER TEGHTNIGAT. P1PORT NPO.20

VURRAT.T. WATPP ,RF fTPCfWF PCTMTTIAL

Ganges DiversionsQ /

1. Surface water abstractions for irrigation inside Bangladesh wo--ld reAapre a substantial par1 of +he Ga.nges low flow. U-era, 0+ mtes of in-country requirements vary depending on estimates of the size and number of pro- ects which woTl. A Aw. fr.mP +ha Ganges, whether fii1 dopmr. of the coastal areas is included, and the extent to which groundwater reo cs es wuld be u sed. 2. AA4,-.Accordng to the RUnd4 l1-eky-e Re rew (,,-.- 10, 19oA p)- claims for the minimum amount of irrigation diversions downstream of IF.-na., have ri-en-ee-S fr.t.0.. cfr . -usesin1 toAr4-.oI,n cusecs -, - Ma 1 8oA .LO.0.f2~O.JACV3. ~ ~ ..1. ili *.J.JCICJ L.JUe~.AC.. .1.1L .L7C%./C UJ 4/,C.X/. L.L3~e L L&A AACLJ C./-.I Three meetings with the Indian Government between 1960 and 1968 raised

Cell- req4UiL.,.1enJILs0 to 1L8,097 c,U0secs, 297,3.52 cuecCU0 r.iU 2,010 cUsVes. AIn the IBRD Preliminary Review of the IECO Master Plan dated November 1965, a fs-Lgure of 52. ,oJo cusecs iLs used fo.Lthe U Untodiadu V.aL(pJ.Ua)U1- Barisal projects for the month of January (no figure was given for April

) *1 ijie .LDIU irid;.e raLs.I .LU1 01LUWO UILLLY cuusevsU:U l diverted to the Southwest Region and 6,000 cusecs to the Ganges North Bank

In another section, the IECO Master Plan shows a total diversion water Apri;l f 4the .3.~'.U.LJ.VAICiLIreqireruentF U)off 57,00.)I,J.3J C.UtCcueci LJ.i M.J ±.1.4. 4. C.)or ULLA VLL3.JLCwho-le Gangesuu.ii~,o JJOJ.BDarrage .. PDrojec-tICJCL L which includes the Ganges-Kobadak, the North Bank and the Faridpur-Barisal p_ojecs _ r'-1 ,4TT _ S L UUb C\VU L*11 k ) ILC}.

14.1. ~ ~~~~~I'LLUFr, -Om ~~~Pltes Uea A-laA±da adAbiisaniU 4-LiU ± LI ± o'serv-e'u ~±vU thatULdLd u somue ofLUIiU). theLdI con-koU1V fusion in estimating the diversion requirement may arise from the definitf.1on of which projects to include and which to exclude as receiving Ganges diversions. Table la contains estimates by Harvard of the water require- rmenrts for the f-ully de-veloped proJects. There iLS very liLttle difference between these estimates and the water-use requirements computed by IECO. ]:t is difficult, however, to relate the figures given in' Table la to the figures used in the discussions with India and IBRD.

1/ This Appendix is a modified version of a technical memorandum prepared at

Top t-1h.eLA Ce.-4-,-e. UCIILIC). LV. for--L.£UjJLL4.L 'ati4-4onL JI 3.)Stu4.d.4,es 1II.AU.LC of-PU) A.) e O. earvar.4LL UTT-4-4 A . V CI. 0.1_L 4-.tJ , tIA.A4-Ade C/U. i-LC.. 4-col-ober CU k/C -1.2kU16 8.Q . APPENDIX A Page 2

5. Irrigation requirements- at canal heads for full development in the Faridpur-Barisal, Ganges-Kobadak, and Ganges North Bank projects total 91,000 cusecs (Table la) compared with average flow in the Ganges in April at Hardinge Bridge of about 70,000 cusecs. Apparently, even without Farakka Barrage, total water requirements for April could not be met entirely by river diversions.

6. The water deficit becomes even more pronounced if the irrigation demands include any for the coastal embankment or sunderban reclamation projects. West of the Gorai, these areas total 2.575.000 acres and the additional water requirement would be approximately 40,000 cusecs.

7. The water requirements calculated by Harvard are based on future cropping patterns given by IECO. It is nossible that these Datterns could be altered to reduce water requirements during March and April. Ultimately, however. the alternative future croDping natterns might increase the water requirements although this is considered unlikely.

8. T.R.21 shows that the groundwater can be developed and used in the upner half of the Southwest Region and in the Ganges North Bank areas. The water requirements for full development can be met almost completely by groundwater withoult mini no. With groundwater develonment. thp irripation requirements during March and April can be taken as those for a year of average rainfall and shortages in excepntionallv dry years can he taken from the aquifer which is replenished in subsequent high-rainfall years. Table 26 shows that the rainfall recharge in Kushti2 and J.essnre is not nnite sufficient to meet dry season requirements for full development of the whole northern h.qlf of the Southwest Region=- Tetailed studies mav show some lint.egr2ted surface and groundwater to be desirable in that area. However, the required suirface trwater input would be low because high water-use effici encie are reached with such integration.

9. In the SW1 LDU the surface water requirement from the river would he considerably less than 40, 000 CusecS because:

- low-lift pnimping within a closed system requires relatively little water;

- return flows will discharge from horizontal sub-

s,,rfa dr,ai ag e anrA

=waterw- d 'be sto.red in. closed es-tu~aries.-

1 n T | ~~~r.rc + a,, ¶.r

1t/~ ~ ~ ~ . U 1 1XO SLVS UJ W U CL' y'iHVO |4. W.i.i U'.. '..4JtL Iu9 U1s VV'.J..II U1. WA. DUZ Uli. U can be stored in the estuaries or the irrigation return flow that can be reusedA, bUU itU is U gh±LtIIluUthau 'datUa oUn Which14-Uto bDae U1ths catLculatilon exist in Dacca. If it should turn out, for example that 1.4 million acre-feet can ble slored or recapature' fror return flows, 4the total rement .L,L 4reqthe river during April would only be about 1 million acre feet or approximately 17,Itfycusecs.

9/In uthe crica morlthl of Aprl-L forL a 90%/ dr y-r APPENDIX A Page 3

11. 'rable lb shows that the April flow in the Ganges at the Hardinge Bridge was more tnan 55,000 cusecs for 27 out oI 30 years of record and more than 50,000 cusecs for 29 out of 30 years. In other words, even if 40,000 cusecs were diverted by tne Farakka Barrage, most of the water requirements for full irrigation development might be met from the Ganges and from tubeweiis, combined witn estuarine ciosures and subsurface drains to transport return flows.

12. However, alternatives to diversions from the Ganges cannot be developed without some cost to Bangladesh: tubewells in the Faridpur- Barisal, Ganges-Kobadak, and Ganges North Bank project areas and subsurface drains and estuary closures in LDUs SWl, Sw3, SW9, SWlO and SWll.

TABLE I a. BANGLADESH - SECTOR STUDY

APPENDIX A

PROJECT BY PROJECT 'WATER REQUIREMENTSY/ MONTH OF APRIL,. HARVARD ESTIMATE;S

rGross Area Irrigation of Project Requirements 2/ Completion (000 Acres) at Canal Heads- nate- 3 !

FaridDur-Barisal SW2 630 10,345 1986 0 ivv 540 5,5 1988L~70 SW4 882 13,540 1983

Total 2,052 29,441

Gan es-Kobadak SW5 223 3,826 1980 SW6 126 1,826 1978 SW7 345 5,122 1980 SW8 17 294 1977 SW9 550 8,957 1990 (after 6th Plan) SWiO 406 7,408 1986 SWll 420 6,883 1990 (after 6t.h Dlan) SW12 488 7,694 1971-1972

Total 2,575 42,011

North Bank of Galnges NW4 4/ 333 5,947 1975 NWi7 508 10,894 1975 NW9 165 3,127 1975

Total 1,006 19,968

GRAND TOTAL 5,633 91,420

1/ These figures are based on IECO patterns, water requirements, and 90% dry rainfall. 2/ In the critical month, April, for a 90% dry year. IECO/EPWAPDA MasterPlan, Vol. II, Chapters XI and XIII, at completion date. 31 IECO/EPWAPDA Master Plan, Vol. I, Chapter VII, p. 125. 1j/ Estimate; data for this project not available. Same as LDU NW9 but -prorated on the basis of the area shown. TABLE 1 b BANGLADESH - SECTOR STUDY

APPENDIX A

APRIL FLOW IN C-LNTC-ES AT MUMlING-E BTDC-E

Year April Less 40

1934 75.5 35.5 1935 66.8 26.8 l 0g'3 5. 6 10.6 1937 63.7 23.7 1938 ~~~~ ~~78.3 38.3 1939 61.8 21.8 1940 67.6 27.6 1941 55.3 15.3 1942 64.3 24.3 1943 64.0 24.0 1944 87.3 47.3 1945 68.6 28.6 1946 72.1 32.1 1947 61.4 21.4 1948 68.6 28.6 1949 81.1 41.1 1950ncr77.-7 ')37.7 -L '3 jU I1. -P 1951 70.4 30.4 1952 64.8 24.8 1953 44.5 4.5 1954 52.7 12.7 1955 76.6 36.6 1956 82.5 42.5 -19JnE-"-7 9n5. 5 . 0 1 1958 79.3 39.3 1959 105.0 65.0 1960 78.9 38.9 1961 67.1 27.1 1 a62 94.8 54 8 1963 84.5 44.5

Mean 72.1 32.1 Std. Dev- 13.4 13.4 Std. Dev. 13.4 13.4| PIATE A.l a

PROJECTS IN SOUXVOt'i ST ARLA |{ \|Tr#r1 S -ICoostcl L-nb I-rl rjc SWY-t Gonqus - r o i.P-oject, ~ Jecsore Ulsil Pl osc r.< t-2 t ~ ' SW-2 Foridpur -Barzisnl ProJjeci, 5v*Z^ BOriSGt Unit- Phase I SW-)' Gar.;i:s-K,)t,oJak Prolec!, -,7, i Jessore Unit - Phose V P4!l SW-3~ Faridr.u -Barisnl Prr,jre,d,l _ z..... _ &eirit

SW-50 4 ,coiForidpur- PrujecGJe ssor e Urdl -Phose Mt r~ %r$ jtj Fnridnu- U-ft SW-II1 Gongrs- Kobadak Proiect , ):-. . SW-5 Gonges -Kobodol Prn jecl, Kur nX| ~ > \ l^ Jestore Unit-1 Plse SW12- Gnls-KobodrJk rjc, ,''. :, ,;- 9 ,1 SWI-G Garqes -Kotodak Projeci, KseoUi hs nJI t ')9ji\ tt Jtssroze Or. - Phose 11 SW- 13 Svires.0, PrrjtOi|}1>, ; : ,; ):^'- - SW-7 Gcini;s -K(-bcidc Project, :,,-a Jessore Uni I- Ptose 11 tt tsC \t

K{U H9=I_II

t''K t SI !T'-A J. .SW- 7 g> i\b

>, .* ! sIi-t? - .

sJ \ E t )2 r:,S; )/,2)(

i(r I,, .- ;k- x'cot : ,!*( j ,,- _,,r...-.z=K.H 6MNARIbA, !

2't:JESSC r tI .. E.- > \ .... ^

2 LrSvll,j\, f rt/-s2 i i

! !' D ! A ; < 0~~~~~~~~

SCAEINAMLE

85-~ ~~7 I/,C-EPAP/N^S liEt A1i , ittZ1f

| ~~~~~~PROJECTSIN NORTHiWEST AREA 8-1( tA I ~~~~~~NW-I Stlvuchi Project \ . e { #*re ~~~~~~~NW-2 f r.V,a Pro jecl ) ,, N4W-3 13,ohmop,ul,o Right flood Enoketr : - i:NW-.4 Choatn Fi,l Projec1i'; itiW -5G--urd-ic. Dev.op-,,li ond Pun.1 p llririgtion- Northern DlaIrIcts ¢ '< ' . r NW-G Kvrlgrom Pro ject I)tt t<...... ).1 § i ~~~~~~NW-7Pobno Projecl f A, g " tk 5'J ttw-8 Song or Pro jecl 7 }s:h _ *NtJw-9 Soz-hIrn flaisahlh Project > , tYr t}S- NWV-IOTeesto Picject. p. - ' NW II Tee3lo South Embankqment Pro ject . Y,;\<9 1 ,,, 3 | ~~~~~~NW-IZrentullo Pro ject P;g, -| ''tA t! Y f

*Projecs P s4ibly Invol,ed': withi Ganages Diversions t D A.ro

| */ ;>- ), f~~~~~~~~~NW-5 rt-%

L ,'2,x,-S.X<9--t.,,-x$5~~~~~~~t~-1

| I N D I A ; - > dM-s20 l~~~~~~~~~~~~~~~~~W-I

5~~~~~~~'JNIW-5 -,f*BJst(t

16~~~~~~~~~~~~~~~N- tqw-"Z12S,4 1

§~ ~ ~ ~~~~~~~~~~~~~~~~~~~~~~P RANGGPDES - SECOR,,uiY goO 10 20 30D 40 50 NO I N D I AR. SCt.LE~~~4IN" EOETLC.rOt IIE

} Source: l~~~~~~~~~~~~~~~~~~~~~~~u) _ _ uu- 8JIErO-I2WIt9D St M'illl P.ANEASTPAK51AI ,19NW NW 5 .

APPENDIX B Pzage l1 BANGLADE5H

LAND AND WATER RESOURCES SECTOR STUDY

VOLUME VII

WAT ER

TECHNICAL REPORT NO. 20 - OVERALL WATER RESOURCES POTENTIAL

APPENDIX B

THE GANGES AND BRAHMAPUTRA BARRAGES WITH LINK CANAL General

1. The following is a summary of work done on the Ganges and Brahmaputra Barrages and the link canal in 1967. The 200,000 cfs capacity of 1he link canal would be excessive if not used for flood relief and navigation. Only about 40,000 to 50,000 cfs would probably be ample ior irrigation. The large size was adopted merely to arrive at a relatively high cost estimate to cover unforeseen items. The design criteria are included and may not be technically sound. The cost estimates for the barrages are also not firm. The tentative nature of the work must be kept in mind and additional study will be necessary before detailed consideration can be Justified. 2. An essential point is that this scheme has merit only if enough land -isready for irrigation with pumps, canals and distribution systems so that the additional water supply can be used effectively upon completion of the barrages and canal. The cost estimates and initial and ultimate benefits must all be thoroughly reviewed.

3. The technical feasibility of constructing a link canal between the two barrages was studied with the WAPDA Directorate of Design. The possibility of diverting Brahmaputra water into the Ganges at Farakka Barrage in India should perhaps be considered because it might eliminate the need for a Ganges Barrage at or near the Gorai Offtake. This approach will require international cooperation both in construction and operation which may become a liability to Bangladesh. However, India and Bangladesh would also have to cooperate if some Brahmaputra water were used to irrigate an area in West Bengal. Both countries would depend on the diversion system and possibly storage in the Brahmaputra Basin.

Major Works and Cost Estimates

4. The following major works are required for the Brahmaputra diversion:

(1) Brahmaputra River Works ($000,000)

(a) A barrage across the Brahmaputra 400

(b) An inlet structure on the Old Brahmaputra 140 APPENDIX B Page 2

(d) Levees and river draining works upstream and downstrean of the Brahmaputra barrage 50

(e) Dredging of the Old Brahmaputra 30

(f) Two barrages across the Old Brahnaputra for diversion of irrigation water 120

Sub-total 800

(2) Ganges River Works ($0003000) (a) A barrage across the Ganges ? ) (b) An inlet structure on the Gorai ) River to control flood flows ) and irrigation releases ) 300

(d) An outlet structure on Brahmaputra diversion channel 60

(e) Levees and river draining works (upstream and downstream of barrage) 20

Sub-total 400

(3) Diversion Channel

This channel would cross the Northwest Region and would connect the Ganges and Brahmputra Rivers. It would be 100 miles long and have an average gradient of 18 feet per 100 miles. The following assumptions have been made:

(a) Maximum discharge: 200,000 cusecs

(b) Average velocity: 4 feet per second

(d) Average width at peak flow: 2,000 feet APPENDIX B Page 3

(e) Land width required for channel plus embeiiiankijent a-rIkment: 400t,uuu feetI IF,

(f) No use of existing channels considered in cost estimate bringing the total of agricultural lands plus homesteads to be acquired to 50,000 acres

(g) Cost of excavation plus construction of embankment: Rs 7$/ 1000 cu ft or Rs 2.0/cu yd

(h) Cost of land acquisition: Rs 10,000/acre

(i) Average depth of excavation: 15 feet

(j) One structure across channel for diversion of irrigation water

The cost breakdown for the diversion channel work is:

($000,000)

(a) Excavation of channel and construction of levees on both sides 270

(b) Land acquisition 100

(d) Barrage across diversion channel 30

(e) Railway bridge across channel, three road bridges across channel and three road bridges across drainage streams 25

Sub-total 5°0

Area Benefiteci and Cost Per Acre

5. The high-cost diversion scheme would have to yield benefits as soon as possible. To make it viable, project units of, say, 50,000 to APPENDIX B Page 4

200,000 acres would have to be made ready to receive the water. Integrated surface- and groundwater use must be considered in order to prevent waterlogging and to reduce surface water demands.

6. Areas that could be irrigated are suggested below:

In Southwest 3.5 million acres In Northwest 0.5 " " In Mymensingh 1.5 " " In Dacca 0.5 II t

TOTAL 6.0 million acres

7. The average cost for irrigation and drainage development with pumps and distribution systems but without extensive flood control is estimated to be Rs 1,500 per acre. For development of 6 million acres this cost would be Rs 9 billion or $1.8 billion (U.S.).

8. The total cost of the Brahmaputra diversion including the Ganges Barrage is $1.7 billion. Irrigation and drainage development being $1.8 billion, the total cost of the project would be $3.5 billion. With 6 million benefited acres the average cost would be almost $600 per acre. RESTRICTED

INIERNATIONAL BANK FOR RECONSTRUCTION AND DEVELOPMENT

INTERNATIONAL DEVELOPMENT ASSOCIATION

DA? TC,T AnTVQ T3

LAND AND WADR RESOTuTRCES SECTO STuDY

VOLUME VII

WATER

TECHNICAL REPORT NO. 21

THE GROUNDWATER POTENTIAL

December 1, 1972

Asia Projects Department

BANGLADESH - SECTORY STUDY VOLUME VII - WATER

TECHNICAL REPORT NO. 21

THE GROUNDWATER POTENTIAL

TABLE OF CONTENTS

Page No.

SU01ARY AND CONCLUSIONS ...... i-ii

I. GENERAL - GEOLOGIC AND HYDROLOGIC SETTING ...... 1......

A. Regional Geoloev ...... 1

B. Brief Description of the Alluvial Deposits ...... 2

C. Brief DescriDtion of Maior Wpter-Bearina Areas ......

II. GROUNDWATER RECHARGE ...... 8

A. Present GIromndwater Fluctuations ...... 8

B. Sourc esof Irirdwater=. RechPra.. =.- .....

. Water Balnance Studaii for Thnln,rgaon ....

D. Potential Rninfall Pecharge"12

General-12 Factors Determining the Relation Between Rainfall &-d Groqndwater Recharge ...... 12 Effect of Water Taole Depth . . .13 T.Me Extent Of Bu-nd-ing vX.,..v*vviv;vXXvvX.v;@[email protected] 1 Infiltration Capacity of the Soil ...... 14 Total Ruanoff Percentage -11. Total Rainfall by Region ...... b14 Total Evapotranspiration byr- Region 15 Potential Regional Recharge ...... 16

E. Future Water Table Fluctuations and T,N,tIje.b of .rrA ga..lWell.A.%.s-on Le 'lDOSS, ...... ' I7

4 V_&A1 s V~~Ln ~'Y.dAL. - J.L, 4;A4ULJ.2.LLJ.-, ±LUI1 V U! AII.- U 7T4-VVV~L ±0CUJL: -LLme 7 The Future Dynamic Equilibrium of the Water Table ..... 18 N1)on-.Benefic-i':l Evaporat.ion...... 1. Acreages Irrigable by Groundwater by Region .. 19

Future Water Tables Levels ...... 20

/ Prepared by Acres International, Mr. Marinus Maasland (Consultant) - 2 -

TABLE OF CONTENTS (Continued)

Page No.

III. AQUIFER TRKNS>3SSIBILITIES AID TUBEWELL PERFORMANCE ...... 21

A. General ...... 21

B. Analyses of Aquifer Characteristics in the Northwest Region from ADC Tubewells ...... 21

C. Analysis of WAPDA Tubewells .. °33......

D. DPHE Tubewells ...... 23

E. IDC Tubewells ...... 0 ...... 24

F. Notes on the KTCCA Tubewell Project in Comilla ...... 24

G. Conclusions ...... 25

IV. CHEMICAL CHARACTERISTICS OF GROUNDWATER ...... , 26

V. THE EXISTING THAKURGOAN TUBEWELL PROJECT ...... 27

A. History .***...... 27

B. Description of Existing Wells *...... 27

C. Well Performance ...... 27

D. Comparison of Screen Performance ...... 27

E. Screen Head Loss ...... -. 28

LIST OF TABLES

1. Runoff of the Tangan River 2. Recharge Resulting from 55 Inches of Monsoon Rain 3. Present Distribution of Land Types in Bangladesh 4. Present and Future Area Conditions 5. Breakdown of Areas in per cent of Gross Area 6. Runoff Rates and Effective Rainfall for Various Land Classes 7. Calculation of Maximum Regional Effective Rainfall Percentage 8. Calculation of Minimum Regional Effective Rainfall Percentages 9. Typical Calculations of Future Regional Evapotranspiration for Dinajpur-Rangpur Districts 10. Summary of Calculated Average Evapotranspiration by Districts 11. Estimated Future Regional Recharge for Dinajpur/hangpur - 3 -

12. Estimated Future Regional Recharge for Bogra/Pabna 13. Estimated Future Regional Recharge for Rajshahi 14. Estimated Future Regional Recharge for Mymensingh 15. Estimated Future Regional Recharge for Sylhet 16. Estimated Future Regional Recharge for Dacca 17. Estimated Future Regional Recharge for Comilla/Noakhali 18. Estimated Future Regional Recharge for Kushtia 19. Estimated Future Regional Recharge for Jessore 20. Estimated Future Regional Recharge for Faridpur 21. Summary of Potential Regional Groundwater Recharge by Districts 22. Net Potential Recharge Available for The Bunded Areas, by Districts 23. Acreages which can be Developed on the Basis of Groundwater Alone, and Numbers of Tubewells Possible or Needed 2A. Optimum and Recommended Depths for Two-Cusec Wells 25. Data From Various Water Supply W:!ells 26. Thakurgaon Tubewell Project - Summary of Well Test Data 27. Summarv of Results of Grain Size Analysis of Aquifer Materials in Various Areas 28. Data of Different Proiects of IDC 29. Summary of Water Analysis 1967 Post Monsoon Season for Barisal District 30. Summarv of Water Analysis 1967 Pre-Monsoon Season for Sylhet District (Wells) 31=I - iimmn.rv f WTt.Pr Analvyis 1907 Prf-M_Mnnoon Season for Svlhet District (Rivers) 32. SummanYnr of Water A.nalysis 1967 Post-Monsoon Season for Bogra District 33. Summary of Water Analysis 1967 Post-Monsoon Season for Chittagong 3is a srioitr 36. Summary of Water Analysis 1967 Post-Monsoon Season for Comilla District

,5 Su n_J..,-r -fLJJ. 7rTat+o A na lysIsr 19 6'I7 P^ot-M Seaon forvr TDna-ea Dis-rict+ - 36. Summary of WTater Analysis 1967 Post-Monsoon Season for Dacca District

'47 qllrm a YTT -rIJA+oW An:nl-irc a 1 OAt7 Poc+_M-vnc^nrn qacnc^rw -rnR-v- sArlrn;- 38. Summary of Water Analyasis 1967 Post-Monsoon Season for Faridpur District 39. S,ryim of- ate Analysis 19617 --- Seasn fr- Jesoren TDistic ~~~/ - V, I - - - -'V~... .L- .>'/ -I ~ WJt . 4 J. L 3 C 3~'I ..1. t4 4 ~ S4 4..)14 4 h0. Pumps Installed in Thakurgaon Area 41i Schedule of Original Thakurgaon Pint Tests

LIST OF PLATES /

IBRD - 10021 Groundwater Isopack Map Showing 1966 Difference Maximum and Minimum Levels IBRD - 10022 Maximum Depth to Groundwater as Measured from Ground Surface During Calendar 1966

1/ These plates appear at the end of this Volume. LIST OF FIGURES

1. Rainfalls and Simultaneous Fluctuations of the Water Table. 2. A. Water Table Fluctuations B. WfTater Table Fluctuations C. Water Table Fluctuations 3. Specific Capacity of Thakurgaon Tubewells 4. Discharge Frequency Distribution for Screen Types BANGLADESH - SECTOR STUDY VOLUME VII - WATER

TECHNICAL REPORT NO. 21 - GROUNDWATER POTENTIAL

Summary and Conclusions i. Groundwater is bound to become increasingly important for agricultural development in Bangladesh. Groundwater constitutes a major source of water available to areas where irrigation from surface sources is difficult or impossible. Flexibility of supply gives it special importance since,groundwater supplies can meet cropping needs during the dry season when surface flows are at a minimum and irrigation requirements high. ii. The presence of extensive groundwater can be attributed to two principal factors: relatively high rainfall and favorable geology. With a minimum average rainfall of 50 inches in the western part of the province, increasing to 200 inches or more in the eastern part, the importance of rainfall in recharging the groundwater is obvious. In addition, the generally flat terrain, coupled with the large areas of relatively pervious soils and permeable underlying sediments, is favorable for rain percolation. iii. The alluvial deposits typically range from silts and clays to sands. Over much of the area, silts and clays predominate in the top 50 to 80 feet, with sands forming the major part of the deposits at greater depth, particularly in the northern two-thirds of the country. These changes in vertical distribution are associated with changes in stream flow and types of sediment transported during the glacial and post glacial period. Gravels or mixtures of sand and gravel are found at only a few localities, mainly in the northern areas. Evidence from the many hundreds of wells that have been drilled (and other indications) show that the entire area of Bangladesh is underlain by groundwater with water table depths ranging from zero to about 30 feet, depending on location and season. iv. Regardless of its depth, the principal aquifer system is hydraulically connected with the rivers. The regional groundwater reservoir thus formed is partially drained by streams of the plain as their stage declines during the dry period. During the annual monsoon, however, it is recharged by a vast increment of fresh water from rainfall. As a consequence, there is excellent opportunity to develop very large groundwater supplies on a sustained basis. v. The total volume of groundwater in storage is enormous, since the alluvial strata in which the water occurs have been shown by deep drillings to have a thickness of 3,000 feet or more. Of course, only a part of this stored water is available for irrigation use, since the cost of pumping limits the clepth from which water can be economically extracted. For most -ii-

areas in the province the depth of wells has been limited to 400 feet, with turbine pumps which are set at less than 100 feet. iv. WAPDA, ADC and the Directorate of Public Health Engineer- ing have compiled data on wells drilled for irrigation, municipal and domestic supply. The performance of the wells varies widely but these variations appear more closely related to well construction and development methods than to aquifer characteristics. It appears that high- yielding wells can be installed almost everywhere in 3angladesh the coastal belt, and the complex geological areas of the northeast. v. In many parts groundwater reaches the land surface towards the middle of the monsoon and even earlier so that a significant amount of rainfall is rejected as recharge. Hence, if initial groundwater level had been lower, a greater part of the rainfall could have infiltrated. This happens when tubewells have lowered the groundwater table by the end of the dry season. In other words, monsoon recharge would be increased by groundwater pumping during the dry season. Water table fluctuations do not change significantly in areas where net groundwater withdrawals remain less than the potential recharge. vi. Large-scale groundwater development projects, chiefly for irrigation, have been proposed for many parts of Bangladesh. In order that development be most efficient, beneficial anca economical, prior and continuing studies should be made in all project areas. For project areas to be properly evaluated, the geologic and hydrologic setting not only of project areas but of the province as a whole should be analyzed. Further studies are therefore essential. vii. By far the most important conclusion of this report is that, with the exception of limited low rainfall areas in the west, recharge should be sufficient to support full development of irrigated agriculture for virtually the entire area to which surface water supplies are not readily available. Aquifier conditions in these areas are also generally good. However, the actual pace of groundwater development will depend on economic and implementation capacity considerations--i.e., the development of a viable contractors industry, the strengthening of supervisory agencies such as ADC and WAPDA, the accumulation and analysis of additional groLudwater information and the adaptation of available tubewell technologies to the region's special conditions. BAM(T'T AnTYi. QU

LAND ANVD WATER RESUUPUES SECTOU T1UJJX

VOL-uM1 VII

-WA'TER

TECHNICAL REPORT NO. 21

T1HE GROUNDWA'1'ER POTENTIAL

I. GEOLOGIC AND HYDROLOGIC SETTING

A. Regional Geology_/

1.01 The primary geologic features of the study region are the Indian mass of ancient rocks, the Himalayas to the north and the vast fold system of the Burma-Malay arch. Bangladesh is located where these three major geologic complexes meet. The relatively undeformed ancient rocks of India have moved north to their present position during the past 300 million years and are now apparently pushing under the Himalayas and also possibly pushing beneath the thick, soft sediments of the Burma-Malay arch.

1.02 The India basement complex rocks has been shown by geophysical studies to extend to depths of 15,000 feet beneath Calcutta and to 20,000 feet beneath Dacca. They are probably about 20,000 feet beneath the surface near Bogra and dip gradually from their outcrop in India toward the southeast.

1.03 The Malay north-south fold region is exposed in the hill tracts and extends north into the Sylhet region toward the Shillong Plateau in Assam. This complex, steeply'-folded region has been shown by geophysical studies to extend to within 40 miles southeast of Dacca at a shallow depth beneath thae surface, perhaps only a few hundred feet or less.

1.04 A hinge line in the basement complex which extends from Calcutta through Dacca, has been proposed by geologists but evidence is not at all clear as to its nature and it may be a regional dividing line between the India block and the Burma fold arch. This line extends into the Sylhet area where it may merge with the east-west fault zone at the south flank of the Shillong Plateau.

1/ Thomas, R. G., A Brief Description of the Hydrologeology of

- Bangladeish, 1970. 1.05 The Shillong Plateau, while including some sediments, is mostly basement complex. The Plateau extends westward from the Burma fold arch and the Brahmaputra River. Geophysical evidence suggests that the south boundary fault does not continue westward beneath the alluvium, although there may be some discontinuity in the basement itself.

1.06 The vast alluvial region south of the Himalayas has been called the Himalayan Trough. This trough extends from Bangladesh to India, through the north tip of Bangladesh and into Assam between the Shillong Plateau and the Himalaya foothills. The trough to the east, however, is narrower and large outcrops of basement complex north of the Brahmaputra River suggest that it is not as deep to the west.

1.07 The youngest established marine sediments in the region are probably of Pleistocene age in the Burma fold arch. In other areas, the youngest marine sediments seem to be of Eocene age. It therefore seems likely that the Bay of Bengal extended over most of Bangladesh in Eocene time, but that non-marine sediments were more or less continuous in parts of the Himalaya Trough and in the present delta area of Bangladesh. during most of Tertiary time.

1.105 In addition, it is clear that Pleistocene sediments of the Burma arch have been heavily folded. It is likely that much of this folding has occurred in Quaternary time and it is also likely that much of the uplift of the already high Himalayas had occurred by the Quaternary Period. While these arras were being uplifted, the Himalayan Trough and the Brahma- putra-Ganges delta were subsiding. Folding and faulting of Quaternary alluvian deposits is reported and, as indicated by major earthquakes, the entire region is still extremely active.

B. Brief Description of the Alluvial Deposits

1.09 Alluvial deposits, probably of Quaternary age, extend over nearly all of Bangladesh except for the Chittagong Hill tracts and the fringes of the Sylhet area. While older alluvial deposits are exposed north of Dacca, east of Bogra and in large areas in West Bengal, little is known about them.

1.10 In the Calcutta area, brackish water marine shells were found at 950 feet indicating estuarine conditions. Wood fragments and "kankar" (calcium carbonate deposits formed in ancient soils) are found commonly in wells at all depths in the Calcutta region, but are rarely reported in Bangladesh.

1.11 In any event, it seems clear from geonhvsical data that the alluvial deposits, which are reported to be only 600 feet deep near Bogra, are at least 2.000 feet deep near Dacca. -3-

1.12 History of the alluvial sediments is complicated by the change in world climates. During glacial periods, sea level was as much as 500 feet lower than at present and it is likely that even greater amounts of material were being carried by rivers from the Himalayas than at present. During non-glacial periods, sea level was 100 feet or more above present sea level. So far it has not been possible to clearly identify the events which have occurred since the last glacial period. However, it seems likely that during this period the Brahmaputra and the Ganges removed tremendous amounts of alluvium near the ocean while depositing a:Lluvium in the higher valleys below the glaciers. The old alluvium north of Dacca and west of Bogra was probably cut away at this time. Present scour depth of the Brahmaputra is reported to range from 90 to 200 feet so that depth of scour could have been 5J0 feet near the present shore and 300 feet near Bogra. Thick sands at about 500 feet in the Khulna aistrict may represent the backfilled course of the old river system.

1.13 The nature of the older alluvium is not clearly known in most of Bangladesh and may be complicated by major Pleistocene changes in river courses. For example, the Brahmaputra and Ganges may have drained into the Indus. Heavy mineral content of' the older alluvium tends to confirm this, but thie data available are very poor and the idea is simply a hypo- thesis at this time.

l.l1 The large alluvial fan of the Tista River seems to have successi'ully forced relocation of the Brahmaputra River near the Shillong Hills just aS the Sun Kosi fan has done with the Ganges in India to the west. The present surface of the Tista fan partly covers the older alluvium where it has not been removed by erosion south of Dinajpur but is continuous with the Tista Brahmaputra alluvium south of Rangpur.

1.15 Alluvial deposits of meandering streams with a wide range of stage are of two general types: meander belt deposits of coarse texture (primarily sand) and flood basin deposits of fine texture (primarily silt and clay). As the stream rises to flood stage, overtopping its banks, it fills the interfluvial areas to form lakes. The velocity of flow of wate:^ decreases abruptly as the sediment-laden floodwater leaves the stream cha-nnel and the coarse-textured component of its load is dronDed. forming a system of natural levees adjacent to the meander belt. Silt and colloidal particles of the clay minerals in suspension are spread by the muddy flood waters trapped in the interfluvial areas as the river stage declines. Settlement occurs as the water evaporates or sinks into the ground. forming a layer of silt and clay.

1.16 A transverse section through the deposits from master stresm to major tributary can be visualized as a broad iens of clay and silt bounded -h -

at either extremity by prisms of sand and gravel. At depth, these prisms of sand and gravel broaden and merge, forming a bed of coarse-textured deposits continuous from stream channel to stream channel.

1.17 When the thickness of the interfluvial clay deposit exceeds the maximum depth of the river channel at flood stage, the meander belt of the river becomes fixed. Clay is very difficult to erode and where its thickness prevents undercutting, it stands as a permanent barrier to river channel encroachment.

1.13 Within the broad clay lens, at any depth, smaller lenses of silt and fine-grained sand occur. These are the result of short-term diversion of flood waters from the major streams through temporary breaks in the natural levees during the rising stage of the rivers. Such breaks are called crevasses. Because discharge through them into the flood basins occurs before the stream has overtopDed its natural levees. the velocitv of flow is great enough to spread sand and silt over many square miles of the interfluvial areas. The deposits formed are generally no more than a few feet - or at most a few tens of feet - in thickness, because the crevasse in the natural levee is generally closed as the stream reaches maximum flood stage.

1.19 The principal system of aquifers formed by the processes described above occurs generally over depths of hundreds of feet. Its upper surface is at or near the land surface in the northern part of the Northwest Region and occurs at greater depths beneath clav and silt deposits in other areas. Regardless of its depth of occurrence, however, it will be shown in a later sention of this renort that the nrincipnl aquifer svstem is hydraulicallv connected with the modern rivers. The regional groundwater reservoir thus formed is, nprtially drained by the streams of the Plain 25 the4r stage declines during the dry period. This groundwater reservoir is a well-knit hyvroro1ir svytem hbeneath the Plain which si annuallv re.^arged1 hvb arst increment of fresh water from rainfall. As a consequence, there is excellent opportunity to develop very large groundwater supplies from thp arnqifer system on a sustained basis.

C. Brief Description of Major Water-Bearing Areas

1.23 The map showing 1Major Hydrogeologic regions (Plate 17 in Technical Report No. 20) shows the major groundwater subdivisions of Bangladesh,

a) The Ti st Fan - The area shon.m as (A) is mostly the Tista fan, but includes some Brahmaputra River deposits. This is a most favorable rPe. Surrfa c s a rprmeabl allowing maxmm percolation of rain, and water tables are high. Groundwater is unconfined and -5-

domestic water supplies of good quality can be obtained froTm Wfl1S as shallow as 25 feet. Tubewells 100 to 150 feet deep can yield up to one or one and one-half cusecs of watfer and tuehwells of sore 253 to 300 fnet depn with about 120 feet of screen yield discharges as high as four cusePs in the existing Thnkurgaonn pro1pnt. Snrface tanks are generally scarce because they do not retain water. b) Higher Floodplains - The Old Brahmaputra and Middle Meghna mroop}i-ns(B) and the Higher Ganges Floodplain (G) are both highly suited for groundwater development. The area shown 1 nsc() h(sc w^oll1 _ 1r'±iit.orS rt- n-vrcz4hrrEir r acribysandry rildecz at the surface which are underlain by aquifers of sand and fine gravel. The aren shown as (B) has anceven hiher proportion. of permeable soils and sandy ridges, many of which merge into sandy sub-strata at shallwT depth and are underlain by aquifers of sand and fine gravel. Shallow wells provide cilff; c on+. dorme +stiosuppl4es, h+.bu! T.Tnwlls of 200sn +tn30r feeit. depth are required for irrigation. Much of the area has unconfined aquifers wi s-hsicon-f-Ined conditions prevailing in certain areas. Wells have specific drawdowns of 7 to 15 feet psyr cusec and h1,.navebehen drill1d ,,n,1yr print mnyr+11 a c) LoweT,- C-asa-ea msA T-,.- J--I are shown as (D1 and D2), respectively. Eighty per cent of the landscape of4't L nges Flodpain isovere by a o three-foot depth of clay with a clay content of 60 to 30 per cent, whle,LLone-IhalIf 0of theJr cl..ay 4racio is ,mn.oiloie- z VI [±~L~lJIiI1Q.J. IL UL~ L .LaY J. 1 1-U U.LVII ±L0 LIIVIJi VLU 1 L.JI.-L~Ul" UV. ~IILAO layer is underlain by an undefined depth of silt and clay mixture containL.1ing a hLiLLrghl peICrcntage ± of. r1I,icawhIi chL1 c aus es an isotryy which sharply decreases the vertical permeability. However, the clays are well str-uctured ad crack when drying, so vertical recharge can occur.

The Lower Jamuna alluvium has surficial layers having a high silt

contenl;JL1t~iLU61151 andu sign"'fcant-.--LL -LIOV amo>unts ofS--L1Ip.d. r.ica- The. 1 '-oJLUI11 l -layeayer -sisJ.. more'I or varied in texture, however, than the Lower Ganges Floodplain. Nevertieless, tuh1e vertLicaLL perr,eabilit 15is 1Jfz;LyrpVo t U t U Ud 5obeoWLmeh low.

Water :Level observations by WAPDA and DPHE indicate that the wat'er table r'Lses f'o'l.lo-w thL1e r.onsoan rainfall in th4uese areas in much the same way as in the northwest region. Several tubewells of 1.5 to 3-cusec capacity ha-ve been installed in these areas for industrial, municipal and domestic purposes. -6-

d) Sylhet Basin and Southern IIeghna Basin - 'The area shown as E) makes up the Sylhet Basin and the Southern Meghna Basin, the latter extending further into the Coastal Area shown as (I). T'ne surficial layers of the Sylhet Basin are predominantly low-mica silt and clay deposits. T'he clay miner'als are mainly illite with some kaolinite. The southern Meghna Basin between the IlHeghna River and the eastern Indian border is covered by estuarine silts 15 to 20 feet in depth that are continuous and high in mica.

In general, this area is deeply flooded and rather under- develcroed, and little is as yet known about the suitability of the aquifer for groundwater development. Howvever, the Agricultural Development Corporation has successfully installed some 100 wells in this area. e) Older Alluvium - The areas east of Bogra (F) and north of Dacca G7arem older alluvium and may even include some shallow Ter- tiary sediments. These areas have been faulted and may well be folcled. In some areas, the surface materials are thick clay, in- hibitCing repid percolation. In other areas, this is not so. In general, the acauifers may be more complicated and semi-confined but generally have high water table levels. Recent findings (MacDonald, 1971) indicate that the aquif'er is excellent.

Generally speaking, shallow wells deliver sufficient water for domestic purposes, although in some areas tanks are needed for water supplv. The underlying aquifer materials have a high permeability and are highly suited for tubewell development. f) Complex Geology Areas - The area shown as (H) includes the Chitta- gong Hill Tracts, the hill areas north and west of Sylhet and Comilla and the north Mymensigh areas. 11 are underlain by highly folded formations making it difficult to nredict where groundwater supplies can best be obtained. In general, the sands do yield water to wells but most existing wells are for domestic use. Indlu.strial. municipal-supply and irrigation wells are, however, operating in some areas. e.g. in Chittagong; Comilla and Svlhet. Rpcent groundwater studies (Hunting and M. MacDonald, 196d) in the Sylhet and Chittagong Hill Tracts have est2hlished thst irrigation wells can he developed successfully in these areas, while recognizing that tubewell siting detsiled knowleldge of local geologic conditions and test drilling.

Cprcnbvsical work in theP Gomilla area east o-f t,he Megna River indicates that the folded sediments of the Hill Tracts are at shallow pnth and may be nprnoridin monst. of the wa.ter to wells. Both chaI.M domestic and deep irrigation wells are found here, but the area is -7-

complex and wells even close together encounter very different materials. However, the sediments seem to be as permeable as those farther to the northwest and west. g) Coastal Area - The Prea shown as (I) includes alluvium extending into the coastal area and is somewhat finer grainecL. In general, there is saline water at depth generally overlain by a layer of fresh water at 60 to R- feet" depth. Areas surrounded by saline estuaries have water of poor cuality near the surface; however, in several areas shallow wells do provide good to brackish domestic water. 'Ihe Directorate of Public Health Engineering (DPHE) has installed thousands of small diameter wells (internal diameter 1.5 inches) of 60 to 80 fAet denth in this area iincier the tRhiral WIater Supply Scheme"' whose objective is to provide one hand-pumped well for evry 32 npeolpe. As of Jiilv 1907, T)PTTF repnorted

Knihulna 7;221 Small wP.lls Chittagong 8,910 Small wells

Fari lniir __ Small weTIlls Barisal 12,500 Small wells

In some areas, the shallow groundwater is unsuitable for domest-ic ciomtion snd well depths of 70 to 90() fet ar required to obtain fresh water. It is unlikely that many irrigation or large domestic wells can be installed and operated to yieLd water of good quality continuously over a significant 4 pnerirod of +timen +.ctl rin II. GROUNDWATER RECHARGE

A. Present Groundwater Fluctuations

2.01 An important factor in the operation of a well field is

ithe Ia oLf gr'UU.L1Uodiwate extracted dUrLJ. a piLoLL o.f p.UILnguse. Pumping results in a lowering of the water table and an accompanying increase in thelpu-xp lift Uad pum,ping cost. Unless the pmIped water is periodically recharged, this expense can become prohibitive and event-ually the well field becomes valueless.

2.02 There is abundant evidence that even now, without significant pumping, groundwater levels fluctuate in the course of the year. Observations of water table levels in hundreds of wells throughout the Qountry show that the water table rises everywhere during the rainy season and recedes during the sybsequent ary season, reaching a minimum at the end of the dry period.

2.03 A first attempt at mapping water-table fluctuations and maxdmum depths of groundwater below land surface was made in 1967 by Camp, Dresser and McKee (CDM) from data available with the Directorate of Public Health Engineering (DPHK). These maps are attached as Plates 2 and 3. The contours on both maps are crude because they are based on relatively few data. Better maps can be prepared from the extensive data that have been gathered by WAPDA and published annually in Water SuDply Papers and, more recently, in Hydrological Yearbooks. Refinement of these maps would have considerable value for several purposes: - Improved pre-project recharge evaluation; - Delineation of areas where little or no recharge occurs because of shallow water tables at the beginning of the monsoon season; and - Delineation of areas where centrifugal pumps can safely be used.

2.04 Typical water-table hydrography are shown (Figure 2a, 2b, 2c) for WAPDA observation wells in the districts of Dinajpur, Faridpur, Khustia and Jessore. As stated, the water tables rise due to the monsoon rains and decline in the dry season. The groundwater is clearly in a dynamic equilibrium, i.e., the monsoon recharge and dry-season depletions are in balance. The depletions are (a) beneficial and non-beneficial transpiration and (b) flow of groundwater to the rivers. Groundwater regeneration is a principal source of winter flows in the river system.

2.05 From Plate 1 it is clear that, over most of Baxigladesh, the groundwater level now shows annual fluctuations from 10-20 feet; the average being about 12 feet. If storage coefficients

FAO, Groundwater Investigations, Final Report, 1966, and WAPDA Water Supply Papers and Hydrological Yearbooks. - 9 -

are between 10 and 15 per cent, most areas then have an annual water storage of between 1 md 3 fPee+. ' 1hi4 c- be cnmpared +o +he-vaporation requirement of a winter rice crop of about 2 feet.

B. Sources of Groundwater Recharge

2.06 It is important to identify what the present and ±LLLuLLLre saarces Li rec1are.L' r. ILec. IaLge car, oLucumJ. -JJ1- -a rmlWFer~oLii. ways: (1) Seepage frorm the grounrd surface by- infiltration and percolation of rainfall; (2) Seepage from the ground surface of flood waters; (3) Influent seepage from rivers, streams, ponds, beels, hoars, or other bodies of water -lying above the water table; (4) Influent seepage from irrigation canals and direct percolation from irrigated lands, particularly wnere excessive amounts of water are being applied; (5) Artificial recharge using either wells or some type of spreading ground; (6) Regional underflow.

2.07 Recharge in the horizontal direction generally assumes negligible values because of the extremely low hydraulic gradients prevailing in the country For the area as a whole, this factor can be neglected.

2.08 Artificial recharge is presently not being practiced and is also not advocated for the future. Except relatively small areas now being irrigated, there is at present no recharge as a result of irrigation. In the future this will change, and will have to be taken into account.

2.09 Measurements in observation and domestic wells show that the regional water tables are nearly always above the river levels except at high discharge stages, at which time bank storage takes place. At these maximum stages some rivers overflow their banks and, under such conditions, there is direct recharge from the river to the groundwater. In other periods there is no recharge from the rivers, since the river level is below the water table.

2.10 The behavior of the streams reflects these zonditions relative to recharge. Most streams in the country , particulally those which traverse areas with sandy subsoils, gain in a downstream direction (Peterson, 1964, Tables 1-4). This is to be expected during the nonrainy season, when there is no direct surface runoff. One typical example is shown-in Table 1 where the increase is due to influent seepage from groundwater. Groundwater regeneration has also been - lo -

studied at Harrard, where aquifer characteristi cs were determined from dry-season recession curves for 12 rivers.

2.11 Some 30 to 40 per cent of Bangladesh is periodically inundated. The total area inundated expands and contracts in accordance with the season and with the local rainfall, reaching a maximum near the end of the monsoon period. The area flooded depends on the terrain, being greatest where the slopes are flat and least in the areas of greater relief. High stages in the major rivers also inhibit drainage outflow from the surrounding areas.

2.12 The extent of flooding therefore depends on local conditions, and varies widely between areas. It follows that flooding can then not be a general explanation of the groundwater recharge which takes place all over Bangladesh.

2.13 As the floods recede, water will remain on the surface for some time in the beels and hoars (low-lying areas) which are distributed throughout the -cotntry, One of the largest is the Sylhet depression lying west an, Pjuunwest of the town of Sylhet. Other extensive low-lying areas occur along the lower reaches of the Atrai River, along the Kangsa River north of MYmensingh and along the Surma and Monu Rivers southeast of Sylhet. To the extent that these areas are not drained by surface streams, they must contribute to the present groundwater recharge. Again, however, beels and hoars are not significant everywhere in the countrv and thev do not explain the annual water table rises.

2.14 Since the above factors cannot explain the present re- c.hnrpup it. mnsft ho the resuilt. of infilt.rantin and nercolnation of rain. This conclusion is strongly supported by the readiness with which wate.pr levels in~ cbhervat;Aon wellsirlsp with the monsoon rnin nffter the overlying zone of aeration is saturated.

2.15 Many water-table hydrographs and rainfall histograms are pres-Q ted the AO report of 1O96A6 and in seererO WA.PTA Wntpr Supply Papers. One typical set of rainfall depths and consequent w"ater-tableWi±,eiuU±t fLlucDualU-onsi dLL4--4J.I.ii for thle ULtjdiLSt-rl.t; 4LL ofLI4. P RajshjahiaL_ dOJcJ1J ls tLd'1Ii.4l~ akl-en fr om th~1Iee FAO report and is included here as Figure 1.

2.16 The annual rainfall at Sapahar and Nazipur was 54.4 and 17',77.8 0 Lnches,2~t.. in 195, rr ofr -whicl...U 1. tUhe.L rriorisoon rains contU-LIL. .L.`e r' .7'7 aL.n 6u.8n

1Harvard University, December 1969.

2FAO, Groundwater Investigations, Final Report, 1966, and WAPDA Water

zJu.FJl.y Paper ad.I HydoloL) .'JL'4. ' Yearook... inches respectively. The monsoon rains caused the water-table levels to rise by a maximum of 22 feet in observation well R2 and by a minimum of 13 feet in R5. The resulting recharge is estimated in Table 2 below with a storage coefficient or effective yield of 0.10 and 0.15 (typical values for medium and lighter-textured profiles).

TABLE 2

RECHARGE RESULT'ING FROM 55 INCHES OF MONSOON RAIN

Water-Table Recharge in Feet and Inches of Water Rise in Feet Assuming a Storage Coefficient of

15% 10%

23 3.3 ft. or 39.6 in. 2.2 ft. or 26.9 in. 13 1.95 ft. or 23.4 in. 1.3 ft. or 15.6 in.

2.17 As is evident from Figures 2a, 2b and 2c, the water table fluctuations in these wells are typical for those in the Dinajpur, Faridpur, Kushtia and Jessore districts. These areas have been identified in Chapter 1 of this Report as those with a relatively low vertical permeability. The empirical evidence indicates therefore that even in areas with less permeable soils groundwater recharge is substantial.

C. Water Balance Studies for Thakurgaon

2.18 Useful water-balance and infiltration studies were made for the Thakurgaon Tubewel1 Project Appraisal and are summarized in the IDA Report of April 1971. The significant point of these analyses is that most of the rainfall occurs in such a fashion that it can infiltrate if the water table is low to permit percolation. Thus, if the water table is drawn down by pumping, much of the rainfall will infiltrate and be stored. The Thakurgaon report refers to t;he following project studies:

(a) "FAO in 1965 studied the area and were the first to showT clearly that the water table reached ground surface in some areas for much of the year. The study concluded that, while present recharge over a 1,000 sq mi area was about 14 inches in 1965, the potential recharge in the Thakurgaon area would be more than sufficient to supply the 365 tubewells under full pumping."

(b) "Alam, in a report dated April 1970, has estimated that out of 91 inches of rain about half is lost to evapotranspiration. He also points out that with the average water table fluctuations of 10 feet only about 24 inches of rainfall can be stored as recharge under present conditions. Lowering of thae - 12 -

water table due to incrrased pumping would result i-n i-n c reas-e Ad i--nfi 1 t atir nt A cadstorg n-

2.190 l rflont Oen, ui ng requrements-e-stimat under full irrigation development show that in an average year the water table would fall to about 1L feet by the end of the irrigation season and, after a drought year with a one-in-ten probability of occurrence, to about 30 feet. Groundwater extractions would be com= pletely replaced by recharge in an average year while, after a drought year , co t recharge might be delayed one or two seasons. It is clear, however, that the long-term potential recharge is more than adequate to prevent diepletion of the aquifer "- pwmiUing.'

£ (.2.2 ) !!~~~~~AJi stud.UU) wasWC'Z) maeofteL,-1II1dUt 01 UL,LI '1ll., o I £LLVt::Iierdang U1d_LI r, ael CC C-UV UUCbv Thakurgaon where data on grourdwater levels, stream-flow and rainfall were availblcu anUL sinc hlios adlar iaiUXD1L±i1 ImUos t U1 U-LI:l JtU D icc it is believed that the situation is representative. It was found that pu,,,ving to meet irrigation requirements in an average year would reduce stream-flow and flow would stop a month or two before the monsoon season. The small nur.ber o0 existnig .L04lolft U pumps may, therefore, nee' lo le replaced by tubewells or sumps may need to be constructed in the stream c[hdlanin 'iloUenabdUl L h e pu[IIps LU UoC uedU.

Di. Potentla_l Ra_lnfal_l 1RezUerge uenera'l

2. 1 Conditions f0or groundwat er rechiIarge are generally favorable. The practice of subdividing the rice areas into Daddies or terraces by the construction of low dilkes or bunds increases infiltration, since these bunds are of such a height thet they store some six inches of water whilch remain untlIL LfiLltr--ted or e-vapoaUe. ine Uchracu ter of the monsoon rains, in which large quantities of rain fall within a four- to six-month period, also aids infiltrElIUn, as the soll seldom becomes dry during this period and there is thus little requirement for water to replenish soil moisture. On the other hand, concentrated rainfall in the form of big storms will generally increase the runoff.

2.22 If, in future, irrigation is to be based on groundwater, the groundwater aveilability for pumping has to be estimated for the future situation (with irrigation) rather than for the present one. Moreover, it is the future potential recharge which has to be assessed as well as the new dynamic equilibrium in which both recharge and depletion are again in balance.

Factors Determining the Relation Between Rainfall and Groundwater Recharge

2.23 Total precipitation can always be divided into runoff, evapotranspiration and recnarge. 1ihe division will depend on the following factors: - 13 -

(1) - rainfall distribution over time (2) - land use and vegetative cover (3) - extent of bunding around the fields (h) - infiltration characteristics of the top soil (5) - permeability and storage capacity of subsoil layers (6) - water table depth below land surface.

2.24 In the folloing paragraphs, an estimate will be made of the division of total rainfall between runoff and effective precipitation (the sum of evapotranspiration and infiltration). As a second step, the total monsoon evapotranspiration will be calculated to arrive at the net recharge from rainfall.

Effect of Water Table Depth

2.25 Figure 1 shows that groundwater tables rise sharply at the onset of the monsoon. Maximum elevations are reached by the end of August in this case and the groundwater levels remain approximately stable during September. The heavy rainfall during the last week of August 1965 had hardly any influence on groundwater levels while a similar rainfall in the week of July'19th caused a sharp rise. Obviously, by the end of August the groundwater table had risen to the land surface and consequently the aquifer rejected further recharge. Figure 1 shows data for Rajshahi which is a relatively law rainfall area. It is known that in higher rainfall areas groundwater tables reach land surface even earlier and consequently a significant amount of the rainfall is rejected as recharge.

2.26 An important conclusion to be drawn from Figure 1 is that if initial groundwater levels had been lower, a greater part of the rainfall could have infiltrated. This will hannen when tubewells lower the groundwater table at the end of the dry season. In other words, present monsoon recharge can be increased bv groundwater numning.

The Extent of Bundinz

2.27 Even with deep grounLwater tab1e;. it is unlikely that the total monsoon precipitation would infiltrate. Surface runoff will occur from unbunded fields if rainfall intensities are higher than the infiltration cnapaitv of the soils.

2.28 Less than half of the cultivated fields are presently provided with bunds (Table 3') This sitiiat1on will nhange drastically with the nrovision of irrigation water since one important step in preparing fields for irrigation is the constnimtion of proner bunds. Tt is exnected that in the future 8O per cent of the presently unbunded fields will be provided with bunds. Future bunded acreages are gi-ven in Tables .andB 5. Riahtv_ rather than one hiindre, n-r c-ent bunding is assumed to calculate a conservative recharge estimate. - 14 -

Infiltration Capacity of the Soil

2.29 Potential groundwater recharge on a bunded field is defined by t,i rain.-La patternl, tl-, inllitratw|vlo caoait Jv ol" 1bo4v1s an-s1u the height of the bunds. It is noted that even with an infiltration capacity as lIw as 0.0-1 inch- per hour or 0.00 feet per Cay, about feet of water could infiltrate during a four-month monsoon period, which ismore thLlan thL'e evapotrans p4 a" on reqireen fo a- booo 2Src iS II1Ji C'ILO0 CL1~11V C'ci ~ _C'±SJ I.r74AL 0~111ril U .I1 c JJ U .1.1 C UO I _LUV- crop, and also more than the total annual net irrigation requirement (aft~erci C'- dueduuctionUOUU C'±4I± ofP4 returns0CUj11UP to groundwaJUU1 t er'1/ overV0 m0sthDC of DIMI-gladesh.A On the basis of presently available evidence, there is no reason to assumtha the average _lnflt__ ration rate over extended areas is less than 0.01 inch per hour. Therefore, infiltration rates wil-l-I I±± notu4 1,0 be0 1 a.c _l.imitingLijil 14±1i,IdOLU fLactUor f'or-0/7 rechtargeItUJ if_4..I~ fie'lds2.L iO arec.0 properlyjI p4.V bunded.U

.Lta-lrLunoffLrena-

2.30 if surface ruIoff is to be estimated w-ith a reasonable degree of precision, a computer simulation analysis will be necessary to assess thre effects of va-ritions in the amount and distribution of rainfall, in the extent and height of bunding, and in the percolation rate, on the amouintu of' r1charge. 'In thUH abUsence of such a m,odel stuAy, surf'ace runoff has been estimated on the basis of ranges of percentages for various types

04.idulU. 1111 D UIUUjID 4Ud Ct 44 0-3 Id'L. t 0. L, 41 UIUL ± of' landu. Ile assuM-D.utio ns ar PItein 'able 6 For the bUundued fle.lU plots, losses will not exceed 10 per cent as long as the rainfall is moderate ~~~~~~~~~A _ 2 _- -4_ - a ._2 _ . |2 -7 / . |------andU reasonabUly evenlly ditrlibUUted X*/ W1ithlil;ic ea rainill, tie chladIltn increase that either the bunds will overtop or that the infiltration rate will becorie a constralnt to recharge. For the purpose of these calculations, a maximum of 30D per cent runoff has been taken. Our studies indicate that thls percerntage is rarely reached since ligh intensity ralns are very in- frequent.

2.31 For the unbunded fields and homesteads, similar assumptions have been made. Thne runoff percentage is somewhat more difficult to estimate for these areas, but they havF only a small weight in the total. Weighted maximum and minimum effective rainfall percentages are calculated in Tables 7 and 8.

Total Rainfall by Region

2.32 Bangladesh, exnluding the Chittagong area, has been subdivided into 12 representative areas for analysis on the basis of average monthly

l/ This conclusion is based on a simulation study for the Rangpur rainfall station for the monsoon season of 1953. - 15 -

rainfall at eleven stations-/ and average monthly isohyetal maps._./ These areas and their representative rainfall index stations are given below. T'hree stations have been adjusted to make them representative for the larger area.

District Grouping Representative Rainfall Index Station

Dinajpur/Rengpur Rangpur Bogra/Pabna Bogra Ra ishahi Rajshahi Khulna Khulna Mymensingh imensingh (+10%) Sylhet Sylhet Dacca Dacca Faridpur Dacca Comilla/Noakhali Comilla (-10%) Barisal Barisal (+10%) Kushtia Kushtia Jessore Jessore

2.33 A delineation of characteristic rainfall areas on the basis of onl;y eleven stations will, of course, require further refinement when specific project studies are undertaken.

Total Evapotranspiration by Rgion

2.34 Regional evapotranspiration wias estimated for the district groupings by separately consicdering cultivated and non-cultivated acreage in each district.

2.35 Evapotranspiration from cultivated land is based on rice evapotranspiration requirements given in iable 11. T.R.20. These are the hiaheSt Avai]ahhe and have the effect of reducing the potential recharge.

1/ Eight stations from Acres-Ilaco-Bahint, Febuuary 1971; data for Sylhet Kushtia and Jessore were taken from wApnA Water Suppl;y Papers.

2/ IECO- WAPDA, Master Plan, Supplement A. 196)i 2.36 Evapotranspiration from non-cultivated acreage was estimated at 75 per cent of the mean evaporation index given in Table 8, T.R.20. The regional evapotr2nspiration can then be calculated from the following formula:

(F.B.A) EL + 0.75 (F.U1B.A + UC.A) E1 Regional Evapotr. = Ex= -

F.B.A. + F.UB.A + UC.A.

Where

F.B.A. = Future Bunded ArEa in million acre feet F.UB.A = Future Unbunded Area in million acre feet UC.A. = Uncultivated Area in million acre feet E) M=Monthly Rice Evapotrenspiration in inches of water. El = Evaporation Index in inches of water.

2.37 A sample calculation is given in Table 9 and results for all areas are summarized in Table 10.

Potential Regional Recharge

2.38 The future regional recharge has been calculated in Tables 11 through 20, the results are summarized in Table 21 for all districts except Khulna, Barisal, Chittagong and the Chittagong Hill Tracts. The hill areas in Sylhet, Comilla and Mymensingh have also been excluded.

2.39 Non-beneficial evaporation from beels, hoars, and low-lying areas along the rivers and other areas will continue. 'These losses have been accounted for during the monsoon in the calculated regional evapotranspiration in Table 10. 'The dry season evaporation losses in the non-bunded areas are given in Table 22 and are deducted from the regional recharge given in Table 21. The remaining recharge is related t9 the bunded areas and is given in ft/acre in the last column of lable 22.1/

2.MD In assessing the recharge figures, both the maximum and minimum potential recharge for Sylhet are very high and exceed arny future evapotranspiration requirement. Due to the very high rainfall, the runoff factor may be somewhat higher than for the other areas. No effort was made to improve the analysis because the monthly rainfall in Sylhet exceeds the evapotranspiration requirement during the period March through October and is insufficient only during four months of the year (November through Februarv'). Even if the effective

1/ The calculation ignores the effect of reinfall during the cirv sneason- - 17 -

rainfall were only 60 per cent of the average, the monthly rainfall in Sylhet would still be adequate during the period April through October to meet evapotranspiration requirements if the rainfall distribution is reasonably uniform. (The latter point requires further study). Never- theless, the irrigation requirements are so low that recharge potential will never be an issue. If the underlying aquifer is suitable for installation of irrigation wells, all irrigation requirements in Sylhet can be met by groundwater Dumping.

2.Ll Tfhe Mymensingh and Dinaipur-Rangpur Regions have also a high potential recharge. However, the frequency of high rainfall intensities is such that those estimates are considered valid.

2.12 At the other end of the scale, it appears that the Rajshahi and Kushtia districts will have insufficient recharge to support full development from groundwater even for maximum recharge assumptions. Use of surface water is necessary in these districts to attain full irrigation developmenz. Intearated surface and groundwater use would minimize the required volume of imported surface water because of the high efficiency with which this water would he used. The latter alternptive must also be ceomnareri to using surface water in "closed" polder systems with water tables permanently at grouind sqirfnew -_ aTmethodl whirh agwain imnlies a high efficiencv of water use because the deep percolation losses are then very low.

E. Future Water Table Fluctuations and Niimher nf Trrigation Wellq Possible

Thp Preqpnt -hrnarnmi ERmlilibhri-im of thp Wntpr TnhlA

2.A13 At the present time and without significant purining, the annual water table fluctuations have been estimated to average about 12 feet by nT)M-DPET, l96(R. The depletion of the groundwater is causel by three factors:

(1) Beneficial evapotranspiration from cultivated areas due to capillay rise of groundwater; (2) Non-beneficial evaporation; and (3) Dischcr e into the ives

2 .L) The present distrilbuition of' e hetween the three ahoTe-mentloned factors cannot be established without very detailed information on the land topography'fl,~brTnvw ter tabe k AeprthA and aran±tc Adinc-rIc ri.n u nt

2 However, it c+nn be oln. +.tht+. +.the effcti.v d+itnc, from which groundwater flows into the river in the five-to-six month dry season is 4 limitedto abot,,+. one A on=half mi es no- les fronr +the _-I.,river er.rrna and is therefore not a significant factor in the overall groundwater dep-leti;on.

2 .L6J Fu.`ermore, tUhis wateris.L prii deriveu Iror,. so-called bLaI storage. Ihe latter builds up as the rising river levels cover the wide channel - 10 -

,-e's of [these rivers in the ear-ly part of.Jthe r,.onsoon n T , water returns in part to the rivers in the dry season and the remainder is Ulost to non-beneficiaL evaporation.

2 .X7 S of1Vt1I~U- teI Ul,.nc rive'r are deeply incise and haves banks. These rivers behave somewhat differently with respect to ground- -1 F 4-.T.412 - 4 -1- 4-__ -.0 I) _ - -- - watLer rechiarge aniu depletior,. WVUitI U1 sUp rises of 25 feUoUr r.Ire in the river water levels the groundwater will initially flow laterally into

'rlhe subsUo ilUiui± rui ei 1, rti';[aigtU Ud IdiLat U lt: r,IUU1iWat§ -lVees± With those of the river. The non-beneficial evaporation losses along the -- ... 4- T .4.U.. ~-I - -LU.1 -- _ rivers wili be less uinaer utuse cuiruirisuznces. IN-vertrleless, Ulit latural distance from the river from which groundwater discharges into the river remains small.

2.4U8 It is conclIudeduthat thie rivers derive groundwauer Iljuws [filri.y from bank storage and use some rainfall recharge from lands near them. The groundwater availability as determined in une recharge calculauions issuu significantly affected by the discharge into the rivers.

The Future Dynamic Equilibrium of the Water Table

2.49 If, in future, groundwater is to be pumped and used for irrigation, a new dynamic equilibrium will eventually be attained. Since it is not possible to quantify present losses by type, it is also impossible to estimate future losses and water table depths accurately. However, the process by which the new eauilibrium will be reached can be described.

2.51D If water is to be withdrawn through pumping, the new equilibrium must be based on higher recharge, smaller depletions by other means, or both.

2.51 In areas where the groundwater now reaches the surface before the end of the monsoon season, more room for -recharge can be created by drawing the water table down further by the end of the dry season. In addition, an increase of the bunded acreage will decrease the runoff and so increase the recharge. In the potential recharge calculations contained in Tables 11 to 22, these two factors which will make for increased recharge have already been taken into account.

2.52 Under the new equilibrium, total recharge will be balanced by the sum of npt pumping (gross pumping minus deep percolation) and non-beneficial losses. If recharge is ample, the to-tel potential reciarge will not be used. If, however, net pumping requirements are only slightly lower than or exceed the potential recharge, losses must be minimized.

2.53 The uses and losses to be accounted for are those of beneficial and non-beneficial evaporation. On the irrigated lands the irrigation applications wrill, under the new situation, cause a net downward movement of water in the profile, eliminating the capillary rise from groundwater. The net effect will - 19 - be that without subsurface drainage, the water table will rise to land surface in all areas irrigated by means of surface water. In tubewell areas the crops will consume the evapotranspiration requirement and most excess water applied will return to the groundwater (recirculation). The net effect will be that in tubewell areas, the cultivated acreage will withdraw the evapotranspiration requirement plus some non-beneficial losses. Non-beneficial evaporation wLll also continue from low-lying areas (beels, hoars, and low areas along the rivers) as long as the water table remains shallow.

Non-Beneficial Evaporation

2.54 The non-beneficial evaporation from the non-irrigated area has been accounted in the recharge estimates given in Table 22.

Acreages Irrigable by Groundwater by Region

2.55 To arrive at acreages that can be irrigated by groundwater without inducing recharge from the rivers, the net requirements per irrigated acre must be compared to the potential recharge. For this comparison, integrated surface and groundwater use has been ignored. On the basis of arguments given in para. 2, it has been considered that minimum runoff will occur in regions; where the rainfall is so small that the potential recharge constrains the irrigation potential.

2.56 The number of acres that can be irrigated is dependent on the water requirement per acre, which in turn depends on the cropping pattern on the one hand, and climatic factors on the other. Both influences are dealt with in Chapter 3 of Technical REport No. 20. It appears that the variations causecd by climatic factors are limited. For the purpose of the present first approxi- mations, they are ignored. A water-intensive cropping pattern - with heavy emphasis on boro rice requires, as an average over Bangladesh, a net irrigation requirement (net of additional recharge) of about 20 inches per acre. A less water-intensive cropping pattern requires approximately 15 inches. The possible acreagres for the two conditions are calculated in Table 23.

2e57 The results show that for nearly all of the acres considered, all the bunded plots (approximately 75% of all land) can be fullydeveloped on the basis of grouncwater alone, even if water-intensive cropping patterns are used. This conclusion does not hold for a relatively small area on both sides of the Ganges (the Kushtia and Rajshahi Districts).

Numbers of Tubewells Possible

2q58 The numbers of tubewells which would have to be installed to serve! al1 these areas depends on climate, cropping patterns and the permeabilitv cf the top soil. A typical design peak requirement is taken as 9 inches per acre per month. If the peak monthly utilization is 801. and the tubewell hns a capacity of two cusecs, the number of net acres served per tubewell is (12/5) (ft-l) 0.80 x L (AF/day) x 30 (days) = 130 acres. On this basis. the number- of tubewells to be installed is calculated in the last column of Table 23. The number is 12.,000 wells which is only an order of magnitude- since the design peak will differ from place to place and 9 inches may not be a reasonable average. Pb reover, in the same-! areas other ty-pes ofLIrrigatio may take precedence over tubewells. Also, in areas of deep and prolonged flooding tuLewells are difficult to dig or mailtaln.

Future Water Tables Levels

2.59 water tables fluctuations -wll nobt c-uige S igIiicaruti'y in a.laS where net groundwater withdrawals remain less than the potential recharge.

2.60 Water tables will decline with overpumping, i.e., with net groundwater withdrawals over extensive areas greater than the calculated recharge for the bunded area. This will continue until the overpunping is balanced by influent flow from the streams and/or decreased non-beneficial evaporation. The depth at which water tables will stabilize can only be determined by detailed model studies for specific areas. It is noted that in Table 23 no allowance is made for net groundwater withdrawals in excess of the potential recharge. - 21 -

III. AQUIFER TRANSMISSIBILITIES AND TUBEWELL PERFORMANCE

A. General

3.01 The suitability of an aquifer for water extraction is defined by the term "transmissibility" (T) = permeability times aquifer thickness (D). Most tubewells do not penetrate the aquifer fully so transmissibility is then interpreted to be (approximately) permeability x the length of the per- forated screen of the well. Since screen lengths vary widely in Bangladesh, considerable variation is found in the transmissibility even if the aquifer permeability is constant. The most consistent analysis of aquifer characteristics and tubewell performance is found in the recent report by Sir M. MacDonald and FPartners, 1971, on existing ADC tubewells in the northwest region.

3.02 Other analyses of Aauifer characteristics have been made for tubewel) projects of WAPDkIa ; the Directorate of Public Health Engineering (DPHE)3J and IDCj/. Information on the tubewells of the Kotwali Thana Central Co-operative Association (KTCCA) is available from Mundorff (1966) and ADC (1970).

3.03 Chapter IV gives the results of chemical analyses of groundwaters and some river waters.

3.o4 The Thakurgaon tubewells of TWAPDA are discussed in Chapter V.

B. Analvses of Aauifer Characteristics in the Northwest Region from ADC Tubewells

3.05 The results of the analyses of tubewell performance data and drilling logs f'or the ADC tubewells in the northwest are given in a report by Sir M. MacDonald and Partners, July 1971. The project area for the 3,000 ADC/IDA tubewells lies wholly in the northwest region between the Ganges and Brahmaputra Rivers and includes all or parts of the, Districts of Rajshahi, Pabna. Bogra. Rangpur and Dinajpur. The western half of Raishahi District. the southern part of Pabna and various sections of north Dinajpur are excluded, as they are part of other existing or planned projects.

3.06 Extensive tubewell data are available for the area from individual production wells constructed by the ADC, of which some 500 have results and data of sufficient detail to be of use in examining aauifer properties. However, full-scale aquifer tests to an acceptable standard have been carried out on only four. In testing ADC production wells, three pumping stages were used lasting 90 minutes each at discharges of 1.50, 1.88 and 2.25 cusecs, respectively. Drawdowns were measured only inside the wells.

V IBRD/IDA Report No. PS-6, April 1971. MnDonld. HParris R.. .June 26. 1969. y/ DPHE and CDM, March 1968. 3.07? wrr the~ 4table prsr.e -i,, tihe Tr^cDon^ greport, the {'rllovin'y r9%.J 7 U 4. 'J" ~C~.'lh I c44 .o lJ n 4zon- 4l ". nqIC -n n-.- +Ji f% Iru n approxi-mate T values have been calculated for various typical aQuifers in the northwest region fr p rofle1 of up to 3'' + reed+ph:

_~~~~~~-(z sA^^4l ;Y Q -rnA nA Mrr1 = .10 "IlQnn /f'+ - r cswid | .1 v vl l .i v t.4 I.4v.~4OA . 4 4. ** .1 - Ganges floodplain over sand, T = .26 cusec/ft = -rGangesflorllin over 'avel,rT = .30 c - Tista-ErahrLaputra floodplain, T .36 cusec/ft - U-og,a Blraid, AT ='~.3Icacft - Snherpur failure area, T .11 cusec/ft

- irorthnJl£ 11 i-L- UTi, U4Jp e.L r h T. =j .12 cusec' - fNorthern Tista, lower reaches, T .21 cusec/ft - i-ediront area, T = .19cusec"ft

- Pie rcnt - Barind transition, T .10 cusec/ft

3.8o The report also includes the results of analyses of optimum econoinic depth^Ps for tJwo-cusec tuie-nells which vary fro-,- 1'5 to I1 ' fee 4,i4h screen lengths from 60 to 90 feet for the various aquifers (see Table 24). These resu-its are appi cable to the .northwest region and are of great i-terest because they sholw that relatively short tubewells and screens can yield high dischlarge capacities. T -s isane concept-- for Bagladesh where very deep tubewells and long screens are cos,o.ly used (see Tables 25 23) even iLn t'le nortiAlJeiest regio0n i'lo uaua are aviLL-aue at.. tU11 s. e n11tLhU e1.LUi1I ance of the ADC tubewells outside the northwest region.

3.09 The ADC program has covered other regions of Bangladesh as we ll. The program ov A during the ir P Pi i hllion beow .

Name of District 1967- J 1968-69 196'-70 Total

Dacca 10 7 33 50 ltmensingh 20 31 5 103 Tangail _ 15 15 Faridpur 10 16) 13 39 UorrThLLa 39 77 105 221 Noakdhali - 10 l4 2! Bogra - 27 25 52 Rajshai I1 16 107 134 Fabna - 30 L. 7S Ransur 16 3 57 107 Dinajpur - 22 53 75 Jessore - 22 41 63 Kus htia _ 12 12

106 292 573 971 = No. of tubewells

3.10 The installation of these tubewells has been financed from Rural iorks Programme funds. - 23 -

C. Analysis of.WAPDA Tlbewells

3.11 The existing Tha'mrgoan Tubewells Project has been reviewed in the IBRD/IDA R~eport (1971) (see Section V of this report). The technical performance of the tiibewzeLls has been very satisfactory and Table 25 gives transmissibilit,ies, discharges, and specific drawdowns for some representative wells in the project.

3.12 Tranisnisibilities are reported by Harris R. McDonald (1969) for tubewells in other areas of Bangladesh.

Tentulia Panchagarh Area (Tista Fan) Well No. T (cfs/ft)

1 .17 2 .17 3 .22 4 .20 5 .20 6 .09

North YV ensingh

TWell No. T (cfs/ft)

1 .27

Rangpur Area (Tista Fan)

IWJell No. T (cfs/ft)

.12

3 .,0 4 014 5 .l(5 .19 7 .113 3 .18 9 .16 10 .13

D. DPHE Tubewells

3.13 The DPHE reported in 1968 that it was preparing to irmprove or construct tubewells for municipal water supply in 35 munici-alities throughout Bangladesh and had carried out^ about 20 puifping tests at thiat time. Transmissibilities as high as 0.30 cusec,/ft were me-asured in Rogra. Rajshahi and Jessore. Somewhat lowrer values were reported for Comilla, Chittagong and Sylhet. However, deoths are not given and, therefore, it is not nossible to - 24 -

interpret these figures satisfactorily.

3.14 Data available for 37 municipal water supply wells of the city of Dacca show discharges varying from .3 cusecs to 2.1 cusecs with an average of .9 cusecs. These wells do not have a gravel pack. The data on gravel packed wells are included in Table 25. The general performance of DPIHE tubewells is not satisfactory because of the poor construction methods used up to 1967. These tubewells and those of IDC are discussed in this report because they have a w.ide geographic distribution and show that aquifers do exist in regions other than the northwest.

3.15 It is nmown that since 1967 many more wells have been constructed by DPHEE throughout Bangladesh but data for these are not available. However, the activities of DPHE have indicated that groundwfater can be developed by tubewells for municipal purposes in almost any city.

3.16 Table 27 presents the results of a number of grain-size analyses of aquifer materials which show that aquifer material does not differ substantially over the eountry . Figures from Sakarganj, Khulna and Noakhali show a somewhat finer grained material but are still in the same order of magnitude as those from Bogra, DJnajpur and Rangpur where aquifers are known to be very suitable for groundwater development.

3.17 General discussions on the occurrence of groundwater and well data, including permeabilities, for 58 Chittagong tubewells are presented by Welsh, 1966 (unavailable).

E. IDC Tubewells

3.18 These tubewiells have generally a six to eight inch diameter, often without gravel pack. Yields ranging from one to two cusecs are reported for Kushtia, Rajshahi, Daccav Jessore, Pabna, Xhulna and Chittagong. Data for a number of these wells are presented in Table 28.

F. Notes on the KTCCA Tubewell Project in Comilla

3.19 By 1966 about 60 wells had been drilled in the Kotwali Thana and !kh4 were successful. Outside Kotwali Thana 13 wells were drilled of which only four were successful. M. J. Mundroff (1966) reviewed the reasons for failures and suggested remedial measures. In summary his findings were:

"In some arc-as wells wJill be unsuccessful because no satisfactory acuifers are present. These areas a-pparently include a strip along the Indian border, about three miles wide, strips on either side of the Mavnamati-Lalmai Hills and the hills themselves.

I"Present test drilling and well drilling methods are satisfactorv. In view of the relative inaccessibility of most of the sites, large machines qre not feasible Tmnrovement could be minde on collection and handling of samples. - 25 -

"Larger surpplies can be obtained from thinner sections of the aquifer by improving well construction and development. It is suggested that, where the aquifer is less than 80 to 90 feet thick, a lh-inch hole be drilled and screens with a slot size of 0.030 to 0.040 inch be used. The screen should be centered in the drill pipe by means of guides and the annular space filled wzith gravel 1/16- and 1/8-inch size. Development by some means, preferable surge block, or an air compressor will be required.

"Provisions can be made for measuring drawedown during the pumping test and a permanent provision for measuring static and pumping water levels could be made on selected wells.

"'ihere the top of the well screen is more than 100 feet below the pump and 1.5 cusecs or more is needed it would be desirable to use an 8-inch pipe; 6-inch screen would still be adequate, unless the desired discharge approaches two cusecs.

"A limited program of water level observations is highly desirable. Monthly measurements on five or six wells distributed over the area should be adequate. It is important to keep careful, complete records."

3.20 Since 1966 the KTCCA tubewell project has been expanded to other thanas as well. A plate showing the location of knaown tubewells and tubewell fields was prepared by IDA for the agricultural section study. TIst of the KlCCA wells were constructed by hand boring methods using either percussion or jetting to sink a 10- to 12-inch bore hole to a depth necessary to accommodate 120 feet of screen. Six-inch brass screen is conmmnlv used Reliable discharge measurements are lacking but most tubewells in the Comilla- Notwali area are said to vield 1.0-1.3 cusecs.

r.. foncl usions

3.21 It is apoarent that eroundwater has been extracted by tubewlells of various sizes for various purposes throughout Bangladesh. The performance of the wells varies widelv but these vnriations anpear mre closelv relate-d *bo well construction and development methods than to aquifer characteristics. I-t appears that high-vielding wells can be installed nimost everywo¢here in Bangladesh (see Plate 2.). - 26 -

TV. CHEMICAL CHARACTERISTICS OF GROUNDWATER

4.01 Tablh-s 29 to 39 grive the chemical analyses of groundwaters and sone river waters. Samples have been collected by the Directorate of Public Health -Rgineering(flPI-?4) and its Consul-tants, Gamn. TDresser and McKee (CDM) (1968) and anaylzed in the DPHE laboratory. The tabuleted results are frnm a collection of some 900 analyses.

4.02 The hardness and calc-iium cont.ent are rplqtivplv high in most sarples which is good for irrigation but undesirable for domestic purposes. The iron content varies but is often on the high side. All attached analyses show a content of total dissolved solids that is sufficiently lo-L to make +hese waters suitable for irrigationn However- this is not. true for several of the samples available for the southern region. - 27

V. THE EXISTING THAKURGOAN TUBEWELL PROJECT

A T TJ- .- _ A. HEsor-

c,)v' 1 t tV-L rYT1L61 a U. -VcU J.U WC lU U U .. lEU L J LU 1" 5 .01 Th xistir ±1±wur-go. ±UUbeWe'' rroject, finan.ced by a German, credit to WAPDh, was started in 1961 and completed in 1966. During I4at l LI t,uL3)V) Utiof prUJeLctedU _UV tUUb-We.Lls Were .LIS itaiU alliUaILdUU operational. Scheduling difficulties occurred at the beginning of cons t-ractin, e.g. tubewell and powerhouse instUalation were comUpleted in 1964 while transmission lines and distribution channels were not

orAjle±e-ly reaUy UIr,l± 196UU. ftbbJnbce.U1 IfroUmI lA lWadeIrl for 1iral Development (ARD)of Comilla began in 1966 and was instrumental in building up an effective agricultural extersion Service in The area.

5.02 The material in this sectiUon is tak'en form the IDA Report No. PS-6, April 1971.

B. Description of Existing Wells

5.03 Of the 380 wells originally drilled in the 1963-64 period, about 365 were put into operation and were still operational in late 1970u The 15 wells not used apparently had too low production for the project Uesign. Average horsepower is 30 and average design production is three cusecs. Power requirement was estimated at 22 kw per well for a total design of 8,400 KW. Table 40 shows the distribution oI puup sizes.

5.O Well depth averages about 270 feet and screen length about 125 feet. The pump casing is 14-inch diameter pipe. However, about one-third of the wells have Hagusta fixed-gravel screens also 10 inches in diameter with about one inch of gravel. The Nold wells were gravel packed with sand of one-to-four-millimeter size and n tural pack was used for the Hagusta screens. Drilling was by reverse rotary and the wells were developed by pumping until clear. They were pumped at 130% of the rated capacity until there was less than 15 parts per million sand content and until the specific capacity did not increase. Pump tests after development were carried out on the schedule shown below in Table 41.

5.0q Puiqps are Bangladesh-assembled KSB turbine, water lubricated witn bronze impellers and stainless steel snafts. Tne strainer is five feet long. Mot-ors are 400 volt, three phase, 50 cycle and tropicalized with Star Delta starters.

C. Well Performance

5.o6 The wells have been tested regularly since they were installed, Figure 3 shows the distribution of specific capacity for a large sample of wells at the time of drilling in 1963-64 and in June, 1970. It will be noted that while average specific capacity remains the same, the wells at the low and high ends of the curve have improved.

D. Comparison of Screen Performance

5.07 Figure 4 shows a frequency distribution of discharge for both Nold amd Hagusta screened wells as well as the average for most - 28 - of the wells. The reason for the poorer performance of the Hagusta screens is not clear but the Hagusta screens which had been pulled were clogged in the gravel filter with silt. On the other hand, it should be noted that some Hagusta-8creened wells do perform as well as any with Nold screens. It would appear, therefore, that well development with Hagusta screens is mechanically more difficult than with Nold screens and gravel packing.

5.0 A comparison of screen length of the two types with drawdown per cusec shows that Nold screens generally are in a narrow range of 2 to h ft/cusec while the Hagusta screened wells have a higher range of 2 to 8 ft/cusec.

5.09 It may be noted that for the Nold screen the figure for feet of drawdown per cusec discharge per foot length of screen averages about 0.027 with a minimum for all screens of about 0.023. In other words, the normal wells have a specific capacity of about .003 cusec/ft. of drawdown for each foot length of screen (1.35 gallons per minute per foot of drawdown per foot of screen).

E. Screen Head Loss

5.10 An attempt was made to estimate head loss due to the well screens. 1,Thile a plot of the drawdown versus discharge from soie representative pump tests is practically a straight line, the line does not pass through the origin but instead through a value of three to five feet drawdown zero discharge. Analysis of the pump test data indicates that the initial one-hour pumping at 130% of design capacity causes drawdown which does not recover during the next 1/2 hour 25% pumping period.

5.11 During the later part of the step drawdown tests it appears that the screen-head loss is about 10 to 15 % of the total drawdown. The data also indicate that development of the well was still occurring during the test. Available data indicate that well losses seem to comprise a maximum of 25% of the total drawdown.

5.12 Development was further checked by comparing specific capacitv with transmissivity. Even taking into account the poor values of trans- missibilitv. it would annear that many wells still were not comnpletelv developed. Figure 3 showing improvemnt in extreme values of capacity sinep wells werp cnmpletedj tends tn confirm the fact that many wells were not fully developed. This indicates that future wells should be more carefully developed and that sereen loss should be checked, if possible, with a piezometer in the gravel pack, or even a shallow piezometer within a ardi of the well. BANGLADESH SECrOR STUDY

RUNOFF OF THE TANGAN R:[VER AT RANIGANJ (Sta,284) , AND AT KAHARPARA (Sta 286) (in acre feet) _

Station I Month l I No Year Oct Nov Dec JaLn Feb Mar

284 1953-54 13,180 3,930 3,940 3,2180 2,430 1,740 286 31,180 21,22 0 21,420 :L2,C00 10,11]0 ,280

284 1954-55 8,07,0 2,340 2,240 2,250 1,950 1,580 286 17,9 00 11,720 9',620 8, E10 7, lLO 6,400

284 1959-60 23,150 4,750 2,660 2,340 3,070 2,0710 286 103,490 20 , 23D0 12,220 8,820 7,7 10 7, 83 0l

284 1960-61 9,540 2,6B0` 2,720 286 45,3130 13,1710 11,090

1 Station 286 is about 18 miles downstream of St:ation 284.. T'hese data are frocn Peterson, 1964, Table 1. TABT.RF 2

BANGLADESH SECTOR STUDY

A A->-~~,v Ar, ~' '~ rr~A,,- F'r ' rAYTC,T T'C' n'Vr~ Tn.TTC' AAf,.\T T) A T M RECnT-rGE REStU`iG RjIJI 55 IIENELIEj OjF InIUIOV PINt

Water-T_b½l Rcech-rge in Feet and Inches of Wl,ater Rise in Feeti ssuming a Storage -oefficient of 15s 10%

23 3.3 ft. or 39.6 in. 2.2 ft. or 26.9 in. -I 9 ft+ or in. 1 . + 15+ in BANGLUDESH SECTOR STUDY

PRESELNT DI STRIBU5TION OF LAND TYPES IN BANGLADESHS (rrmillion acres)

Gros s Cultivated Distric:t Area Bunded Unbunded Uncultivated Homesteads Open Water

Dinajpur 1.157 0.85 0.61 0.10 0.09 0.02 Rangpur 2.37 1.14 0.91 0.i2 G0.16 0.04 Bogra 0.96 0.61 0.17 0.09 0.05 0.04 Pabna 1.02 0.11 0.89 0.08 0.08 0.04 Rajshahi 2.34 0.73 1.26 0.14 0.12 0.09 I viensingh 4.07 1.49 1.93 0.30 0.19 0.16 Sylliet Less Hills 2.86 0.66 1.76 0.15 0.08 0.21 Dacca 1.84 0.24 1.35 0.09 0.1 0 0.06 ComLilla 1.656 0.34 0.82 0.16 0.20 0.14 Noakhali 1.19 0.52 0.34 0.10 0.10 0.13 KushtiEL 0.,88 0.29 0.43 0.08 0.0S 0.02 Jessoreh 1.153 0.22 1.14 0.13 0 . 1.1 0.03 Khulna 1.70 0.82 0.61 0.10 0.11 0.06 Faridpur 1.72 0.01 1.39 0.15 0.08 0.09 Barisal. 2.71 1.42 0.91 0.08 0.13 0.17 Bangladesh less Chittagong & Chittagong 28.80 9.45 14.52 1.87 1.66 1.30 Hill Tracts Districts BANGLADMHSI'ECTOR STUDY

PRESENT AND FUTURE AREA CONDITIONS (million acres)

Gross Bunded Unbtnded Open ]District Sum Area Present Future Present Future Uncultivated Hlomesteads Wlater

:Dinajpur, Rangpur Future 4.04 3.21 1.52 0.22 0.25 0.0'S

Bogra, P abna Present 2.16 0.72 1. 06 0I.17 Future 1.57 0.21 0.13 0-.09

Raj sliahi Present ~2.34 0.73 1.26 I.1 .1 .0 Raj shahi Future 1.74 0.25 0.14 0.12 0.0'

ll,lymensinghPresent 4.71.49 1.9 3(D30.1 INlyr;m.ensin,gh Future 3.03 0.39 0.19 0.166

Sylhet Less Hills PFre,ent 2.86 2.07 0.:35 0.15 0.08 0.21

IDacca ~~Present 1.84 0.24 1.35 09.lo06 l)acca Future 1.32 0.27 0.09 0.10 0.06

Comilla, Noakhali Present 2.85 0.86 Future17902 1.79 0. 23 0.26 0. 30 0. 27

Present 0.8 0.29 0.4 3 EKushltia Future 0.8, 0.63 0,09 0.08 0.06 0.02

Jessore Present 1.13 0.23 0.13 0.:l 0.0 3

]<-aricipur Present 1.7:2 0.01 1.39 (.15 0.(8 O.C') Futuire 1.12 0.28 0.1 0.0 0.0 1. From Taible 3 aissumaing that 80 per cent of presently unlbundled cultivated ar-ea will be bunded in the future. BAN4GLAESH SECTOR STUDY

BREAKDOWN OF AREAS IN PER CENT OF GROSS AREA

Gross Bunded Unbunded Open District Sum Area Present Future Present Future Uncultivated homestead:3 Water

____-- ~~Present 10 49.26 37.6525456114, *Dinajpur, Rangpur Future 100 79.46 7.43 5.45 6.19 1.49

Bogra, Pabna Present 100 33.33 49.07 7.87 3.70 Bogra, ~~~~~~Future 7:2.69 9.72 78 S02.237

.Rajs'hahi Present 100 31.20 53.85 165.98 Rajshahi ~~~~~Future 74.36 10.68 5.13 3.8:5

Present 10 36.61 47.42 Mymensingh Future 100 74.45 9.58 7.37 4.67 3 9'3

Present 23.08 61.54 Sylhet Less Hills Future 100 7:2.38 12.24 5.24 2.80 7. 34r

Dacca Present 100 13.04 73.37 4.89 5.44 .Dacca ~~Future 71.74 14.67 48 .432 3.26

Comilla, Noakhali Present 100 30.18 62.81 40.70 8.07 9.12 9.47 Future 6.180 10.53

Kushtia Present 100 3'2.95 48.86 9.09 6.32 Future 7:1.59 10 .23 90 2.27

Present 1013.50 69.934 Jessore Future 100 69.32 14.11 797.98 6.75.51 1.S4

ari,dpur Present 1(0.58 80.315.72 , ,-55 LFariadpur _ 1 PFuture 100 65.12 16.28 3.72 4.05 5.23 .1 From Table 4 BANGLADESH SECTOR STUDY

RUNOFF RATES AND EFFECTIVE RAINFALL FOR' VARIOUS LAND CLASSES DURING MAY TO OCTODEER (in. per cent) ___ _ _

Runoff as a Percenta(ge Per Cent 'Effe-ctive of Average Mcnthlv Rainfall Monthly Rainfall. Land Type Minimum =Maximum= Maximum Minimuii.

Bunded F:ield Plots 10 30 CIO -70

Unbunded and/or Uncultivated Land 20 40 80 60

Homesteads 25 50) 75 '0

Open Watear 100 10C) Nii 1Ni

I03 BANGLADESH SECTOR STUDY

CALCULATION OF MAXIMUM REGIONAL EFFECTIVE RAINFALL PERCENTAGE

Distr.c ~ Max:imum Effective Bunded Unbunded DistriLct ISuSum Rainfall Factor Present Future Present Future Uncultivated Hom2estcads (I:Regional,' 1q0fi;l) ^,.0,l1 1 1 - i

P-resent 8:3. 4 3% 44.33% 30.10% 1~~~ D:inajpur, Rangrpur Future 86.45% 7:1.51:% 5.94% 4.6

Present 80.08 30.00 39.26 Bogra, Pabna F'uture 84.02 6.5.42 7.78 6.30 4.52

Present 79.79 28.08 43.08 Rajshahi Future 84.09 66.92 8.54 4.78 3.85

Present 80.29 32.95 37.94 M, mensingh E'uture 84.07 67.01 7.66 R. V0 3.SC35C

SyihetF Less Hi.lls Present 76.29 20.77 49.23 Future 8:L.22 6.5.14 9.79 4.19

Present 78.43 11.74 58.70 Dawcca E'uture 84.30 64.57 11.74 3.91

Present 74.92 27.16 32.56 Comilla, oakiali E'uture 78.19 56.53 6.46 7.30 7.90

Present 81.14 29.66 39.09 KuashtiLa .7-:7 F'uture 8.5.00 64.43 8.18 5.12.12

Jeassoire Present 79.54 12.15 55.95 . 5 E'uture 85.12 62.39 11.29 6.38 5.06

Present 75.64 0.52 64.65 Faridpur E'uture 82.10 58.61 13.02 6.98 3/SI

1 Effective rainfall factors calculated using area precentages froin Table 5, and maximum effective I-- rainfall factors from Table 6. BANGLADESH SECTOR STUDY

CALCULAT ION OF MININN REIGIONAL EFFECTIVE RAINFALL PERCENTAGE S

District Sum Minimum Effective I3unded UnbIunded Rainf all Factor Present Future Present Future Uncultivated Hormeste.ads (Regional) 70 11 ______1 1. ______60606% _60__ 50

Di.a pur. Rartgpul' Present 63.42% 34.487 212.577 1Dinajpur, Rangpur Future 66.45% 55.62% 4.46% 3.27% 3.1C7

B,ogral, Pabna Present 60.50 23.33 29.44 4,72 3.01 flogra,Pabna ~~~Futuire 64. 44 50.88 5C.347230

Present 60. 31 21.84 532.31 6 I Rajshahi ~~~~~Futulre 64.62 52.05 6.41 25

Present 60.84 25.63 28.45 Mymernsingh Future 64.63 52.12 5.75 4.42 2.34

Pres enit 57.62 16.16 _36.92. Sylhet Less Hills Futire 62.55 50.67 7.34 3.14 1.40

Present 58.80 9.13 44.02 DlaccaP FutLure 64.67 50.22 8.80 2.93 2.72

Present 56.29 21.13 24.425 Future 59-55 43.97 4.84

.ustia.Present 61.2.5 23.07 29.32 K.ushtila Future 65.1.1 50.11 6.1 5.45 3.41

Present 59.58 9.45 41.96 Jessore Future 65.1.6 48.52 8.47 4.79 3.38

Present 56.46 0.41 48.49 F'aridpur Future 62.91 45.58 9,77 5.23 2.33

1 Effective rainfall factors calculated using area percentages from Table 5s and minimum effective rainfall factors from Table 6* BANGLADESH SECTOR STUDY

TYPICAL CALCULATIONS OF FUTURE REGIONAL EVAPOTRANSPIRATION FOR DINAJPUR-RANGPUR DISTRICTS _(inches of water) _-

Total Evaporation TotEal Evaporation from E'uture Unbunded 3 erage from Future and Uncultivated 3 Average Month Bunded Area AreasT

May [(3.21 x 6.6) + (0.:39 x 5.0)] 3.73 = 6.20 inches

June [(3.21 x 5.8) + (0.:39 x 4.3)] 3.73 = 5.za4

July [(3.21 x 6.1) + (0.:39 x 4.5)] 3.73 = 5.712

Augus't [(3.21 x 5.9) + (0.39 x 4.5)] 3.73 = 5.55

September [(3.,21 x 5.5) + (0.39 x 4.0)] 3 .73 = 5.1-5

October [(3.21 x 5.1) + (0.:39 x 3.5)] 3.73 = 4.76

Millions of acres (from Table 4) x monthly rice eva.potranspiration. 2. Millions of acres (from Table L.) X .75 (evaporation factor) x evaporation indexc.

Millions of acres (from Table 4) TABLE 10

BtANGIADJ-H SECTOR STUDY

SUJMMARY OF CALCULATED AVERAGE EVAPOTRANSPI?ATION BY DISTRITTS (inches f water)

District

Month May Jun-.- July Aug Sept Oct

fl1~-~fi-~-~,,- Pn~,-~,,-~-- - )C CZ AA 7- r- 4 . 7 DJ n pu-r langpur | 6 5.sAA 57 55A.A6 51

Bogra, PalD-a ^ 6.22 4.77 >'.7 4.67 A.40 4.53

-, ~ ~~~~~~~~~ r 'I A. Onr A ,Cn A -7 A.

I ,,,)J J.i3 'A.UO ~~~~~~~~±. ('I±

I frrnlun-i 6.9A 5 A

Sy '1-e' Less Hills D5.4 /k 4 .35 4.3 0 4.2 44 -L- i I~~i~ A- r A nlA a

Dacca 6.70 4.90 5.17 5.00 4.52 4.57

Comiila, Noak'haiii 6.51 5.42 5.61 5.00 4.72 4.76

Kushtia 7.21 5 52 5.04 4.79 4.59 4.63

Jesscre 6.61 5.46 5.54 5.28 4.65 4.69

Faridpur j 6.75 5.06 4.96 4.76 4.42 4.45

1/ Calculated by method described in text and shnown in Table 9. BANGASEDSH[SECTOR STUDY

"TTM h!Tj -- _V_RE(T/T~7 A- h ' 'TT 1 Ln~fl- T' r .1'?1 T ThTI V7\1 T Ur'hA TIThT-)/ Enh 1 7 (3.CTUhT1-rl .I.

ES O .I J.!±.l mLEE £ U L1U ZU 1 ± L'421-. LAlt L LJJf LJ4L I Z1.J.I\ L~rU.)~ C~14L) a e. r0J.

Rainfa 1 T Ef:E Rainfafl:l Regional. 3 Net Infiltration Recharge Month _ Max Min Evapotr Max Min Max Min

May :12.14 10.50 8.07 6.20 4.30 1.87 0._30 -

June .19.41 16.78 12.90 5.44 11.34 7.456 11.34 5.33

July .17.6c)9 15.29 11.76 5.72 9.57 6. 04 9. 6. 0.4

August :13.24 11.45 8.80 5.55 5.90 3.25 5.90 3.25

Septenber :11.03 9.54 7.33 5.15 4.39 2.1.8 4.39 2.18

October 6.71 5.80 4.46 4.76 1.04 --0.30 1.()4 -

Total Recharge 32.54 1.6.8

Soil Moisture Deficit 0 0.3

Available Soil Moisture 4.00 3.7

1 Average Rai:nfa:Ll from Table 2, T.R. 20. 2 Average Rainfall times factors given :iLn Tables 7 and 8. 3 F:rom Table 1]0.

NOTE: T'he three footnotes apply to TableslL through 20,. BANGLADESH SECTOR STUDY

ESTIMATED FUTURE REGIONAI, RECHARGE FOFR BOGRA/PABNA (inches of water)

Rainfall Eff Rainfall Regional Net Infiltration Recharge Month Max Min Evapot:r. Max Mim Max Min.

May 7.06 5.93 4.55 6.22' - -

June 13.04 10.96 8.40 4'.77 6.19 3.63 2.19 -

July 1 3 .68 11.49 8).82 4.77 6.72 4. 05 6.72 3.68

August 13.48 11.33 8.69 4.67 6.66 4.()2 6.66 4.02

SeptemTber- 9. 6 6 8.12 6.22 41.40 3. 72 1. 82 3. 72 1. 32

October 6 . 76 5.6 8 4. 36 4. 53 1. 15 -0.1L7 1.15 -

Tota:L Recharge 20.44 9.52

Soil Moisture Deficit 0 0.17

Available Soil Moisture 4.l10 3.83

ND BA]}GA2DESR SEC'rOR STUIr

-:IMA'EDFUTURE REGIONAL RECHARGE FOR RAJSHAHI (inches Of waterj)

RaLinfall Efi-f Rainfall Recion.al Net Infiltration Recharge Month Max Min vcEpo tr.rMa M Maix. Min

May 4.72 3,, 97 3.05 7. 35 - _ _

June 10.06 8 ., 46 6.50 5 .62 2. 84 0. 88 -- -

July 1.2.06 10. 14 7.79 5. 15 4. 99 2.$4 3 8_ -

August 10.02 8.43 6.48 4 .89 3.54 1.59 3. 54 1.12

Se 5n'Lember 8.08 6.79 5.22 4 68 2.11 0.54 2. 1 0.54

October 4. 92 4 .14 3.18 41. 74 -0-. 6 0 -1.S5 -- -

Total :Recharcre 9,.4 1.65

S'oil Moisture Deficit 0., 60 1. 56

AVa'.ilable Soil Mois ture 32.40 2-. 44 BANGLADESH SECTOR STUDY ESTIMATED FUTURE REGIONAI RECHARGE FOR MYMENSINCGH (inches of water)

Rain:fal'L Eff Rairnfall Regional Net Infiltration Recharge Month Max Min Evapotr. Max. Min Max Min,

May 12.85 10.80 8.31 6.92 3.88 1.39 -

June 19.77 16.62 12.78 5.21 11.41 7. 57 11.29 4.96

July 16.82 14.14 10.87 5. 15 8.99 5.72 8.99 5.72

August 17.31 14.55 11.19 4.91 9.64 6.:28 9.64 6. 28

September 13.63 11.46 8.81 4.59S 6.8:7 4.22 6.87 4.22

October 7.45 6.26 4.82 4.66 1.60 0.1L6 1.60 0.16

Total Recharge 38.39 21.34

Soil Moisture Deficit 0 0

Available Soil Moisture 4.00 4.C00 BANGLADEH SECTOR STUDY

ESTIMATED FUTUURE REGIONAL RECHARGE 'OR SYL tIET (in.ches of water)

Rairfall Eff Rainfall Regional Net: Infiltration. Recharge Month Max M4in Evapotr. _ lax _ lMin Max Min

May 23.2 18.76 14.51 5.47 13.29 9.(04 9.2'3 '5.04

June 32.8 26.64 20.52 4.40 22.24 16.]L2 22.24 15.12

July 26.0 21.12 16.26 4.85 1.6.27 11.9)6 16.27 11. 9 6

August 24.8 20.14 15.51 4.30 1.5.84 11.21 15.84 11.21

September 20.2 16.41 12.64 4.02 1.2.39 8.62 12.39 8.62

October 10.6 8.61 6.63 4.43 4.18 2.20 4.18 2.20

Tota:L Recharge 80.21 55.15

Soil Moisture Deficit 0 0

Available Soil Moisture 4. 00 4.00 BANGLADE,H SECTOR STUIDY

ESTIMATED FUT'URE REGIONAL RECHARGE FOR DACCA (inches of wat er)

Rainfall Eff Rainfall P.egional Net Infiltration Recharge Month Max Mmin Evalpotr. Max -IMn Max Min

May 9.46 7.97 6.12 6.70 1.27' - - -

June 13.83 11.66 8. 94 4.90 6.76 4.04 4.03 0.04

July 12.84 10.82 8.,30 5.17 5.65 3.1.3 5.65 3.12

August 13.58 11.45 8. 78 5.00 6.45 3. 78 6.45 :3.78

Septemrber 9.3.2 7.86 6.,03 4.52 3.34. 1.5:L 3.34 'L.51

October 5.74 4.84 3.71 4.57 0.27' -0.86 0.27 -

Total Reclharge 19.74 8,.46

Soil Moisture Def'icit 0 0.86

Available So:il Moisture 4.00 3.14

H 0" 13ANGLADESH SECTOR STIJDY

ESTIMATED FUTURE REGIONAI RECHARGE FOR COMILLA/NOAKHALI (inches of wVater)

RainfalL Eff Rainfall Regional Net Infiltration Recharge Month Max Min Evapotr. Max Minm Max Min

May 10.13 7.92 6.03 6.51 1.41 - -

June 18.85 14.74 11.23 5.42 9.32 5.81 6.73 1.81

July 17.39 13.60 10.36 5S.61 7.99 4.75 7.99 4.75 hugust 14.46 11.31 8,.61 5S.00 6.31 3.6D1 6.31 3.61

September 10-76 8.41 6.41 4.72 3.69 1.(69 3.159 1.69

October 8.31 6.50 4.95 4.76 1.74 0.19 1.74 0.19

Total Recharge 26.46 12.05

Soil Moisture Deficit 0 0

Available Soil Moisture 4.00 4.00 BANGLADESH SECTDR STuDy

ESTIMATED FIJTURE REGIONAL RLCHARGE FOR KUSHTIA (inches of wxater)

RainTall Ef f Rainfall Regional Net :nfiltration D iec>arce

Month Max Mlin Evapotr. JJa x A _1 Aixi

MEay 4.72 4.02 3.0 8 7. 2:L -

June 10.06 8.56 6.56 5.52 3.04 1.04 - -

Juzly 12.06 10.27 7.86) 5.04 5.23 2.82 4.27 -

August 10.02 8.53 6.5 3 4.79 3.74 1.74 3.74 1.60

September 8.08 6.88 5.27 4.59 2.29 0.63 2.29 0.68

October 4.92 4.19 .3. 21 4.6:3 -0. 44 -1.42 - -

Total Recharge 10 . 30 2.2 8

Soi:L Moisture Deficit 0.44 1.42

Available Soil .4oi E;sture 3.55 2. 58 co BANGLADESH SECTOR STuDr

ESTIMATED FUTURE RE-IONAL RECHARc;E FOR JESSOPE (inches of water)

Rainfa1l Eff Ratinfall Regional Net Infiltrat:ion Rechrqe Month Max lMin Evapotr. M*aax ! ir Max ;iri

May 6.3() 5..36 4.11 6.61 - - -

June 13.48 11.47 8.78 5.46 6.01 3.32 2.0'L

July 14.03 11.94 9.14 5.54 6.40 .3.6.C i 4(0 2.92

August 1:2.13 10.:33 7.90 5.28 5.05 2.62 5.05 2.52

September 8 .93 7.60 5.82 4.65 2.95 1.17 2.95 1.17

October 6.0c2 5.12 3.92 4.69 0.43 -0(.77 0.4:3

JTotal Recharge 16.84 5.71

Soil Moistu re Deficit 0 0.77 |t

Available Soil Moisture 4'.00 3.23 HJ \0 BANGLADESH SECTOR STUDY

EST'IMATED FUTURF REGIONAL RECHARGE FOR FARIDPUR 'inches of i7a-ter)

Ra.infall Eff Rainfall Regional Net Infilt-ration Richarac Month Max Min Evapotr^. M ax Mir M ax .il

May 9.46 7.77 5.95 6.75 L.0 - - -

June 13.83 11.35 8.70 5.06 6. 29 3.64 3.31

July 12.84 10.54 8.08 4.96 .. 58 3.12 S.58 2.7(3

Aucrust 13.58 11.15 8.54 4.76 16.39 3.78 6.39 3.7(32

September 9.32 7.65 5.86 4.42 3.23 1.44 3.23 1.4 41

October 5.74 4.71 3.61 4.45 0.26) -0.84 0.26 -A

Total Recharge 18.77 7.998

Soi:L Moisture Deficit 0 0.84

Available Soil MoiSture 4.00 3.1(5 0~ BANGIADESH SECTOR STTDY

SUPIIZIARY OF POTEI'TIAL REGIONAL_ GROUNDWATER RECHARGE BY DISTRICTS

Potentictl Recharge Gross Area Less PoD. Rechar-ce 1 1 Open Wat erI Max 71in Max Min | Max ri District (inches) (feet) (million acres) (MAF 2,

Dinajpur, Rangpur 32.54 16.80 2.71 1.40 3.98 10.79 5.,7 Bogra, Pabna 20.44 9.52 1.70 0.'79 2 .08 | 3.54 1.,64 Rajshahi 9.48 1.65 0.79 0.:14 2.25 1.73 0.32 Mymensingh 38.:39 21.34 3.20 1.78 3.,91 12.51 6.96 Sylhet 80.21 55.15 6.68 4.60 2.65 17.70 2L2.19 Dacca 19.74 8.46 1.65 0.'70 1.,78 2.94 1.25 3 Comilia, Noakhali 26.46 12.05 2.20 1.()0 2.58 5.68 2.58

Kushtia 10.30 2.28 0.86 0. 19 0.86 0.74 0.1.6 Jessore3 16.84 6.71 1.40 0.56 1.60 2.24 0.'90 Farildpur3 18.77 7.98 1.56 0.66 1.63 2.54 1.08 _TOTAL 60.46 3'.'3 1 From Tables 11 through 20. 2 Million Acre Feet

3 lyi fres3^ grounA--ateWL artea considered BANGLADESH SECTORFSTDY

NET POTENTIAL RECH.ARGF. AVAILABLE FOR THE B3iNDED AREAS, BY DTSTPICT

Future Non-Beneficial Non-Irrigated Evaporation from Evaporation froro Potential Rec^.arge Acreage Non-Irrigated Areas Non-Irrigated Available Less Open Waterl- Less Open Water'- Acreage 3 for Bunded Acrarege 4 District (mill. acres) Inches F'eet (IAF) boI-LX. 'I in. Max. bin.n _ ___) __(M (fcet/acre)

(]) (2) (3) (4) (5) (W) (7) (8) (9) Dinajpur, Rangpur 0. 77 12.6 1.05 1.81 9.93 4.70 3.11 1.43 Pocra, PFebna 0.';1 13.6 1.13 50.58 2.96 1.C9 1.£9 0.O3

Rajs;hahi 0.'51 13.7 1L.14 0.58 1.20 - 0.69 '- Mvr-nensinCIh 0. 88 13.7 1.14 1.00 11.51 5.C9I 3.80 1.97 Sy1het Less Hills 0.5;8 13.7 1.14 0.66 17.04 11.53 8.23 5.57 Dacca 0.46 14.3 1.19 0.55 2.3J9 0./3 1.81 C.53 Conilla, Noakhali 0.719 13.8 L.15 0.91 4.77 1.67 2.O6 0.93 KuaStia 0.23 13.7 1.14 0.26 0.48 - 1.76 Jessore 0.47 14.2 1L.18 0.55 1.69 0.35 1.50 0.31 Faridpur 0.51 14.0 1.17 0.60 1.94 1.48 1.73 0.43

1 From Tab-le 4 (Fucure Unbunded + Uncultivated Areas + Homesteads) 2 Evaporat ion Index (Table 8 of T.R. 20)times 0.75 for period Novernber-April. 3_vapGr tion from non-bunded acreage (Co. 4) times non-irriaated acreage (Col. 2 4 Obtaine4 by subtracting non--beneficial evaporation fccrm potential recharge givea in Table 21

5Cols. 6 and 7 divided by Future Bunc.1ed Acreage (Table 14) BANGLADESH SECTOR STUDY

ACREAC;ES WHICH CAN BE DEV:ELOPED ON THE BASIS OF GROUNDWATER ALONE

ANID NUMBERS OF TUBEWEL,LS POSSIBIE OR NEEDED __

Future Max. Pot. Recharge Bunded Available for Areas Bunded AreaE2 Acreage for (,roundwater Number of 2 Cusec (million (MAF) Development 3 Tubewej.ls Possible or District acres) Max. (million acres) NeE~ded' at 20"/acre at 15"Jacre

(1) (2) (3) (4) (5) (6)

Dinajpur Rangpur 3.21 9.98 3.21 3.21 24,700 Pogra,, Pabna 1.57 2.96 1.57 1.57 12,100 Rajshahi 1.74 1.20 0.72 0.96 , 50O Mymensingh 3.03 11.51 3.03 3.03 23,300 Sy.1het Less Hills 2.07 17.04 2.07 2.07 15,900 Da,cca 1.32 2.39 1.32 1.32 10,200 Comilla, Noakha.li 1.79 4.77 1.79 1.79 13,800 Kusht:La 0.63 0.48 0.29 0.38 2,200 Jessore 1.13 1.69 1.01 1.13 7,800 Faridpur 1.12 1.94 1.12 1.12 _ 3.600

TOTAL 17.61 53.96 16.13 16.58 124,100

1From Table 4 2 From Table 22 3 Underlined: development constrained by groundwatter availability

4 T]his implies one tubewell p(er 130 net acres and approximately 170 gross acres

* 'ithoiut consideration of flooding, cost and other water souzrces | BANGILADESH SECTOR STUDY

OPTIMUM AND RECOM;MENDED DEPTHS FOR TWO-CUSEC WELLS

OptimuiTn Conf iguration Re commended Configuration

Well Screen Housing Blind ie1l Screen Housing B:Li nLd Area feet feet feet feet f;et -e t feet feet

Ganges/Barrind 150 77 50 23 .15P 80 60 15 Ganges/sand 14L0 75 35 30 140 75 50 15 Sanges/grave1 150 85 50 1 150 85 60 5 Brahnmaputra 130 71 50 9 135 75 50 1( Bogra Barind 110 55 50 5 115 60 50 5

Rangpur-/Dinajpur Barind _ 150- 85 6 0 5+ Sherpur failure area _ _. Ian to max 180 pos 60±, 5

N. Tista (a) 185 125 55 5 .170 90 1 70 10 N. Tista (b) 145 90 50 5 .160 90 60 10 Piedmont 170 85 50 35 170 85 6 0 25 P jedmornt/ Barindc 190 109 60 21 185 90 70 25

1 Screen length decreases are compensated foor by dra;qdown increascs.

Source: Si:r Murdoch Mac3Donald and Partners, 1971, which incl]udes a mapai: showing thae ar ea locations. BAN GLADIESH SECTOR STUDY

DATA FROM VARIOUS WATER SUPP:LY WELLS

Stra…- _3- iater ner Dia- ;ner Gravel. Original DraLW- Comiple-. Deptha meter 'ength Packed Yield do-,rn ted r1k s .______(inches) (feet) - ((Cusecs) ______COYJLIA v

South We:Ll Dharm3sagar ,213 feet 6 96 o .7 16'-" 1 935 iletes-t l965 c ave Northl WUe1Ll Dharmasagar '266 6 88 No .8 16-0 196'2 (cuCs;.r 'fa'-. dr:a:J dova of l!? 3 -' e,;-t - -''- cuse- or, a ciras cO.m Cf. 16I)'-3

DAC(CA Rzi?way Workshop 1243 1L5 PSes 14

DAItSANA

Railway Station .294 8 IOL0 Yes 2.1 G--lC 196-3

_____ - _ .______-- __ __ - _. ______- __ _- _ - ______DINAhJPlJ, .

Kanchagh.at Vell No :L 1452 8 1L36 Yes 1.3 31 --6 1 I ]3a1u Bar:L We:Ll No 3 373 8 -L53 Yes l.() 2h9-0

ISHURI) Sugar Cane Farm :268 6 72 No .17 L.-O 195 S.M. Farm :203 6 88 No .6 3- 199ht 196D i(Otesvt C)etr f-V- ,3 cus-o at ft ea.ra

JAHALPIJR 64

-Madrasha Wel'l No 1 470 1LIo .5 10--_0 196:3 .xnLapara 'riel:l No 3 L53 6 :L04 No .6 10--C) 196) Kei No 2 437 6 :L04 No .6 5 - __196_3____

JESSO 1 Il

H'ousing Sc tlet nentm :271 - 80No I 7_7______--O _ -L BAIGLADESH SECTOR SiTUD'

DATA FIROM VARIOUS WATER SUPPLY WELLS (Continued)

Strai-- btrai- Hate.cl ner Dia- ner Gravel C)riginal Br -- Cornple- …_ Dept,h meter tenl-th Paked YielEd

KHUIJNA RuLsa Well No 2 579 6 96 No .9 19-0 19 6 Shaicpara Well No 3 579 6 lot. Ho . 'i7 19TO Jessore Road WJell No l 60 3 6 100 To 1.0 10-l 19

MIUNSHIGANJ I

WelEl ITo 1 382 6 72 ,No .5 ',-7 196 NYiE:NSI NGH I.C.A. Technical House 38() 6 120 No .9 3-0 162I Well No 1 28L 6 80 No .5 Wlell No 2 299 | 6 80 N.o5 Kalibari Well No 3 337 6 80 NIo *5 Gaziabari Well No 4 347r 6 80 INo 5 1 VWell No 5 253 6 88 No ,5 Kallishbari Well No 6 33'> 6 101 No .7 Bagmara Well No 7 39-7 8 89-7 'Yes 2.1 27 19616) CiLrcuiLt House Well No 8 35-L 8 153 Yes 2.)4 j 221196_ RAVJSHA' HI I _ l

SLte 2 We:Ll 2 2715 6 80 iNo .9 j -0 | Sate 3 We l 2 28 5 6 80 N9 . . 6-6

S&bWJGANJ 'i'ell No 1 287 6 80 io .8 9-6 1S64 .'n all Lzel s co', WE'll 10o 2- 290 6 80 No .8 13-6 19,k r v. goieoucr ui.u Well No 3 270 6 80 No .8 13-6 19661or.-eo :3t airs i-. Well lqo 4 24' 6 8 0 iNo 1.1 13-0 19`4 Sera jgaLj - logs ind:ic;s ot r l' of strai:lner cOU-0jF OeIj . " U9X'L'tF d:!ptlG _e _ -c11_ _ __ 1l. . .

CE. BANGLAI)ESH SECTOR STUDY'

DATA E'ROM VA]RIOUS WATER SUPPLY WELLS (Continued)

_ _ .~Strai - t rai _ .ate A 2 1- fnerDia- rer Grael C'iginl-- D th m-i!ter 1,e r. -tjpL._h ( _-a kc,_, , ._ _1 ! T._l17I I .

| hWellINo 3 4LL5 8 180 Yes 1. 5 3 2.3 l9c|, ~. e. .

~~~~~~~~~~____, ______. .. ______.... - I t- {.c 'CLT> ŽJ .n--_ :.ll NSo :16 )466 3c 8 7 111 Yes .5 6iL|<,

! - - ,. '.

'iell No 21 4 3 177 Yes 2.1 ? 1%i !

W.J1 No 22A 0hYs -Le -I -~ _ ._._ _ _ -_ ___ I42-t

ydell No 233A 4153 8 196 es _ _- '. - __ .______. _- ______

.111 No0 9 hh46 8 200 Ya >s*

_.______.-. . _ _ _ _- L - t vIell 4l-!;' No 50A 463 8 20L' es _ _ 196L :

______- _ .______- _ _0 -de1 N'o ,5 )46' 8 20C( es 1.I8 , . '

W11 L6,4 9 51 8 2 . I1 -

DATA FROM VARIOUS WATER SUPPLN' WELLS (Continued)

.- __ __ _Strai- Strai- Rated

nor Dia- ner Gravecl Origini 1 Draw- C071-1-C l .epth meter Lecngth _ Packed _ield I di t-

DACCA

ire11 No 57 384 8 174 Yes _ 1961 19t66 r1i'ost, 8ES C^.. v!-.JLLih fz.Lt. draws

-Wcll No 58 h88 8 232 Yes _ _ 1961 iOO:l 1 C

fWLtL j i ,

_ _~~_ _ - _- _- _ .- . __I .dell No 59 495 8 2C01 Yes _ -. 9 -V. ; ^ ' cj

_ _ . ~~______._ ___ . ~ .1 _ __ -

Well No 61 499 8 201 Yes 1.8 I61 1966 >cts 1.3 -it 27.' f't cjra-;

W-Jell No 62 L171h 8 2C1 Yes 1.8 _ 1961 .- j66 !t;t -. c, Wit''' f7 a C'~~~dr33.) fdraw

Source: DPHE and CDM, March 1968.

0 BANGLADESH SECTOR STUDY

1 THAKU.RGAON TUBE,WELL PROJECT - SIMMARY OF WELL TEST DATA

Transm.-Ls- Scree,n Specific s ibi li lty Dis charge Drawdown Lenrgth Dr awdown T Q S L S /Q Wirell No cf s /ft cfs fee fee t f -t,/cfcs

20 0.33 4.1 :L5.2 L20 3. 7 40 0. 24 2. 8 1L5. 1i130 5. 3 250 0. .54 4.3 10.1.8 1 20 2. 4 15 0.38 44 12 .9 3 1]20 2 .9 262 0. :36 3.1 33.75 ? 1:.1 13 4 0.46 4, 0 21. 5 ? 5.3 200 0.154 4.2 1]0.63 31 2. 5 320 0.:28 3.7 1L8.43 131 5.0

Source: IBRD/IDA, Report No PS-6, April 1971

BAN_GLADESH SECTOR STUDY

StTh'LMA:RY OF RESULTS OF GPAIN SIZE ANALYSIS OF AQUI:TER dATrERIALS IN VARTOCUS ,5.\PEAS

Size r?.nge and Size PTnve and Ave . o: . i.teHa::-in d . COjeI' .- i r .- Gra:in 5:'1ze Gz:2;- SiZf Yr :D 3; District (1/1000 inch) (l/-LOOC irch) ½ icicni. .

Lakarg2nj (83.0 - 22.0) (O0 - 15.. 1 12.8 .99 1,

'Po; r a Dina ji Dur (14.o - 25.0) (8.0 - l.().:

.Uanm pur 18. O 11.7 1A 2 - -r -

Dacca (1L4 .0 - 22.0) (8.0 - 12.0) L7. 3 11.O

Fzl_ i -11jpur (:L3.0 - 28.0) (6.0 - 18.0 X e s soree :L56. A 10, 7 1 -, . , Kusnitia (16.0 - 25. 0) (8.0 - 2 G0 - - CL°.8 z~~~3.,8 t,

Khulnca (L4 . C - 18. 0) (8.0 - 12.0) 15L 55 1.63

I1§sen,sinih (22.0 - 2'5.0) (Th.0 -- 21 0) _ _.0 183 1 .3

Pabna (12.0 - 3;2.0 (7.0 - 25.C) 2.aj shahi 20. 12.3

Nioakhal-i (14 . O- L, .2) (o, - 0.),s :Ll .l3.9 ^.-r, . :

9.5 7 C,

Note: No material with less -han a C.006 inch grain size is includen.

1 Scurce: DPilE afnd CD?M, March 19A8.

arvm vT S T^un ST"um- TABLE.28_

J'U1et".Ei:

__~ _ ~ 7Y7rnec-t. |7 th cat v>;lAŽtlvt~L of: 'rubv;a11 Tuboewells Di.schariet Rlunningc HIours

SI1 No4 li2rs•.JL'o c P ot -. !S (.i ___ilcj ~(fret) ! cuSY2cs) Per Month

Sctabaarj Suqar 3 6 300 1.5 208 I i1 (PIP Ldc.; | 6 | 400 1.5 208 IDC 6 6 350 1.5 20)8

2 | Triple Supej-rhos- 238 .2 60-540 plhate Fer-tilizer [ 8 229 .4 Factory NJorth 8 | 217 .7

I Paternga1 Ctg=. 8 1 231 1 .5 8 265 .4 8 ~~~~210 .4

3 J Kushtia Sugar 14 400 | 2.8 180 |milis DC 2 14 400 2.8 720

4 Khulna Shipyard 2 6 575 .7 540 Ltd. 4 575 .4 5 IDC Iron & 3 4 80 0.3-.7 6n0 Steel I0 6 | Chittagong 8 502 1.1 | Housing 2 8 1 25< | .

7 > scrDrn lv2,-f i n,, Y- 7 ; ASn Ltd.; Chiiittagong 8 225 .3

8 303 1.0 } | 1 8 j ~~~~~~~~~~~~~~~4001.10

8 ihNorth Bengal 1 8 262 1 5 164Iugar- Mills Co. Ltd. 6 282 1.5 21)8 Gopalpur, Rajshahi 6 296 1.5 1 l5 6 301 1.5 168 6t 1 l 250 1.5 158 6 1 ~~~350 15 1:26 6 1 250 1.5 1:30 6 1 250 1- 1.5 320 6 250 2.0 24l0

V 1 1 6 250 1.5 6 250 1.5 1L2 6 250 1.5 1:2 6 250 1.5 128

6 250 1.5 192

|16 196 1.5 558 8 27 6 2.0 527I

______1 _~fi _ _% J_ _ _ eore DPuPV_ 1_1______andaE_ _ _ _ _fT,A __ _ _' marc._ _ _ _ _ 1968______I______L, 2 . 0 TABLE 28 (cunt/..) BANGLADESH SECTOR STUDY

Qu>'LU;E !: DLA' Gi' DFI-:, ? P! ( iS ;-F IDC

|TukeO.?el1 | |of Tubew11 | TubxIe Ils IDis hlage Running Hou-s SI'No of Projec-L INOS (inches) (-f~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~(nce)(et)(ies .S1 No NO21c r Pro-.cat |No sJ _____t.i _en_ ___tecj_ 2±¶ /,onth -|

Pus.;lirlll Cotton 2 6 446 .4 344 if.lil1; I,td.; 6 360 .3 344 | Kaiganj, Dacc.a

10 j W. Rahrnan Jute 1 6 4 1_8 mi lls Ltd. 1 6 450 1.8 120

11 Co-operative Jute Mills Ltd.; | Palash Dacca 1 8 500 .9 60

12 Pak Jute Mills Ltd. Ghorasal, Dacca 1 6 500 .4 300

13 QauirLi Jute Nills Ltd., Sirajganj, Pabrni 1 6 270 .5 120

14 Thakurgoan Sugar mills Lt;o., Dinajpur 2 6 333 1.2 240-700

15 |Khulna Newsprint 3 14 336 1.6 720 Mills Ltd. 14 1.6 14 336 .9 720

1]6 |4obarakganij Sugar

i0 Mills, Jessore | 2 1 8 1 400 1 1 3

17 North Bengal Paperl I 0 1 I I Mills, Paksey, 1 6 400 2.0 90

18 Rajshahi Sugar 3 6 286 1.0 60 Mills, Harian, 8 400 1.8 120 ajhhj8 ann4 1.8 1A0

______J__ .1 1 ______1 ______3 ______BANGLADESH-3ECTOR SIUDY

SMURY OF WATER ANALYSIS 1967 POST MONSOON SEASON FOR BARISAL DISTRICT

_Well Well Well Wdater pH Iron Chloride Hardness Alkalinity Total Dis- Computed Remarks Town No. DiLa. Depth 'Temp.. (Dlg/1) (mg/1) I'mg/l CaOa 2 J) hgL Ca:)3) soledY ! C02 Lab Code (In.) (Ft.) °F Calcium ITotal P Tota solids (mg/l) No. -~~~~~ j - - - - ~~~~~~~~~~(mg/i)

BoarLalF 2 6" 800 88 7.9 L 0.1 88 20 36 0 292 495 5.5 1-7-D433

Ehola 24 _L" 857 85 7.7 2,.4 168 54 110 0 33:2 637 li. 1-12-D437 F Patuakhali 6 26L"26 82 6.8 81.6 94 152 348 0 4Wi 765 120. 1-34-D436

PattiakhaLli 1 6" 970 86 8.15L o,5L 6.5 15 30 0 44)40 55° 6.5 1-34-D435z - I ~~~L L Piropur 2 i½" 850 87 7.9 0.3 7)40 52 96 0 %42)4 1750 7.8 1-36-D43:1

PiroJpul _ 1 _ 46 85 7.1 6.6 L 144 180 282 O 484 80 61S5. 1-36-D432 L F Jha:Lakati 16 _ _ _ 84 7.95 0..4 210 24 _ 42 O 4oB 820 8. 1-19-D434.L

Total Dissolved So]Lids by Filterable Residue Technique L Laboratory F= Fi.eld

DIS;TRICT SUMMARY

Well Water Iror,= Total Debpth Teimp. Grezater Total Total Dissolved _ 0MX _ ]F) PEI O.D-.0-29 0.30-0.99 0.00-1.99 Than 2.00 Chlor'de Hardness Alkalir_ity _]Lids Co_mput_

MINIMUM 46. 832. 6.8 0.10 0.3 . 4 6.5 3CI. 292. )495- 6.5

MAXIMUK 970. _ 5. 8.1 - 0*5 8.6 7_4. 348. 484. _ 1750. 120.

AVERAGE 591.5 85.3 7.6 o)4 |403.[25.86 207.2 134e9 831.7 31.9

1 'well 3 wells:3 welI wells II-I BANGLADEMI-SECTOR STUDY

SUmMARm OF WIATER ANALYSIS 1967 PRE-H4ONSODN SEASON FOR SIMRET DISTRICT (WELLS) Thum Weill Well Well Water pH Iron Chl oride Hardness ALkaLinity Total Dils- (bmputEdl Reinarks No. Dia. Depth J)mp. (mg/l) (mg/1) (m4g/l CaCO3 ) (mg/l CaC03) solved 002 (In.) (Ft.) F Solids (mg/i) (In. )CalciumTotal P Total (mg/i)

Sn .rT 6 1- 92 6.7 F 4.9 F 9 ,4 18 0 92 140 32 17-35-D135

SJR.ANGANJ 48' 1½ 500_ 7 .3 F 2 .0 F 0-5 74 142 t 218 260 - 17-32-D136

CaRATAK 16 1½ 124 - 6.6 F 3.2 L 2.0 6S 9 0 0 160o 45 17-18-D135?

MDULVI BAZAR 2 1½ 16c - 6.25 2 0 _ 3.0 10 22 0) o 56 - 17-27-D14o

MiOULVI BAZAR 5 1½ 126 - 6.5 16 L 1.5 2,2 37 C) 68 105 40 17-34-Dl41.

&kBIGANJ 5 it 165 _ 6.7_F4.0L 1.0 35 65 () 128 200 38 _ 17-17-D142

SHDAR _ i - 648 6.85 L 2.4 L - 16 28 () 65 _ - D285 MEDICAL L ODLONY - - _ - 7.1,5 1.3 - 2L 42 t) 90 - _ D29],

AM!BER OLONrY - - _ - 6.85 1.3 28 45 0 65 - _D2919

1/ Total Dissolved Solids by Filterable Residue Technique F- Field L = Laboratory Samples Collected April and Jiane, 1967

DI STRICT SUNMARY FOR WELL WAATER

W1ll Water Iro 'Total Cbmpu1ted Depth Temp. Greater Total Total Dissolved CO2 ___ ~~~~(Ilt) COF) PH 0.00-0.29 0.30-0.519 1.00-1,,99 Vhan2.00 Chloi-ide Hardriess .AlkaLlinilly iSol-ids

MINIMUM 92 - i5 1.3 2.0 O.; 9-0 5-.0 I6.0 32

KXIMUM 648 - - 20.0 9.0 142.0 218.0 260.0 45 AVERA(rR ?60 -- 6.8 - - l. ,%. 2.6 45 19. 1153 39 ~[ME,OF SAMPlES 7 0 9 0° 2 7 6 9 5' 6 4

'-D 1wg BANGLADESH - SECTOR STUIDY

SUMMABY OF WATER ANALYSIS 1.967 PRE-4OC)NSOON SEASON FOR SYLHET DISTRICT

Total Remarks Well. Well WeLll Water Dissolvn Computed Town No. Dia. Depth Temp. pH Iron Chl.oride Hardness Alkalinity Solids-/ C02 Lab.. Code! No (In.) (Ft.) OF. (mg/l)i/ (mg/l) (mg/l, CaC0 3 ) (mig/l,CaC0 3 ) (mg/i) (mg/l) G-alciuin Total P Total

SyLhet River Sample Surma - 7 OF 2.JFL 1.3 16 30 0 24 80 17-.35-D134 Suiamganj River Sample Surma - 6 . 7 LF 1 LF C.5 16 24 C 24 185 _ 17-32-D]37 Chhatalc River Surma - 6 .8 F 2 L cl. 5 22 26 0 28 - 17-8-D138

3/ Total clissolved. solids by f:ilterable residue technique. F = Field / Supernatant. L = Laboratory Samples Collected ApriL, 1967

DISTRICT SUMI'ARY FOR RIVE1R WATER

i]ron (mg / To-tal We ell Water Greater Total Tcotal Dissolved Computed Depth Temp. pH 0.00-0.29 0.30-.0.99 1.00-1.99 Than 2.00 Chloride Hardness Alkalinity Solids C02 (Ft.) OFj)

Minimum River 6. 8 _ * 1.1 2.1 0.5 24.0 24.0 80.0 vlaidmLol River 17.0 - -- - 2.32 1.3 30,.0 28.0 185.O Average 6.c9 - - - 2.21 0.77 26,,0 26.0 132 - Number of Sarnples 0 3 0 0 1 2 33 0

I- BANGLADESH - SECTOR STUDY.

SUCT4ARY OF WATER ANALYSIS 167 POST-MONSOODN SEASON FOR BOGRJDISTRTICT

Total Well W,ell Well Water Dissolvecs Computed Remarks Town No. Dia. Depth Temp. pH Iron Chloride Hardness Alkalinity SolidsL C02 (In.) (Ft.) OF., (mg,/l) (mg/1) (m.g/l,CaC0 3 ) (mg/l,CaCO3 ) (mg/i) (mg/i) Lab.Code No Calcium Total P Total

Bogra 226 1-1/2 66 81 6 . 7 F 0.1 F C. 38 68 0 96 155 31. 2-3-D4t73 Santahar 1 i-1/2 46 79 .66 0 _,L 62 102 :182 0 168 225 75 2-2-Dh7

1/ Total dissolved solids by fi:Lterable residue technique. F = Field L = Laboratory

DI:STRICT SUMMARY

Iroii ( 11/1) Total Well. Water Greater Total Total Dissolved Computed Depth Temp. pH O.OC)-0.29 0.30-0i.99 1.00C-l.99 Than 2.00 Chl-oride Hardness Alkalinity Solids (CO2 (Ft.) (OF.)

Mlinimum 4t6. 79. 6.6 C).1 0.L1 - - 9.0 68. 96. 155. 31. Maximum 66. 81. 6.75 - 62. 182. :168. 255. 75. Average 56. 80. 6.7 - - - - 35.5 125. IL32. 196. 53. 1 Wdell 1 Well 0 ell. 0 'Well BANGLADESH S;ECTOR STUDY

SUMMARY OF WATER ANALYSIS 1967 POST-MDNSOON SEASON FO]R CH:ITTAGONG DISTRICT

'Well Well W4ell Water pHl Irork Chloride HardLnesEs Alkalinity Total Computed Remarks No. Dia. Depth T'emp. (mg/i) (mg/1) (mg/l CaCC3 ) (mg/l CaCO3 ) D)issolved C002 :Lab. Code (In.) (Ft.,) OF Calcium Total P Total solLds ]/ (mg/i) No.

C. Razar 1 6 ,41] 84 8 . 20L 0 .2F 560. 32. 58. 0 ,424. 1:35. h.5 3-6-iD429

C. BaLzar 8 1½+ 26 80 7 .8F o.IF 11.5 69. 122. 0 136. 200. 3.9 3-6-]D430

1/ Total Dissolvead Solids by Filterab'le Residue Technique C = Cox's; L = Laboratory; F = Field

DEISTRICT SUMMURY

Well Water Iron (mg/)_ Total Depth Temp. Greater Total Dissolved Computed (Ft.) (OF) pH 0.00-0.29 0.30-0.959 1.00-1.99 than 2.00 Chloride Hardness Alkalinity solids CC)2

Minimum 26 80 7.8 0.1 - 1.5 58. 136. 200. 3.,5

Maximum 411 84 8.20) 0.2 _ 56CI. 122. 42L. 1435. 4L5

Average 218.5 82 8. 0.15 - 285.75 90. 28c). 817.,5 4.2

2 wells 0 well 0 well 0 well BANCLADESH SECTOR STUDY

SUMMARY OF WATER ANALYSIS 1967 POST-MONSOON SEASON FOR COMILLA D]iTRIlCT

Well Well Well Water pH Iron Chlor- Hardness Alkalinity Total Commuted Remarks No. Dia. Depth T'emp. (mg/l) ide (mg/l CaCO3) (mg/l CaCO ) Dissolve4j CO Lab, code (In.) (Ft.) OF (mg/l) Calcium Total P Tot2l solids" (mgyl) NID.

_. _ _ _ _ _)_

Rrahnnanbaria 46 1½ 171 82 6 . 8 F 4.2 56. 86. 204. 0 176. 3h45. 49 5-4-D425 1Rrahmanbaria 2 6 508 81 7.5L 1.5 31. 62. 1154. 0 154. 2,25. 8.5 5-4-D426

PrahnnanbcLria 86 1½ 132 82 7. 1F o.]L 6. 60. 1:29 0 160. 105. 24. 5-4-D427

Chandpur 1 1½ 69 81 6.95L 2 0 .F 8. 204. 222. 0 256. 325. 50.L/ 5-8-D5050

IChandpur 2 1½ 69 80 7.05L 8 .6] 33. 144. 214h. 0 256. 375. 36.1 5-8-D506 Chandpur 3 1½ 72 80 6.81 19.1 77. 236. 35 8. 0 368. 54o. ]L0. 5-8-D507 Chandpur 4 1½ 69 80 6.85L 20.11 80. 236. 3:34. 0 332. 515. 80. 5-8-D508

Chandpur 5 11½ 72 81 7 *1 F 1O.F 11. 266. 378. 0 hu8. 495. 62. 5-8-D510 I'omi'Lla 1 1! 2L-0D1 Sadar 1 1½ - 82 6 . 9 F 15. 1. 46 100. 0 1C4. 1)5. 25. 5-10-D518 Ashuganj 2 1½ 115 81 6.65L 77., 1L09. 132. 288. 0 215. 555. 85.&' 5-3-D519

1/ Total Dissolved Solids by Filterable Residue Technique IN= Laboratory; F = Field 2/ 002 from lab. pH

DISTRICT SUMMARY Well Well Iron I( L) T'otal Depth Temp. Greater Total Total Dissolved Computed (Ft.) (OF) pH 0.00-0O.29 0.30-0.99 1.00-:L.99 than 2.00 Chloride Hardness AlkaLLnity Solids C02

Minimum 69 80 6.65 - o.4 1.57 4.2 1,. C1o. 104. lo5. 8.5 Maximum 508 82 7.5 - - - 77. 109,. 378. 443. 555. lo4.

Average 141.8 81 6.99 - - - 9.2 41.2 241.1 2469. 351.5 25.35 0 well 1 well 1 well 8 wells BANGLADESH - SECTOR STUDY

SUMMARY OF WATER ANALYSIS 1'967 POST--MONSOON SEASON F()R DACCA DISTRICT

We:Ll Well Well Water pH Iron Ch:Loricie Hardness Alka]inity Total DiLs- Computed. Remarks Town No,. Dia. Depth Temp. (mg/1) (mg/1) (mg/i CaCOr (rmg/l CaCCI solved CC) Lab.Cod (iWn. ) (Ft. ) °F Calcium TotaL Fp S[ solids ! (mg/iL) No. ~~ ~(mg/l ), ,_ _ T 4 ~ ~angal 2 8 '6' 81 6 .65E - '120. 132. 240. 0 1Q 6-29-D500 Narayanganj 74 15 111 80 , 1 L 3 L7. 36. 56. 0 256. 400. 33. 6-29-D501 Munshiganj 56 1½ 259 82 6-75I 1 6L 133. 128. 210. 0 192. 450. 6C).- 6-25-D503

Munshiganij 1 6 - 82 6.75I 2 . 4 L 66. 106. 202. 0 167. 350. 62. 6-25-D50h Khiilgaon 1½-2 93 27 (C 6 . 6 F 0 . 2L 5-5 58. 96. 0 118. 195. 5';. 6-5-D515 Khilgaon 1½ls 93 27"C 6 .5F 0 . 7L 4. 56. 86. 0 118. 195. 68. 6-5-D516 Tangi 3 1o2 192 83 6.95I 11 .F 1O. 59. 107. 0 168. 245. 34.L./ 6-15-D535

Tangi 1 6 400 81 6S. 9 F o0 6 F 1. 104. 178. 0 242. 320. 55. 6-15-D537

Joydebpur 5 11½ 160 81 6 *9 5 " 6 .L 4. 94 - 144. 0 200. 255. 40. 6-15-D538

Joydebpur 1 8 400 80 6-95F 9 F 2. 77. 128. 0 176. 230. 36. 6-15-D5,39

Saver 2 1½-2 109 81 6 . 2 5 L 4 .5L 1. 18. 22. 0 52. 115. 70(.2 6-35-D541

Manikgan,j 4 11 132 81 6.85LJ 1 4 .4L 14. 1 03. 214. 0 212. 270. 55 *i/ 6-23-D542

Shivalaya 1 1½- 166 79 6 .8 F 1 3 F '109. 248. 398, 0 426. 620. 11(. 6-40-D545

Narsindi 109 1½-2 125 81 6 . 7 5 F 1 1 L 18. 96. 206. 0 198. 265. 55. 6-31 -D5,58

Gorashai 20 1½2 159 82 6 .7 0 F 2 .L 13. 71. 109. 0 308. 245. 11C). 6-17-D596

I)ISTRICT SUMMARY 11Well Wllater_ Iron (mg/1) Total Depthl Temp. Grreater Total Total Di.ssolved Comp. 0 ,(Ft.) ( F) pH 0.00-0.29 0.30-0.99 1 .00-1 .99 Than 2.00, Ch]Loride Hardness Alkalinity Solids C02

MINIMUM 93 79 6.25 0.2 0.3 1.1 2. 1. 22 52 115 33 MAXIMUM 1565 83 7.1 - 0.7 1.6 14.4 109. 398 426 620 110 AVERAGE 212 81 6.76 - 0.5 1]*35 7.23 37.1 159 199 -l1i 60 I well 3 wel'ls 2 wells 9 wells _ TotaL Dissolved Solids by Filterable-esidue Techn:Lque L = Laboratory, F = Field (D 2/ C02 from Lab., pH. BANGLADESH - SECTOR STUDY

SUMIARY OF WATER ANALYSIS 1967 POST MONSCOON SEASON FOR DACCA DISTRICT

Name of Water Iron Chloride Hardness Alkalinity Total Dis- Computed Remarks ToDwn River Temp. pH (mg/l) (mg,/i) (mg/L CaCO ) (mg/:L CaCO3) solved 002 Lab. Code ODF MITCTlum 1T P Total solids 1/ (mg/i, No.

Narayanganj Sit,alakka 82 7 . 0L 1 6L 3. 42. 60. 0 58. 100. 11, 6-29-D502

Tangi Tangi river B1 7 .I1F 07 05 49. 70. 0 70. 110. 5, 6-15-D536 Shivalaya Jamuina '77 7.8 F 3.3L 1.5 66. 88. 0 84. 170. 2.6 6-40-D543

Manikganj Kaliganga '77 7.*(5L 4. 7L trace 64. 88. 0 82. 155. 1.8 6-23-D544

Narsind.i Meghna 81 7.1F 0.5L o.5 18. 24. 0 30. 57. 4,5 6-31-D557

Ghorasal Sitalakha 76 8.3L ° 9L 1.8 88. 127. 0 226. 190. 2,.4 6-.17-D597

DISTRICT STJ1T2ARY

Well Water Iron (mg/i) Total Depth Temp. Greater Total TotaL Dissolved GDmp. (Ft.) (OF) pH 0.00-0.29 0.30-0.99 1.00-- .99 Than 2.00 Chloride Hardness Alkalinity Solids CO2

MINIMUM River 76 7.0 - 0.5 16 3.3 0).5 24 30 57 1.8

MAXIMUM River 82 8.3 - 0.9 - 4.7 3-65 127 226 190 11.

AVERAGE River 79 7.59 - 0.7 - 4-0 1.56 76 91 130 4.55

0 river 3 rivers 1 river 2 rivers

1/ Total Dissolved Solids by FiLterable Residue Technique L = Laboratory F = Fielcl

CY\ BA[GLADEESH - SB,TOR STUI)Y

IJEMARY OF WATER ANALYSIS 1967 POST-MONSOON SEASON FOIR DINAJPUR DISTRICT

Well Wrell Water Total Dis- Town Well Dia. Depth Termp. Iron Chloride Hardness Alkalinity solved Computed Remarks jNo. (In.,) 'Ft-.) OF pu (me±) (mIng/i) (ng/'i Cacu2L uauu-w so.L1s- LJU.m1g, Lab .code ______~~~~~~~~~~~~~~~~~~~~~~~~~mg,j~VkmI~ ~ ~~ -;aC,j o(iga]. C=5m Total P Total (ng/T) (m'71L) No.

Sadar 2 8 380 83 8.F 4.lL 5. 10. 12. 4.-L70. 275. 3.2 7-9-D4L,o

Sadar 1 8 460 84 8 .F . 1 L 4. 10. 11. 4X. 1L72. 240. 3.1 7-9-Db44

Sadar 1 1½ 26 85 6 .F 1 0 .6 L 9.7 38. 55. 0 56. 135. :LOO. 7-9-1D442

Thakurgaon 1 1½ 46 80 5.7F 0 .8 L 52. 63. 87. 0 34. 245. 95. 7-25-D470

Parbatipur 1 1½ 67 80 6.31? O. 3 L 64. 49. 74. 0 84. 200. 75. 7-20-D471

Parbatipur 1 6 274 80 7. 41' 2 .5 L 46. 37. 54. 0 64. 120. 4.15 7-20-D472

1/ Total Dissolved Solids by Filterable, Residue Technique L = Laboratory F - Field

DISTRICT S11MMAEfY

I[ron tii1 Well Water Greater Total Depth. Temp. than Total T'otal Dissolved Compuated (Ft.) (°F) pH: 0.00-0.29 0.30-0.959 1.00-1.99 2.00 Chloride ]Hardness Alkalinity So:Lids C02

Minimum ;26 80 6. c.l )0.3 - 2.5 4. 11. 34. 120. 3.1

Maximum 460 85 - _ o.8 _ 10.6 64. 87. 172. 275. 100.

'AACJ .83 82 S9. * rC.) - ',.55j I.,) 48.8, 96.7 j5 ono 4.6 -7

2 wells 2 wells 0 well 2 wells BANGLADESH -. SECTOR STUDY

SJMMAlY OF WATER ANALYSIS ]L967 POST-MONSOON SEASON FOR FARIDPUI DISTRICT

Well Well Water Total Dis- Well lDia. Depth Temrp. :[ron ChLoride Hardness Alkalinity solved Computed Remarks Town No. (In.) (Ft.) OF pH (mig/l) (mg/I) (mg/i CaCO2) (mg/L CaD09 solidsl! C02 Lab code

- ______Ci ciu.m Totata P Total (mg/J No.

FaridpUbr 77 1½ 52 81 7*1L O 107. 460. 632. 0 486. 91C). 65.2Y 8-7--D521. Faridpur 2 6 350 83 6 *9 5F l. 23 280. 460. 0 560. 46o. no. 8-7-D522 FaridpuLr C W R 82 7*3EF O02 29. 304. 448. 0 500. 545. 40. 8-7.-D523 FaridpuLr 3 6 148 831 7.4r 5.r 35. 304. 436 0 456. 48o). 28. 8-7--D524 Faridpur 6 6 303 82 6.95 1L2.h4] 26. 252. 420. 0 480. 520. 95 8-7.-D525' Gopalganj 1 1½ 90 82 7 . 1 5 L 6.8] 48. 162. 272. 0 48o. 64C). 57. 8-1(-D527 Madaripur 103 1½ 92 82 7-o5F 15.F 7. 240. 384. 0 468. 510. 72. 8-18-D530 Madaripur 38 1½ 80 81 6. ` 15.F 94. 280. 4oC). O 46o. 655. 90. 8-18-D5:31 Rajlbari. 91 1½ 40 81 7.1 o.81L 3. 236. 364. 0 364. 4hC. 52. 8-215-D532 RaIbari 2 6 450 82 6 . 95 F 2.3 13. 236. 408. 0 432. 495. 81. 8-25-D533

1/ Total Dissolved Solids by Filterable Residue TechunitqLe 2/ C02 from Lab. pH L Laboratory F Field DISTRICT SUMAR`Y

Iron (mjgV) Total Well Water Total Total Dissolved Computed Depth Temp. than Chloride Hardness Alkalinity Solids CO2 (Ft.) (OF) 0H 0.00-0.29 0.30-0.99 1.00-1.99 2.00

MiLnimLm 4O 81 6.95 - 0.4 - 2.3 :3. 272. 364. 400. 52. Maximumi 350 83 7.h _4 0.8 _ 15.0 107. 632. 560. 910. 110. Average 178.3 81.9 7.02 - o.6 - 7.47 38.5 422.4 478.6 551.5 69. 0 weill 2 wells 0 well. 8 wells BANGLADE]SH -- SECTOR STUDY

SUMMARY OF WATER ANALYSIS 1967 POST-MONSOON SEASON FOR JESSORE DISTIRICT

Total Remarks 'We.11 Well Well ,Water Diss-1-in- Computed I'awn No. DiLa. Depth Temp. pH Iron Chloride Hardness AlIcalinity Solids '7 CO2 Lab.Code No (In.) (Ft.) OF. (mg/l) (T4/l) (mg/l,CaC03 ) (nmgL, aCOa ) (ng/l) (mg/i) Ca-lcium Total P Tiota ……

Jessore 1 6 - 80 7 .4F 7.575L 84. 340. 0 406., 470. 26. 9-4-D390 Jessore 1 1-1/2 167 84 7 .2 0 6^6L 7.5 228. 368. 0 424., 480. 45. 9-4-D391 Jessore 2 6 298 84 '7.1' O.4L 9.0 ]L02. 404. 0 480. 545. 55. 9-4-D392 Jessore 1 6 347 85 '7.2F 0 .1 L 10. 248. 392. 0 466.. 530. 53. 9-4-D393 Jhanaidan 1 6 289 84 7 . 3 F 1 .rF 1. ].64. 216. 0 228., 270. 21.' 9-7-D394 Jhanaidah 30 1--1/2 172 83 '7.2F 5.6L 0.5 L60. 220. 0 232., 25'0. 27. 9-7-D396 Kotchandpur 6 1-1/2 137' 83 y.2F 4.5,F 2.5 ]L96. 272. 0 290. 310. 33. 9-7-D395 Magura 7 1--1/2 210 85 'T7 1F 6.CF 10.,3 284. 404. 0 42Q., h30. 58. 9-17'-D397 Magura 1 2 210 84 7*0F 6.8F 1.3 304. 408. 0 432. 475. 75. 9-17'-D398

/ Total dissolved solids by filterable residue techniquea F = Field L = Laboratory

DISTR:ICT 'SUMMARY

Iron_~~~~~~rngZl ~~~~~Total Wel1 Water Greiater Total Total Dissolved Cc,mputed Depth Temp. pH 0.00-0.29 0.30-0.99 1.00-1.99 Than 2.00 Chloride Hardrness Alkalinity So:Lids C02 (Ft.) (O°F.)t

Minimum 80. 7'. < .1 0.4 1.5 L.5 1. 220. 228. 250. 21.5 Maximum 85 7.4 - 0.6 - 6.8 10.8 408. 480. 545. 75. Average 83.6 7.2 (.1 0.5 - 5.73 5.57 336. 375. 41i7.7 43.94 2 Wells 2 Wells 1 Well 4 Wells ID BANGLADEH SECTOR STUDY

PUMS INSTALLED IN THAKURGAON AREA

Discharge Rated Bowl71 No No CF5 Head-feet_ Diamete:r (31ihes) Stac es Ho:rsaepCver

46 1.4-2.1 52 13 20

48 1.9-2.45 52 12 2 20

52 2.:3-2.8 52 12 2 25

78 2.8-3.5 52 12 2 35

72 3.:2-3.,9 52 12 2 35

66 3.7-4.5 42 12 2 35

1tIC BANGLADESt SECTOR STUDY

SCHEDULE OF ORIGINAL THAKURGAQN PU TESTS

Discharge Rate- Fler Cen-t of Final Length of Time Design Discharge (hours)

130 1.0 25 0. 5 50 0.5 75 0.5 100 0.5 130 8.5 Recoverv Measurements 0 . 5

Iii

,,-

| RAINFALLS AND SIMULTANEOUS FLUCTUATIONS FIGURE 1 OF THE WATER TABLE DISTRICT OF RAJSHAHI

I ~~ ~ ~~~~~~~~~~~~K4 1 HFFHHIEH IXI I ' I

L- !zKKdfr1 i_ L V ±_LtŽ1- -9tI-4 I

-14 1K272 FLCTATIN I

I L ii, IIIEx!44ThZI1IIIZ -N _ NE t- 17ii- I

IH'4'141KI AIN'IN"I4CIAPE I HIHII~~~~~~H2222 ~~~~~~VTLUCUAIONS IN HEtBIlI

SNOuvnilIorlld 3J18V1i I3M

9961 9961 2961£961 Z961 19'61

~~fldr7'7T -O O _-g _gc-z 7$ 1S|54l -- | j l

------

rNv9,dIG - r

I'Nt91930~~ ~~~ t 00I I ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~rnI

V N V~~~~~~-- ~ ~~~~~~~~~~~~~~~ ------(T-

8nldV.LN HOSIN --.- l

Nov,D8nliVH1 -

------I - ~ ~~------~~ ------

061 40

30 ------

------1 ~ - - -

o - _ - ~~~~1~~ _ -I- ---*------

-- - .::L7:~~~~~~~------

(L ~ ~ ~~~~~~~~~~~~~~~-~ ~ I---F 8 (BRITHIDANGA) L 20 ____~~… - F 12 (BHAIFIAPARA o -…------~~~\- ---- POONA,) -- I ~~~~~~~~~~~~~~~~~~~~F2(KALYANPLIFO Li IC) Li - -- --

------: HE:4-- - --

z ------I I - -- 1----

>i ------

ui - - …- -1 ------K2--ER MA A Li

-LJ

- ~~~~K4 (JANIFPUR)

It - - - 7- - z

0~~~~~ ~ ~ -- J::------iAJ (MAGURA)

z-l-~J2 (NA'RAIL:U -

bl fRlctS- KU SHTiAJESR-

19 61 19 62 1963 19 6 4 j 965, 19 66

WATIER TABLE FLUCTUJATIONS 40

30 -- ~~~~~~~~~~~~~~~~~~~~~~~~---

- --- - :.. ~~~~~~~~~------ITUR 9

hi ~~ --~ ~ ~ ~ 7 _7 = I ------=

- OIc,TRICT - PARIDPUR~~4- - - 4~~~~~~~~4

>------

20 J 4CI 0- or~~~~~~~~~~~~~~~~~~~~~JI(JSOE

I.U RCT -KSHIAJSS R _IAIS > - KIIH IA ..j ~~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 4lZ-u1 iAJ96 __192 j 193 Ix16416516

Sl~~~~~~~~~~~~~AE AL LCIAIN

SIPECIFIC: Co APA CIT Y OF THAKURCGAON TIUBEWELLS

100 --

80 _ __ 87 WELLS 1963-64 __ ORIGINAL PUMP TESTS 0 70 0 258 OR1IG_N- _ I U] - -~~~~~~~~~~~~~~~~~~~~85 'WELILS- <60 CA.PACIT-- GPM/FT

LtU 50 ______I - 5 8 2 R

4 0 _ - ______

L0 30_ - __v --- -_-

U _0

0 10 20 303 40 50 60 70 80 903 1100

SPECIFIC CAPACITY -- GPM/FT

IBRD -548,2(R) DISCHARGIE IFR'EQIUE'NC'Y DIS'rRIABUTION FOR SCR,EIENi T'YPE S

% TOTAL - 327 WELLS

30 - _- _

20 -- -_ _ _

Gt0 0 wmmummm…- o/ HAGUSTA SCREENS NOLD SCREENS 30 126 WELLS! 1201 WELlLS

O_ "___._H '__ _ __

0.00- 0.51-- 1.01- 1.51- 2'.01- 2.51- 3.01- 3.51- 4.01- 0.50 1.00 1.510 2.00 2'.50 3.00 3.50 4.00 4.50 UCFS IBRD - 54,80(R) RESTRICTED

INTERNATIONAL BANK FOR RECONSTRUCTION AND DEVELOPMENT

INTERNATIONAL DEVELOPMENT ASSOCIATION

BANGLADESH

LAND AND WATER RESOURCES SECTOR STUDY

VOT.TTME VTT

WATER

T-TNTGfAT. RRPnRT NO. 29

INTERNTAT.T.TAT.Al WATER ASPEGTS

December 1, 1972

Asia Projects Department

BANGLADESH - SECTOR STUDY

VOLUME VII - WiPZATER

TECIbICAL REPORT NO. 22 1'

INTERNATIONAL WATER ASPECTS

TABLE OF CONTENTS

Page No.

SUMMARY AND CONCLUSIONS ...... i

Is INTRtODUCTION ...... s.o...... oo...o.os ...... 1

II. THE GANGES SYSTEM ...... o...... 1

A.*Water Resources . 1 B. Rainfall ...o .o.s... .ooo oo ...... o. 2 C. Land Resources and Irrigated Areas. 3 D. Program of Development in Ganges Basin 3 E. Farakka Barrage ...... i...... F. Flood Control in the Ganges Basin 5 G. Water Storage ...... 5 H. Long-term Projections ...... 5

III. BRAHMAPUTRA BASIN IN INDIA ...... o ...... 6

Ao Water Resources ..... *..O...... 00..*...... 6

C. Land Resources and Irrigated Areas ...... -... 7 Do Pro-ram of Devreop ment+. 8 E. Long-term Projections ...... 8

IV. POSSIBLE EFFECTS OF INDIAN DEVELOPMENT ON BANGLADESH. 10

A. Ganges Basin o...... o ...... oo.oo.o. 10 'R qnl no Tnt.rX.q;n-n ; n Innaacq Tol+ s 12 C. Influence of Ganges Low FlovBon Navigation 12 . TInflionrce of nf ne - T.nw Flnws oRn Frq"r 1') E. Influence of Ganges Low Flows on Fisheries E F= Ghanges in Pat-teyrn of .S-il±. TLroi G. Ganges Water Quality 14 H. Brahmaputra Basin e-...... lh I. Diversions from Brahmaputra Westward *....-.... 15

J. Possible Effects of TndA !dLP A hn Bangaldesh Projects 16

REFERENCES . .o...... o ...... o ..o... o. 18

1L/ L11IZS reorLt;UL wasv: prpare buy IL. InL-reLy(Cnu+) -2-

TABLES

1. Ganges-radma River at Hardinge Bridge 2. Irrigable and Irrigated Areas in the Ganges Basin of India 3. Existing Irrigated Areas in Indian Ganges Basin by Category (1969) 4. On-Going Irrigation Projects in Ganges Basin of India (Ref. 5) 5. Brahmaputra-Jamuna at Bahadurabad CTfTMADIr ATT CONCLTUTTTQTfThN .3U .LrLUL.Itj A1i'd i VA./JEU..LV 3.J.LUId 3. i. Almost all the rivers and streams of Bangladesh have their headwaers the cout`y 4iththe exepio_--_ 4of- Mg1- 4hh 11 LLWC% outs-ideU UL'S u;UJ.16A QU 3-L U.L T.T-4VVYLUL ULI k .V3k9LUW±ULon.L J WJI ±'1CU LLL0L, L'L±e main rivers derive only a negligible proportion of their flow from run-off -wit,"n Baingladesh. Itu is int-rizAleCL-L: UIhat .MEJoI ProbleMIS arise 01 cor .eion with the development of the resources of these international rivers. ii. The potential uses of water in India affect the planning and design of water projects in Bangladesh. Thle extent anrd -importance of the effects depend more on policy than on technical feasibility since India will shortly have the means of diverting almost aii the dry-season flow of the Ganges. tWhat is less clear, however, is the need for India to do so and the timing and amounts oI the incremental demands for irrigation water in that country. Also there is doubt concerning the optimal method of operating the Fara

BANGLADESH - SECTOR STUDY

VOLUME VII - TWATER

TECHNICAL REPORT NO. 22

INTERNATIONAL WATER ASPECTS

I. INTRODUCTION

1.01 Almost all the rivers and streams of Bangladesh have their head- waters outside the country. Furthermore, with the exception of the Meghna River, the main rivers derive only a negligible proportion of their flow from run-off within Bangladesh. In these circumstances it is inevitable that major problems arise in connection with the development of the resources of these international rivers. Although immediate problems relate essentiallyto the Ganges, in the future other rivers will certainly be involved. This applies not only to major rivers but also to minor rivers and water courses.

1.02 This Report considers the international waters problem from two points of view:

(i) The influence that on-going and future developments in India may have on the discharge and behavior of the svstems in Bangladesh.

(ii) The extent to which Indian development might Dre_ludice future water and agricultural programs in Bangladesh.

II. THE GANGES SYSTEM

A. Water Resources

2.01 The Ganges at Hardinge Bridge drains a catchmpnt of about 380-000 square miles. The average discharge in the period 1934-1963 was 412,000 cusecs or about 300 million acre-feet per vear. The lowest recorded flow is 42,000 cusecs and the highest about 23 million cusecs. The average dry season flow is about 80,000 cusees.

2.02 Almost all the flow of the Ganges (about 90) derives frnm the Himalayas and more than half is contributed by three important middle reach tributaries, the Gogra, Gandak and Kosi. The largest southArn trinbutar, the SoneJcontributes only about 7% to the flow.

2.03 Table 1 gives the recorded flows in the Ganges at Hardinge Bridge for the neriod 193h-1963. latAr vsars are not. at. hani ht. i+. i- q r +.nA that the five-year mean 1964-1968 is less than for the last part of the tabulated neriod. An imustial feature of this discqharge da+a is +h.at +here is a defined increase over the thirty-year period. The increase appears consistent throughout hoth the lnw flow and high flow season.. T.h trend in records has been examined by Tschannerl (Ref. 1) and by the project consulta+nts for the GangesBarrage (Ref 2). Trheir f4- are, however,-gs still inconclusive and the matter calls for further attention as part of filrh^r +.1r+; .a nf .+h^ RZ -LA,_ R-^- nn An ^P .+h^ WMS ^nmnl ^Y - 2 -

2.04 It is clear from Table 1 that there are still vast unused water resources in the Ganges system albeit largely concentrated in the wet season period of July-October.

2.05 Much of the dry season flow at Hardinge Bridge is no doubt the product of regeneration from the river banks (effluent groundwater) including some return flow from the vast irrigation systems in Uttar Pradesh. The extent to which this is true should be evident in the chemical quality of the dry season water and data should be sought from Indian and Bangladesh hydrometric surveys. The amo t of regeneration is a matter which will, no doubt, be given prominence- in any international discussions relating to the influence of upstream developments on Ganges flows in Bangladesh.

2.06 The annual silt load of the Ganges at Hardinge Bridge is reported to vary from 1/4 to 3/4 million tons over the period 1958 to 1962 (IECO 1964). ECAFE quote an average figure of about 3 million tons a year. The Kosi and Gandak rivers together are said to contribute about 70% of the silt load compared with 30% of the discharge. The high silt content of these two tributaries detracts seriously from the value of reservoir storage projects.

2.07 Groundwater development is believed to have lagged seriously behind other irrigation developments in the Gangetic plains (perhaps even more so than on the Indus Plains) with consequent waterlogging. In Uttar Pradesh about 8,000 tubewells operate under a state tubewell program and withdraw about 2 million acre-feet a year but this is only a small part of the reharge. The groundwater resources of the Gangetic plains are immense.2/ Groundwater is sometimes seen in northern India as the cause of waterlogging and salinity rather than a valuable source of irrigation supply. Further data on the groundwater situation in the Gangetic plains should be sought.

B. Rainfall

2.08 The rainfall of the Ganges basin in India varies from about 60 inches near the delta to about 30 inches in the western parts of the Gangetic plains. The rainfall is highly concentrated in the period June to September but variations are wide both in time and space and reliability is often poor even in the wet season (Ref. 4). Except for certain areas such as the southern districts of Bihar state most parts of the Ganges basin in India require irrigation for intensive crop production. For dry season cropping irrigation is almost everywhere essential.

1/ The amount of regeneration between Farakk and Hardinge Bridge was a maioi point of dispute between India and Bangladesh in discussions of 1968. 2/ Dr. K. L. Rao stated in 1967 (Ref. 3) that "... India's groundwater resources are also of considerable magnitude. They are particularly prominent in the Tndo-rOangetic alluvial nlains of Puniab (now Harvana and Puniab). TJttar Pradesh, and Bihar. - 3 -

C. Land Resources and Irrigated Areas

2.09 The Indo-Gangetic plains are formed for the most part of fertile alluvial soils. The potentially irrigable areas and existing irrigable areas are believed to be approximately as shown in Table 2 (Ref. 5). The reservation must, however, be made that the figures are derived from publications that perhaps err on the optimistic side and the achievement at the present time might be less than the 29.5 million acres tabulated.

2.10 In India statistics of irrigated acreage are usually presented in two broad categories; (i) major and medium schemes and (ii) minor schemes. The first category includes all large systematic irrigation developments whereas the second category is largely composed of small river diversions, low-lift irrigattion by pumps and traditional devices and tubewells (excluding tubewell fields in major canal irrigated schemes). For India as a whole in 1969 the acreage irrigated by minor schemes about equalled that of major schemes with approximately 46 million acres grossl.in each category. In the Ganges Basin it is believed that the relative proportions are about the same. Table 3 gives the irrigated areas in the Ganges Basin by states. Some of the figrures in Table 3 have been derived from published statistics for 1969 and others have been estimated from information on other years. In the cases of the last four states in the table the figures have been deduced from a knowledge of the general distribution of irrigated lands inside and outside the Ganges Basin. No accurate figures are available.

2.11 There is very little information on the rate of expansion in irrigated land in the Ganges Basin as a whole but in the State of Uttar Pradesh one source (Ref. 5) indicates that major and medium schemes have expanded from 4.9 million acres to about 7.2 million acres (gross) or approximately by 45% over 20 years or a little over 2% per annum. This figure is smaller than the published rate of growth for gross acreage which was about 2.6% for the period 1949/ 6 2 (Ref. 5). Expressed in round figures it is therefore probable that about one-third of the total area given in Table 3, or 10 million acres have been added to the irrigated areas of the Ganges Basin of India over the last 20 years.

I). Program of Development in Ganges Basin

2.12 Table 4 lists the on-going major projects and medium projects over 50.000 acres in the Ganges Basin of India. Of the total of 13.66 million acres it is not known what proportion has already been developed. It is understood, however, that in most cases, the land development and hence effective irrigation lags seriously behind the main civil engineering works (dams, barrages and main canals). If priorities are therefore correctly assigned to the developient of the irrigation distribution system a large growth in irrigated areas will occur in the 1970's. Tt will be noted that about two-thircds of the total area of these on-going projects are on the lower tributaries - Clora. (Gandak.Fosi and Sone. Of these the first three are believed tc: contribute a large proportion of the dry season flows that

1/ Net irrigat;ed area is about 85% of gross area taking major, medium and m yor schemes +oge+her - 4 - still reach Hardinge Bridge. As developments'proceed in the basins of these northern tributaries there is likely to be continual pressure from the local people who will wish to make use of the valuable dry season flows. The scarcity value of water in the dry season will be raised by the poor opportunities to construct storage reservoirs. This situation may not only give rise to conflict of interest with Bangladesh but also with the proposed operation of the Farakka Barrage.

2.13 The rate of progress of the on-going and new projects over the next ten years is largely a matter of conjecture but it is not unreasonable to assume that it will be at least one-half million acres per year. If the capacity of the canal headworks is designed at about 7 cusecs/per 1,000 acres gross the total diversion capacity would thus grow at the rate of 3,500 cusecs per year or by 35,000 cusecs over the next ten years. Such a potential incremental diversion of flow is small compared with the mean monthly flows for July to'November (see Table 1) but is about 40O," of the mean drv season flow at Hardinze Bridge. Although it does not follow that such a large diversion would be feasible in the dry season, the opportunities for using dry season flows would clearly become potentially very large.

E. Farakka Barrage

2.14 This barrage is now scheduled to come into operation in 1972 but since no previous construction target has been achieved, it might well be 1973 or even later. The barrage itself is said to be substantially comnlete but the link canal to the Bhazirathi and the control works on that river lag behind schedule. The headworks to the Bhagirathi are designed to divert ahoiit )40;000 rcsens but the mode of onprating the sc.heme is not yet decided. At one stage, it was claimed that the barrage would merely be iiusp to augment the eJbb flowfwh of +:ha tide i n the approarh to Calcutt+a by the diversion of water through the Bhagirathi into the Hoogly estuary. In t.his wavj it. was cla'imedj the ehh flow would he augmented by about 10n above its present flow of 1[0,000 cusecs. The augmented ebb flow would thus approach +he flood tirdp flnow and hence balance the sediment. transport -in and nut of' the Hoogly. Now it is understood a more complex mode of operation is proposed wherebyr +.the tid1l waveru +.transient., wioul d be modrifipid in n manner that would reduce the amount of inward sediment transport.

2.15 Superimposed on the problem of Farakka operation for slit control purposes in the Hnooglyr it is understood that there is a difference of opinion on water use and discussions continue betwTeen the riparian states. Some Indian agencies feel that such a large diversion of Gag drys flow should not be allocated to the purpose of sedimentation control in the I1rT .Th ;7n. ,w 14 -AA4A A1,A Ak - AA sEe+ eS4 _- - 1,4-4 -__ 4-_- 4 4 A q _4A - 4l! l,4 WICJJ.4 I U .1 ,1 L-C' u L J V'V CL'S.14 US ULI13 LiX .1AL C 0-4. especially in the Gandak sub-Basin. IWhatever the outcome of the present

-d-;scussions it seerm., evident tnhat the baLrrag wWLa± lle o4peratd i4-44 a44 1 y on an exper-imental basis. In a case such as this where the incremental flow

-I/ £10 Ld4..-ULL idat4,-1 the canal I-±l4-lehedca -ILI Jr between 6 and 9 cusecs per thousand acres gross, in the middle of the Gainges bZsli. can accurately predict the response to a given method of operation and the optimum can only be determined at full scale.

2.16 The most iLnportant factor on which information is lacking at present concerns the manner of operating the barrage during periods of critically low flow. Although there is some dispute on the flows recorded at Hardinge Bridge, it is recognized that the dry season flow fell as low as 42,000 cusecs at the end of April 1953 and has been below 60,000 cusecs on nine occasions since 1934 (1935, 1936, 1937, 1939, 1941, 1942, 1947, 1953, °54j. Furthermore, these low flows last for prolonged periods. For example, the average flows for April and Nlay 1953 were 44,500 and 49,400 cusecs respectively and in the same two months both averaged under 54,000 cusecs for 1954. An Lnportant aspect of the Farakka scheme to Bangladesh is the proposed method of operation of the barrage during these critical periods. At one stage, it was hoped that in April and May the diversions for siltation control might be much less than -the capacity of 40,000 cusecs. Recent thinking, it is understood, now favors full discharge at this time of the year.

F. Flood Control in the Ganges Basin

2.17 Mlany hundreds of miles of flood embanlaaents have been built alongside the Kosi, Gandak and Gogra rivers. On the Kosi, the embanlments are 3 to 10 miles apart; on the Gandak they are sited about 200 to 300 yards from the banks of the river channel and on the Gogra they are generally about a mile from each bank. So long as such wide spacing of the embankaments is adopted it is unlikely that the river regime will be altered significantly - certainly not at the border. Although in the distant future there may be pressure to protect more land by adopting a closing spacing of the embankments, it is understood there is no indication of this happening. If anything, steps are being taken to make the wide spacing more acceptable to the local people by raising villages and roadways in the river areas on the riverside of the embankments.

G. Water Storage

2.18 It will be seen from Table 4 that the main storage works being constructed in the Ganges Basin are on the western tributaries of the Chambal, Betwa and Ramganga Chauca rivers. There are two reasons for this. First the need for storage is greater in this region of the basin where irrigation is more intensively developed. Second, the silt load of the rivers presents less of a problem than on the Gandak and Kosi rivers which,carry about 70' of the total Ganges silt load. No major reduction in the silt load can therefore be expected until storage reservoirs are built on the Gandak or Kosi rivers and the opportunities to do so are probably poor. - 6 -

H. Long-term Projections

2.19 If the potential extent of the irrigable areas of the Ganges Basin of India is correctly stated at about 50 million acres, as given in Table 2, it seems certain that there will be a need to develop it at some time. Furthermore, there will be a tendency towards intensification of cropping on the existing irrigated area of 29.5 million acres. The existing use of water on the presently irrigated land is not known. but is probably of the order of 2.0 acre-feet per acre. The ultimate development, with allowance for reuse of groundwater, might call for a diversion of about 4 acre-feet per acre. Thus,the potential increased annual abstractions would be approximately (50 x 4) - (30 x 2) = 140 million acre-feet (YiAF). It is clear however, that there would be serious constraints to meeting such a demand if only because there is a scarcity of good storage sites to make dry season flows available at the diversion works. To enter into judgment, it does not seem unreasonable to suppose that in the long term there is a real potential demand on Ganges water for irrigation of the order of 100 YAF above the present levels of abstraction.

2.20 Various schemes for the diversion of Brahmaputra and Tista water into the Ganges have been put forward but no details are available at the time of drafting this paper. It is understood that Indian engineers have suglgested a scheme to divert part of the flow of the Brahmaputra from a point near Guhatiln Assam westward into Bihar State (no doubt joining the Mahananda river).- On a lesser scale it should be a relatively simple matter to divert part of the Tista flow into the Mahananda but without storage on the Tista the value of such a scheme would be seriously limited by the poor dry season discharge. Clearly there are technical advantages in diverting some of the abundant flow of the Brahmaputra westward. Such diversions would permit, for example, greater use of Ganges water in the middle reaches of the Basin and at the same time would restore and improve opportunities for gravity irrigation in the south-west region of Bangladesh. Further discussion of these factors is given in Sections III and IV.

III. BRAHMAPUTRA BASIN IN INDIA

A. Wiater Resources

3.01 The Brahmaputra drains the following areas:

Square Miles

Tibet 113,000 TnrH P. 9Q' - Bangladesh 1,000

207,000

1/ This scheme was largely prompted-by the desire to have a navigation canal linking the Ganges and Brahmaputra rivers through Indian territory. 3.02 The average discharge for the period 1956-1963 was 676,000 cusecs equal to an anmual run-off of 488 MAF. The minimum discharge was 116,000 cusecs and the maximum 2,519,000 cusecs. A typical dry season dishcarge (January-April) is about 160,000 cusecs though it may frequently remain as low as 120,(00-130,000 cusecs for prolonged periods. Table 5 shows the average monthly discharges for the years 1956-1963. The sediment load is high in absolute terms. For the period 1957-1962 it averaged about 630 million tonls (Ref. 9).

B. Rainfall

3.03 The rainfall in the Brahmaputra Basin of India varies from as low as 43 inches on the Nowgong plains to 500 inches in the hills around Cherripunji. Over most of the plains it is however, around 80 inches a year and occurs mainly in the period April to September. In the dry season the rainfall is slight and inadequate for winter cropping.

C. Land Resources and Irrigated Areas

3.04 Of the total cultivable area of Assam amounting to 7.72 million acres it is stated that 1.5 million acres receive irrigation mainly on minor schemes. Medium schemes totalling 162,000 acres existed prior to 1950. In the Third Plan period (196-1965) four medium schemes were started and a further one in the period 1966-1969. The aim was to add a further 40.000 acres gross to the irrizated area by 1969 (Ref. 5). From these data it appears that the gross irrigated area of Assam is:

Thousand Acres

Medium Schemes 200 Minor Schemes 1300

Total 2.500

3.05 The Totentiaflv irrig-able land of Assam has been stated to amount to 4.15 million acres or 2.65 million acres more than is irrigable at present. Tn a paper in 1958 (Ref. 8) it was claimed that about 2.9 million acres of land could be irrigated from the tributaries of the Brahmaputra to permit doubhle cropping. The assumntions were crude. Tt pronosed to use the waters of the tributaries which were estimated to provide about 73,000 cusecs from flow. Of the 5.9 million acres which were sinple-cronned at that time about; half could be commanded and brought under irrigation and the 73;000 nsFiern nf water reAources woluld he s.nffinipent tn servre the area at an application rate of 60 acres per cusec. These figures appear to represent an up)per limit of irr-iatiAon develoTnm-entt in Aftsarm

n(6 rrTha ny%li on+.;onrnv-q+.n of An nt -rDnP-r miiqo; QHr'rc ? nh fory season irrigation since it is based on the gross area and not net irrigated area. There ,ou`lTd however, be considerable ret flowr and the net incre- - 8 -

mental abstraction is not likely to exceed about 50,000 cusecs plus perhaps 10,000 cusecs for intensification in the existing irrigated areas - 60,000 cusecs altogether. Allowing for variations in demand throughout the year this would probably be equal to a net annual withdrawal from the Brahmaputra system of about 25 MAF.

D. Program of Development

3.07 In view of the on-going irrigation schemes in Assam it is unlikely that the rate of expansion in the near future will exceed 20,000-30,000 acres a year.

3.08 Despite its reputation, the Brahmaputra does not appear to cause such extensive flood damage in India as many other rivers. The reported average annual damage in Assam for the period 1953-1968 (Ref. 5) was Rs 56 million which is less than half that reported for Bihar or 'West Bengal and about a third of the figure for Uttar Pradesh. In absolute terms the damage is nevertheless large and furthermore there is clearly great pressure to protect land from flooding owing to the dense population of this state. The outlay on flood control in Assam has been relatively high. Over the last 20 years it has amounted to about Rs 270 million, a figure exceeded only by the states of Punjab (Rs 290 million) and Bihar (Rs 440 million). By 1957, 574 miles of flood embankment had been constructed along the Brahmaputra and its tributaries and by 1970 the amount of embankment had been extended to about 480 miles on the main river and 1,400 miles on the tributaries. These figures mean that almost one-quarter of the main river reach in India is now protected by marginal embankments. There is no information available on the effects these measures have had on river stages and it is probably too early to form reliable conclusions from the few years of recording.

3.09 There are various on-going and proposed schemes for hydroelectric power development in Assam but none could have a significant effect on the river flows within the context of this paper.

E. Long-term Projections

3.10 As indicated in Sections C and D above, the potential for ir i-ation in Assam is limitRd bv the extent of siiitahlp land. TRirthir- more, demand for irrigation is less pressing than in most parts of the sub- -ontnArPn+. bec'iauisP the ra.infall ls apnprallir favrnrabh1e for wtP+. san e-re- production. However, in the long term it is conceivable that Assam may almost triple its present irrigated acreage of 1.5 mlllion acres but thjc might well take 30 to 50 years or more depending on the demand and implement.ation capacity. In te short term it is unlikely that th.e rate of growth in irrigation will have measurable effect on the flows in the main - 9 - river but uLtimately a net demand of some 60,000 cusecs in dry season flow might be abstracted in India and this at some periods would represent about half the presen-t dry season flow. The opportunities for water storage are said to be poor (within Indian territory) but some storage works could no doubt be provided to meet part of this demand. The high silt content of the rivers will reduce seriously the useful lives of storage reservoirs.

3.11 India is moving rapidly to a state of almost complete containment within marginal bounds of the Brahmaputra rivers and its main tributaries. No information :is available on the long term flood control program for Assam but this state might be achieved within the next 10-15 years.

3.12 As the demands for agricultural production increase in India and in Bangladesh, there may be a need to divert Brahmaputra waters to irrigate lands to the west of the Brahmaputra-Padma main stem and no doubt a case will be made to use such diversions to supplement the Ganges flow. Pro- blems attached to such a scheme are large but it is technically feasible. The fact remains that in this part of the sub-continent the main water resources are in the Brahmaputra basin whereas the predominant irrigation and other demands are on the Gangetic plains and in the western parts of the Ganges delta. The case for diversions westward may become just as pressing as it has in the reverse direction in the Punjab but the scope will be more limited. Owing to the topographic conditions it is unlikely that Brahmaputra waters can be diverted far enough westward to be of extensive benefit to Bihar and W6est Bengal. Indirectly however some water could be used to substitute for what would otherwise be Ganges abstractions to the Bhagirathi-Hoogly from Farakka (see Section 2.E) and to the southwest region of Bangladesh, thus permitting larger abstractions in the middle Ganges basin. The approximate timing of a maJor diversion of Brahmaputra flow cannot be estimated from present information as it depends on the extent of groundwater resources in the Basin and on the economics o1 its development.

3.13 Although storage potentialities are poor in the Brahmaputra basin of India there must be many sites on the tributaries suitable for such limited storage as might be required for hydroelectric power production and irrigation. These storages would be much too small to have anv influence on flood contro'L. On the main stem of the river, storage in Assam is believed to be infeAasble owinn to the large area of land that would be inundated, the a..ount of resettlement involved and the quantity of silt load. Unstream in Tibet there is said to be an excellent storage site. It might however prove to be too far upstream to act as an effective flood control reservoir. For any other purnpose. such a reservoir can only belong to a distant future program of development. - 10 -

IV. POSSIBLE EFFECTS OF INDIAN DEVELOPMENT ON BANGLADESH

A. Ganges Basin

4.01 Indian developments in the Ganges Basin will seriously reduce the amount of drv season flow entering Bangladesh. Quite apart from the matter of Farakka barrage, where from 1972 to 1973 it is proposed to divert up to h0,000 cusec down the Bhagirathi-Hoogly, there will be strong pressures within India to permit greater use of the dry season flows for irrigation. This pressure will come particularly from farmers in the new project areas in course of construction on the northern tributaries, notablv the Gandak. Gogra and Kosi. The proposed Farakka diversions alone represent a potential difficulty for the successful operatior and development of the Ganges Kobadak scheme if India is to abstract 40,000 cusecs regardless of the residual flow. In some years daring Anril and May this would leave only a negligible flow in the Ganges and even if sufficient to supply the G-K pumping units, there would be nrobiem of maintaining water denth at the nuimp intakes. Further expansion of irrigation from the Ganges in Bangladesh should, therefore, be linked wi t.h a resoliition of the (,anaes water disnuite. It has been suggested that major irrigation developments from the Ganges could be based on nine month. inste2d of year-round flow This wolild. however; seriously detract frorm project benefits.

4.02 As regards further demands on the dry season flow for irrigation in Tncia. there is clearly t.he notentiality to use almost all the dry season flow of the Ganges. This possibility could arise within the next few yrears= The uise of dryr season water in Tndia is, thereforej becor n a matter of policy rather than of technical feasibility. In the longer term, India might well wr.sh o expand irrigation to the extent that an additional 100 >iAF would be abstracted from the river and its tributaries. Taken toget__touthe - i-riwirth +.- +li,the,lI- propser%~ni-'.ccH EaaWn-,k' Hi-lzversions, crri +1-,this itT(iilrwouldH aclnenin+ frvro o bu 130 MAF a year or almost half the average run-off (300 MAF) and some two- thirds of the r---off in a poor year (200 M-œF). o)0 ShouldA abstracti-ons occur on +tl;s sca-le, th-1e reduct4on ln -,lows into Bangladesh would have a number of major consequences. First, there be dl st4-lnc li4-tation to the lrrlgation -woUld. a UJ3.U.O VUJ.14I .Jvseason_al C %~L± JI Va VJ~± v'J vUi deve-lopmentVV 'J.of' L in the southwest either by gravit y flow from the proposed Ganges barrage or by - jJ11pingfro. th1-e naural dlst-lbutaries. Scn t wo 'd be further encroachment inland of the margins of saline water intrusion. TLI-rd 'avigatlonwould le allected on 'le rGanes an' on Une rora-l. Fourth, 1iLL U, na±LUV.d U.LU -ULLL i U LA. UL u U lA l1 I_r_1 u± U Lr JJa± 2UUJU it is claimed that the forestry of the western part of Khulna District would ue adversely affected. Lir U±,h itU Ls a'Lso cUdair,eu u[IatU fisheries wou'ld suffer. Sixth, it is possible that certain methods of operation adopted by India for Ganges control works (barrages and dams) mig1tu chi1ange Uie sedJu[Lent discharge and regime of tne Ganges. These factors are discussed further below. - 11 -

4.04 The most extensive area suitable for large-scale gravity irrigation in Bangladesh lies in the lower part of the delta between the Gorai and the Padma rivers. Some additional areas could be incorporated along the west bank of the Gorai but further west topography becomes unfavorable and the soil conditions more valuable. There are plans to develop extensive irrigation in the southwest region incorporating the land area described above and also the existing Ganges-Kobadalc area. Command would be obtained from the proposed Ganges barrages and various estimates have been made of the service area and the water requirements. From a preliminary assessment of the land capability, it appears that the gross commandable area lying between the Padma and the Gorai is about 2~ million acres. This is essentially all paddy land. About 80% of it is covered by clay soil of low permeability and the rest with soils of moderate permeability.

4.05 At full development, an irrigation scheme in this area would have a water requirement of about 1 cusec per 60 acres of paddy. Assuming a net crop area of about 2 million acres, the maximum diversion capacity required wouLd therefore be about 33,000 cusecs for 100% cropping. If the surface area is extended to include land west of Gorai and part, if not the whole of the Ganges-Kobadak command, the total irrigation requirement would probably go up about 40,000 cusecs. There are further proposals to use Ganges waters in the northwest regions by pumping from the proposecl Ganges barrage pond. Some gravity command would also be possible. However, since these areas could alternatively be served by gravity from the Bra- hmaputra River they have not been taken into consideration.

4.o6 Another possible call on surface water resources in the southwest region is to provide fresh water supplies into the empoldered areas of the coastal regions. Excluding poldered areas that are in effect isolated islands, the total gross area is about 2 million acres. If it be assumed that about half this gross area could be served by fresh water canals deriving supplies from the Ganges and the water requirement is taken as one qusec per 100 acres, this would create a demand of about 10,000 cusecs measured at the polder boundaries, or, 12,000 cusecs measured at the Ganges headworks. If these rough figures can be substantiated by more detailed analysis such as would be undertaken as part of the Southwest Regional studv. the total surface water demand would be over 50,000 cusecs. This quantity is more than the lowest recorded monthly flow in the Ganges and over half the mean low-season flow. There is thus a genuine conflict of interest between India and Bangladesh concerning the use of the Ganges low-flow. EFven if a large margin of error is assumed in the above figures, the problem is still evident 4.07 It can be argued that Bangladesh need not extract water from the Ganges in order to com-an-d the sou-t4hwest region by- gravit y, but could adopt lift irrigation from the Brahmaputra. Before any judgment could be entered into on +thisalternaive, it calls for careful analysis from botn economic and technical points of view. The commandable area may prove to be limited owing to topographic conditions. T1e coUs o1 a barrage, tnougn large in absolute terms, is usually not more than about 20% of the total cost of the irrigation works it will serve. In such cases, gravity irrigation is likely to prove cheaper than lift irrigation. However, the Ganges barrage - 12 - project as so far conceived, would be a costly structure. There should be a careful review of its optimal height and a comparision with lift irrigation before a judgment can be passed. The alternative of groundwater development would also need to be considered although there are definite limitations known in this regard. The land east of the Gorai has a thick clay cover Vhich would form an aquiclude even if aquiferous strata exist at depth. In the southern part of the area (south of the 230 parallel), the ground water is likely to be poor owing to marine intrusions.

B. Saline Intrusion in Ganges Delta

4.0u The present saline zones of the coastal regions are oI two types. The perennial zones of the west of the Gorai River and the seasonal zone in the southern part of Bakerganj. Clearly, the depletion of the low flow of the Ganges would have no effect on the perennial zone because it is not influenced by variations in Ganges discharge at present. The smaUl movements that take place in its salinity margins are associated with local runoff and monsoon rainfall. In the eastern zone, reduction in flow in the Gorai distributary and its subsidiary distributaries will cause extended saline intrusion. in the land areas this should be largely controlled by polder schemes and the introduction of fresh water canalization and by the rainfall. In the estuaries and inlets the salt wedge will penetrate further inland.

1.09 The most vulnerable area to further salt intrusion is the main stem of the Padma and this does not seem to have received sufficient attention. A major reduction in the combined dry-season flow of the Ganges and Brahmaputra rivers could have an important effect on the position of the saline wedge in the estuary proper. The degree of penetration cannot be estimated except. from detailed hydrometric data and models, but will certainly be of sufficient magnitude to influence the design of future polder projects, and particularly the siting of their fresh water intakes.

4.10 Professor Thijsse, in a repors prepared in October 1964, produced a graphical indication of the movement of the saline wedges. This shows that a reduction of the combined low flow of the Ganges-Brahmaputra system, of about 100,000 cusecs, might result in the saline wedge penetrating the main stem a 2 yurther 15 miles, but this is no doubt only a rough indication. In a report-- dated December 1968, Leedshill de Leuw stated that "sufficient data are not presently available for definitive studies of the effects of upstream flow depletion on salinity incursion in the coastal embankment area." Clearly, this is a matter of considerable importance and must be taken into account in all future project planning in this region.

1/ Report on Hydrology of Bangladesh by J. Th. Thijsse, May-October 1964. 2/ Goastal Embanianent Project - Engineering and Economic Evaluation, Volume 1, Leedshill Leuw Engineers, Dacca, December 1968. - 13 -

C. Influence of Ganges Low Flow on Navigation

4.11 A reduction of the Ganges dry-season flow to about 40,000 cusecs from the average figure of about 80,000 cusecs (allowing for Farakka diversions alone) would reduce the water depth in the reach near Hardinge Bridge11 to perhaps 1 or 2 feet,depending on the configuration of the river channel.- The river would therefore, to all intents and purposes, cease to be navigable except in the lower reach where levels would continue to be controlled by the Brahlnaputra. Similarly, the Gorai distributary would cease to be navigable in its upper reaches, but this is in any case so during years cf low flow, or when large sand bars occur at the confluence. There has been very little navigation on the Ganges owing to the limited trade between Bangladesh and India. Even before partition, a more southern route was adopted for traffic into Calcutta from Assam. Potential losses in transportation should be revalued in the light of recent political developments and the likelihood of increased trade with India.

D. Influence of Ganges Low Flows on Forestry

4.12 The principal forest areas of the southwest are in Khulna district, and include the well-known Sundarbans. The forests may be divided into three broad categories: fresh water., moderately fresh water and salt water - in decreasing order of commercial value. It has been claimed that a reduction in the flow of the Ganges and its distributaries would result in salt intrusion into the valuable fresh water "sundril' forest. From present evidence, it seems that the salinity of these forest regions is little influenced by Ganges flow. The salt balance in the forests of Khulna district is more controlled by local run-off and direct precipitation. Despite these considerations, a depletion of Ganges dry-season flow may have some influence on commercial forests and further studies are required.

E. Influence of Ganges Flows on Fisheries

4.13 All major water-retaining structures built across a river are liable to affect fisheries in some ways. Barrages do not, however, form a major obstacle except in the low-flow season and hence the effects are usually small compared with those of a high storage dam. It is possible that the valuable Hilsa fisheries will be affected. The migratory habits of Hilsa may be altered either to the advantage or disadvantage of Bangladesh. A more significant potentially adverse influence is likely to occur in the Gorai River and its distributaries if depletion in the Ganges seriously reduces both the period and amount of low-flow. Again this is a matter upon which there is little information and one which will call for further study.

1/ An accu.rage stage discharge curve is nnt avail1 thl Htlm ohYc'f wrtting this paper. - '4IL -

F. Changes in Pattern of Silt Load

4.14 The operation of Farakka and other control structures now being built in India will change to some extent the pattern of silt discharge in Bangladesh. Sediment will be retained in the Farakka barrage pond and will be flushed out during the onset of the monsoon floods, thus increasing the silt load during this period. These changes in the pattern of silt discharge shouid not, however, be detrimental to Bangladesh. Temporary adverse conditions might arise if early spates of short duration pass througn the silted pond at the end of the dry season. Such an occurrence might aggravate the difficulties already encotntered in maintaining the intake channel to Ganges-Kobadak pumping station. There is a case to study this subject in cooperation with Indian authorities.

G. Ganges W4ater Quality

4.15 As irrigation develops in the Ganges Basin, problems will arise in water quality in the dry-season flow of the lower reaches. NIot only will the return flow from the irrigation system contain toxic salts and chemicals, but also there will be a need to dispose of saline ground water effluent into the river as part of the sub-surface drainage of saline zones upstream. The situation is unlikely to become serious in the early future (the next 10 years) but must be taken into account in planning. One of the advantages of diversion from the Brahmaputra, is that it would overcome this problem at least in Bangladesh.

H. Brahmaputra Basin

4.16 The effects of Indian developments on the Brahmaputra flows are less immediate and of small consequence than on the Ganges. They are, nevertheless, important to the long-term planning of developments in Bangladesh for the period beyond about 1985. It is anticipated that the emphasis on Brahmaputra development in Assam will remain on flood control for some years to come. India must be rapidly approaching the stage when the Brahmaputra and its main tributaries are fully contained within marginal embankments. This will have the effect of raising slightly the peak discharges and hence also river flood levels in Bangladesh, but these changes are unlikely to be large. It is not possible to estimate the influence on river stages without detailed Imowledge of the river hydraulics and the proposed system of flood control is India. Hydrological data should be sought from the Indian authorities, including records of river stages before and after embankment construction. Such data should not only be of assistance in assessing the effects of double marpinal embankments in Bangladesh but also in calculating the combined effects of the Indian and Bangladesh works. There should be benefits from mutual exchange on this matter.

4.17 The Indian flood control program will probably increase slightly the amount of sediment transnort reaahing Bangladesh but again, the effects will be small and almost certainly unmeasurable in hydrometric terms. Trrilg ation development in Assam will continue and the abstraction for irrigation in the long term may build up to about 60,000 cusecs above the nrA.Ant lair1 -_ Tf all this water is taken from the rivers without the provision of storage it would represent a major reduction of the dry season - 15 - flow. Although there is no immediate problem, because the rate of development of irrigation in Assam will be slow, this is clearly a factor that must be taken into account. Navigation on the Brahmaputra is of greater commercial importance on the Ganges. Future developments might affect it adversely to a very small extent in that the low flow will be depleted, but at the same time flood control measures will give rise to a degree of channel improvement. In any case, navigation on the Brahma- putra is unlikely to be affected at all in the short or medium term, (before about 1990). Any depletion of Brahmaputra flows in the dry season will further accentuate the problem of saline intrusion in the delta area discussed in connection with the Ganges.

I. Diversions from Brahmaputra Westward

4.18 Diversions from the Brahrmaputra to the Ganges can be made either entirely through Bangladesh territory from the proposed Brahmaputra barrage site to Hardinge Bridge entirely through Indian territory from the Tista river into the Mahananda basin or through both territories from a point near Gauhati in Assam into the Tista sub-basin and then into Bihar State and southwards to the Ganges. The second scheme was put forward as much for navigation as for water transfer purposes. The third alternative might provide the more loeical and economic solution for both countries. The merits of diversion west and their timing call for carefuL examination as can be illustrated by the followine recorded river flows:

DRY SEASON FLOWS 1959-60

Thousand Cusecs

1959-1960 Nov. j Dec. Jan. Feb. MIlar. Apr. m|ay Jun.

Brahmaputra 402 215 154 120 I 133 162 282 I 963 Ganlges 309 |192 1358 103 | 87 78 68| 133

Total 711 410 292 22 1 220 260 350 1,096 - 16 -

I.1'i ,11..,-,,.,,,s f1i-P4 ,l-. .,-n sese'I W------+ sequer.c in t.h.e per'iod- 1 and clearly more severe conditions occur from time to time. The critical period of Gar--.ges- flow-P1 extr.dsA fPr-o TJ..ii^, To ne inclusiveir whaieran +t.ho lo% flow period of the Brahmaputra is shorter, the rise occurring about a month ear .1_A_ & u"- t hAA A4 + k4 the dhA --.AAeO'io.Ien d-a4h ;dn, n theoC-*ah bc;n will exceed the available flow it appears that some 20,000 to 40,000 cusecs migh+ be transferred from the B-ahiLaputra with.mout cre.ating undue roblem- in that river.L/ In the long term it is unlikely that a greater transfer will be advantageous at least in t periodT-h January to April- If, for example, the demands in Assam built up to 60,000 cusecs and some further major diversions are req1i red for use in B_ngladesh_ fhere i.wolc hp. llttle residual flow available for transfer into the Ganges--even disregarding the problems of navrignation. TIn lat Mav andi Tiinp_ and pr%-hapn mlsot in nl-mhe,' however, there are ample opportunities to pondei substantial transfers.

L,.20 The potential use of Brahmaputra water for irrigation in Bang- laudesh carLrz'o yetu be quaalfled-L-,. Itt had be-Ien ilndicat~ed -that U1t_e u-L-ltate demand for irrigation in he Southwest Region might be 50,000 cusecs. Part Udrawn fromII tUhie Gages or lilhe Miheg;nid.a wouLulId VK toUU beUSpple.LLJLU tUif Brahmaputra either diverted through the Ganges or from th6 river reacl -b elJow IV.he confluence. F'or the Nlo-rth4.est Region, and possib-lly al,'so for t- Northwest Region, there will be a further oemand on Brahmaputra fl -w_/. The total-ross AemanA from the Brahmatra ;-slde B ngladesh - 4y -. . I±-. la IjjC). , 5,.. -)4ALI0II4- . 41- 1 V -1 CfIIlfU 4. .Lt4.t4- -.. more than reach 80,00 cusecs. Such a demand, when taken together with a possible demand of 60,000 cusecs in Assam, would at times be greater than the dry-season flows quoted above (para 3.01). These figures are, however, cniPde and relate to a veryv adiranced state of develonment. tfhat will not. come about before the year 2000. The actual diversion requirements would not be as great as the gross requirements at cn2l heads because of recirculation and recharge (see T.R. 2(), nevertheless, the figures illustrate that. in the 1onng term a nonfient. conild evpn arise on the use of the Brahmnaputra River despite its abundant flow.

Possible ~ffects of' fliian DQ-veloprentstu,on Bangladesh Prgojects

4 421 ih.e possible effects of future Indian devrelopm,ents on Bangladesh projects are summarized below:

(a) With reduction in river flows in the dry season the saline tr4 11 r.ove ,l ',r+,.n ,,,, t a ua-y wid mgight cause the intakes to Chandpur,I' and other of the proposed lower polder projects, to becomeL saline for part of the year. It is recommended that studies be undertaken to estimate With bett,er confidence the probable extent of- itrusio4 of the saline wedge for varying degrees of depletion of river

affected are Barisal and Comilla-Noakhali.

1/ Assuming that water transfers are cheapter than the marginal cost of storage of flood water on the Ganges. 2/ See Technical Report No. 20 and Appendix 'A' to Technical Report jo. 20. 3/ This does not imply doubt concerning the present location of the Chandpur intake. The useful life of the structure is almost certainly adequate even if the need for eventual resiting or modification occurs. - 17 -

(b) Coastal embankment projects are likely to be affected in two ways. Firstlv, reductions in the drv-season flow (or extension of the periods of flow) will add to the difficulties of water management within the polders. Fresh water supplies will become scarce and the remaining water will tend tn become saline. This will annlv essentiallv on the lower part of the Southwest Region east of the Pursur Ri ver.

(c-) Thf Gnges Kobadnk sche-me is likely to miffer setavere problems as a result of Indian developments on the Ganges and troubles will ri; aqnnnsq aq Farqkka harrage comp-q i ntzo nnprnti onn Even at the present time the flow to the pump intakes is qeli j-l iynnimpeded hy siltato and the s*-i+ua+-ion will clearly become worse with lower levels in the Ganges. Until some agreement is reached betWeen -angladesh and n-ndia, aV-nnsien of the Ganges Kobadak scheme, from the present 5O,OOO irri- -,n+ate -nroeS +tonr.ads its pnotn+-a --P nwAn Offl 00 n--a rnEaAmA - Qa~ .A~ tflJAcw^+a**.kJX AJVt.J1 '.rJ'nr ' o7a¼ should be approached with caution.

(d) In regard to the regional and other special studies there is Ca r.LeedA to t-aKe account-- of1th0 poe+-ia dvlp,,2e-s discussed in this paper over a whole range of items. In particular suudi4es o-f 4the u->.h-st ar.d North.west .- 4gions should include an examination of the potential water uses a.Ld compare +hese0Wi511. U IJ.t_ al a unme. rarious assumed rates of development in the upstream areas.

±LLII: DI'LdIUrW1O a"g.LuU W".LL c%LIJ U a±±Ltucw IJUT, iA a .Le:55r degree than those lying within the Ganges basin of Bangla- d,-.iL1 - 1

1 . 4l T -4n U- 4T It A TT_:r-4 , A 4',: 44,,, .XL Li Was.OL U4"L VUAoh. u J * ,, os1O Y 'a .i. , Efficient Use of Water Sources" 19....?

2. Associated Consulting Engineers "Ganges Barrage Project, Volume I" 1.L7%,7 Otc,, -

3. Dr%.DrLJ0iv0 W. T.LJei~~ PDoAM 11T3.-4-.g.LILLL .1A(L%Aa--A Developmenr.t1J~ V V ALV±J1 V ofPLA ITaterVV- hVJ. LV'U4EOReouce L.AA- India" Published by Government of India, Ministry of Irrigation and T b-. n/, ruw:V.u, .I..71)v .

4-4. r.P. S. ~eel.teeH>sr 6 OU----uu .U,y ofO Dst-LVL U b±± -ctwdse W vzstlbuQionUJ. tJJ±±4LLtUL ofL Ra_""LLLL.LJ=uali ±11 Bihar". Journal of Hydrology, April 1971.

5. "INDIA -- Irrigation and Power Projects (Five-year Plans)"., Government of India, Ministry of Irrigati-on and Power, Central water and Power Comaission, April 1970.

6. "Development of Irrigation in India". Published by Central Board of Irrigation and Power, 1965.

7. "tIrrigation and Power in thle Three Planls , 1951-66. D-v Re_ _-V ,__o_,od_ t -a.... __i __m_.__ _ ,n._ 8. Sundavan anu Kesnaviarl Hnuw Assam Can Reliev Food hortage in India." Journal of the Institution of Engineers (India), Jan. 1968.

9. "Master Plan -- Supplement A Clirmate and Hydrology- -- Bangladesh Water and Power Autnority -- by IECO,1964. TABLE 1

BANGLADESH - SECTOR STUDY

GANGES-PADMA RIVER AT HARDINGE BRIDGE

Annual Average Discharge Thousand Cusecs

1934 - 416 1949 - 426 1935 - 338 1950 - 413 1936 - 418 1951 - 304 1937 - 351 1952 - 403 1938 - 424 1953 - 398 1939 - 302 1954 - 336 1940 - 287 1955 - 575 1941 - 276 1956 - 570 1942 - 384 1957 - 389 1943 - 367 1958 - 417 1944 - 331 1959 - 451 1945 - 377 1960 - 438 1946 - 362 1961 - 578 1947 - 397 1962 - 488 1948 - 534 1963 - 489

Average 1934/48 371 Average 1949/63 - 445

Average Annual Discharge 1934/63 - 412

Mean Monthly Flows 1934/63 Thousand Cusecs

January - 110 July - 639 February - 97 August - 1,390 March - 83 September - 1,290 April - 72 October - 626 May - 75 November - 254 June - 154 Deeember - 118

Data abstracted from Reference 9. TABLE 2

BANGLADESH - SECTOR STUDY

IRRIGABLE AND IRRIGATED AREAS IN THE

GANGES BASIN OF INDIA

(Million Acres)

S ra W.EJL"CL.L.L'y I-r arPot,eun'9 Irrigable Area

Uttar Pradesh 36.0 17.2

Bihar 15.0 7.1 Haryana 4.5 3.1

Madhya Pradesh 3.5 0.8

Rajasthan 0.6 1.1

"Jest Bengal 0.2 0.2

Total 49.8 29.5

l/ Stated in Indian documents to be the "potential,l irrigated area which relates to the area served by canals and water. It is claimed for U. P. that over 95% of this is actually irrigated. TABLE 3

BANGLADESH - SECTOR STUDY

EXISTING IRRIGATED AREAS IN INDIAN GANGES BASIN

BY CATEGORY (1969)

Potential Irrigated 11w'on Acres

Major and Medim -w~~~~~~~~~~' uSshes.X PLUIVI,Os-t.;11tm12 IVL9 -.L

IJUn.l L.L+UI 7. *d It.1 17.:'

LJV%FA .L Q%%=O .U (e.L- B r ~~~~~~~~~4. 2.67.:l

R4adh-aa a.4 0.7 3

IJ.O~~~~~~V2 .11.0

Rajasthan 0.6 0.5 1

West Bengal 0.2

*1M.4 i . -Y

TABLE 4 BANGLADESH - SECTOR STUDY rage

ON-GOING IRRIGATION PROJECTS

IN GANGES BASIN OF INDIA (Ref. 5)

Name of Scheme River Storage Capacity | Potential |Construction- of Reservoir Irrigated Area Period MAF (live) '000 Acres

UTTAR PRADESH

Major Projects | Matatila | Betwa 0.63 I 410 I (including 112,000 acres in Madhya Pradesh) I 1952,/66 Sarda Sagar Chauka 0.34 185 I 1957,62 Ramganga ( Ramganga 1.60 1,645 1961/74 Western Gandak jGandak j Nil I 659 I 1961/74 Lower Sarda I I I I (improvement Groga Nil 1,500 | 1968/80

Larger "Medium" Projects (over 50,000 Acres)

Daimau PumDped i I Canal - Staage 1 154

Bhopauli k'umzpec II Canal I I I 60 Zamania Puped | I I Canal C I 1 6u

Tons~PudCr ~ i ET_I__~ E __. ~_ TL_J~ I~ ~ ~ ~ ~ ~ ~~~~_)1 130 I'Mrain-pur rumpeu Canalf - -- .1 - _.L I e^ %appiravved PrOL-J ecb 60

I I I 4,862 BIHAR Major Projects I I I Badua j Badua | 0.89 105 1958/66 Sone Barrage (including

ht leeI^n~ oh.. ~ I I Sone Nil 734 1966/01'4

124 TABLE 4

Name of Scheme River Storage Capacity Potential Construction of Reservoir | Irrigated Area Period

Geridak Gandak A1Vf'I 1- I 2':

Chandan | ~~Chandan |0.11 | 174j | 1961/74 Larger nMedi.umf Projects (over 50,000 Acres) ` Ac

I I oINR600 I

MADHYA PRADESHIII Major Pro,jects | I I Chandi-Sagar | Chanbal 5.61 I 50 195I/? | (via Kotahr I (Dam completed

Barna | Barna n 0.33 179 1960/74

Medium Projects (over 50,000 Acres) j

NONE |

RMJASTHANP R A E

Major Projects Kotah Barrage | Chambal I Nil |I0 I I~~~~~~~~~~~~~~~(Miadhya Pradesh) | I ~ ~~~~ J (RaJasthan) I Rana Pratap Sagar Chambal 1.27 150 (dya Pradeslh) I (Rajasthan) Medium Projects (over 50,000 Acres) I I NONEII

_0 .1 I Total of on-going major and larrI s I

1/ The stated "construction period" appears to relate to the main CiVil engmeermng wors onlyr. The development of irrigable area is believed to be still on-going in all cases listed in this table. TABLE 5

BANGLADESH - SECTOR STUDY

BRAHMAPUTRA-JAMUNA

AT BAHADURABAD

Mean Discharge 1956-1963 Thousand Cusecs

Ja Feb. Mar. April May June|_ July| Aug. Sept. Oct. | Nor. c.

4 0 101 115 161 243 590 I 13 1 1,4 J 1,5495 1,23t 773 30'_ 2L35

Mean Annual Flow - 676

REnIc;4-

INTERNATIONAL BANK FOR RECONSTRUCTION AND DEVELOPMENT

INTERNATIONAL DEVELOPMENT ASSOCIATION

BANGLADESH

LAND AND WATER RESOUVRCES SECTOR S1TUDY

VOLUE VII

WATER

TECHNICAL REPORT NO. 23

RAINFALL ANALYSIS

December 1, 1972

Asia Projects Department

BANGLADESH - SECTOR STUDY

VOLUME VII - WATER

TECHNICAL REPORT NO. 23

RAINFALL ANALYSIS

TABLE OF CONTENTS

Page No.

SUMKARY ANI) CONCLUSIONS ...... i

I. INTRODUCTION ...... 1

II* FLOO])S ...... 2

III.o UwTv@@@X**vv@v*oe@@@*@@ 2

IV. ESTIMATES OF RAINFALL PROBABILITIES ...... 3

V. RAINFALL DURATION FREQUENCY ...... 9

VI. DROUGHT DURATION FREQUENCY ...... 9

VII. ILLU'STRATION OF THE ANALYSIS ...... 10

Rlajshahi Area ...... -...... 10 IRaneDur Area & a...... 12 Ciomilla Area # & a 0 a aa * 13

LIST OF APPENDICES

1. Methods of Estimation of Rainfall Probabilities - Stations List and Location - Data Correcetions 2. Monthly Rainfall Amounts and Probabilities by Stations (Alphabetical order) Mean Monthly Rainfall Variation of Monthlv Rainfall Probabilities of Rainfall Reaching or Exceeding Specified Amounts in Anv Month 3. Weekly Rainfall Amounts and Probabilities by Stations (Alphabetical order) Probabilities of Rainfall Reaching or Exceeding Specified Amomnts in Anv rnn.-,r1,vP 2-wp1e Peined Amounts of Rainfall Expected to "'e Reached or Exceeded in Anv 9-vAAe RimningPAPe-inoi Profile of Probabilities of Exceeding Specified Rainfall Amnousnts in Any Wieek (n.5 inches, I. inices, 2.5 inches) 4. Drought Duration Frequency and Rainfall Duration Curves

1/ This report was prepared by B. Oury from records provided by IIACO International Land Development Consultants N.V.; probability analysis contributed by the National Climatic Centers U.S. Department of Commerce; and frequency-duration analysis contributed by ACRES International(Over- seas) Limited in association with H.G. ACRES Limited and Booz, Allen and Hamilton International, Inc.

BANGLADESH - SECTOR STUDY

VOLUME VII - WATER

TECHNICAL REPORT NO. 23

RAINFALL ANALYSIS

SuISIARY AND COUlCULuSIONS i. Rainfall varies widely not only seasonally but from one region to another. Seasonally about 8'0 of the rainfall occurs in the five-month period of the monsoon (May-September). The rest of the year is climatically unsuitable for crop production througnout most of the country. From a regional standpoint, most of the land west of the Brahmaputra main stem has a rainfall that is only marginally adequate for reliable wet season rice cultivation. On the other side the rainfall increases rapidly towards the east and excess water rather west of the main stem of the Brahmaputra have a mean rainfall between 50 and 70 inches. In the southern part of the delta and almost throughout the eastern part of tne country, the mean annual rainfall is generally in excess of 80 inches and the extreme northeast is between 100 and 200 inches. These variations in rainfall have great importance in the assessment of agricultural potential not only in terms of direct contribution to crop growth but also in relation to potential groundwater recharge and to flooding. li. For agricultural production, consideration of the probable cw rainfal' isamoer mportant thL.an +hei meYna rpvSlehisj 'nprt.i- cularly so in Bangladesh where deviations from the mean are wide. In efiect, although the average r%Luu.LLs utadquate tv cr-0p Water requirements in the monsoon, deficiencies occur in some months almost every year ±-U m.ostL areas except he ve hg 6 ( zones. iii. For this reason, probability analyses have been prepared to determine 4the-- -Ae'e va- e of rainfall for wreekly sim",3wons as well as mo.hly totals using rainfall data collected over 36 years in nine different locations throughout Bangladesh. Thee results, discussed in this Technical Repor-t, pr- vide a more accurate picture of climatic hazards to agricultural production than has hithertw been available. Against ULts backgromund, far More realistic assessment of irrigation, drainage, and planting dates can be obtained than with average rainall statistics. iv. Results of the rainfall analysis for Bangladesh have been assembled in one volume only for monthly rainfall under our voluime for monthly precipitation probabilities and four volumes for weekly precipitation probabilties. One set of these volumes is deposited with the World BRnk nnrd annoher set will be deposited with the relevant Government Agency in Dacca. - ii -

v. For each station, tables show the mean monthly rainfall; corresponding minimum and maximum, lower and upper quartiles and the median of the monthly rainfall. They also give the probabilities of rainfall reaching or exceeding specified amounts in any month. The analysis of weekly rainfall gives the probabilities of rainfall reaching or exceeding sDecified amounts in anv consecutive two-week period. It also gives the amounts of rainfall expected to occur in any two-week running period during the crop season in nine years out of ten (90% probability), four years out of five (80% probability), three years out of four (75% probability), two years out of three (or about 65d probability), and one year out of two (50% probability). The profile of probabilities of reaching or of exceeding snecified rainfall levels. namely 0.5 inches, 1.5 inches and 2.5 inches in any week is also shown on graphs for the nine stations. vi= (iven field cron water reqiirements (i.- consumntive use. percolation and actual field losses), rainfall probability estimates can he ised for estPimating the probability of thieir being met e,ither partiallv or in full, or of being exceeded by natural rainfall. The rainfall analvsi s also prov-ides nuantitative evaluations of rainfall duration frequency as well as drought duration frequency. Obviously, rainfall fiefi c-i e.ne-ies reannotn be e'onsidered alone be 1cuse the specific impact of rainfall inadequacy in any given area is closely linked to the filtration capacity of the soils. This i illustrated hy the illustrat-.iue analvses given for Rajshahi, Rangpur and Comilla in Section VII. AiANGLADESH - SECTOR STUDY

VOLUME VII - WATER

TECHNICAL REPORT NO. 23

RAINFALL ANALYSIS

I. INTRODUCTION 1. The primary climatic problems of Bangladesh are flood and drought.

Po o- %.ALdrA C.. M.LL1 furlerLJ. cor.tr11iDut.,es toJ..I thU ins"^biJJiLieL.aL Iy of cro..p oupLut. R nli fall varies widely not only from season to season but from one region to

anothe (see ,A*alyticaMLU apI ).L. Seasona.L'Ly, abUUUt VUb oLf th rai.nLfLLaL'L occurs in the five-month period of the monsoon (May-September). The dry season Ls thu;, 'y -LwsLu±tule fUr crpUu JJVUUULc iLLOX WiLthUUt irrigatJ.on throughout most of the country. Frorn the regional standpoint, most of the L.C4J. rl;%QJVWA LIV UL C%.1JGIakJLA.UaG 11LCGL.110UtSISJ k11nL1&JU1-, DUglae,A JeLAJ;OLICLA-LIJ lt ZS:AD rainfall that is only marginally adequate for reliable wet season rice

cI'tiva J.V ion I spe.Liy fo.Lr dUs. in th1e eas L.LL.L IIaLf Dof lc- ULth rainfall increases rapidly towards (Sylhet) and water supply is no longer a lim'iting factor to attaininLg full prod-uction. The greater part of the regions, west of the malin stem of the Brahmaputra, have a mean rain- P ,- 48Arn 4-- 7 n 1 1 -_ 41- -A. -_.___s1_ .|2fi1_-__ - _ u ___u_q____1 J-C".L _Ll LU U ±vv±UIul. lA1 UISUti UUldieIli pdUlL. V.1l Udle US..L1id WIK aimos throughout the eastern part of the country the mean annual rainfall is generall-' in -acess of 80 inches and the extree rnortheast is bet-weell 100 and 200 inches. II. FLOODS 2. Large areas, as much as a third, of Bangladesh are subject to flood annuallv when the malor rivers are in spate, by overbank spilling or the rough innumerable spill channels. However, in some years, there are abnormal floods, which do a great deal of dama8e either because of their speed, timing or extent. If there is an early flood, it can ruin young rice and iute plants in the fields or destroy seebreds= If there is a long flood just after the aman has flowered, there is often a sharp fall in vie.ld. These floods rise and fall fairly quicklv. but if they last over four days a great deal of rice plants are destroyed. Moreover, floods or unusual he:Lht drown short-stemmed rice ,nlants on intermediate and relatively high lands. The loss from flooding of these types runs into huLndreds of million rirnees. The water that. nauses the floods laroelv originates from outside the country. Therefore, its occurence cannot be foretold from Bangladesh rainfall data alone. Flooding is aceentuated when a heavy storm coincides with a rise in the water level of the rivers in anv nf -_V rnarti_milar ------arep. Flood inundation_--_------_--_--______causes also serinus dislonation communications by washing away roads. Damage to houses, loss of human life and c-att.le are qnite com-monn dnring floodns Flood al so aftfeets rniral health1 adversely and various diseases become prevalent. Planning efficient drainaLge .s-stems fnr remnwval of* Inta aclnmf ated rnof' gneratei hy rainfall and gradual improrements in flood protection would provide relief from these prnbl ems.

I.J.J.* LU1JUU.LLJ

3. In spite of the overall abundance of rainfall in Bangladesh, severe d-Urought p%Y-er4od doi occuvr, ciaus4ng C=" s rblJnwT9.rops tha+v are the most liable to suffer are broadcast aus, either grown alone or, in 'I we"1r- ngareas, nixed with broadcst anan- and 4lute. They are sown in February-March and have to depend entirely on the meager rainfall, that occurs during this period, for their germination and initial growth. The distribution of rainfall is also very erratic and damages occur during the initial stage of the crop life. IRRI aman (IR-20) grown on lands that never flood to any significant depth, even in the wet season, frequently suiffers from water shortage at the time of flowering from the 15th through 20th of October, and traditional aman about two weeks later. There are instances of inadequate rainfall and periodic droughts in any given limited time span, even during the monsoon months of May, June, July, August and growing worse in September, October and November. The minimum rainfall during the months of November through April is 'nil'. During the dry season most of the land remains uncultivated because of the absence of rainfall.

4. These variations in rainfall have great importance in the assessment of agricultural potentialities not only in respect of direct contribution to crop growt,h but also in relation to potential groundwater recharge and to flooding X An important component of the agricultural development strateor being formulated is the promotion of' high-yielding IRRI rice cultivation as extensivelv and as rapidly as possible. Irrigation will be expanded as rapidly as possible to enable a crop to be grown in the dry season and to make monsoon season crops more secure. However. even after 10 years of development, it is unlikely that more than 20% of the land considered suitable for high-yielding rice cultivation will be irrigated. The remaining land (well over ten million acres) will be dependent on natural raintfall and flooding. Therefore, rice production from this land will continue to dominate the foocgrain supply of Bangladesh within the foreseeable future. 5. The Soil Survey Project of Bangladesh has identified areas where it considers that IRRI rice varieties can be grown in the monsoon season without irrigation, and other areas where it considers that supplementary irrigation will be desirable for their nroduction. In view of the continuing imnortance of rainfed production and the critical situation regarding food supply in relation to ponulation growth in Bangladesh (4gnoring the effeets of the present disturbed conditions), it is important to know the influence on yields of rainfall deficienov as well as of excess rainftall occuring at nartieular times of the crop year. This will allow a risk factor to be introduced in predicting' futture production from rainfed areas. it will also allow an assessment of irrigation and drainage requirements.

6. For example, the IRRI varieties being considered for cultivation a-re: TR q9-1-176 and TR 272 for broadnast culltivation dulr4rin the nerriod March-April to June-August; and IR 20 for transplanted cultivation during -the perio-d July-NNovember, either alone or follow4Lng an earlier broadcast crop. Allowances for "average" rainfall deficiencies were made in the yield pro4ections usea for the Study Detaile rait'nall analyses hb.ould help to determine more precisely the duration of the rainy season: in particular, tLhe point 4n time after which probabili+y of adequate raThn is acceptable for planting aus; and the point of time after which the probability of adequate 4 v.=-.v 40a r,-1r.4Pvn on.nv Al or. +kn O+ eO+p~4P Av,.-.4^-4n A.- '-M^na -n4,lAo r ain. is too %low forW. 5.M5n* 0.Also the eslt4.ate ~sJ5 oreuti .. %V.5Sor.* .* rice4n5t y4elsJ, in terms of absolute quantities (or proportions) in the event that rainfall probability data during critical growth periods would be useful in formulating 4nputs -requirem-L,ats and assessnng i -4.fro.e- risnk. v ., 4. .e.-a C-

J For further discussion see T.R. 20 and 21. - 3 -

7. Rainfall deficiencies cannot be considered alone because the shortf-al i4s clIosel- linked wit th-,-11,e 4nfilt4-ratl4on rat4es and4 wat er holding I...-.- L _ L.Y LJI~.Z. U ±I UII Ulii J I _Li_iL . U..-L L u u ~ IIUWO±AJ.U.Lllr, capacity of the soils. For example, the large Barind tract of some 1.5

MIL-LL.±.LLVII d.U._ kiLLI UIM LIV..F ULIWUO~U IVr, IVi/LA~ '_L~JJO QjL.LO WJ. LL LLrI.± LI a.vai JD. soil moisture capacity and hence droughts are less damaging here than in

the riduge s0oi's. withUL 9r,".KI 'ler clay oontentLI foundIL cxtensi_vel.y elsewerLiin L this region and west of the Gorai River in the southwest region.

8. Rabi drought and kharif flood pose continuous threats to crop production in Bangladesh. Hlgh moisture stress during the m,,onsoon is shown by the low ratios of actual evapotranspiration to potential evapo-

transpiration.*UIneven precipitation, UogethL'.er wi Ull Uthe 'Low prep'Lanting4LL1, soil moisture storage, is responsible for spring drought.

IV. ESTIMATES OF RAINFALL PROBABILITIES

9. Probability analyses have been completed to determine expected amounts of rainfall for weekly, bi-weekly and t-n-weekly sunmnat i 1, as w-el as for monthly totals, using daily rainfall data for 36 years' records (1934-

±9b9J'v)- ' lor nine diiferentJ 'locailons, namely: Barisal, Bogra, unchtago-ng,fl t o__1A_1_____L__Sr ___ __n11@___ Comilla, Dacca, Khulna, Mymensingh, Rangpur, Rajshahi. It is believed that the geographic coverage is adequate to provide an estimate oI thne ciimatic hazards to the agricultural potential of Bangladesh. From this analysis one can read out the probability occurrence of too little rainfall (drought), too much rainfall (possible flood), and of the right amount of precipitation for crop growth in any week, 2-week, and 3-week running periods as weli as in any month. The alternatives during the kharif season are either too little (drought) or too much (flooding) precipitation. If the rainfall intensity is taken into consideration, the probability of these two unfavorable conditionis during the kharif season is increased.

10. Results of the rainfall analysis for Bangladesh have'been assembled in one volume only for monthly rainfall under the title: Monthly Precipitation Probabilities for 9 Stations, Period 1934-1969, dated November 12, 1971. For weekly rainfaLl four volumes are available, as follows: Weekly Precipitation Probabilities for 9 Stations1 Period 1934-1969.. dated November 19, 1971, including Book 1, 3tations No. 0006, Bogra and No. 0009, Dacca Book 2, Stations No. 0073, Mensingh and No. 0205, Raj'shahi: Book 3, Stations No. 0206, Ranf:pur and No. 0258, Barisal; Book 4, Stations No. 0306, Chittagong, No. 0356, Comilla and No. 0510, Khulna. One set of these volumes is deposited with the World Bank, another set wil be deposited vlth the relevant Government Agency, in Dacca..

11. Given the field cron water requirement-s (i.e. consnmptive use, pe:-co- lation and actual field losses), rainfall probability estimates can be used for estimating the prnbjbilijr of t4heir being met eithe partially or in fu.ll or of being exceeded by natural rainfall; i.e. this gives a basis for estimating t.he potential for rainfed a-ri"lture. This is the .. ajo concer in case of inputs programs of Bangladesh agriculture. Also, rainfall probability es-timates can be used for est4-miating the probability of r-equirinig either supplemental irrigation water or drainage. The probability of receiv-

lng any -- n- of-preclpi+at'ion durALIig a certain pteri0d, U, .iS Ul"e some as the probability of requiring an irrigation (or drainage) amount equal to the crop field water requirement minus precipitation. With the rainfall proba-bilities being estmn±ated, n-nA +Ic c-rop respons to +' ond +the prices are known, the total direct product from irrigation (or drainage) cai We cac 'a.ted.

12 ). A grow4ng plant reursa d-I-ymitr p-ly +hakn+ re LL. ,t'J.LI .. OLiA.UL4.4.u o a a. J_JStt... -VL..- ~ SL - .~.-.. according to the stage of growth.I/For planning for rainfed agriculture (as 0.0as Por 4LI" -chduling ofP s--JleuLr.a- ir4-r r- of dra4|.^ge), parti-- cularly in climates such as in Bangladesh rainfall must be considered on a week'y rathler l11-an monthl'j ba-sisr. Por '>he w sor r.onthl of the dr season, the rainfall quantity and distribution has a much smaller effect on _URJPJI - emLentl Lirragatd;vnL5 n lrqu.LKOL_e - Ae -Lnts. .

13. The weekly rainfall analysis indicating a 33% probability (one year out of threlle0) aIrLa 5%b p±ULIaiLjL.L.LLJy (Uoin year± oUt o4± L'W.jj o.f re.t4LIIrg 0.'5PW of rain in various districts of Bangladesh is summarized below. Though, not with u-ll iLaterializatiUn Uo aLu poUtntials, thiLs - GuLdU .LCZ.V rain. agriculture possible over a growth period of 28 weeks in the area of Comilla; 27 weeks in the ar-eas of Dacca, Nymensingh, Barisal', ChLittagong; 26 weeks in the area of Khulna; 25 weeks in the areas of Rangpur and Bogra; and 23 weeks in the area of Rajshahli. Supplemental irrJigation may be required in somke years in the early months (notably in March, April, May) and in the final weeks (notably- in Ocober ad in the first -week of Ltoveber) of the rainfed agriculture season.

i/ See T.R. 20. LEINGTH OF THE RAINY SEASON AS EVIDENCED BY WEEKLY RAINFALL PROBABILITY PROFILES

A - un the basis of a 33% chance of gettmig or exceeding 0.50 inches of raintfall in any week

Comilla Third week of March -- first week of Novermber 33 weeks Dacca tt I n _ i1 33 weeks Mymensingh Fourth week of March -- fourth week of October 31 weeks

Barisal Second week of April -- first week of November 29 weeks Cuittagong I'l--l 2 weeks Khulna i " -- 29 weeks

Rangpur Second week of April -- fourth week of October 28 weeks Bogra Tnird week of April - fourth week oI OctoDer 27 weeks Rajshahi It -I t t

B - On the basis of a 50% chance of getting or exceeding O.50 inches of rainfall in any week

Comilla Tnird week of April -- fourth week of Octooer 28 weeks Dacca Third week of April -- third week of October 27 weeks Mymensingn t " -- IT it 27 weeks

Barisal Fourth week of April -- fourth week of October 27 weeks Chittagong t it- I' 27 weeks Khulna Fourth week of April -- third week of October 26 weeks

Rangpur Fourth week of April -- second week of October 25 weeks Bogra First week of May -- fourth week of October 25 weeks Rajshahi First week of May -- second week of October 23 weeks 1h. The nature of the relationship which exists between crop output and the water supply is rather jntricate. Appreciation of this relatioonship is necessary for evaluation of the probable contribution of agricultural inputs at the different levels at which plant water requirements are met. Crop yields generally decline as the level of water deficit increases, but the rate of decline in yield. is disproportionately sma ler than the rate oI decline in the level of meeting plant water requirements. This is generally true f or al crops, subject to some qualification Decause of special cnarac- teristics associated.with the fruiting habit of certain crops. Under the prevailing standards of farming and use of inputs, and measured purely in terms of production, the relationship between crop yield and water implies a diminishing rate of return to water at the higher ieveis of satisfaction of plant water requirements as i+43ustrated. in Figure 1, which suggest (on the basis of the Revelle Report)- that the follMowing percentages of optimum (or theoretical) yield can be obtained at declining levels of meeting plant water requirements:

Percentage of Satisfaction Percent of of Plant Water Requirements OptLmUm Yield

100 100 90 98 80 95 75 9 65 85 50 6

The table suggests that under farming conditions prevailing in Bangladesh a reasonably hien crop output can be obtained when crop water requirements are satisfied above 50% of theoretically desirable optimum requirements.

1/ Report on Land and Water Development in the Indus Plains, the White House Panel, Washington, D.C., January 1964, pages 417-29. - 7

RELATIO1NHIP BEM1IJEEN lLELD AND FLANTWVAThIA hEWUIAF'b

I 1v

t { 90 | t THEOH!_ VALU I FROI yMI-b(S I (REVELLE REPORT}:io

7010 1 I1 1l lll I g I I_ _ _ __ I_ _ _ __ I ,';1I I __ _ _ _ I I IXoot 18 AI I I + +

;LI ' Ii"' ______II_ I

I 0 d L III I I______I _____ I _____ I ____ I_I

201_0!0 v? 1 5 100 1 II l I II I I I__

I ~~~~Plant Water Requirements as Prc~ernt of' Optimum j

201F Fig.1 -I * U±. d..ILyv UjJD±IIIUIII clI± ± diA. .J X0± J ±.d.iiLD ± tJ.L1, L1 tfiIll 4-U Ij Uc only under controllable conditions such as with full irrigated agriculture

ad,i rare.L withWL .ca.L1 dCUagricLtuLLrL. ,inceU1 5aI±UU.LL,U.Lagric 'VUL -J. U UUc1-Vil is generally rainfed in Bangladesh it is unlikely that 100% of plant water req:..u_L-:1irerlnts can bue r.iet in a- tlr.ell:_y r,l-.e frmkiual; tcan beI-s pe,ly assumed, however, that Bangladesh farmers will endeavor to maximize output da LUweri leVUl o0 cuveirage oi pl ndtlU WdU-t I-tI U le'i±mU-1-lrom±rai UpaldlLdL.- Correspondingly, the probability of meeting 90%, 80%, 75,g) 65,% or 50-f0% even of Optinr- W crop water requlrelentsincreases as the corresponding amounlts of' rainfall to reckon with declines. The rainfall probability analysis for Bargladesh suggests tLlat far±r.ers generally- face variVio- le-vels of probaUbii.tle (or risks) of meeting 75` to 80% of optimal crop water requirements from rainfall dalone.

16. It seemIs that the b-ULk of the falmers iII Bangladesh have oULy a notional idea of optimum crop water requirements. On the basis of their past experience, they generally have a reasonably good, yet solely qualiLatlve judgement of local rainfall frequencies on the basis of which they perform traditlonal cultural practices. To fill the gap of quantitative rainfali evaluation, a set of information of operational relevance to agricultural development programs and projects has been gathered from tne probablity analysis of rainfall.

17. This set of quantitative information of direct overall operational relevance, regardless of specific water requirements of any particular crop, gives the amounts of rainfall that can be expected to be reached or exceeded, in ary 2-week running period, at the nine stations covered by the analysis, nine years out of ten (90; probability), four years out of five (80%.- probability), three years out oi Iour (7f% probability), two years out oi three (or about 65% probability) and one year out of two (50 X probability). This one set of quantitative information is assembled in Appendix 3, Tables 9 through 17. Correspondingly, the profiles of probabilities of exceeding specified rainfall leveis, namely 0.5 incnes, 1i. incnes, 2.5 incnes in any week and showing the peaks and troughs of the rainfed agriculture season are shown in Appendix 3, Figures 1 througn 9 for the same stations.

18. This report does not provide quantitative information oI equa ly direct operational relevance-the probabilities of meeting crop water requirements in full or in agronomically and economically meaningful proportions. The rainfall analysis also provides quantative evaluations of rainfall duration frequency relevant for determining drainage requirement, as well as of drought duration frequency relevant for determining supplemental irrigation water requirements. This part of 2 he analysis is a contribution of Acres International (Overseas) Limited.-!

/ See T.R. 20 2/ Draft Technical Guideline, Rainfall Analysis, East Pakistan, by Acres International (Overseas) Limited.in association with H.G. Acres Limited: International Land Development Consultants, N.V; Booz, Allen and Hamilton International, Inc.; February 1971. - 9 -

V. RAINFALL DURATION FREQUENCY

19. To determine the drainage requirements, maximum values of rain- fal1l on 1. 2. 3. 5. 10 and 15 consecutive days have been computed for the months of May, June, July, August and September for each of the 9 stations. An examnle may clarify this part of the analysis. For examole, the highest rainfall on a day in May 1934 was 8.5 inches, the highest rainfall on a dav in May 1935; 6.3 inchAs nnd so on. For evArv year in the period of recording the highest value of daily rainfall is selected. This gives 36 values of hiphest dai1y rainfall in MaY fonr nperiod of recording of 36 years. Frequency distribution of these values is plotted. The same ProcedUre is followed in dr.t.Armining the highest rainfall on 2, 3, 5} 10 and 15 consecutive days in May. The highest rainfall on 2, 3, 5, 10 and 15 rOlnfeGAtAVP: clqVS iS f'innd through mTnnv- tnotals This meanns tlhat. fnr - period of, say, 5 consecutive days, the totals of rainfall frcm 1-5 May, 2-6 May, 3-7 M:-r- 27-31 Mayr nre cnm,ruted. Tn 4-iSz Irr 27 vnIiio-u of 5-days' totals of rainfall in the month of May are obtained. Out of these 27 vnlue-s the highest o.ne is selected. This gives 36 values of highest rainfall on 5 consecutive days in May for a period of recording of 36 years. Frequency of distribution of these values is made, and so on. The res+lts of the analysis described above, Rainfall Duration Curves, are shown inAppendix 4, Fizures 1Oa, lOb, lOcr, through L8a 18b, I'8c As man, FigWBarisaue In- fo- indicates that in the month of May (a) a rainfall of 7.6 inches in one A-r occurs once ir.2-n n--- 4-te-aerag -,a () the 4rainf '1 4- 10 consecutive days which occurs once in 10 years on the average is o R 4,-,.-0

VT. DRDOUCyHT DURATION FREOUENCY

20. Fo determi11.n1Ling suLppler.env'la- irrigatio,ULUn water reurr.rt, U minimum values of rainfall on 15, 30 and 40 consecutive days have also been com,JLL./pu flor IL'e 7 st ations. 1Le selectued periods are: (1) owpiaubr- October; (2) November-December; (3) January-February; (h) March-April; and (5~) TXy=J. -rocedureThe s 4-he sar,. "asdscribed4above fPor th4 r-.al duration frequency analysis. In this part of the analysis, however, only the lUWest v'ues of rainfall on 15, 30 and 4o consecuive dayYs are selected periods, a graphical presentation of the results as so-called drought curves was har1dy possible- For this reason, the results of the dro-ught duration analy-sis have been presented in Table], Appendix h which shows, for

2.1 inches or less in 30 consecutive days occurs once in 10 years on the average, an) rainfall on 30 consecutivethe days which occurs once in 5 years on the average is 5.7 inches or less. - 10 -

VII. ILLUSTRATION OF THE ANALYSIS

21. Estimates for nine stations have been derived on the basis of the period of records 1934-1969, i.e. 36 years, though there were some missing observations. A brief summary of the method used for estimating rainfall probabilities is given in Appendix 1. Results of the analysis for the stations of Barisal, Bogra, Chittagong, Comilla, Dacca, Khulna, Mymensingh, Rajshahi and Rangpur have been organized in alphabetical order in Appendix 2 for monthly rainfall, Appendix 3 for weekly rainfall and Appendix 4 for drought duration frequencies and rainfall duration frequencies.

Rajshahi Area

22. Table 1, Appendix 2, shows the mean monthly rainfall for Rajshahi. Table 2 shows the corresponding minimum and maximum, lower and upper quartiles and the median of the monthly rainfall for Rajshahi which suggests that among the nine areas covered by the analysis Rajshahi received comparatively the least rainfall throughout. Table 10 gives the probabilities of rainfall reaching or exceeding specified amounts in any month in the Ra.jshahi area.

23. Table 21 gives the probabilities of rainfall reaching or exceeding specified amounts in any consecutive two-week period in Rajshahi. Also given in Table 30 are the amounts of rainfall expected to occur in any two-week running period during the crop season in nine years out of ten (90% probability), four years out of five (80% probability), three years out of four (75% probability), two years out of three (or about 65% probability), and one year out of two (50% probability). The probabilities of reaching or of exceeding specified rainfall levels, namely 0.5 inches, 1.5 inches and 2.5 inches at Rajshahi in any week are shovm in graph fom in Figure 8.

24. The analysis indicates a quasi-certainty of no rainfall at all in Rajshahi for about 6 weeks from the two-week ranning period overlapping the last week of November and the first week of December (Nov.-Dec.) throughout the two-week running period overlapping the last week of December and the first week of January (Dec.-Jan.), that is for more than a full month period during which irrigation is evidently required for crop growth. The probability of zero rainfall would appear to be steadily around 60%< (or 3 years out of 5) from January through the first part of April, with an alternation of weekly peaks and troughs as showqn in Table 30. Rainfall probabilities along with the amounts - 11 -

of rainfall to be expected then rise very sharply from the middle of April through early June to reach the monsoon peaks around the middle or June and throughout the first part of September. Characteristically, the monsoon rainfall recesses in the last week of July (week 21, counting the first week in March as week 1) with the weekly rainfall amount dropping by half immediately after reaching a major peak in the previous week (week 20) to resume afterwards to lower peaks. In other words, there is only a 50% chance that the amount of rainfall would exceed 1.5 inches during that single week, far below crop requirements for that week. Other major recesses in the monsoon rainfall occurs in the first week of September (week 27) when there is only about a 40% chance that the amount of rainfall would exceed 1.5 inches. and in the third week of October (week 33) when there is only about a 15% chance that the rainfall would exceed 1.5 inches. It is like1cv, however. that soils in this area would have retained enough moisture to allow the crops to go through these comparatively dry periods without damage. Yet serious crop yield declines may occur. Whether this is so should be further researched through experimental farming. Char- acteristically, of the Raishahi area, these tr.ughs in the monsoon rainfall are equally spaced in time (5 weeks, i.e. about one month). In this respect the profile of probabilities of reaching or exceeding 0.50 inches in any 2-week running period is especially interesting as it also illustrates a minor trough in the rainfall pattern in the second week of June (week 15) which is again equally distant in time from the vent trough. In other words the comnarativelv drv weeklv nariods during the rainfed aqri4culture season are equally spaced in time in the Rajshahi area (weeks 15, 21, 27, 32, 33), a characteristic that may help chAedule necessary supplemental irltion.l

25. G-nmnarat5velir. the analyssiq indieAteA onlv three maimr npak occurrences, one in the week before last in July (week 20), a second in the third week of Spntemher (Week 29) and a third in thAe last. week ot' n.tnrher (week 33), as the monsoon is about to withdraw completely shortly after. Interestinglv. the distance in time between the Julv and Sentember neaks is twice (8 weeks) the distance in time between the September and October peak (4 Veeks).

nv.~~~~~~-es ts tui' *(-5,>alccfmL. PrMGcuLI-t::Uu110r an-L.Vs1 101- ,aujhShIM are given in graphs form in Figures 17a through 17c, for the months of May, Junle,T_ e July,T. 1 - August,A- -_ . 1. SeptemblerQ - - I __ _ arid provide*3 - additional- 3 *3- 4X*- - - - infrmo>ation to help in determining drainage requirements. For example, the figures show that in the month of May (a) a raia of 4.O iCheS in one daych- occurs once in 25 years on the average, and that (b) the rainfall in 10 consecutive days which occurs once in 10 years on the a-verage is 5 1nches. - 12 -

27. On the other hand, drought duration frequencies for the Rajshahi area indicate that for the period September-October (a) a rainfall or 0.3 inches or less in 30 consecutive days occurs in 10 years on the average and (b) the rainfall on 40 consecutive days which occurs once in 5 years on the average is 2.6 inches or less. For the period May-June (a) a rainfall of 1.2 inches or less in 30 consecutive days occurs once in 10 years on the average, and (b) the rainfall on 40 consecutive days which occurs once in 5 years on the average is 4.1 inches or less. This information is of direct relevance to determine supplemental irrigation water requirements. fiangpur Area

28. The analysis indicates that the rainfall agriculture season covers 28-weeks in the Rangpur area on the basis of a 330/0 chance of getting or exceeding 0.5 inches of rainfall in any week and 25 weeks on the basis of a 50 o/o chance of getting or exceeding 0.50 inches of rainfall in any week. Table L Appendix 2, shows the mean monthly rainfall for Rangpur Area. Table 2 shows for each month the corresponding minimum and maximum, lower and upper quartiles and the median of monthly rainfall. llangpur receives a considerable amount of rainfall, more than a third more than Rajshahi, over a short period of 25 to 26 weeks and about 40% less rainfall than Comilla over a shorter period.

29. The analysis of weekly rainfall data indicates a quasi-certainty of no rainfall at all in Rangpur for 8 full weeks from the middle of November through the first week of January, during which irrigation is required for crop growth. The probability of zero rainfall declines rapidly thereafter to 50% by the middle of February and there is chance of getting at least 0.50 inches or more of rainfall one year out of three in the last two weeks of March with the monsoon setting in for good by the middle of April to reach its first and highest peak by the end of June followed by a trough in the second week in July. There are four lower peaks in the third week of July, the middle of August, and the last week of August and in the middle of September. Major troughs occur only in the second week of July and the first week of September. The monsoon withdrawal stretches over about six weeks and there is no rain at all in the third week of November.

30. Also given in Table 31 are the amounts of rainfall expected to occur in any 2-week running period during the crop season in nine years out of ten (90 o/o probability), four years out of five (80 o/o probability), three years out of four (75 o/o probability), two years out of three (or about, 65 o/o probability), and one year out of two (50 o/o nrobabilitvy). The probabilities of reaching or exceeding specified amounts of rainfall, namely 0.5 inches, 1.5 inches and 2.5 inches in the Rangnur area in anv week are shown in graph form in Figure 9. - 13 --

31. Results of the rainfall duration frequency analysis for Rangpur are given in graph form in Appendix 4, Figures 18a through JB c for the months of May, June, July, August, September and provide additional information to help in determining drainage requirements. The figures show that in the month of May (a) a rainfall of 7.6 inches in one day occurs once in 25 years or more on the average, and that (b) the rainfall in 10 consecutive days which occurs once in 10 years on the average is 17.5 inches.

32. On the other hand, drought duration frequencies for the Rangpur area indicate that for the period september-october (a) a rainfall of U.4 inches in 30 consecutive days occuB once in 10 years on the average and (b) the rainfall on 40 consecutive days which occurs once in 5 years on the average is 2.8 inches or less. For the period May-June (a) a rainfall is 4.3 inches or less on 3u consecutive days which fall once in 10 years on the average, and (b) the rainfall on 40 consecutive days which occurs once in 5 years on the average is 9.3 inches or less. This information is of direct relevance for determining supplemental irrigation water requirements during these two periods.

Comilla Area

33. The data indicate that Comilla has the longest rainfed agriculture season, extendirLg over 33 weeks on the basis of a 33 0/0 chance of reaching or exceeding 0.50 inches of rainfall in any week (one year out of three), and over 28 weeks on the basis of a 50 o/o chance of reaching or exceeding 0.50 inches of rainfall in any week (one year out of two). The mean monthly rainfall is shown on Table 1, Appendix 2. Table 2 shows the correspondinc minimn and maximum, lower and upper quartiles and the median of monthly rainfall for' Comilla which suggests that among the nine areas covered by the analysis Comilla has the most regular rainfall pattern throughout. Table 6 gives the probabilities of rainfall reaching or exceeding specified amounts in any month in the Comilla area. It indicates that one year out of -three the area receives at least one inch of rainfall in February and at least two inches in March and thus has enough moisture for early planting.

34. Table:L7' gives the probabilities of rainfall reaching or ex- ceedinz sDecified amounts in any consecutive two-week periods at Comilla. Also given in Table 26 are the amounts of rainfall expected to occur in anv 2-week running period during the crop season in nine years out of ten (90% probability), four years out of five (80% probability), three years out of four (75% probability), two years out of three (or about, 65% probability), and one year out of two (50% probability). The probabilities of reaching or exceeding specified amounts of rainfallL namely 0.5 inches, 1.5 inches and 2.5 inches in the Comilla area in any week are shown in granh forms in Figure 4 L 4 ,A qTohf nnslnalc a 4nd ,n+.aQ n rmqi_ _ar+.ajn+.v nf nn rinfall at all to *v @_gv4__* ~ _ __ -- ______in Comilla for a 8-week period from the middle of November through early JTn-ay,r dng r wi.v t,li -irri-matiMn is renqiirA for cron arow.th. The probability of zero rainfall decline rapidly to one year out of two by the end of February-- oA +there iE ahavr,e ofr get++-ngvsome rainffall +Wo vyars out of three by the week of March, with the monsoon setting in by first week 4 Of J_p-...lAt* q,`lnbly raochh itsc f4'rw+ Tp%e,nd4n% +-he firs.+. wa1eo f MAy f-nlnh.rAd vJ. .L. tflys]swWJ. ALI.. _

36.* eu1ts of the rainfall dration freqaen-c -- alw-a ro Co- 4 li are given in graph form in Figuresl3a throughl3c for the months of May, T-en T-J - Ann,, . .nA p"-a arAd4+44ndA 4tr P.m 4r.- 1toh1el in determining drainage requirements. For example, the figures show 4.1,- i4r the month, of (a)0 zN -4ainfll oe 7. 0 4nches Jn -.-- A aa,..,a Ufl* v a.C U.- 'AAS.. tJ l..J %-* Jj lL*L.&.t3 - I .- .LUfS*Q - SJ** tOJ 'Jt%L once in 25 years on the average, and that (b) the rainfall in 10 consecutive A.-s -U4 ehl, oWcC- onc- in 10r years on t.kU eae -- 412.5 lrf ches. %A&U W"LA 'L ~U3.L v .LI J.t/JW .. A &1AW CLV%V± .4. .LO_ .) .L"%.

37. On the other hand, dirmought dation fV,uen,.es feor te Co411a area indicate that for the period September-October (a) a rainfall of 2.00 -InMsore r rQ 3'n_ con,sective d1 occursonce 101he r __ a-verge and (b) the rainfall on 40 consecutive days which occurs once in 5 years on the ave.age i4s 5.,4 or less ForV. ,-.pAriAod A'-A4p1 (a) a zer- I in 30 consecutive days occurs once in 10 years on the average, and (b) the

*;nfall~ .4t LA-UV 40U .VV 0. WD.Ac JtocLcs0 orI.cein 511 yeaJirs on t-nte a-verage is 0.7 inches or less. For the period May-June (a) a rainfall of 4.0 inches r ess .j- In consecutiv-s o--ccurs once. 10 years on IIie average, anu (b) the rainfall on 40 consecutive days which occurs once in 5 years on the average is l0.h inches or less. These figures indicate much less droughts in the Comilla area than in the Rajshahi areas, with correspondingly, much less need for suppiemental irrigation. They also dicate that planting may ta'ke place much earlier. APPEDDIX 1

- Note on Method of Estimation of Rainfall Probabilities

- Stations Covered by the Analysis and Their Location

- Corrections Performed on the Daily Rainfall Data Used as Input

APPENDIX I

METHODS OF ESTIMATION OF RAINFALL PROBABILITIES

In dealing with rainfall phenomena, the characteristics of the "true" probability curve are unknown and must be estimated from the sample probability curve. The estimate of the probability from a sample will almost always be in error. The problem, therefore, is to find a method which will reduce this error of estimation. Smoothing out the meaningless irregularities in the sample curve is a way of reducing the overall estimation when only one sample of relatively small size is available as in the case of rainfall data in Bangladesh. Weekly rainfall totals do not exhibit Normal-distribution characteristics since there is usually a large number of cases when the rainfall amounts are zero (a lower bound) or near zero. To represent the situation in which no rain fell during the week of one or more years. the expression for the cumulative probability becomes

G (x) = P + (1-P) F(x) where G(x) is the probability of occurrence of rain amounts less than or equal to x inches. The function F(x) is given either by empirical estimate or a Gamma -tyne distribution and P equals the proportion of the sample in which no rain was recorded. The rain and no rain cases are senarated and the function P(x) is weighted by the Dronortion of rain cases in the sample. Let y equal the number of years on which no rain fell ani N ealial the total samnle size- Then

P = v with 0n v e N N

For example, if no rain was recorded on six of the thirty years in a specific week, then P = 020 for the period. As the probability of no-rain P, increases the probability of rain amounts decreases. A mathematical model to provide a reasonably good approximation of' r2infa11 iutinn is the inconmnplte. rTaTmqm nn-tinnn r-aa-rdless of whether weekly, monthly or seasonal amounts were being studied. This method not only provides a cons stent basis for smoothing the curv.es but it also provides a means of investigating the space and time changes in rai.n- fall probaDiiiTY analyTicalyJ. -The Gamma distibu-tion isapositivel skewed distribution which is applicable to climatological variables which haea p.hysican 1 lowrav boundvra zero,of but+ no nan.. +on-satisticaluppeor bondi such, as one encounters with precipitation data. The results where interpreted in relntion. to crop water req.u.iments in as ano + cor= responding weather stations to provide information with which far more assess,,.ent of plar.ting as well" as harvst-ing dates for r-in- realsi.L LLOL'L-. O..-LlI.- -4 U '.A. fj..La.LUJ.JL CO VVn -L-JJ &J~.± V~OU.LAr, UA~U'Q 0 J.1.5./i. fed agriculture can be obtained than could be using average. The same appl.les also to- 4the - 44- of-e'xar,atio ir aio a-d dinage rqu.irii,.nts

BANGLADESH

AGRICULTURE SECTOR STUDY

STATIONS COVERED BYr THE3 ANALYS:ES AND TREIR LOCATION

Tab. No. Name WM:O No. Latitude Longitude Elevation

0006 0 0 Bogra, B,angladesh 41-858 24 5:L'N 89 22'E 66 Feer

0009 Dacca, it 0 0 41-917 23 46'N 90 23'E 33 "

0073 0 IMyriensingh," III 41-861 24°46'N 90 24'E 63

0205 0 0 Rajshahi,, " ll 41-856 24 23'N 88 36'E 75

0206 0 Rangpur, " 41-852 25°45''N 89 15'E 112

0258 Barisal, " irs 41-932 22 0 42'N 90 0 22'E 10

C306 Chittagong,". ' 0 0 41-940 22 21'N 91 50'E 46 "

0356 Comilla, if" 0 0 41-923 23 28'N 91 1°'E 29 "

0510) Khulna, 0 0 " " -. 930 22 49'N 89 34'E 16 "

-SD Pr 0d

al)a CD z

IFJH APPENDIX 1 TaDie 2

BANGLADESH

AGRICULTURE SECTOR STUDY

CORRECTIONS PERFORMED ON THE DAILY RAINFALL DATA USED AS INPUT

STATION YEAR MuNTi CORRECTIONS

0006 44 08 Day 33 = 00.43 Charnged to Day 31.

0006 48 04 Day 31 .71 Changed to Day 30. 0006 56 05 Reported as zero precipitation. Changed to not reported.

0006 61 06 Day 31 = .07 Changed to Day 30.

0009 37 05 Cards 1 and 2 were reversed.

0009 49 06 Reported as zero precipitation. Changed to not reported.

0009 52 06 Month reported as zero precipitation. Changed to not reported.

00073 51 05 DMonth reported as zero precipitation. Changed to not reported.

0206 41 11 Day 05 punched as 0A59. Changed to 0059.

0258 51 08 At 1st of month, day is missing with a minus one in Columns 13-14. This caused computer to skip other information on card. This was corrected using information other than -1.

0306 36 07 Day 21 was Dunched in card after day 30= Changed to Day 31.

0306 49 05 Mlonth reported as zero precipitation. Changed to precipitation not- reported.

0356 61 10 Day 40 changcd to Day 31r

0510 51 04 Day 31 changed to Day 30. APPENDIX 2

MiONTHLY HAINrAiLu AU,yUINUS AN-DuPRO-BA-BILITIES

BY' STATIONS

- Mean Monthly Rainfall in Inches - Variation of Monthly Rainfall in Inches - Probabilities of Raini.all Reaching or Exceeding Specified Amounts in any Month

Period of Records: 1934--1969

Stations: Barisal, Bogra, Chittagong Comilla, Dacca, Khulna Mymensingh, Ra.ishahi, Ranamur

BANGLADESH - SECTOR STUDY a) Mean Monthly Rainfall in Inches Based on Number of Years With and Without RainfaJll

S tation Jan Feb Mar Apr May June Jilly Aug Se> Oct Nov Dec

Barisal o.58 0.59 1.1j9 3.27 7_ _ 16'8- -, 159 ' A? ]3ogri i o.52 0.44 0.962.20 -7.14 26.88 -4- 0.36 0.07 Chittagong 0.43 0.77 2.17 4.48 10.39- 22.29i-:. 25.35 _-22.7 12.56 -8.i7 1.45 O.'i7 Comi:la 0.37 1.25 1.74 11.25 20.57- 19.16- i5P8o- 569.() 5 1 .'1 0.17 ])accai o.43 o.84 1.80 b.9.4 6 1i. .75 12.84 13.58 9.Itt 5.714 0.914 0.09 Khulna o.56 o.54 1.25 3.11 ...6.28 13.18 13 .70 11.72 8.66 6.o 1.02 O.:L0 ]Lymensingh 0.146 o.64 1.83 .17.fl 1J4e78 -1.61 12. -i8&L- AI83 0.54 0.08 RajsSha0i 0.56 0.51 0.91 -4.65 10.06 12 .06 1.3.0%4 8.8 !7 0.:39 0.08 Rangpur 0.57 0.53 1.11 3.40 12.06 -:19.I ID.7ON 2-;_11.03 - 6. i71 0.28 0.04

b) Gamma Distribution Mean Based. on Number of Years with MeausurELble Rainfall/

Station Jan Feb Mar A a June July Se) .~~~~~_ jr . _ l _ _ Oct NoV Dec

Barisal 1.08 0.89 1.70 3.147 > ^~-- --2;- hAT 2 l1.,72 0.75 Bogra 0.79 o064 1.45 2.33 -77IlN< i.88 13 :54 13.11T -9*66 6.9)6 o.68 0.30 Chittagong 0.85 1.10 2.514 4.75 Si0 39- 22.29 -5.3 ,22.7 2 12-4ZA ,8J1 2.20 1.149 Comilla 0.66 1.83 1.91 [2% 20.*T - -i-;.16 I$.80 94 2.I48 0.78 I)acca 0.69 .1 1.62 0.33 Khulna 0.97 0.81 1.36 3.19 - 6.28 13.-8-13.70 -I17 ^ 8.5 ' 6.b- 1.47 0.56

Mymensingh 0.88 0.85 1.88 [ 11.83 17.g- 37iJ78 . 1 2.51 - -6.83 1.08 0.41 Rlajshahi o084 0.77 1.26 4.651 10.06 12.06 l2o0.0 8,08 r3 0.75 0.:38 Rangpur 0.99 o.65 1.35 3.66 12.8 _ _19.14115.79 _3 ..C.-3 j7.15307 0.31

:L/ In other words, mean monthly rainfall when it rains. There are no months without rain from May through October :lnclusive. Mean monthly rainfall (a) must always be lower than., or equal to, the GrammaL distribution mean rain-- pl t; fall (b). Period of' records 1934-1969, with a few missing data. FHW c-i oo~~ ~ ~~ ~ ~,a ~ ~ ~~C *0 ~~~m In

a- - - , ------I~~~~~~~~~- I'-ic'j I 9 o--.n a -tm-i A --- 't'rc~~~~~~~~~~------tn------L------\ I-- - N o-- -- I------J-

a 0 C.)- a .~ . . a . ., . .1 1. I . .~ .1I a . . a . a a cooD ;- U-: a OC) CDN a 00 -0(zC 9 00Cc-i A~C D C,o.,--an -a o00 -- :ao 00c. C,P a o o o o a ooaoo 0

a -- --m------a - o --- a I------a------C------t------a ------on------a------a - n- t- a a PNOC, a a c-aCDt-- a NAC,Zt--~ - a . I-U 'n A ciano-T- aCD-Ž---n0 I c-CDI tnt-c a manN; ~- a -flNOC ~ ci 's-a u'.IV C.. a C.,.a..a.. c " a - 0 ~ P r. . a . ID a --at--~~~~-m a ~oc-ttm- a A-U O tflDt--tnfA A NP, ' oa- - O~Pn coCCC a LNn In a -nt- A a-c-i a ~~~~~a ~ ~~~~c-i-- a I-t- c- - -a2 - a-.---.…a... - 4…--~~~~~~~~------

a AI N-tn O -C OW t-c --rn aC, P-aco n--- a cc cc-tnn a r-- c- ~ a *Ca nC a mfatma- a ~r-n

a . n. a a . a . " ,. a . a . I .A ~~~~~~~~~~. . a .a.I a CA ------l -- a ~ AJ-tt m c - -a- -a ---- o-i-a------a --- n a--- A N----C--- to ------a-(-t--- a----C-- a t Iaa-,na N -r N a -N a -ccCDa -cc a .-- It U a a N CI- --

a r 0':a t-Cf Cl inAt-i A aat-t Cc-NP-Car--N At-C a cn--, moo I J-anoC.)a 0-tt-aCC a a -i-Nt---t-a NAt--tArt a -'tO--'nr---~ ~A Aa-A-\t2 c-m------O t f'-n n - O - .------a -N------a_ - t- P-- -AC-c- a -c N -N A N-t------a -c-C- mt-N---C---- a- t- to------a ------a------. a - Let a - N N o aI I 1'- N C I ~ C I l P ~ an O'NJ I CO a

a a a .. . . a . . A . . I I 'n- a . . a . . a . . -P . a~~~~~~~~~~~~~~~~~~~~~~ a a ------a- A--- a------~ a--- N- -- e n ------a ------a ------a a -Ct-~ -N-a a - aN',t a tC- - O t O A t-C't n - - -N - aCD- -- tn -C) n:n-fa, a ) rNC0t- a 10n- a NC tnt- a DN N m AC' tn-n-n-CCPQN Z aDm rm- i-r) -n- a o "C'an_ -- ar

a------~-a a------nn a i ----- t - - --a -C p - -- m-o A ----- m------a------N------a -- -- mm----- a ------

a a Nanant-"I -t a -CDC 1n m - a 0 a -o A ca c : a an-cotrnNi ca -n-m :- t-Nna c a C a-cCC a mm-ct--an)-~~ a a ~ C; n-I- al N )r mC A ~ n o~ A DPJtnOI-N It A ,C--t-iC a C4n N ia N C J -Nan a m ncanr- O m N O C aa 0c-fc-~~~inCt-o m a-cit a m Nocna a --- nm--in ~~~~a ------a O -N- An------a- a------N A.7 - - --a ------E N - a -(*~N a- cc a - c- -. t

-- …--- …---… -a … -a---…----

C)a C ~~C-Dnmm a ~C>C)CDl aD'Q C 0 tC;-t a CtC) -mc"C ONnA . a 0N - ' a) C>-nC,t-ian' nt a 0 0 0 a

a,N------a ------I ------a------c------a N-n------c------A --- o--Nn- a aS a . D . a . ' C, a Z.- . aa . . a -- . .O a, . . O --a -c'-C a -- aC a a P q a a a a a a a a a a a a a~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~a tEaA a ~~C,CD m a -N C a m an a m -i--rt- C a c-- m a C -D - - mn aC - a OCOON a a O~C. -- ---a 000 -C-a-----a------0C------M 0- 0---- c a C O N a C c a a ~~I4 aaa aaa

--~ -,~A ~a ~ ~ s1. ' a ad aie~

a - a ------a ------a ------a -- - BANGLADESH AGRICULTURE SECTOR STUDY

PROBABILITIES OF RAINFALL EXCEEDING SPECIFIED AMOUNTS IN ANY MONTH

BARISAL

Rainfall (inches)

60.00 5(.00 0.00 40.00 - 0.0C 0.0O 35.00 0.00 0.01 0.01 0.01 0.00 30.00 - 0.04 0.03 0.03 0.01 0.00 25.00 0.01 0C.12 0.10' 0.09 0.03 0.01 20.00 0.00 0.04 0.28 0.27 0.24 0.08 C).03 15.00 0.01 0.10 0.55 0.58 0.51 0.24 0).10 112.00 0.02 0.18 0.74 0.78 0.71 0.40 0).20 0.0() 10.00 0.00 0.04 0.26 0.85 0.89 0.83 0.55 C).31 - 8.00 0.010 0.01 0.08 0.38 01.93 0.96, 0.512 0.70 0.46 0.01 5.00 - 0.04 0.22 0.61 0.99 0.99 0.9'9 0.90 0).74 0.05 J4.50 0.01 0.00 0.06 0.26 o.65 0.99 l.OC0 0.919 0.93 ().78 0.06 0.(0 4.00 0.02 - o.08 0.30 0.70 1.00 1.00 1.CO 0.95 C).83 0.0f8 3.50 0.03 0.01 0.11 0.36 0.75 1.00 1.00 1.00 0.97 C).87 0.1() 3.00 0.04 0.02 0.15 0.42 0.79 1.00 1.00 l.C0 0.98 0).91 0.13 0.01 2.50 o.o06 0.04 0.20 0.49 0.84 1.00 1.00 1.CO 0.99 C).94 0.16 0.02 :2.00 0.09 0.07 0.27 0.57 0.88 1.00 1.OC0 1.00 0.99 C).96 0.21 0.C)3 1.00 0.21 0.20 0.49 0.76 0.96 1.00 1.00 1.00 1.00 C).99 0.34 0.07 (.50 0.32 0.35 o.66 0.86 0.99 1.00 1.00 1.C0O 1.00 1.00 0.46 0.12

MONT4 JAN FEB MAR APR MAY JUN JUL AUG SEP C)CT NOV DEC |F

Hi tXi CD . t g 'Values of probabilities greater than, zero but less than 0.01 have not bEfen givern here. ro BANGIADES H

AGRICULTURE SECTOR STULEf

PROBAB:ELITIES OF RAINFAIL EXCEEDING SPECIFIED AMOUNTS IN ANY MONIH

]BOGRA

Rainfall (inches) 6o. oo 510.00 410.00 0.00 35.00 _ 0.00 30.00 0.01 0.0)0 0.01 0.00 0.00 25.00 0.00 0.05 0.03 0.04 0,.01 0.01 20. 00 0.01 0.1), 0.11 0. 13 0.O4 C'.03 15.00 ().00 0.06 0.32 0.34 0.34 0 14 C0.08 12.00 D).01 0.13 0.483 ° 57 0-55 0.27 0.14 110.00 0).02 0.22 o.6L 0.74 0.70 0.40 0.22 8.00 0.00 ().04 0.35 0.75 0.87 0.184 0,57 0.32 5.00 0. 02 0.12 0.63 0.92> 0.98 0.97 0.84 0.55 4.50 0.03 C).15 0.69 0.94 0.519 0.9?8 0.87 0.59 4.00 0.00 0.04 0.18 0.74 0.96 0.99 0.9?8 0,91 0.64 3.50 0.01 0.00 0.05 0.21 0.79 0.9'7 0.99 0. 99 0,93 0.69 01.00 3.00 0.022 0.0C1 o.o8 0.25 o.85 0.98 1.00 1.00 0o.96 0.74 0.01 2.50 0.03 0.02 0.12 0).31 0.89 0.99 1.00 1.00 0,,97 0.79 0.02 2.00 0.05' 0.04 0.:L7 0.37 0.93 0.99 1.00 1.00 0,99 0.84 0.03 0.00' 1.00 0.18 0.15 0.33 (.56 0.98 1.0() 1.C0 1.00 1.00 0.93 0.12 0.01 0.',0_ ;_0.35 0.30 0.47 0.70 1.00 1.0(0 1.00 1.00 1,00 0.96 0.25 0.05

MONTH JAN FEB MAR APR MAY JUN JUIL AUG SEP OCT NOV DEC

(Dt

Values of probabilities gr'eater thani zero butt less than 0.01 have not, been given hiere. N* BANGLADF.SH AGRICULTURE SECTOR STUD!

PROBABILITIES OF RAI21FALL EXiCEEDf; 'SPECIFIED AMOUNTS I ANY MONTH

CHITPAGONG

Rainf,all (inches)

60.00 0.OC) 0.01 0. 02 500.00 0.01 0.04 0. 04 40o .00 0.04 0.11 0.11 35.00 0.00 0.029 0.19 O. 16 0.00 310.00 ). 00 0.01 0. 18 0.30 0.25 0.01 0.00 25.00 - 0.02 0.3-3 0.45 o. 36 0.03 0.01 20..00 C)0.01 0.07 0.55 0.63 0.5 0 0.10 0.03 15.00 0.00 0.04 0.19 0.79 0.81 0.67 0.29 0.11 0.00 1:2.00 0.01 C).08 0.33 0.90) 0.90 0.78 0.48 0.22 0.01 10.00 0.02 C).12 0.45 0.95 0.94 0.84h 0.64 0.33 0.02 0.00 B.00 0.00 0.03 C).18 0.61 0.98 0.97 0.90 0.79 0.48 (.03 0.01 5.00 0.)0 0.11 O).33 0.84 1.OC) 0.99 0.97 0.95 0.75 0.08 0.02 ,4.50 - 0.01 0.1L4 0.36 0.87 1.00) 1.00 0.'97 0.97 o.80 0.10 0-03 14.00 0. 01 0.02 0.17 0.4 L 0.90 1.0C) 1.00 0.98 0.98 0.84 0.12 0.04 3.50 0.0)2 0.03 0.21 ().45 0.93 1.OC) 1.00 0.99 0.99 0.88 0.1L4 0.05 3.00 0.()2 0.05 0.25 ().50 0.95 1.0C) 1.00 0.9 9 0.99 0.91 0.16 0.06 2.50 0. 04 0.07 0.31 0).56 0.97 1.0() 1.00 0.9 9 1.00 0.94 (.19 0.07 2.00 0.0)6 0.11 0.38 0.62 0.98 1.00) 1.00 1. (0 1.00 0.97 0.23 0.10 1.00 0.15 0.27 0.57 0).76 1.00 1.OC) 1.00 1.(00 1.00 0.99 0.34 0.17 0.50 0. o40.3 0.69 0),85 1.00 1.O0) 1.00 1.00 1.00 1.00 0.44 0.23

MONTH JAN[ FEB KkR APR MAY JUN JUL AUG SEP OCT N!OV DEC

Values of probabilities greater than zero but less than 0.01 have not been given here. B.ANGLADFE,sE

AGRICULTURE SE]CTOR STJDY

PROBABILITIES OF RAINFALL 'EXCEEDING SPECIF:[ED AMOUNTS IN ANY iMONTH

COME;ILA

RainfaLl. (inches)

610.00 50. OCI (D0.00 O. O) h.O.CI (D.02 0.02 35-. OC 0.00 o. o5 O. 0!50. 00 30. OC0 0. DO 0.01 (.12 0.) 0 . (0l 0.00 Cl. 00 2'5. O0i 0.01 0.02 0.26 0.22) o. o6 0.02 C0 .03 20.0CI 0.03 0.08 0.48 0.40 0.2l0 o.0o8 Cl.07 15. OCi 0.08 0.22 (.74 o.65 0.C,2 0.25 c0.16 1.2.00 0.00 0.L4 0.38 (D.87 0.80 o.7 5 0.44 Cl.26 0.00 1.OC, 0.01 0.00 0.20 0.52 (0.93 O.88 0. 87 0.60 C'.35 0.01 8.0ci 0.02 0.01 0.28 0.68 (D.97 0.91, 0. 96 0.76 cl.47 0.03 5.0Oci 0.05 0.06 O.49 0.89 1.00 0.99 1. 00 0.94 0l.69 0.09 4.5c, 0.07 0.08 0.53 0.92 1.00 0.99 1. 00 0.96 0.73 0.11 0.00 4.oCI 0.00 o.o8 0.10 o.58 o.94 1.o00 1.0( 1.C00 0.98 C0.77 0.L4 - 3.50 - 0.10 0.14 0.63 0.96 1.00 1.0(0 1.C00 0.99 c0.81 0.17 - 3.00 0.01 0.13 0.19 0.68 0.97 1.00 1.0(0 1.C)0 0.99 cl.85 0.21 0.01 2.5CI Cl.02 0.16 0.25 0.73 0.99 1.00 1.00( 1.C)0 1.00 ci.88 0.25 0.02 2.00' C.o4 0.21 0.33 0.79 0.99 1.00 1.0( 1.C00 1.00 Cl.92 0.31 0.02 1.OC C01.13 0.34 o.56 0.91 1.00 1.00 1.OC) 1.00 1.00 0.Cl97 o.47 o. o6 0.5cl 0.24 0.44 0.73 0.96 1.00 1.00 1.0( 1.00 1.00 C'l.99 0.57 0.09

M)NTH JAN FEB MAR APR MAY JUN JUL AUG SEP OC T NOV DEC 1'I

Values of probabi:Lities greater than zero but less than 0.01 have not been given here. x FRANG-TADESH

AGRICULTURE SECTO OR SIUDY

PFROBABILITIES OF R?AINFALL EXCEEDING SPECIFIED AMOUNTS IN ANY MONTH

DACCA

Rainfall (inches)

50.00 40.00 0.,00 35.00 0.,01 0.00 30.00 0,00 0.,02 0.00 0.01 25.00 0.,01 0.,07 0.02 0.03 0.00 0.00 20.00 0.00 O,,03 0.18 0.09 0.12 0.02 0.02 15.00 0.02 0.12 O.h3 0.30 0.35 0.09 0.05 12.00 0o.05 0.25 o.,63 0.51 0.57 0.57 0.22 10.00 0.00 0.09 0.39 0.,76 0.68 0.73 0.36 0.16 0.(00 8.00 0.00 0.01 0.16 o,56 0.,87 o.8h 0.86 o.56 0.24 0.01 5.00 0.07 0.37 O,83 0.,98 0.97 0.98 0.86 o.h5 0.03 h.50 0.01 0.09 0.42 0,87 0.98 0.98 0.99 0.90 0.50 0.o4 h.0O 0.00 0.02 0.12 0.47 0,90 0.,99 0.99 0.99 0.93 0.55 o.o6 3.50 - 0.03 0.15 0.53 0.,93 0.99 0.99 0.99 0.96 O.60 0.07 3.00 0.01 0.05 0.20 o.60 0.96 1.00 1.00 1.00 0.97 0.66 0.10 2.50 0.02 0.08 0.26 0.67 0.,98 l.0O0 1.00 1.00 0.98 0.72 0.13 2.00 0.Oh 0.12 0.34 0.74 0.,99 1.,00 1.00 1.00 0.99 0.78 0.16 o.0o 1.00 0.1h 0.28 0.57 0.88 1,00 L.OO 1.00 1.00 1.00 0.91 0.29 0.02 0.50 0.27 0.43 0.72 0.94 1.00 1.00 1.00 1.00 1.00 0.96 0.39 0.06

MONTH JAN FEB MAR APR MAY JUN JUL AUIG SEP OCT NOV DEC

Values of probabilities greater than zero but less -than 0.01 have not been given. here.

tD Z -_t1 HU BANGLADES:H

AGRICUTIURE SCTOR 'STUDY

PROBABILITIES OF RADNFAI1 EXC,EEDI'NG SPECIFIEI) AMOUNTS, IN ANY MONTH

KHULNNA

R,ainf all (inches)

60.00 50.00 40.00 35.00 0.00 (.00 30.00 0.01 0.01 0.OC) 25.00 0.014 ).05 0.01 0.00 0.00 20.00C 0. 00 0.12 (.114 O. O 00. C 0l0.01 15.00 0.00 0. 02 0.33 (.36 0.22' 0.0C6 0.04 12.00C 0.01 0.07 0.53 o.56 0.h4 0.17 0.09 10.0oc 0.0:2 0.114 0.67 (.71 o.6c) 0.31 0.15 8.0OC 0.00 0.00 0.04 0.26 0. 82 0.84 O.78 0.50 0.25 0.00 5.0Ci - 0.02 0.18 0.58 0.96 0).97 0.96 O.83 0.51 0.03 4.50 0.01 0.00 0.04 0.23 0.155 0.97 0.98 0.97 0.E18 o.57 0.04 4.0CI 0.02 - 0.05 0.28 0.72 0.98 (.99 0.98E 0.S91 0.63 0.05 3.50 0.03 O.01 0.07 0.35 0.78 0.99 (.99 0.99 0.595 0.69 0.07 3.Ocl 0.04 0.02 0.10 0.42 0.84 0.99 0.99 0.99 0.597 0.75 0.09 2.50 0.06 C.03 0.15 0.51 0.90 1.00 1.00 1. OC) 0.98 0.81 0.13 0.00 2.0C 0.09 0l.06 0.21 0.62 0.914 1.00 1.00 1.OC() 0.99 0.87 0.17 0.01 1.OC 0.20 0.19 0.43 o.83 0.99 1.00 1.00 1.OC) 1.C)0 0.96 0.33 0.03 0.5 031 O5_ 0 63 2-93 1O 1.00 1.00 11.O0.OC) 0.99 o.47 0.07

MONTH JAN FEB MAR APR MAY JlJN JUL AUG SEP' OCT NOV DEC

Values of probabilities greater than zero but less than 0.01 have n1ot been given here. 1_ L

r31H BAINGLADESH

AGRIECULTURE SECTOR STUDY

PROBABILITIES OF RAINFALL EXCEEDING 'SPECIFIED AMOUNTS IN ANY MONTH

I MYWMEN'SINGH Rainfall I (inches)

60. Clo 50. 0C C). 00 4o. o 0).01 0.C00 35. C0O 0,.00 0.02 0. OC) 0. 1 0.00 30.CO 0.01 0.06 0.0]- 0.03 0.01 0.00 25.CIO o,03 ().15 O.O5, 0.C)9 0.03 0.01 20. C0O 0.00 0,.08 (.34 0.17' 0.23 0.09 0.03 15. GO 0.101 0,.25 0.63 0. 3 0.48 0.27 0.08 12.00 0.00 0.03 0..h2 C).80 0.65' 0.66 0.46 0.4 10.CO 0.01 0.106 0.57 0.89 0.8C) 0.79 0.62 0.22 8. C0O 0.02 0. 13 0. 73 0.96 0.91] 0. 8i9 0.76 0.32 5.00 0.07 0.34 0.92 0).99 0.99 0.98 0.92 0.55 4. 5 Cl.00 00 0.00 0.09 0. h0 0,.94 1.00 0.99 0.98 0.94 0.60 4.CO - - 0.12 o.h46 0,.96 1.00 0. 9 9 0.99 0.95 0.65 0.00 3.50 0.01 0.01 0.15 0.53 0,-97 1.00 1.OC) 0.599 0.96 0.70 0.01 3.00 0C.02 0.02 0.20 0. 60 0,.98 1.00 1.00 1.0C0 0.96 0.75 0.02 2.50 0.03 0.04 0.25 0.68 0.,99 1.00 1.OC) 1.00 0.97 C.80 0.03 2.0C0 o.o6 0.07 0.33 0.76 1,.00 1.00 1.OO 1.00 0.97 0.85 0.06 0.00 1.CIO 0C.17 0.22 0.55 0.92 1,.00 1.00 1.0C) 1.(0 0.97 0.95 0.21 0.01 0.50 0C.29 0.39 0.72 0.97 1,,00 1.00 1.OO 1. 00 0.97 0.98 0036 O.06

MONTH JAN FEB MAR APR MAIY JUN JI AUG SEP OCT NOV DEC

Values of probabilities greater thian zero but less than 0.01 have not been given here. | CDI- BANGLADESH

AGRICULTURE SECT'OR STUDY

PROBABILITIES OF RAINFALL EXCEEDING SPECIFIED AMOUNTS IN ANY MONTH

RAJSHAHT

Rainfall (inchles)

60.010

140.00 35.010 30.00 C.00 0.OC) 0.00 25.00 C).01 0.02 10.01 0.00 0.00 20.00 0).03 0.07' 0.03 0.01 0.01 15.00 0,00 0.114 0.25 0.13 0.06 0.04 12.00 0,,01 0).29 0.45' 0.29 0.15 0.07 10.00 0.010 0,03 0.44 o.62, 0.44 0.27 0.12 8.00 0.00I 0.0.1 0,.10 0).62 0.76 0.63 0.144 0.19 5.00 0.00 0D.00 - 0.05 0,,37 0.88 0.95 0.89 0.77 0.38 4.53 - 0.OL .06 0,,45 C).91 0.97' 0. 92 0.82 0.142 4.00 - - 0.02 0.08 0,54 ).994 0.908 0.95 0.86 0.147 0.00 3.50 0.01 0.01 0.03 0.11 o.63 0).96 0.99 0.97 0.90 0.53 - 3.00 0.02 10.02 0.01 0.:14 0,,72 0.98 0.99 0.98 0.914 o.58 3.01 2.50 0.Oh 0.h04 0.09 0.19 0,,81 (.99 1.OC) 0.S99 0.96 O.65 0.02 O.O0 2.00 0.07 13.06 0.hJ4 0.25 0,,89 (.99 1.OC) 0.919 0.98 0.71 10.04 0.01 1.00 0.19 O.16 0.315 0.144 0,,98 1.00 1.OC) 1.CI0 1.00 0.85 9.114 0.02) 0.50 0 L 03.28 0. 51 0.!58 0,,99 1.00 1.OC) 1.00 1.00 0.92 3.26 0.05

MONTH JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Values of probabilities greater -than zero but less than 0.01 have not been given here. (D t H I- CQ BA:NGLADEISH

AGRICULTUDE SECTOR STUDY

PR0BAB1LIT'[ES OF RJAINFALL EXCEEDING SPECIFIED AMOUNTS IN ANY MO:NTH

RANGPUR

Rainfall (inches) 60.00 50. 00 0.00 0.00 40.00 c0.01 0.01 0.00 0.00 35.00 0.00 cl.04 0.02 0.01 0.01 30.00 0.01 0.09 0.05 0.02 0.02 0.00 25.00 0.02 c0.21 0.12 0.05 0.04 0.01 20.00 0.(o 0.08 cl.42 0.25 0.13 0.10 0.03 15.00 0.C)1 0.26 o.68 0.47 0.32 0.;23 0.09 12.00 0(.3 0.45 Cl.84 0.64 0.50 0.36 0.16 10.00 O.(5 O.60 C0.91 0.76 0.64 0.48 0.22 8.00 0.00 0O() 0.10 0.76 c0.96 0.86 0.78 0.l1l 0.32 5.00 - 0.02 0.23 0.94 .s99 0.96 0.94 0.1B 0.53 4.50 0.01 0.03 0.27 0.96 1.00 0.97 0.95 0.85 0.57 4.00 0.02 0.04l 0.31 0.97 1.00 0.98 0.97 0.88 0.61 3.50 0.03 0.00 0.06 0.35 0.98 1.00 0.98 0.98 0.91 0.66 3.00 0.04 (.01 0.09? 0.4l 0.99 1.00 0.99 0.99 0.93 0.70 2.510 0.06 0.02 0.13 O.L48 0.99 1.00 1.00 0.99 o.,95 0.75 ().00 2.00 0.09 (.03 0.19 0.55 1.00 1.00 1.00 1.00 0.'97 0.80 (.01 0.00 1.00 0.19 0.15 0.39 o.71'2 1.00 1.00 1.00 1.00 0.99 0.88 01.09 0.OIL 0.50 0.30 (.32 0.57 0.82 1.00 1.00 1.00 1.00 1.00 0.92 0).22 0.03

MONTH JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Vet tv Values of probabilities gre,ater than zero but less t;han 0.01. have not been given here. *

APPENDI'X 3

WFW1T.Y PATNTAT.T. AMfTMTq pW PRnRAVTTTTT

'RY STATTONS

- Probabilities of Rainfall.Reaching or Exceeding Specified Amounts in>1sAny Coseu-ve 2-week Perlod Amounts of Rainfall Expected to be Reached or Exceeded 4-J. A- J L.LLLL n LFo.L'JU.% 4*A.& XY C2-weelk Run-L"I-,i Pen;od Probability Profiles of Reaching or Exceeding Specified

Any Week

P'eriod. of Records: 1yy -196Y

Ci'in4.- L.? Barisal, Bogra, chittgong Comilla, Dacca, Khulna YNymensingn, Rajshahi, Rangpur

:BANGLADETS1

(T.6o1. .. ..d 5... tl6, ~~F1rl 1r t*6 1no b.0556t 0516 01.6 ol .

biof.U (iod0..

35.01

30.01 0,010

25.01 0.010 0.019

2V.01 0.020 0.053 0.012 0. 10 0.010o 0.0L0 O.Ca 15.oD 0.0l0 0.053 0.1. 0.06h 0.002 0.0137 0.101 0.020 0.018l 0.008 0.031 0.01 0.0E10 12.OD II. 12 (.0on 0.005 0.245 0.050 0.10a6 0:102 0.11.6 0.019 0.016 0.0008 0.169 0.001 0.0L7 10.00 0.05 0. 8.2 0.llA 0.11.5 0.269 0.301 0.191 0.2!6a 0.170 0.3133 0.2120 0.136 0.055 0.019 6.10 0.020 0.031. 0.100 I'.1.lb? os o. 625 o. 660 o. 667 O. ;lo 0o6lS 0.555 o. 29o 0.11.0 0.I15 0.169 0.0(5 o.aa. 5.50 0.003 0.015 01.29 0.173 0.1336 0.671. 0.695 0.71. 0.60a1 0.708 0.819 0.1M1 0.191 0.1101 0.195 0.069 0.012. 5.OD 0.110 0.019 1.061 11.155 ,.202 0.370 0,713 0.71.0 0.769 0.661 0.768. 0.1.03 0.506 0.W1.3 0.69 0.235 0.113 0.019 6.50o 0.01 0.013 0.006 0.010 1.062 018.06 (.236 0.1.08 0.105 O. sc 0.016 0.122 0.0116 0.31.6 0.571 0.,97 0.1.1.6 0.260 0.130 0.026 1.01 0.011 0.010 0.016 0.015 0.110 11.223 0. 277 0.1.1. 0-.796 0.01.0 0.060 0.120 0.063 0.005 0.639 0.555 0.1.99 0. 30 0.100 0.031. 3.50 0.100 0.010 0.005 0.001 0.005 1.14.7 (1267 C..123. 0.1.95 0.837 0.090 0.901 0.836 o.il05 0.061 0.708 0.618 0.157 0.31.6 0. 171 0.01,6 3.01 0.007 0.011 0.035 0.07P 0.039 o.196 ((.330 0,379 0.51.5 0.075 0.927 0.933 O. 805 0.9039 0.500 0.776 0.6013 0.6Si9 0.10D 0.203 0.060 2.50 0.037 0.017 0.050 0.101 0.063 13.260 0.101. C'..1.1 0.60D 0.910 0.056 0.960 0.127 0.969 0.5145 0.A1. 0.700 0.5086 0.1,63 0.233? 0.001

2.01 0.010 0.051 0.011. 0.019 0.012 0.070 0.11. 0. 101 13.31.1 (0.4.1 C'.519 0.661 0.91.1 0.977 0.979 0.960 0.903 0.5173 0.504 0.017? 0.556 - 0.1136 0.278 0.113 0.010 1.00 0.010 0.03a 0.072 0. 031 0.010 0.036 0.101 0.200 0.162 11.151 (0.553 C'.8607 0. 727 0.966 0.991 0.9"0 O.9go 0.991. .50.89 0.91.6 0.001 0. 127 0.622 0.329 0.155 0.020 0.0310 1.01 0.010 0.005 0.103 0.076 0.001 0.103 0.11. 0.003 0,263 .01). (1,.665 (1.710 C. a 0.905 0. 990 O.990 0.995 0.999 0.991 0.579 0. 918 0.097 0.733 0.(1. 0.215 0. 068 0.015 0.50 0.11n 0.00C 0.165 0.152 0.175 0.11.1 0.277 0.227 0.1.51 0.8.13 3.71.1 o1.Bo o1.0B (.a ." 0.0000.99 0999 1.OO 1.100C 0.096 0.901 0.9"O 0.1%.1 0.A.3 0.307 0.111 0.000 0.12.

2-* P..60d 39.1.0 1.162 1.3.1.1 45..6 1.7.68 1.9.50 .51.02 . 1.2 . 3.1. 5.6 . 7. .8 910 11.12 . 1.11 . 1116 .1718 10.20 .21.22, 2301.4 25.-26 ,27-.26 9251.3 31-32 33.31.h 35,36 37.30 3951.0 61a62 h30.1

CD BA WGLADSS 1H

(W-k. I ol~~l ;111_1?raa..IItIn.

(Va.I.. atp-obabillttaa r..at., 2m%.ro641. h.. 0.01 h-. cci Wa.,sty.b. h.)

W3Oc.11 (nh.

I.0.00 33.00 33.00

00.00 0.010 20.00 0.010 0.021. 0.012 0.0230ol 15.00 0.013 0.04,3 0.01.8 OA.0. 0.071 0.021. 0.024 0.21. 0.1210 12.00 M.M0 0.016, 0.031 0.0907 0.39 0.10, 0.128 0.46? 0.079 0.021 0.0l 0.o07 0.3D26 11.30 0.019 0.035 0. 0?) 0.146 0.157 3.177 0.118 0.12 0.150 0.062 0.C63 03.630 0.30. 6.o0 3.015 o.oOO 0.1531 0.007 3.1.3 0. 330 0.4,55 0.397 0.o1I. 0. LIS 0.266 0.101. 0.3?)2 0. .00

5.50 0.021 0.106 0.183I 3.2)05 0.1,19 0.1.71 3.037 O0.75 0.1.59 0.515 0oj1S 0.291 0.J22 0.183 5.30 ~~~~~~~~~~~~~~~~~~~~0.01.00.02a 0.125 0.319 0.32.1 0.531 3.1.60 1.562 0.2.5 o.528 0.575 0.Y79 0.3441 0.3)56 0.212 1.50 0.,01.2 0.033 0.160 0.260 0.3937 0.906 0.5L6 3.-616 0.019 0.521 0.633 0.166 0.1,0 0.391. 0.21,6 4.3o 0.020 0.011 o.oih 0.3151 0.105 0. I9 0.1.06 0.624. 0.5.1 0.670 0.566 0.650 0.702 0.521 0.,02 0.2,35 0.2AL. 3.5I 0.0M) 0.019 o,.o26 0.070 0.228 0.305 3.521~ 0.7.13 3.W71 0.720 0.616 0.720 0.765 0.531 0.7524? 0.2.01 0.329 )3.0 0.021 0.010 3.032 9.04.3 O.07 3.276 0.2.29 0.09: O. ?0.73 0.683 0.701 0.669 0.78? 0.020 0.650 0.027 0.031 0.379 0.000 2.50 0.033 0.317 0.351. 0.060 0.133 0.330 0.502 0.6601 0.8:2 0.714. 3.833 0.725 0.809 0.080 0.769 0.7111 o.950 a0.57 0.017 20.0 0.002 0.003 0.000 0.032 0.009 0.091 0.170 0.637 0.50] 0.72.0 0.057 ).1.o6 0.803 3.701. 0.90') 0.907 0.960, 0.1105 0.601 0.503 0.036 1.50 0.082 0.031 0.023 0.062 0.1L.5 0.132 0.27 0.1.97 3.671 0.8031 0. 926 0.0.07 0.919 0.81,3 0.020 0.063 0.516 0.071. 0.73 0.0T7 0.070 1.00 0.008 0.010 0.071. 0.353 0.119 0.2)30 0.212 0.346 0.607 0.763 0.931, 0. 9.5 0.970 0.81.5 0.303 o.q5.3 0.987 0.0-66 o.oL3 oa85 0.659 0.106 0.017 0.00 0.003 o.00 0.00 0.201 0.0614 0.170 'J.150 0.233 0.32. 0.330 0.2.7 0.07.7 3.81.9 0.9601 0.991 0.97p3 o.9V60 0.959 0.90,6 0.990 0491. 0.5180 0.0563 0.71.6 0.317 0.075 0110D 0.OO 0.300

2.aO11.129114 9.25 1..11.. 10*.0 17r.0 .903 0~0.1..31. 5'0 7.11 9010 .11.12 .1310, 15.1.6 IT1-LO 19.20. 21.22* 23.242 * 296*072 293 333 3.' 334*3KA '343*1.. *.0.. I A, Mul A. MY .= . . . .RVOEPDi

- r - -T r r - r~~~~~~~~~~~~~~~~'- - s- - -~ ~ ~ ~ ~ ~ ~ ~ ~ ~ P3393 1t~8Ifl* 40100010400$ t000.k0Y0770. 740 . 4933 . 4317 40207 0tPU~~ . 000000$ 130000831 * 12080100 BANIG:EADESI

7 .i .r. 7.2. I -hso1 32 -.1.6I 1.1-.. iIh.22+h. 02I. ..2, of 2.-6

2 7.6 f pn.bh0 .£00 ..6 .... 0.I 2,. h.6.0.01 h3.n. r6.. 52028 .-)

4.0.0 0.021 -.35

2000 0.063 0.012 0.095 0.029 0.022

23.00 0.012 0.20N 0.030 0.255 0.2327 0.2*5 0.244

0.00 0.030 0.253 0.075 0.309 0.023 0.,33 0.092 0.010 0.01.2 0.020

5.00 22.09 0.025 0.002 0.305 0.269 0.300 0.240 0.1200 0.l86 0.020 0.0:5 0.0:26 0.024

12.00 1.029 22.00 0.05' 0.240 0.2.08I 0.200 0.50)0 0.239 0.'I)2 0.250 0.037 0.003 0.0:20 0.022 0.000

10.00 (2.035 22.04 0.09 0.20 0.492 0.358 0.595 0.367 0.500 0.300 0.050 0.143 0. I1IL 0.021 0.000

0.00 0.020 0.000 0.019 0.000 11.120 32.1I91 0.007 0.003 0.097 0.612 0.776 0.200 0.707 0.396 0.060 0.3259 0.02210 0.136 0.130 0.027 0.010

5.50 0.002 0.005 0.025 0.013 02.251 122.02 2..0 79 0.000 0.725 0. "9 0.902 0.700 0.377 O3 0.2,32 0.530 0.630 0.3130.n2 0.19* 0.033 0.021.

5.0 0.020 0.032 0.000 0."'2 2.2177 22.040 2.320 0.500 0.752 0.457 0.025 0.750 0.2300 0.2.667 0.621 0.850 0.3.20 0.02i 0.1I50 0.039 0.024.

0.58 0.020 0.025 0.020 0.()2 0.0)'5 0.050 22.00 2.2052 22.357 0.54. 0.8a3 0.727 0.009 0.762 0.21935 0.100 0.589 0.502 0.3,52 0.2122 0.178 0.009 0.010 0.0023

0.00 0.023 0.003 0.012 0.02 0.050 0.062 0.0O5 21.04 I .300 I.400 0.588 0.522 0.706 0.573 0.531 0.2502 0.1042 0.700 0.599 0.097 0.32* 0.299 0.050 0.023 0.032

3.30 0.027 0.009 0.017 0.022 0.000 0.000 0.00 2. 257 02.361 1.150 0.635 D.840 0.605 0.896 0.845 0.5386 0. I'M2 0.833 0.645 0.417 0.02* 0.211 0.070 0.017 0.001

3.00 0.023 0.03a 0.012 0.020 0.030 0.005 0.22 0.2I1 22.35 01.013 22.51 0.-3 0.570 0.000 0.927 0.003 0.50 0.2229 0.093 0.702 0.5043 0.8210 0.048 0.005 0.003 0.055 002

0.50 0.032 0.0(0' 0.020 0.052 0.054 0.220 0.245 0 120 0 2. 397 20.469 22.577 0.732 0.0 0.981,sa 0.958 0.933 0.525 0.2257 0.940 0.7053 0.60 0.5.10 0.2228 0.225 0.032 0.045 002

0.00 0.003 D" 0.003 ' O. 0.052 0.060 0.00020 0.209 0.00 2.40 22.530 22.047 0.7501 0.925 0 920 0.956 0.959 0.50.0 0.2200 0.972 0.807 0.674 0.029 0.31.5 0.210 0.003 0.003 0.)

2.58 0.060 0.000 0.050 0.070 0.022 0.225 0.266 0.021 0.041 1.S27 22.600) C'.702. 0.030 0.05 0.92.7 0.970 0.979 0.557 0.9209 0.990 0.90 0.7&8 0.727 0.329 0.1I5,3 0.000 0.005 0.

2.00 0.000 .0.20 0.090 0.200l 0.002 0.021 0.206 0.356 0 229 21.03 0.406 12.007 0.876 0.972 0 973 0.986 0.992 0.066 0.925 0.999 0.952 0.529 0.552 0.04.4 0.07* 0.006 0.209 0.9

0.50 0.1207 0.249 0.20i 0.620 0.000 0.205 0.335 0.332 0.473 0.052 3.7 55 22.778 22.93 0.920 0.900 0 990 0.990 0.998 0.970 0.2200 L.I0 0.906 0.910 0.830 0 .159 0.273 02237 0.249 0.4

2--50 509 39040 41200 4500 006 7949 09058 51052 .27230 090 7 9.00 11920 23924 15016 21.198 222900 02122 23.20 25106, 07005 09430 31030 33.52 35.26 37025 390.0 01202 529

003 900 0Ur 7005 1.50221 2. 2000J202.,,00107 50-.J-E cOtLo 909-n-0028568 06622.. f , ..06 44 9.271 9..072 2 .2 3. I * 1136130 801.300 . (13901) , 90000UO 4017.9 41211 06r 470 11047 )04 41994- 09001* 00130000

-00 0400 0110o (6(0 se'. 1( l 906 1660 166,0 0001 C I 966'0 166,0 1660. 0 I0 "0". 160 9990 Zle60 1060 1010 I 101' 97(0 Ott 0 060.0 t,i-o odoo mow ito 060

vIllO 0110 ((70 1710C 7690 (tWO 006 0 96610 666'0 99660 99660 99660 9640' (660o ItlS0 1910o lOt 0, 6090 61(0o 1110o 1' 0 6910 6000 6100G 91ICl'0 0

190,0 900 9(0 099,0 1910 E6(60 9760. 066.0 466.0 696'0 (160 1(60 0640' £160 161'0 901.0 W9,09 7900 920. 9010 "910 960'0 0100C 990) (900' 06 I

1(00O O9HIO OttO 6661 90ml.0 (690 966 0 (16 .0 066'0 (76'0 676,0 006 0 (660 6911'0 1110 6190o £060C 461.0 661 ,0 I900 9WO. (900 1000o ((ItO 00

6900 1110 £91 0 E11 I 6(9'0 1190 91.0 676'0 91610 6060 0160Q 6(90 016.4 ((1p10 01990 6tO10 1670 9(1.0 0010 0700 1010o 9700 6900 61(110 06 .1

010:0 1610 711 0 7970 (96.0 715t0 11-0 716.0 (S660 1190D 066 0 9)9-0 61,60 Itt 0 696.0 9(10O 06£E0 7600 7700 910-0 (tOO 1(0-0 010 00

7110o 161 0 1190( 1(6.0 7190 9010 699.0 616)0 919.0a 669'0 111.0 066'0 tzlII E0106 9190 111'C0 69*0 0900 9100 9600o 1009O 06!

1100O (91 0 7960C 6(90 1190 9(90G il'119*0 119 (910 1190 11'.0 961* 02990 (770 0(70 6(0 1909 1000o 0100C 0700 1100 000

9IC'o 6(10 zc01( vs 0 V676 6110Q 0910 6909' 6(10 911.0 199,0 lit'6 6(0EP0 O (6(0MT I1, 1(00 9109o 1(0,0 010'0 069

9(2)0 611 0 9V(0 0 9170 169'0 669'0 69t' 0 99.0 9(10 9190 IW' 656C) 17£'.0 161. 6100,c (I00 910'0 ((00c 001

9000o (010 9610 - 0 9(90 6170 9(90 1010 079,0 969'0 9660o vle,. 6700 660.0 71£ 0 6610c 1100o 110)0 061

000 1900 010 's. 0 01(0 (1(0 7160o (790 (660. 6950 1110. 6410. 60;0 9VOo 7610 9910l 01010 (100 006

900 0 1900l 9710 401'0 660'0 (61'0 910'0 9900 9it(0 1(0 6W)7 7910 910) 9(1o 0100C C0001

900 0 6900 6600 7600 L190-0 660-0 901-0 061-0 (tO'O 6010 111(0 "9010 1900 7600 0(00C III

(1000 700 IOlG 710'0 ((00 9I09 460'0 £910 1010 7t(t~ 9019 6(0,0 190'0 1100C it1

610'0 61000 7900 1900 6(00a 0900 1000 0000

090'0 9(00 910,0 0(00O' 9100' 01010 11010~~~~~~~~~~~~~~~~~~~~~~~~~~~01 0000 9)00~~~~~~~~~~~~~~~~~~~~~~~~~~~~~WD

W000

;o - 11M.- .... tOIl... 00. M l 113612 ~ X l~Ml -11.1IO

Th7ts 40330 90 411.1716 BANGTADESH

AMNC'Jt0E0SL070 7WDY

Ml0Ah23M.Pf.M9IA1.L Mxr.rn.,c. IprIbriro AWIfl tN .Y CoLIJTOIf 3.lyfl 90 (.,,.M... ro urtES -... h. y..-ra 14.cnsto . fr-I .. k T87001%

P... .hbhhtit.. 6,2....f p.abIltIf b t.,r NIh. berto I... th.. 0.1 h .- -O bn. give, On.)

2.0.02 35.00

15.00 20.00

15.00 0.010 8.0021 0.095 0.009 0.319 0.0190 0.20. 0.0)13 0.010 02.03 0.021 0.020 0.021, 0.193 0.063 0.166 0.001, 0.113 0.01.1. 0.O1? 0.011. 0.020 0.0005 13.02 0.001 0.0001 0.0515 0.297 0.112. 0.138 0.1. 0.20.1 0.0500 0.0.1 0.037 0.01.8 0.029 6.00 0.010 0.01.7 0.221 0.2)2. 0.201) 0.62) 0.371 0..0% 0.37&1 0.SX? 0. 386 0.20 0.229 0.171. 0.110 o.c81. 5.10 0.002 0.03 0.0-63 0.260' 0.2721 0.)31r 0.66B 0.1.22 0.553 0.1.2d 0.0010. 8.1.2 0.269 0.219 0.001. 0.1)3 0.032 5.00 O~~~~~~~~~~~~~~~~.010.019 0.010 0.006 0.3106 0.32:1 0.36,3 0.716 0..09 0.617 0.2.0, 0.6415 0.4116 0.323i 0. 320 0.232 0.10. 0.000 0.013 1..03 0.020 0.027 01.312 0.100 0.2172 0.376. 0.41.0 0.706 0.09 0.0,05 0.5.7' 0.701, M.01 0.0105 0.1.5 0.203 0.002 0.C006 0.M33 h.00 0.01D~~~~~~~~~~~~0.028 0.01. 0 .019 0.160 0.1.70 0.1.31' 0A.1.9 0.013 0.601. 0.752 o.610 0.76:1 0. 6205 0.1.96 O.1.00 0.327 0.216 0.317 0.019 3.03 0.010 0.039 0.000 0.-031 0.236 0.530. 0.5005 0.57:L 0.001 0.671 0.010 0.661. 0.0165 0.6g6 0.0:,0 0.062 0.3251 0.256 0.097 0.02? 7.03 0.012 0.021. 3.031. 0.001. 0.01. 0.272 0.00L 0.00), 0.0632 0.891. 0.739 0.872 0.703l 0.06 0.730 3.033o o.61,8 0.1.J 0.331. 0.127 0.0139 2.51 0.031 0.01.1 0.075 0.122 C1.079 0. ]IS 0.661 0.661. 0.791 0.02 0.016 0.930 0.833, 0.91L 0.026 0.7)6 0.7?.0 0.5141 0.362 0.167 0.006 2.30 0.013. 0.0338 0.066 0.119 0.17T C0.126 0.162 0.701, 0.71.0 0.016s 0.907 0.009 0.007 0.001 0. 211 0.898 0.756 0.816 0.591. 0.AR3 0.219 o0.363 1.00 0.0)9 0.o67 0.110 0.11. 0.255 C1.231 0.589 0.032 0.8211 0.03:1 0.97 9 0.921. 0.902 0.931. 0.971 0.91.7 7.872 o.&16 0.6113 0.01L6 0.286 0.110 1.00 0.060 0.027 0.121 0.101 0.211. 0.367 l.322 0.732 0.9l1. 0.9621i 0.903 0.699 0.967 0.202 0.972 0.09I 0.981 0.915 0.0:6 0.7213 0.1.2 0.371 0.1066 0.023 . 0.000 0.000OO 0.127 0.111 0.223 0.298 0.317 0.52h 1.50.18 0.077 0.972 0.9721 0.909 0.999 0.993 1.030 0.990 0.M0 0.997 o.900 0.91,2 0.0221 0.70 0.1.79 0.21.1 O.C0w 0.233 0.10I

2 ..916 3971.1 11..l' * 13.1. 4510.16 4?17.18 *19.50 51.02 1.2 *'3.1 506 7.05 9.10' 11.131 13.11. 15.16 17.15 19.07 21.22 * 23-21, 25.26, 27.28 29-0.1 3032 33'.0) 35.36 P375 39.1. kl0.1.2 1.3.1 -t -~~~~~~~~~~~~~~~~~~~~~~~~~ERX, -rJLY oiamXTEI - ,SLM'E

oorOO mi~~0* , 001300200000 P0022000* 09011, * 10073010 * 3112.7 * 0,301W1 * 000213300 0013000 01501006

wI- o-- 1l APPENDTY 3 * Table 6

0 0 o 0S 0° 0 0 0 0 f

0 o o o o 0 o 0 o o o ,

0 E

'P~~ - 0 ~~~~0 0 0 0t 0 0 0 -G,__ i~~~ n o ooooo oo e0~~~~ I~~~~~~~~

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Wi~~ S0 ~0 ~0 ~~0_=R°e

-' o 0 0o o0 0o o0o 0 0 0 0 0 0 0 o _

^|o o K 85 _@ _o oX- 1 eD _| 9 7 _S O O OOO O OO OO O O_.g

^ W = t o o _ w S ° e ^ X b S > > e. o _~~~~~~~~~

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u~~ f 2

ffi^ : ¢ _ = . o o O O o0

7 W 5 0 S = = _ 4 ,^ oK e _ 2 | _~~~~~~~~~~~~

| vcy uc BANGLAD)ESH-

AM007111.0C01011SP!fl77 I=0l' .

3 (W..,0. . a-.b..d f-. I th-zS YP i%1. 29.o ,,a.. ng .u U. tr. t * M-,d)

iA"oAu (1.u~VhbobA of pla,bisil&m.6 tt. 1e,T2b.V. 8h.010 6.. - b. 0St.. 00*

30.00 25.00 0.4283 0.010 0.010 80.00 0.040 0.451 0.0" 0.032 0,015 OA.* 0.0!? O.018 0.02 15.00 ~~~~~~~~~~~o.106 ~~~~~~~~~~~~O.Cea0.090 0. D9! 0.I00 0,060 0.03 14.078 o.086 08.023 0.000 0.O5 0.00 12.00 0.161 0.a4v. 0.158 0.416 0.190 0,83)3 0.081 0.152 0.139 12.067 0.090 0.106 0.C21 10.00 0.100 0.0497 0.122 0.213 0.253 0,1219 O., he 0.233 M.U2 4.129 0.151 0.157 0.037 C.OD 0.010 0.011. 0.OW. 0.200 O.:0.z 0.1,50 0.665 0.575 0,.522 0.136 11.503 01.515 2.1.6 0.396 0.337 0.121

5.50 O.010 0.019 0.061. 0.316 0.391 0.J,%1 0.T15 0.621 0,.573 0.1.90 11.52. 1).064 0.171 0.4.12 0.379 0.14.0 5.00 0.015 0.027 0.081 0.]356 0.1,01 0.512 O.206b 0.667 0.,626 0.53.7 11.596 11.615 15.531 0.1.91 0.1.6 0.163

h.50 0.021 0.037 0.111 0.102 0.512 0.579 0.810 0.715 0,000o 0.607 0P.&A, 44.060 0.5A4 0.51.3 0.1.25 0.190 LOD0 0.010 0.035 0.651 0.11.? 0.152 0.1179 0.4636 o.855 0.252z 0,731. 0.610 11.016 (.72i 2.660 0.597 0.4.80 0.221 3.50 0.0141 0.011. 0.052 0.071 0.192 0.500 0.630 0.671. 0.893 0.006 0.1707 0.733 c0.71 1).771. 2.726 0.657 0.531. C.258 0.010 0.00 3.00 0.011 0.013 0.023 0.079 0.091 0.251 0.569 0.7120 0.7725 0.927 0.052 0,039 0.791. 11.99 oA.26 23.791 0.216 0.U1 0.30 0.016 0.011 2.50 0.000 0.U0 0.038 0o110 o.,38 0.326 0.636 0.7?! 0.1?? 0.055 0.8a1. 0.006 0.853 0.01.0 o.011. 2.052 0.77T5 0.638 0.351. 0.OSB 0.018 2.00 0.036 0.01 h 0.0161 0.065 0.176 0.193 0.1.21 0.100 0.0158 0.1130 0.9176 0.930 0.,927 0.905 (4.091 01.917 42.906 0.032 0.695 0.1.16 0.052 0.02 1.50 0.059' 03.001 0.C76 0.110 0.261 0.272 0.539 0.101. 0.417 0.j8a2 0.9"0 0.900 0.,960 1.91.8 o.936 o.953 D.0.9 0.801 0.755 0.1.90 0.005 0.069 I.OD 0.100 0.006i 0.071 0.1319 0.190 0.305 0.307 0.600 0.861. 0.1463 0.93' 0.993 0.903 0.901. 0.979 81.900 4.900 o.988 0.920 0.819 0.502 0.125 0.00. 0.50 0.000 *.am 0.000, 0.172 0.101. 0.191, 0.26', 0.335 0.559 0.562 0.038 0.11.1 0.1192 0.M9! l.00 0.196 0,991 0.996 8.992 11.96 42.997 0.959 0.002 0.698 0.323 0O11.1 0.00 0.00 0.00

2-..o,*39410 .. * 61.1. * 13..1 * 15.1, * 87.1.1 * 19.54 51.5.1 * .2 *3.1. 5.6 *7.08 9.10 * l,,2 *13.11. 15.16 *17.18 111.20 I21.721 32.:57* 1.0*2.0*3.2 *3.3 53 7 * 39.0. * 1..12 k 3.1.2

MDQUfl4 I ANU0R0 I'000A6!. I 1RC10 02fl I AT Allt JOLT 00075r S EPTEKBIIA 007O02 * 0004.I.9 * c0000 BANGLADESH

15.00~~~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~~~ ~~~~~~~~~~~~~~~~~~~~~~~AI)0

2.0.02

25.02 20.00 0.010

150w 0.010 0.010 0.08 0.010 o.013 0.020

1..00 0,010 0.038 0.092 0.056 0.032 0.027 0.038 0.021 0. 12

10.02 0.024 0.058 0.156 0.113 0.00 0.01.4 0.077 00.1XL 0.019 5.0r1 0. an

6.0OD 0.015 0.010 0.011 0. 158 0.231 0.2.10 0.401 0.272 0.247 0.281 0.318 0..235 0.198 0.065

5.50 0.02 0.001 0.018 0.195 0.272 0.457 0.2.52 0.129 0. 29 0.J337 0.12b8 0. 280 0,225 0.080

5.02 0.027 0.017 0.020 0.041 0.319 0. 502 0.528 0.371 0.355 5.386 0.;186 0,333 0,256 0.100

4.50 0.010 0.010 0.021 0.016 0.295 0.372 0.063 0.526 0.430 0. h26 0.1.4 0.232 0. 392 0.292 0.1324 0.00

6.0OD 0.012 0.017 0.011 0.7073 0.358 0.435 0. 620 0. 654 0.2.91 0.51 03.509 01.287 0.459 0.332 0.153 0.03.2

3.00 o.on- 0.010 0.020 0.6 0,6 011 0.430 0. 502 o 68 0.2 0.5 0.585 0.578 o.352. 0.533 0. 378 o.My 0.010 3.00 0.018 0.013 0.031 0.010 0. 015 0.105 0.173 0. 51 0.574 0.741 0.791 0.638 0.669 D.652 0.2,33 0. 612 0.2.1 0.235 0.028 0.mo0

2.50 0.029 0.022 0.010 0.050 0.016 0.115 0.165 0.250 0. 60 0.651 0.802 0.851 0.71A 0.756 D.729 0.525 0.692. 0.4917 o.zvo 0.013 0.0X22

2.02 0.016 0.037 0.010 0.010 0.090 0.029 0.155 0.22.6 0. 376 0.692 0.739 0.860 0.909 0.7?85 0.839 2.805 o.628 01.775 0.560 0.358 0.026 0.0on

0.50 0.0U74 0.010 0.065 0.019 0.059 0.1IL0 0.057 0.209 0.362 0.529 0.1781 0. 824 0.913 0.950 0.858 0.931 0.878 0.739 0.85o 0.639 0..21j 0.103 0,040

1.02 0.122 0.029 0.3.10 0.050 0.082 0.236 0.085 0.200 0.511 0.705 0. 859 0.003 0.0958 0.955 0.916 0.962. 0.92.0 'D.852 0.912. 0.731 C.510 0.162 0.873

0. 50 0.~ 0.00 0.00 0.208 0.103 0.198g 0.135 0.177 0.370 0.171 0.393 0.677 0.867 0.913 0.969 agmO 0.997 0.955 0.993 0.982. 0.0950 0.955 0.383 C.657 0.251 0.137 0.00 0.02m 0.02m

8- r1o 79.40 41.42 6431.4 45-.45 I 47428 49.50 51.52 1.2 34. 5.6 7.8 9.10 11.12 13.31 15.30 07.15 19.20 21.22 23.22, 25.26 27.280 2MO3 3a-32 13.34 ' 75c6 373 .*02.6 2.3-2.

INSM JUa8'Y 80802681' Wu07 PF0IL MTY JU11 001. 6A2l? 0noCOYos MDVMEIR

I.4 ci! BANGLA DES H

AGRICIULTUrRESECTOR STUDS

AMUNTS OF RAINFALL EXI'ECTED TO BE REACHED OR EXCEEDED IN ANY rwo-wEEK RUNNING PERIOD

BARIS...

MONTH 2-Week Approximate :Probability Nine Years Ouit of Ten Flour Years Out of FiLve three Y'ears Ouitof Four Tw,o Years Out of Th,zee** One Year out of T,, irunning Growth of (907. probability) (807. probability) (757. Probability) (657. Probability) (507. Probability) I?eriod* Period :ZeroRainfall (7.) (inches) ~~~~~~~~~~~~~(inchesi-(icesinches) _ _inchs) XCOV-DEC (39440) 78.1 _ECUUER (140+41) 78.7 DE!CIŽ3ER (414.42) 100.0 DD_Z:-2ER (42+43) 100.0 DEC_-JAN (43444) 100.0 Di:(--JA' (44+45) 76.6 JA'.;U:ARY (45+46) 7 2. 7 jA:,VA;RY i(46447) 78.7 JA:7UA?,Y (47448) 63.6 JAN-FE3 i(48+49) 54.5 FEiF,UARY (49+50) 68.5 FEiRU"ARY (50+51) 54.2 FFI11.UARiY (51+52) 40.0 F U3- MAR (52+1) 54.5 0.15 MARCH (1+2) 57.5 Y.AJISC (2+3) 30.3 0.03 0.22 Y.ARCH (3+4) 24.2 0.10 0.38 MAR- AP7 (4+5) 33.3 0.04 0.38 M~lAn--P (5+6) 25.0 0.11 0.36 APR IL (64-7) 27.7 0.09 0.44 A?IRIL (7+8) 11.1 0.32 0.47 0.78 1.30 A?R-M.AY (8+9) 8.3 0.27 0.42 0.75 1.37 APR-MAY 1(9+10) 3.2 0.18 0.50 0.67 1.06 1.77 MAY (10+11) 9.6 0.02 0.48 0.70 1.15 1.95 MAY (11+12) 3.2 0.23 0.61 0.82 1.28 2.11 MAY i(12+13) 3.2 0.33 0.87 1.16 1.81 2.99 MAY-JUN (13+14) 3.3 0.38 1.00 1.33 2.08 3.44 MAY- JIN (14+15) 0.0 1.69 2.68 3.15 4.09 5.63 JU7.NE (15+16) 0.0 2.65 3.95 4.55 5.74 7.64 R'INE (16+17) 0.0 2.41 3.63 4.19 5.30 7.07 jUN-JUL (17+18) 0.0 3.37 4.49 4.98 5.91 7.31 JU1N-JU LL (18+19) 0.0 3.24 4.47 5.01 6.05 7.66 J U:.Y (19+20) 0.0 3.49 4.67 5.18 6.16 7.65 J ULY (20+21) 0.0 2.67 3.65 4.09 4.92 6.21 JU'-AUG (,21+22) 0.0 2.83 3.82 4.26 5.09 6.36 JUU -AUG (22+23) 0.0 4.37 5.44 5.89 6.73 7.97 AUGU.ST (23+24) 0.0 3.56 4.65 5.12 6.01 7. 35 AUGUST (24+25) 0.0 3.29 4.36 4.83 5.71 7.05 AUGUST (25+26) 0.0 3.09 4.05 4.47 5.25 6.. AUG.-SEP (26+27) 0.0 2.32 3.09 3.42 4.05 5.01 AUG-SEP (27+28) 0.0 1.98 2.81 3.19 3.91 5.05 SE?K-~3ER (28+29) 0.0 1.66 2.41 2.74 3.40 4.44 S E? I?E R (29+30) 0.0 1.34 2.13 2.50 3.25 4.47 SEP-OCT (30+31) 0.0 1.34 2.20 2.61 3.44 4.83 SE?-')CT (31+32) 0.0 0.98 1.69 2.04 2.76 3.99 OCTGlE3-R (32+33) 6.0 0.45 1.17 1.50 2.17 3.29 OCTOSIER (33+34) 0.0 0.30 0.67 0.88 1.35 2.23 OCTOBER (34+35) 17.6 0.21 0.64 1.52 Ocr-1:07 (35+36) 33.3 0.4.2 NCU..:3ER (36+37) 51.5 Ip. ER (37+38) 51.5 (38+39) 757 I N;C'-DEC (39440) 78.1 DECE~:BER (404+41) 78.7 \ DECE~3ER (41442) 100.0 DECE:'BER (42443) 100.0 DECM3ER (43+44) 100.0

*Weeks, are ninsbered, from I throughi 52, startiing witb the fiLrst week of M.arch. 5*Two year. oujt of three oir about. BA NISADSH

AGRIICULTURE SECT'OR STUDY

AJ'IOUNTSOF RAINqFALL EXPECTED) TO BE REACHED OR EXCEEDED IN ANY TWO-WEIEKRUNNING PERIOD

BDOGRA

MONTH 2-Week* Approximate! Probab-ility Nine Years Out of Ten Four Years Ouit of Five Three YCears Out of Four Two Years Out: of Three*-* One Year Out of Two running Growth of' (907.Probability) (801, Probability) (757.Probability) (657.Probabiility) (507.Probablility) Period* Per-iod Zero Rainfall ______nc______e______(7. (inches (inches)I:nce) (inches) (Tnches;)

\N7- DEC (39440) 100.0 DEC:~IBU (40+41) 100.0 DECEI3EF. (41+42) 100.0 DECIM ER, (42+43) 100.0 DEC- IKE1 (43+-44) 10O.O0 DEC-JAN (44+45) 76.6 .'ANUARY (45+46) 68. 7 J.AŽW:ARY (46+47) 62.5 JANUARY (47+48) 56.2 JAN -FEB (48+49) 5,6. 2 FESRUARY' (49+50) 53.1 FEbRUARI' (50+51) 48.5 FEBRUARY (51+52) 48.5 00 FEB-MAR (52+1) 42.8 00 !MAISOC (1+2) 48.5 MARCHI (2+3) 5,4. 2 MARCH ~~~~~(3+4) 54.2 01 MAR-APR(4+5) ,VLR-APR(4+5)~~~~~~~42.8 01 SttR.APR (5+6) 44.4 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~0.08 APRIL (6+7) 41.6 oo APRIL (7+8) 19.4 0.04 0.17 0.4.9 ApP.-M.AY (8+9) 14.7 0.10 0.21 0.46 0.94 APR-M.AY (9+10) 6.0 0.08 0.34 0.49 0.83 1.45 MAY ~~~~~~(10+11) 3.0 0.23 0.52 0.70 1.10 1.83 MAY(11+12) ~~~~~~~~~~~~~~~~~~~~~9.30.10) 0.79 1.07 1.61 2.51 MAY (12+L3) 0.0 0.77 1.35 1.63 2.22 3.21 ILRY-JLUN (13+14) 0.0 1.03 1.67 19 .136 ?'AY-JLN (14+15) 3.0 1.66 2.41 2.76 3.43 4.49 JrM.,E (15+16) 0.0 1.77 2.68 3.11 3.95 5.29 JUNE 167)0.0 192.73.42 4.32 5.75 J LN -J L (17+18) 0.0 1.22 2.05 2.45 3.27 46 JLYNJUtL (81)0.0 .72663.10 3.99 5.41 JILLY (19+20) 3.0 1.76 2.82 3.28 4.18 55 JiLLY (20+21) 0.0 2.21. 3.00 3.35 4.02 5.03 JUL-AUG (21+.22) 0.0 1.02 1.86 2.28 3.17 4.71 ILL-AUG(22+23) ~~~~~~~~~~~~~~~~~~~0.01.710 2.62 3.05 3.91 5.29 AUL-UST (23+24) 0. .32.90 3.29 4.04 5.23 AUGUST (24+25) 0.0 1.68 2.61 3.04 3.92 5.33 AUGUST (25+26) 0.0 2.29 3.21 3.62 4.40 5.62 AUG-SEP (26+27) 0.0 1.99) 2.76 3.11 3.78 4.81 AUG-SEP (27+28) 0.0 1.62 2.30 2.61 3.20 4.17 S E PTEME?ER (28+29) 2.8 1.25 1.99 2.31 2.92 3.89 S EPTEM~EER (29+30) 0.0 1.3.2 1.97 2.27 2.86 3.81 SEP-OCT (30+31) 0.0 0.53 1.12 1.44 2.15 3.46 SEP-OCT (31+32) 5. 7 0.27 0.90 1.23 1.97 3.30 OCTOLER (32+3 3) 8.5 0.06 0.52 0.77 1.30 2.27 OCGOOER (33+34) 17.1 0.19 0.147 1.05 2.02 OCTORER (34+35) 20.0 0.140.481.1 0O-T-N,OV (35+36) 40.0 NCVFY1E!E0. (36+37) 61. 1 XYIEMEER. (37+38) 7 2. 2 NOVEMBER ~~~(38+39) 7 7 .7 NOV-DEC (39+40) 100.0 DECLMbER, (40+41) 100.0 0 V DECIMBER, (41+42) 100.0 DECEMBEE. (42+43) 100.0 DECM'ER (43.44) 100.0

*Weels are numbered froma I through 52',starting with tha first week of! March. ~'Two years out of three or about. BANGTADFSH

AGRICULTURE SFCTOR STUDY

AI6OtJJrS OF RAINFALL EXPECTED TO BE RF-.ACHEDORl EXCEEDED IN AN~YTWO-WEEK RUNN~ING PERIOD

CHrITA GONG

MIMIrn 2-Week ALpproxiimate Probability Nine Yeara v.ut of Tem Four Yeairs Out of Fivet Three Years Out of Four Two Yearis Out of Three** One Year Out of- Two rUTnning Growth of (90% Probability) (80% Probability) (75% ProbabilILty) (65% Pirobability) (50%. Probability) ___ _ Per iod* Period Zeiro Rainfall______M% (ich-es) (itiches) - (inZhes (in.hes)T_

!"07-DEC (39+40j 76.4 DECE'MER (4+41i) 64.7 DECEP3ER (41+42) 76.4 DECE23ER (42+43) 7. DE_C-JTAN (423+44) 100.0 DEC-JAN (44,+45) 79.3 (45~+46) 67.7 JA!_L_ATRY (464-47) 70.9 JA:.-:A,RY (47'+48) 70.9 JA~-FEB '48+49) 70.9 F ~_RR_ARY (494+50) 61.7 FZHRP.ARY (504-51) 52.9 FF3R'QARY (51452) 35.2 0.165 FE13-MA (521+1) 44.1 0.00) Y~.Rcll (I1+2) 50.0 0.00) YARCMI (2-13) 38.2 0.42 Y.A1C'C (3+4) 38.2 0.40 XLAR-AP2R (4+5) 44.1 0.00) Y.kR-;,PR (54.-6) 31.4 0.30) APIKIL (6+-7) 28.5 (p.11 0.60 APRIL (7468) 11.4 0.31 0.52 0.96 1. 73 AFR-5'AY (8+9) 20.0 0.00 0.15 (i.61 1. 60 A?R-MAY (9+110) 12.1 0.38 0.64 1.21 2.24 Y'Ay (IC'+11) 15.1 0,32 0.67 1.26 2.40 YAY (11+12) 3.0 0.45 1.04 1.34 1.98 3.10 MAY (12+13) 6.0 0.95 1.99 2.43 3.27 4.61 MAty-JUN (I13+14) 6.2 0.70 1.81 2.31 3.33 5.02 MAY-JUN (14+15) 2.9 2.11 3.60 4.27 5.60 7.71 JU7NE (15+16) 0.0 2.46 4.21 5.07 (P.84 9.82 .1't'NT ~~~(16+17) 0.0 4.45 6.07 6.78 El.15 10.25 JUN-JUL ~~~(17+18) 0.0 2.23 3.57 4.20 5.48 7.58 JUN-_JUt (16+19) 0.0 3.04 4.88 5.75 4.5 2 t0.43 JULY ~~~~~(19+20) 0.0 3.40 5.51 6.53 El.59 11.99 JU'LY (20+21) 0.0 2.40 3.86 4.56 5.98 8.31 JUL-AUG (21+22) 0.0 3.04 4.39 5.00 6.18 8.05 JS.L-IAUG (22+23) 0.0 3.74 5.51 6.31 71.90 10.41 A'L.7-.ST (23+24) 2.8 3.19 5.11 5.94 7'.57 10.10 ALUG-ST (24+25) 0.0 2.25 3.76 4.50 6.01 8.54 AUGUST (25+26) 0.0 1.91 3.24 3.89 5.23 7.46 .AUIG-ESEP (26+27) 0.0 2.24 3.32 3.82 4.79 6.35 AUG-SEP (27+28) 0.c 2.93 3.74 4.09 4.75 5.72 sn:2~~~~t~ (28+29) 0.0 1.81 2.65 3.03 21.78 4.97 s -)I i (29+-30) 0.0 1.33 2.38 2.78 3.37 4.B7 SEP-rGCT (30+31) 0.0 1.49 2.34 2.75 3.55 4.87 SEP-OCT (31+32) 0.0 0.59 1.17 1.48 2.16 3.38 MCOBER (32+33) 0.0 0.84 1.37 1.63 2.15 3.00 (CIO-!E (33+34) 2.8 0.71 1.27 1.53 2.04 2.88 0CTO5IE (3.4+35) 17.1 0.26437 16 OCT-,0:C' (35+36) 34.2 04 .3R (36+37) 51.4 H NO'.E2ER (37+38) 54.2 NO'.ZNER (38+39) 74.2 NO'.':EC (39+40) 76.4 DECE`:ER (4C+41) 64.7 DErZNEp. (41-42) 76.4 DECrE3ER (42+43) 79*4

~eeksW are nimb,ered from I through 52, starting with tlhe first week of March. *.'v o years out of thre, or sabout. BANGLADESH

AGRICULTU'V SECTOFRSTUDY

AMOUNiTSOF' RAINFALL EXPECTED T.O BE RE,ACHEDOR EXCE-EDEDIN ANY TWO-WEEKRRUNNNNING PERYOD

Cff~tILLA

MCNTH 2-Week Approximate Probability Nine Years Out of Ten Four Yeairs Out of Five Three Years out of Four Nro Years Out of Three"* One Yea,r Ourt of Two running Growth of (907.Probability) (807. Probability) (757.Probability) (65% Probabl.lity) (507.ProbabilIty) Period* Period Zero Rainfall ______(%) (inches) (inches) (ILnches) (inches) (inches) _

%C.'--DEC (3944cC) 80.0 D IC -, 33ER (40+41) 81.2 DiC:MBEtR (41+42) 100.0 DEEC7YIER (42+43) 100.0 D I_C- JAN (43+44) 100.0 3C-C-JAN; (44+4.5) 100.0 JAN:'.ARY (45+4 6) 74.1 JAUA.'kpY (46+47) 70.9 JAN"AS Y (47+48) 67.9 JAN'-FFI (48+49) 67.7 FEEC?UA?Y (.49+50) 52.9 FICCUARY ~~~(50+51) 52.9 FICU-Y (51+52) 50.0 FIM.AR (52+1) 39.3 0. 05 (1+2) 39.3 0.09 -H(2+3) 30,3 0_09 0.43 C (3+4) 30.3 0.16 0.56 MA?.-APR (4+5) 27. 2 0.11. 0.43 M.A.1-APR (5+6) 14.7 0.08 0.17 0.37 0,72 A??'L ~(6+7) 2 3.5 0.00 0.17 0.74 1.50 Ai-?.IL ~~~(7+8) 2. 9 0.21 0.58 0.791.625 A;.M. 0(.+9) 11.7 0.00 0.31 0.57 1.24 2.53 AIS-NAY ~~~(9+10) 3.2 0.31 0.88 1.19 1.91 3.25 (10+41) 0.0 0.57 1.08 13 .125 iA.Y (11+12) 0.0 0.85 1.47 1.79 2.43 3.52 MAN ~~~~~(12+13) 0.0 1.63 2.58 2.99 3.86 5.28 MAY-JUN ~~~(13+14) 0.0 1.65 2.73 3.26 4.33 6.11 ?.AY-JLTN (14+15) 0.0 3.00 4.36 4.97 6.17 8.06 RYE ~~~~~(15+16) 0.0 4.12 5.70 6.40 7.75 9.64 (16+1.7) 0.0 4.42 5.76 6.33 7.42 9.06 .P2-JLUL (17+18) 0.0 2.00 3.18 3.73 4.86 6.70 ill '-JU L (18+19) 0.0 2.87 4.15 4.73 5.86 7~.64 JUL:L? (19+20) 0.0 2.84 4.22 4.85 6.10 8.08 il'L'f ~ (20-421) 0.0 2.56 3.74 4.27 5.32 6.98 JUL-AUG (21+22) 0.0 2.62 3.81 4.34 5.39 7.04 JU_L-AUG (22+23) 0.0 3.31 4.57 5.12 6.19 7 .83 AU'GUST (23+24) 0.0 3.74 4.73 5.15 5.94 7.I2 AUGUST (24+25 ) 0.0 2.87 3.97 4.45 5.39 6.83 AUGUl.ST (25+26) 0.0 3.16 4.15 4.58 5.39 6.61 AUGI-SEP (26+27) 0.0 2.57 3.48 3.88 4.65 5.82 AUG-SEP (27+28) 0.0 1.97 2.78 3.14 3.84 4.93 SEP7cYER (28+29) 0.0 1.87 2.65 3.00 3.68 4.7 3 SE?IU-, IER (29+30) 0.0 1.84 2.65 3.02 3,74 4.,87 SEP-OCT (30431) 0.0 1.82 2.57 2.91 3.56 4.58 SEP-OCT (31+32) 3.2 0.53 1.24 1.61. 2.40 5.81. OCTLNE('R (32+33) 3.0 0.45 1.10 1.44 1.57 3. 52 OC10BER (33+34) 9.0 0.06 0.65 0.94 0.78 2.69 1,95 OCTYGBIER (34+35) 27.2 .6 OCT-NC'.' ~~(35+36) 34.3 06 _____ ~~~(36+37) 53.1 UOI2R (37+38) 53.1 Jo'.-Z3ER (38+39) 62.5 NC7- DEC (39+40) 80.0 CDs DEC IYB FR ('40+41) 81.2 DFcC>EIR (41+42) 100.0 HH> OECCiCCER (42+43) 100.0 DECFY-EtR (43+44) 100.0

*Weeksi are numbered froym IL through 52, start8nrg with the first week of Miarch. ** To years, out of three or about. BA]NGLA2DE3H

AGRLCULTIURESECTOLR _STUDY

AVIOUNTSOF RAINFALL EXPECTED TO BE RIACHEI) OR EXCEEDED IN ANY TWO-WEEF RUNN[INGPMIOD0

DACCA

MONTH 2-Week Approxim~ate Probalbility Nine Yfears C-ut of Ten Four Years Out'of Five Three Years Out of Four Two Years Out of Three One Year Out cf Two running Girowth of (901 Probability) (807.Probability) (757. Probability) (657.Probability) (507.Probability) Periodk Period Zero Rainfall ______(O.) (inches) (inches) (inches) (inches) i~i

NCV- DEC (39+40) 1003.0 DKCDS ER (40441) 8L.2 FCE!2E5 (4l4-'+~2) 100.0 DECD[BE (42+43) 100. 0 DEC-JA2i (43444) 8:1.2 DEC-JAN (44445) 67.8 JAN`7ARy (45446) 70.9 JAN-UARY (46447) 67.7 JASUARY (47448) 54.8 JAIN-FEB (48+49) 55. 1 FEBRUARY (49+50) 54.8 FE~ IuIt.ARY (50+51) 5L.6 FEBRUARY (51+52) 5:1.6 FEB-MAR (52+1) 583.0 MARC (1+2) 45.4 0.04 MAIRCH (2+3) 27.2 0.11 (0.43 M.AYCH (3+4) 27 .2 0.18 (0.56 .AR -AYR (4+5) 30.3 0.05 03 MAIR-APR (5-+6) 1'5.6 0.11 0.26 0.53 Ail?,IL (6+7) 12.5 0.30 0.45 0.77 1 .29 4 AFRIL (7+8) :1.1 0.41 0.77 0.94 1.28 1L.8 AFPR-MAY (8+9) :3. 1 0.27 0.68 0.90 1.39 21.27 AFR-?,AY (9+10) 0).0 1.11 1.73 2.02 2.60 3.54 M.AY (10+11) 15.2 0.47 1.17 1.48 2.10 3. 10 MAY (11+12) ). 0 1.05 1.67 1.96 2.56 3. 53 MAlY (12+13) :1.1 1.14 1.87 2.18 2.80 3.76 M~AY-JUNX (13+14) 0.0 1.43 2.10 2.40 3.01 3.96 M.A,Y-JLN\ (14+15) 13.0 2.44 3.31 3.68 4.41 5.52 J LNE (15+16) 0).0 2.91 4.11 4.64 5.68 71.30 JUNE (16+17) 0.0 2.00 3.12 3.64 4.70 6.41 Ji'%-JUL (17+18) 4).0 1.73 2.54 2.92 3.65 4.82 JUN-JUL (18+19) 0.0 1.75 2.63 3.04 3.84 5.14 JU'LY (19+20) 0).0 2.72 3.62 4.01 4.75 5.88 JUILY (20+21) 0.0 2.00 2.75 3.08 3.72 4.70 JVL- AUG (21+22:) 0.0 1.83 2.65 3.02 3.74 .. S JLUL-AUG (22+2 3 0.0 2.26 3.28 3.75 4.65 0 AU'GUST (23+24) 0.0 2.63 3.65 4.10 4.96 6.30 AI'GUST (24+25) D.0 2.05 3.03 3.48 4.36 5.76 AUGUST (25+26:) D.C 1.98 2.78 3.13 3.82 4.,89 AUGr-SEP (26+27) 0.0 1.40 2.04 2.32 2.88 3.77 AL'G.SEP (27+28) 0.0 1.35 1,98 2.26 2.83 3.71 sflP7~E3ER (28+29:) 31.2 1.08 1,83 2,16 2.82 3.85 SE-PTD3EIR (29+30) 31.2 1.37 2.10 2.41 2.99 3. 87 SEP-OCT (30+3t) 0.0 1.10 1.68 1.94 2.4 7 3.32 SEP-OCT (31+32.) 3.3 0.40 0.90 1.15 1.67 2.59 OCTOBER (32+33) :).1 0.30 0.70 0.90 1.32 C.08 OCTrj1ER (33.l34) IS.2 0.07 0.34 0.50 0,07 (.58 OCTOBER (34+35) 15. 6 0.09 0.23 0.54 (.15 OCT-SOV (35+36) 40.0 (0.41 3 NCl7 LMER (36+37:) 58.0 C,1 2Q"i2ER (37+38:) 64.5 N0'EME3ER (38+39: 77.4 C NFTI-DEC (39440) 10(3.0 DECLFYBER (404+41:) 81.2 DECEMIER (41442) 100.0 DECC2EMER (42443:) 100.0 DECEZ-BR (43+444) 'L.2

*Week,s are numberedi from 1 throuigh 52, starting withi the first wetek of )larch. *STwo years out of :hree or about. BANGLADES H AGR.ICUL~TURZN SECTOR STUDY

AMOUNrS OF RAINFALL, EXP1ECTEDTO BE REAI3IED OR EXCEEDED IN ANY TWO-WEEKRUNNING PERIOE'

4011IT14 2-W4eek Akpproximate Probability Nine Years Out of Ten Four Years Out of Five Three Years Out of Four Two Years Out of Three** One Year Out o11 T,wo runining Growth of (907. Irobability) (807. Probability) (757.Probability) (657. Probability) (50% Probabill.y) Period* Period Zero Rainfall - -(nhs)(nhe (7. (inches) (inches) (incescnenhes

NOV- DEC (39440) 81.2 DECI2!~E? (40441) 100.0 DECE2ER (4:1+42) 100.0 DECE,MIER (42443) 100.0 DEC-1JAN (4:3+44.) 100.0 DEC-JANT (44445) 100.0 JAN~UARY (45446) 62.5 J..,ANURY (46447) 59. 3 JAN-IARY (474+48) 62.5 JAN-IFES (48449) 65.6 -'EBRUARY (49)+50) 54.2 00 ETBKAP.Y ~~(50+51) 42.8 0.09 1BUARY (511+52) 45.9 00 F El -"AR (52+1) 57.1 0.00 Ž!AACH (1+2) 51.4 0.026.3 yA_?,c,_H(2+3) 34.2 01.02 0.33 Kt RC'i (3+14) 25.7 0.102 0.33 MiA.R-APR (445) 31.4 0.02 02 MAR-APR ~~~(5+~6) 30.5 0.02 .1 0.251 APRIL (6+7) 22.2 0.030.1 0.26 APRIL (746) 11.1 0.37 0.520.012 APR-MAY (849) 5.5 0.28 0.64 0.80 1.11 1.63 APIR-MAY (9+10O) 5.7 0.32 0.75 0.94 I .33 1.96 MAY (10+11) 2.8 0.27 ~~~~~~~~~~~~~~ 0.76 1.12 ~~~~~~~~~~~~~~~~~~~~~~0.601.75 (11+12) 2.8 0.40 0.81 1.01 1.42 2.11 KAY (12+13) 2.8 ~~~~~~~~~~~~~~~~~~~~0.63 0.86 :1.36 ~~~~~~~~0.2422 MAY ~~(13+14) 6.0 .3 0.86 1.13 1.67 2.59 MtAY-LUl (13+15) 0.0 D.1.021 2.49 :3.17 4.27 JVN.E (15+16) 0.0 1.75 2.76 3.234.955 (16+17) 0.0 ~~~~~~~~~~~~~~~~~~~3.38 3.83 4.70 ~~~~2.376.07 JtN-Jtt(17+18) 0~~~~~~~~~~~~~~~~.0 2.15 3.12 3.56 4..42 57 Jt¶-JtL ~~~(17+19) 3.0 1.76 2.94 3.46 4.48 6.03 It LY (m9+20) 0.0 2.71 3.70 4.14 4.97 62 JYLY ~~~~(20+21) 0.0 2.30 3.04 3.36 :3.97 4.90 y.L-AUG (21~+22) 0.0 2.26 3.01 3.34.894 4.88 511L-AUtG (223+23) 0.0 2.48 3.52 3.99 4.9 .0O AUC-UST (2:5+24) 0.0 2.41 3.35 3. 76 4.57 58 AUGUST(24+25) ~~~~~~~~~~~~~~~~~3.11.98 2.79 3.12 ~3. 73 4.64 AUGUST (24+26) 001.49 2.15 2.45 .3.02 3.93 AUG-STP (25+26) 0.0 1.42.00 2 .26 2.74 3.50 AtUG-S;EP (27+28) 0.0 1.52 2.03 2.26 2.68 33 SE?7G~~~~~~~~~(28+29)~~~~~~~~~0.0 1.21 1.72 1.95 2.40 3.1.0 S P1-2VGER (29+30) 2.9 0.89 1.60 192.83.53 SE?-)CT(3(1+31) ~~~~~~~~~~~~~~~~0.00.87 1.55 1.89 2.61 SE?-(XT (30+31) .80.61 1.35 1.67 2.29 3.29 SE?-(rT (31+32)518 1.37 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~2.17 OCIClER(32+33) ~~~~~~~~~~~~~~~11.70.00 0.60 0.86 13 0XOIT,,ER (32+34) 5.8 0.15 0.47 0.63 0.96 1.53 OcCl:(,1: (34+35) 20.5 .14 0.47 1.46 OC,-NO'. (35i+36) 32.3 '.404 M0V':L-ER (36+37) 55.8 !;O'.EMER (37+38) 58.8 NOVE-ER, (3B+39) 6. \01:- DEC (39)440) 81.2 DECE-MER (40441) 62.5 DECE ~ER (411442)

DECEMBEER (42443) 0EGEIBER (4:144~)

**Two years OUt of three or sabout. BANGLADESH

AGRICULTURE SECTOR STUDY

AMOUN4TSOF RAINFALIL EXPECTED TO BE REACHSEDOR EXCEEDED IN ANY TWO-WEEKRUNNIN, PERIOD

MYMEiS INGH

MON-TH 2-IJeek Akpproximate Probability Nine Years Out of Ten Four, Years Out of Five Three Years Out of Four Two Years ODutof Three** One Year Out of Ties ruinning Growth of (90% Probability) (803, Probnability) (757.Probability) (657.Prolbability) (50% Probability) Per iod* Period Zero Rainfall ______(71 (inches) (inclhes) (inches) (inches) (inches)

Ng:-DEC (3R-t40) 100.0 .IICEI'BER (4 0+41) 100.0 r C _-I ER (41+42) 100.0 DEC--.:3FR (4:2+43) 100.0 DEC- jA. (43444) 1D0.0 D !-C- AN (44+45) 76. 6 J~k,7'4izy (45446) 68.7 JAN:;,ARY (4,5+47) 65.6 JANkR y (41448) 65.6 (4E+9).56.2 TEZ?:_Ap4y (49-'-50) 4'6.5 0.02 r 'AR Y (51)451) 50.0 0. 00 r ~?.:Ry (51+52) 45.7 0.04 F Z '-AR (52+1) 31.4 0. 03 0.19 MARCH (1+f2) 34.2 0.00) 0.17 YA-PC'.4 (2+3) 25.7 0.1I4) 0.39 '~ARCi (3-4.4) 22.8 0.06 0.213 0.65 MA~R,AR (4+5) 22.8 0.00 0. 19 0.53 MA-APR (54+6) 11.1 0.4)8 0.15 0.31 0.65 A?:(!L (6+7) 8.3 0.00 0.20 0.30 0.54 0.98 A?RI L (7+18) 2. 7 0.30 0.561 0.77 1.14) 1.65 ,A?R-:'4AY (8+9) 0.0 0.28 0.455 0.86 1.35 2.28 APR-[AY (9-rIO) 0.0 0.76 1.40 1.72 2.39 3.56 AYk (143+11) 0.0 1.28 2 1)0 2.34 3. 02 4.11 MAY (1:4+12) 0.0 1.65 2.43 2.79 3. 49 4.59 MAY (124-13) 0.0 1.01 1.62.13 2.93) 4.21 MY-t J n, (1:3+14) 0.0 1.31 2 28 2.76 3.7-4 5.42 AY-J LN, (14,415) 0.0 2.43 3.151 4.15 5. 23 6.93 JUN:E (+6)0.0 3.41 4. 6I 5.14 6. 1.5 7.69 2E (16+17) 0.0 3.53 4.76 5.30 6.32 7.88 JL1;-.JLL (17+18) 0.0 2.41 3. 48 4.12 5.113 6.86 JLU\-,JL. (18+19) 0.0 3.01 4 09 4.56 5.46 6.84 JUL7 (190+20) 0.0 2.33 3,38 3.85 4.77 6.22 JU'LY (207+21) 0.0 2.33 3.25 3.66 4,45 5.67 JUL-AU'G (2.i+22) 0.0 2.05 2.95 3.36 4. 15 5.40 JUL1-AUG (22+23) 0.0 1.95 2.95 3.41 4.3:3 5.80 AUCG"ST (2:3+24) 0.0 1.93 2 98 3.47 4.4:3 6.04 AtUr~UST (24+25) 0.0 2.02 3.20 3.16 4.816 6.72 A UG'U'ST (25+26) 0.0 2.20 3.25 3.72 4.6? 6.16 AL-C-SEP (2,5+27) 0.0 1.90 2. A 3.12 3.86 5.03 ~.:Ep ~ - (21+28) 0.0 2.0S 2.903 3,32 4,07 5.25 S"7?~3ER (28+29) 2.9 1.33 2.31 2.75 3.65 1.03 SEPIE:!BER (290+30) 2.8 1.33 2.28 2.71 3.55 4.91 SEP-42CT (344+31) 0.0 1.22 2.04 2.44 3 .25 4.61 SE?-C,CT (31+32) 6.2 0.35 1.:14 1.54 2. 39 3.866 CCYI~2E (32z+33) 3.1 0.37 0.91 1.0L8 .95 OCT.03ER (3:3+34) 12.1 0.1L7 0.32 0. 69 34 oL-1CRER (34+35) 21.8 0.14 43.46 Oc, -!-;0v (35+36) .38.7 '3.15 so."'C"ER (3i5+37) 61.7

(37+38) 73.5 ( NO'.",~3ER (383-39) 79.4 DECC3E (344)04) 1430.0 DEC_IaER (42 +432) 1300.0 DEC-STR (4:1432) 10)0.0 DtEC'~1ER (43+44) 120.0

~eeksW are numboared from 1 thirough 52, stzarting wvith the first: week of M4arch. ** o years out of three or about. BJLNGJADESII AGR~ICULTURE S"TOR. STUD)Y AM4OUNTSOF RANAL~I WAYTWO-WEEK RUNN4INGPERIOD

R.kJSHANI

MONThi 2-Week Approximate Probability NLne Years Out of Ten Four, Years Out of Five Three Years Out 01f Four Two Years Ouit of Three"* One Year Out of T3r running Growth of (907. ProbabilLity) (807. Probability) (757. Probability) (657. Probability) (507. Probability) Period-, Period Zerco Rainfall inches)_(inches)__inc__es__ _ __ r_W_T _ ic a

NOV-DEC (39+40) 100.0 DECE!MBER (40+41) 100.0 DECIY'ER (41+42), 100.0 DEC,~ER (42+43) 100.0 DEC-JA.'4 (43+44) 100.0 DEC-JA.N (44+45)1 56.4 JA.%MARY (45+46) 61.2 jANU~AIlY (46+47) 67.7 JA:,UARY (47+48) 58.0 JA-i;.;TB (48+491) 41.9 00 FE]FRUARY (49+50) 575 00 FEBRUARY (50+51)1 60.6 FERRUARY (51+52) 54.5 FEB-MAR (52+1) 62.5 MARCH (1+2) 59.3 MARCH ~~~~(2+3) 56.2 YMARCH (3+4) 46.8 01 MAR -APR (4+5) 53.1 0.11 NA,R-APR (5+6) 75.0 0.00 APERI1L (6Y+7) 65.7 0.00 A EPRIL (7+8) 42.8 0. oo APR-HAY (8+9) 22.8 0.150.2 06 APIR-M4AY (9-10) 21.8 0.03 0.213 0.603 MAY (101+11) 3.1 0.24 0.48 0.60 0.8:3 1.23 HAJY (11+12) 6.2 0.36 0.72 0.87 1.15 1.58 .V, y ~(12+13) 6.2 0.38 0.90 1.12 1.535 2.24 V.,Y-JUN (13+14) 6.8 0.65 1.38 1.67 2.2:2 3.06 MA,Y-JUN (14+15) 0.0 0.85 1.38 1.64 2.15 3.00 JUNIE (15+16) 0.0 1.02 1,6.4 1.93 2.532 3.50 JUtN E (16+17 0.0 1.68 2.41 2.7.A 3.311 4.40 J LN- JUL (17+18) 0.0 1.63 2.51 2.93 3.75 5.07 JUN-JUt (tB+19) 0.0 1.60 2.50 2.92 3.77 5,16 JU"LY (19+20) 0.0 2.08 2.93 3.30 4.03 5.16 JUILY (20+21) 0.0 1.97 2.62 2.90 3.43 4.25 JLUL-AUG (21+22) 3.2 1.15 1.Y2 2.25 2.9 3.95 JUL-AUIG (22+2 3) 0.0 1.70 2.50 2.813 3.6 4.78 AUGUST (23+24) 0.0 1.58 2.25 2.51) 3. 1 4.00 AUGU:ST (24+25) 0.0 1.43 2.18 2.5.3 3.2' 4.34 AUGUST (25+26) 0.0 1.33 2.03 2.315 3.1 4.06 AUG-SEP (26+27) 0.0 1.10 1.56 1 .71f 2.18 2.82 AUGr-SEP (27+28) 0.0 0.77 1.23 1 .4:5 1.89) 2.62 SEPTEMBER (28+29) 0.0 1.26 1.86 2.13 2. 66 3.51 SEPTE,MBER (29+30) 3.2 1.12 1.84 2. 15 2. 76 3.71 SEP-OCT (30+31) 3.2 0.65 1.25 1.50) 2.10 3.06 SE? -OCT (31+32) 3.2 0.24 0.66 0.943 1.43 2.43 OCTOBER (32+33) 15.6 0.13 0.311 .7215 OCTOBER (33+34) 21.8 o. 13 0.521 1.19 OCTOBER (34+35) 25.0 .2 08 OCT-NOV' (35+36) 51.6 02508 N.07Ia ER (36+37 ) 66.6 NO':EMR-!ER (37+38) 69.6 NO'. F-BER (38+39) 7 2.7 NOV-DEC (39+40) 100.0 ( DECLEMBER (40+41) 100.0 F DECDM±ER (41+42) 100.0 O DECUIIBER (42+43) 100.0 D1ECEBER (43+44) 100.0

dr week6 rer numbered f rom 1 through 52, starting vith the first iweek of March.. ,* two ".ea .. t oF three or dbotit. BANGLADESH

AGRICULTURE SECTOR STUDY

AMOUNTrSOF RAINFALL EXPECTED TO BE REACHED ORt EXCEEDED IN ANY TWO-WEEKRUJNNING; PERIOD

RANGFUR

moNThci 2--Week ApproxiLmate Prcobabi Ii ty NiLne Years Out of Ten Four Years; Out of Five Three Years Out of Fouir Tw.o Year's OUt Df Three** One YeairOut of Two. ruinning Groweth of (90% Probability) (80% Probability) (757.Probability) (657. Probability) (503. Probability) Per-iod* PeriLod Zero Rainfall ______(7. (inches) (_i_nc_hes)_ - (inches) (inches) (ohs

NOV--DEC (39+40) 100.0 DECj92ER (40.141) 100.0

DECIZ-BER (42+43) 100.0 DEC-JAN (43444) 100.0 DEC-JAN (44-145) 70.3 JANUARY (45+46) 67.7 JANULARY (46.47) 64.5 JA\UARY (47.48) 64.5 JAN- FEB (48+19) 51.6 FEBRUA.RY (49+50) 51.5 FEIILARY (504-51) 57.5 FEBRLUARY (51+52) 45.4 FEB-MARl (52+1) 45.4 0.04 NARrd ~~~~(1+2) 52.9 0 06 M.AaCll (2+3) 38.2 0.00 MARC`H (3+4) 32.3 0.12 M~AR-APR (4+5) 41.1 0. 02 0.21 MAR- APR (5-16) 40.0 0.25 APRIL (647) 31.4 0l.05 0.19 APRIL (7+8) 17.1 0.11 0. 27 CI.57 0.49 A PR-MAY (8-19) 14.2 0.30 '5.50 0.90 1.0s AFR -M~AY (9+10) 3.0 D. 67 1.21 1.47 1.97 1.54 MiAY (10+11) 0.0 13.90 1.52 1.83 2.45 2.S10 MAY (I1+12) 0.0 0.86 1.52 1.85 2. 55 3.50 M.AY (12+13) 0.0 L.51 2.47 2.93 3.87 3.73 MAY-JUN (13+14) 0.0 1.39 2.48 3.02 4.175- MA Y -JU (14+15) 0.0 :2.80 4.03 4.58 5.67 6.12 JUN,E: (15+16) 0.0 :3.47 4.80 5.40 6.53 7.37 (16.17) 0.0 ~~~~~~~~~~~~~~~~~~~~~~~3.534.90 506.78.28 JUN-_JUIL (17+18) 0.0 1.34 2.50 3.10 4 .37 8.47 JU;-JUL. (18+19) 0.0 1.42 2.55 3.11 4.31 6.59 JULY (19+20) 6.0 1.43 2.94 3.56 4.76 6.35 JULYI (20+21) 0.0 1.22 2.18 2.66 31.66 6.64 JI:L-AUG (21+22) 0.0 1.09 1.97 2.41 3.33 5.38 JUL-AUG (22+23) 0.0 1.23 2.03 2.41 i.19 4.92 AUGUST (23+24) 0.0 1.18 2.02 2.43 3.27 4.48 AUGU:ST (24+25) 0.0 1.18 2.12 2.60 31.59 -.69 AUGUST (25+2 6) 0.0 1.59 2.50 2.94 3.8 5311 AUG-SEP (26.27 ) 0.0 0D.98 1.62 1.93 2.56 5.23 AUG-SEP (27+28) 0.0 L.16 1.76 2.04 2.60 D ,,bI SE PIEMER (28+29) 0,0 1.38 2.14 2.50 3.23 3.48 sE?T'-2ER (29+30) 0.0 0.96 1.75 2.16 3.01 4.40 SE?-OCT (30+31) 0.0 3.50 1.13 1.49 2.30 4.49 SEP-OCT (31+32) 0.0 3.25 0.70 i3.98 1.67 3.54 OCTOBER (32+33) 12.1 0.41 3.70 1.33 3.08 OCTOBEIR (13+34) 24. 2C.284 OCTOBER (34+35 ) 39.3 1.0, OCT-NOV (35+36) 54.5 0.20 NO71-12ER (36+37) 74.3 N'O'.IY.B ER (37+38) 78 .7

NOVEMBER (18+39) 100.0 N;C;-' DEC (39+40) 100.0 C DECEM-ER (41+42) 100.0 DECZY,BER (42+43) 100.0 DECI.MER (43+44) 100.0

* Weeks are n=ubored froms1 through 52, startinj1 with Lhe first weekc of Mairch. **Two years out of thiree or about.

BINGLADESH SECTOR STUDY

PROBABILITY PRCIFILE OF REACHING OR EXCEEDING SPECIFIED RAINFALL AMOUNTS IN ANY WEEK,

(Starting w:Lth the FiLrst Week of March as Week 1.)

BARISAL

PROBABILITY

+ 1.000

Probability ]Profile of + 0.909 exceeding 0.5 inches in any week0 \ . ~~ ~ ~ ~ ~ ~ ~ ~ ~~0.818

C 2 4X \ : + ~~~~~~~~~~~~~~~~~~~~0.7,!7

:V/ | | < j \ A \ Probability ]Profile of exceeding 1.5 inches in any week +0. 545 0.455 A K01> 1I lo/R tt \ni, +

Probability ]Profile of: exceeding 2.5 irches in--any week 0.273 o-- O-- O

+ 0.182

,:; I. fc '. 0. 091

1 ' X ' o'/~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~o 10

+ , CKA\, + s s . ls +l ,,341+ l78l20v1.2224,, * ...... + " 1 2 3 4 .56 7 8 9 6Olli2l3i45I6l7l8192l2223z425Zb27282930313233343536.3738394041424344454~64748495 35152

APRMAR ; IMAY I JUNE |JULY AUG SEPT OCT INOV I DEC I JAN I F EB BANGLADESH SECTOR STUDY

PROBABILITY PROFILE OF REACHING OR EXCEEDING SPECIFIED RAINFALL AMOUNTS IN ANY WEEK

(Starting with the First Week of March as Week 1)

BOGRA

PROBABILITY t 1.00)

/ >: ~~~~~~~~~~~~~~~~~+0.91.7

/! \ jrcl I Probability Profile of 0.836 exceeding 0.5 inches in any week i 0.752

1,'Agte 'i i~~~~~~~~~~~~~~~~~~~~~~~~~.°66EI

Probability Profile of 4D exceeding 1.5 inches in any week +- +-+ ~ ~ ~~.52

0335

Probability Profile of

1 2 3 4 5 > A ... in a week'0.035

-b-< c-;>Su 0--v-; s s-o- <'b v-Xa ) d ~~~~~~~~~().00 t)

1 2 3 4 .5 6 7 8 S1l0 lll2l 3l4l5l6l7lE19202l22213242526272829303132 33 343.536373839404l42/+344454647,48495051i'2

!MAR APR, MAY : JUNE, JULY: AUG SIEPT ' OCT 'NOV DEC JAN ,FEB BANGLADESH SECTOR S'CUDY

PROBABILITY PROFILE OF REACHING OR EXCEEDING SPECIFI]ED RAINFALL AMOUNTS IN ANY WEEK

(Startin.g with the First Week of March as Week 1)

CHITTAGONG

PRODBABILITY

.1. 0(0 + 0.960 Probability P;rofile of exceedinjg 0.5 inches in any week + 0.873

+0.785

+ 0.698

Probability Profile of + 0.610 exceeding 1.5 inches dl. + I I > Iin any week : / '' | 1/ \ i\ A + +~~~ + ~ ~ ~~~~~~~+ 0.524

; '¢< > \ ~~~~~~~~~~~~~~~~~~~+0.436

Probability Profile of exceeding 2.65 inches in + 0.35 any week o--o-- o .0.262

.. . ~~~0.175

0.0087

+ . . . .+ ...... + . . . . . + . . . . + . . . + . . . . + . . . . + 1 :2 3 4 5 6 7 8 910111213,1415L617181921)212223242>526 g7282930,3]L323334353563738394041424_3444546474849505152

MAR APR MAY JUNE . . _ I DEC . I FEB :MAR _APR'|MAY IJUNE JUIJY IAUG SEPT:I OCr NOV *:DEC *:JAN I ]L, BANGLADESH SECTOR STUDY

PROBABILITY PROFILE DF REACHING OR. EXCEEDING SPfECIFIED RAINFALL AMOUNTS IN ANY WEEK

(Starting with the First Week of March as Week l)

COMII.LA

PROBABILITY + 1.0010

+ 0.9110 of < \ ,-, RProbabiliLty Profile v* exceedilg 0.5 inches in any week + 0.819

+.s 0.728 ' I / \. t X

o .637 11o //| J | T+ Probability ProfiLe of exceedbig 1.5 inches tb i \1' ; ,l ~ ~~~~~~~~~inaniy week +o5.

+- + ~ ~ Ui4 i \!a \ ° t X ~ ~~~~~~~~~~~~~~+0.4;55 +~~~~~~~~~~~~~~ of 0.36 1 d,' \ c 'iProbabilityI Profi.Le exceediig 2.5 inches in any week !---O--O ; 0. 27 3

\ +013 +/

t X+\+' \Q /' /> + 0.09 1

.co ' + *...+ +/\+ + 1. 2 3 4 5 6 7 8 9 1.01112131415161718l-92021222 ;~242526272182931D3132333435361i7383()404142433+44546474fi349505152

N V DEC JAN FEB 0 1OCT M JPR,PR MAY JUNE 'JULY' AUG SEPT BANGJLADESH SECTOR. STUDY

PROBABILI]TY PROFILE OF REACHING OR EXCEEDING SPEC:IFIED RAINFALL AMOIJNTS IN ANY WEEK

(Starting with the Firsit Week of March as Week 1)

DACCA

PROBABILITY *1.000

.0.9o4 (\ ji \ j \Probability Profile of exceeding 0.5 inches 0.853 in arny week 4

-~0.7 7 6

0. 690

/ - ~~~~~~~~~~~~~~~~~0.604 s . , , , | ,ProbabilityProfile of exceeding 1.5 inches in any week 0.518

0.431

/ -~~~~~~~~~~~~~~~~~~~~0.346 Probability Profile of 7xi ~ ~~~~~~~~~~~~~~~~~~~~~exceeading2.5 inches 4 0.259 in any week

O~~~ 0 ~~~0.1.73

>~~~b ... - O.~~~~~~0:086

7~~~~~v . ,,. 4~~~~~~~~~~~~~~~~~~~ * 0 .000

12 3 4 5 6 7 8 9 0LI12114151617,| 1t O819202111 1 1 22324N52f1 27282(30J132333;43536373,39404142z34445464148495051521 1 1 1 4 I~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~CDt

PIAAR AI JUII JULY' I AUG SEPT :OCTTov jEC JAN FE BANGLADESH SECTOR STUDY

]PROBABILIT'rY PROFILE OF REACHING OR EXCEEDING SPECIFIED RAINFALL AMOUNTS TN ANY WEE'K

(Starting with the First Week of March as Week 1)

KHEULNA

PROBABILITY I_.000

4/'2 X >rProbability Profile of / j T \ exceeding 0.5 irnches ; 0.860 in anyr week

-- ~~~~~+0.774

/~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~~ ~~~~0.688

Probability Profile of exceeding 1,5 inches + 0.602 in any weekc

ft ~~~+-+ -4 N / ~~~~~~~~~~~~~~~~~~~~+0. 516

0 + 02430

'Prolbabil-ity Profile of031 exceeding 2.5 inches 0 Xk 4/ \ l ~~~~~~~~~~~ar, tweelk ~ ~ ~~in .g

'Cl 0~~~~~~~~~~~~~~~~~~~~~~~~~.172

4 . . .4. ....* . . .4 . * . ... + *.. * ..... + .... + . ... . 1 2 3 4 5 6 7 8 9 lOlll21314151617181S92021,222324252527282930313233343§363738394+041424341445464748s49505152

:MAR APR MAY MJNE JULY AI J SET: OCT NOV IDEC JAN *FEB: BANGLADESH SECTOR STUDY

PROBABILITY PROFILE OF REACHING OR EXCEEDING SPECIFIED RAINFALL AMOUNTS IN AlY WEEK

(Starting with the Firsit Week of March as Week 1)

MYMENS INGH

PROBABILITY

+ 1. 000

2Xg f0/j/\< Probability Profile of * 0.910 exceeding 0.5 inches :,-Z l\ in any week 4 0. 318

+ 0.727

Probability Profile of ; 0.636 exceeding 1.5 inches in any week V 0 \22< X \ , di-@ qo0.5454

/\Vd/ / > \ + 0.455

Probability Profile of + 0.364 exceeding 2.5 inches in any wieek o-ao- 0.273

7 / \ t +4\ 0.182 4\l +. .Ci9l

4 0.CIO0 4 ...... +. . . . . 4 . 4 .F., 1 2 3 4 5 6 7 8 9 +. 10 11121,314151617.18192O02122232425Z62.7282930Q313233343536373b394O4142434A454647484,95051'5 2 , E_AR_ RA A JUNE ;JULY AUG SEPT OCT NOV DEC JAN FEB BANGLADESH SECI'OR STUDY

PROBABILITY PROFILE OF REACHING OR EXCEEDINC; SPECIFIED RAINFALL AMOUNTS IN ANY WEEK

(Starting with the First Week of March as Week I)

RAJSHAUII

PRO0BABILITY +1.000

Probability Profile of 0.910 exceeding 0.5 inches

___ ! .>any \week sin 40.818

i0.727

+ 0. 536

Probability Profile of 545 |><''NV l // \ / X \ ~~~~~exceding] 1.5 inches; 0. 8~~~~~~~~~~~~~~- n week f~ ~~ ~ ~ ~ ~ ~ ~ ~ ~~~++ 0.455

!j 0.364

Probability Profile of 0.27 exceeding 2.5 inches in any week ! \<1 | i \ )00 o~~~~ ~ ~~~~~~~~~~~--o-o:0.182

e0.(91

*g0.000 d'*-iE1t + * - - - d * - * -'*§

2 3 7 .5 9 1 ] 121341X1617,1819,?02t222324*25262728,)93031323 -§343536372,8394ID4142,4344,45464;7484'3)505152H

bEAR, APR ;!MAY I-JUNE JULY AUG SEPT OCT NOV DEC JAN FEBtJ BANGLADESH SECTOR ST'UDY

PROBABILITY PROFILE OF REACHING CR EXCEEDING SP'ECIFIED RAINFALL AMOUNTS IN ANY WEEK

(Starting with the First Week of March as Week 1)

RANGPUR

PROBABILITT

+ 1. OOC)

.. \

j D\'* / /\ @t Probability Profile of 0.818 /\ ~~~K:~~~~~~2~~~ exceeiding O.5 incheas in any we3ek

7 ; / 0.636/ \ \+ \

Probability Proifile of exceeding 1.5 inches +s+i/;Vek\ tj in ,,any week

4c - + -- + 0.455

|FX\SX \, \ + 0.3614

Probability Profile of exceesding 2.5 inches + 0.273 in any wieek

0 -"--°-o ° 0.182

/7/ . ~~~~~~~~~~~~~~~~~~~~~~~~0.091

*t- -*.- w - + * + * - + 4w +-- + * - + * * F-- + - .,...... *- + .\ -..+ .c*-. X. 1 2 3 4 5 6 7 8 9 1C)111213141516171819,2021222324252,627282930'313233343'536373839,04142434445 4647484950515215

MAR APR I MAY JUNE UL _ AU__ SEP'r I OCT NOV ! DEC JAN FEB

APPEND:Cx 4

DROUGHT DURATION FREQUENCY

RAINFALL DURATION CURVES

Period of Records: 1934-1969

Stations: Barisal, Bogra, Chittagong Comila, Dacca, Khulna Mymensingh, Rajshahi, Rangpur

t Pasahangpur Mymonsingh ' Khulna D;occa CoroillP Ch'ittagong Baogra : "r'i-,a .l

0' 0 '

C, ~~ ~~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ',

0000*0 C' 0'0 C o '0 00 000 0 00' ~0 000O0 '0 , , 'C;

0 " ' C' N~~~~~~~~~~~o 0 o C

0 0 0 0 0 0- -0- --0 ' --a------N-- 0- 0 00 N 00C a~ ' 0 0 a 00 -- a o a Co 0 C a' - '''00

00 a'0 a 0000 aa'0 0 00000 aoa 0 - '4'0-

00 000000 ~ 000 00000 0 '00 00000 000 ' ------'------0 , - -0 0 0 , 0 00------00 0---0 0 0------' I I . ,0

,C0 0,C 00 000 ,000-00-000 00 000---OO

---' 0 0 , 0 0 0 , 0 0 0 0 0 0 0 0 0 0 ---- - 0--- 0--0 ------' 0, --0 ------~ ~ ~ ~ ~ ~ ~ ~ ~ ~ I'-' 0

--0 - - 0 0------0 --C------00-0-0:------0 0 0-0------~ ~ ~ ~ 0~ 0 ~ 0 ~0--- ~------~ ~~~'0-- '---

------C 00 ~0 '000000'c~ 000'00C 0:0000'? C'C 0400:00

*-I -~~~~~~~~~~~~~~~~~~~~~~~~------

0------''-''0

I,.,.------,I------.. ., - ---.------

APPENDIX 4 FigLure lOa

RAINFALL - DUPATION - CUR VES PERIOD 1914-169 STATION BA"iILJMA

30_tVTTT-VV,' _ _Y -1T 77 I7~71

i'@AH5l~~~t1~~~~ -'-I l '' I tt'z _ !::i'l i

1. 7~~~~~~~~~~~~~~~~~~~;

-~~~~~~~~~~~~~~~7

t I:7-- ; .jAP& _ _i.I ; |- -ii-.iF 1. ... ' _ I__ ,, 8 _d pi -,-7- .. _. -.. . _-1,'b---r I , v,1 ~L~~~~1, , j. 1 j. Ie . I 7-

4-- -K7T ,4 flXj j ,17

1 2 3 4 5 6 7 5 9 10 10 _

-~~~' - - - - +-t - !Ti1 JUNE

L-2:1---j-0-1 t.. -- 1 -L---1--s;g 1 - __ T0_tj 7__ ~~~~~VV T I~~~~~~~~~~~~~~~~~

T' '' t ' -t- } -1- -i 1 1 4 1 [- l it. j'~ '; 1 j..- 1 l

4442-J

2-6 7 . 9 10- 1 20 :j APPENDIX 4 Figure lOb

RAINFALL - DURATION - C IJ.RVES PERIOD 1934-1969 STATION BARI5AL J UILY 30 K77T. T.lr VFVW -t17 .. :, 1 5r _~ 2 Tajr ViA>1:m t _jj_.::rL .... _ i . --E . . -- I , W ef # .t , _ 20- :::..:.-;. 4:- - ~ t - ,> 7Vt- 1--' '0 7.-. , -7 T T

10 , _ L. 109- .--- -' r-I -,-_ r r , ,------:

jA8->'!-<---o-

- f.-r j12 1 ; 1 i 11: 1 _ * __ _ _ t _ _

6- I -1 -I-

- 1:- I I I i . I

I :::i- 1:z : - I l I : -Fi V|:1 F : 4:I-!.I :

1 2 3 4 S 6 7 a 9 10' 1S 2.0 50

AUG Ui T

3-J - I I _

20 'APH!1it2 ~ 14i i jivVr~4i i I i I | | |- i I, 20 1:-:tt S t, X --- s n ,-A-j-t

6-7

7~~~~- 'T74L~~~~4- 7, I

______. - laEiAL0..

1 t 2 3 ~ !5 -6_ 7 8 9 10' 15 20 s0 APPENDIX 4 Figure l0c

RAINFALL - DURATION - CURVES PERIOD 934 -1969 ';TATI!ON DA Pi S AL 5EP TEMBERE

:-_70 7 7, 1 7- 1- .:TVK - --- t- -; i- --- '- i l -l4-4- .--

2.1 1 1 I 1 :

2,, 3 .I T-l ... 9 20-

I m i7nm 3. 0 dt' l - I-

777 I-i1K'l :1:1' :1:-11 ltiJ 4<-71::T~1.-1I --X--1. :1 - 1I L -7I t 4'-; I . j ,. : I . ,I 1 . .

1 2 3 4 5 6 7 8 9 10 15 20 30

i3 I ti}h|-|~~~~~~V-f~~~~Tft. 17 ; 1.[ [TT- T . F114 Ij J4 .I ~0 r i- ^ t h!:': _I-|_ : ! ::: . I K 1 ' 1 P24-1f1 0WIT1 F I o4 j lIIIX 1 444, Hv

-- ~ ~~~t! M F > 9 F L, f _ _ _

-~~~~~ - ',, t r -- :, r -,-----.! ,

-ti !t 1 t t st[ t t---fl+, Z-!- ; - -- |-2 -tK .-...:. t171

irIi |2|2th 1

12 3 4 5 6 7 8 9 10' ~~ ~~1520 't

APPENDIX 4 Figure Ila

RAINFALL- DURATION-CUiRVES PER 10 D 1934 -1969 STATION BOGRA MAY

20-

Ll4z44LL~~~.~4..LkI4:T1 1 1

4-~~~~~~~~~~~~4 L

4 kg - 2,-I-I Ij I I I 2 x-_ rb 1<-- j---i [fW--- -I I - X<: -;-~ FF -FI- |: 0 I 1 ..-..n ..__..... 2 f 3---X 4 ------I 6Lt-n 7I 1 9 ' 10- 15 20 i 0

._ _ -F;-- ._. __ __- _ _....J,_ ...... b~ ~ ~~~:- ::2- i: -: . ._1 } ! !. 2171------1

JT. E

KH . I---?---1,-I71

- , . - . 1-.. ' '--i-- -r>., . :. _

I- t----II --i -1-i -i- 1I-----S---I'-1-1i 1 1- ' I I; 1- 4- -t 3 3 -7 4 --5 6--t- 910--t- 15 20 -50t

2~~~~~~~IM~ !'',l',AYOF- f! l -g-0.i--..'

'4- 6 UM F,1 ! r AV % .: : I . - -

10~~~~~~3456789 0 0 s APPE.MTY 4 Figure llb

RAINFALL- DURATION-CURVES PERIOD 193A-f'69 STATION BOGRTA DULY

-- I 1 tj'---1<1--: L .1 + - z-----

10' - t_ X___'''''

9 _ 2UST ~~=-=~~~~~~~~7 ]7i:9fijjii78-T 9lo ---:.--- -r------;_-_ 3 2 5I- K _I-i-Z[i - - --

A-- L-l 2 -lylEV 4 -H -J- : +I' 1t -t- ' i -1 Z6_' It' X-__t' l.-I!.-,,'4 - I , ..-Z Ii' '' I----

~~~~ ' T ~~~- ' i T -- I~ l

10- 3 l =X78l---1! 210-I 15 so

-f~ ~ , ~ ~~~~~~~F- : .,...------'-|-'-I---i

2 .. - I t [ _ ;' 2l2 t1 t- -

20l-<- -

+} W-i---,---4--Ij I:Z----t2:- -'W '- -- :

_f 2 in 1.llr APPENDIX JL 12 Figure l:c

RAINFALL - DURATION -C UR VES PERIOD 1934-4969 STATION BOGRA SEPTEMBER =----iI-5'tA =----,-tU. 7 ;-i 4-4 - - -;---lj

.. =. _= .. e. ,_ .,...... _. - _e_... +-_._ -- --- L---T - _: :_ : _: : H---il>: ::- ,__ _7 _-, _ -. i- - : -'::: :: :: :: :1-::::V_ :-i41 :-:: 1I---, li.i+- t ---t - - i 1

Ct;f' i.. -1----I-,' ' ---t. :- ::::,:I1j .1-lf'l- l :;: _ I _:T''-1' ::1 - - - -1- - , ....J ,I ,

20 T< .lj i, jT--1-i 1---I~ . -;-.1-- -j--t---l-i .:i I=t-t;-1-t , ::T:

sY: 3 1-. - .!...1 1--;-- I1-! l

1 2 3 4 5 6 7 8 91.0 15 20 50

q SI t-..I i Lf I-i50S

,t LIlI-...--lU. .f.t.-Lf..l. .. -Ii-=-t~~~~~~.: sm1 U I l--tEi--.T I-T 11 - i :t-"--:: 20 J: ::2 -1 ll t, ~. i 'i*1111 'I , , ! . *!,1 1. -.'. :i -. '

2-.-- 7;-1 }---- 1-,! 1- L 171 1-- 1 1 -1,[ 71'1,. !I- E

- 6 =;-;------L-- I - - +----1-- --1 I -1-- 1-~~~~~!r-l1 l- 4#ll 1F $- - m--r-1 1.L- --. - t .::T::::I ::I::X::: I!-::T' 1 t 1-; ..LT t 1--l- - 1--. 1~~~~~~~~~~~~~~~~~~~~~~~~~ ;;= 4 . :,:::1:1_- :1--:-8:-,:: ::::1: -1:::1 41::.::1::::1 :.181::':t:.i

.~~~~ ~~~~~~~~- LI M- -,F,nFf 910-' i5 0'--

APPENDIX 46 Figure 12a

RAINFALL - DURATION - CUR VFS PERK 10 uD 1934 - 19369 STATION CHITTACrON6 MAY 30 , .,., . ,:,:i,.r...... ,:.. . I I. ...J1 113IIEA7~ tiA -- 1137V.:ii :' - i- I 20~~~~~:. _-_ .. ..It- .L....

10 -1- .t 1lt-t;-tt-,11j= 9-~~ ~ ~ ~ ~ ~~~~~23

1 1:-- i: et t_t:__: :i_;:::_1 = 4_-- I---1-----1---2~~~~~~tF--1:1

t° I .....:1 -, I 2- I 2 .l- . l--I...... -,MT e,: -t 1 t- 91-1- A"C o0 ~ W' -* 2--- +i4I t" 4 I' 5 6~~ < ' 10 -U t ., ., I z 4______I_i LE Li4C -t-r--H--TIFFT-T' f I

1=:i :---I:-:I::. i: .i i -t i. -1 : 1- 1 1 1 I :-tj'- - .--

.t-- I M !L' | I I I I ! 1 i 1 .!

_ T~~~~I ~~~~; - r~~~~~I ~~~~~~ ~~~1 - H -~~~io- + ,5 Io 1 -F-- g-{ t-i-- j--- :-j l :-i1 X- 1 -i> - i7.1t 1 < -t-- ::-{:::::::1!,:UL4 L;::::,: -:::4::

IT.I. t__2_3_4J 5 6 78 91 15 20 50 APPENDIX 4 Figure 12b

RAINFALL - DUtRATION - CURVES PERIOlD I9~4-169 STATION CHITTA60NG 'JULY

SRA$;i| 1 3-'!| - > t t .1'I! - L -J 1

ro.g m.1 - l< tTif__.l:m7i i 0~~I

rr 3- 94-~~~~~~~~~~~~~~~~!~~4. - --ox, :,-, J ''' I -1: I- 1 1-~~~~~ I -- '::.1: : j,::::i :

~1 2~KT7 .... 4t__ 1,t < -~~~~ I 1,l 1 I * -- 1T:':I

2 ------i:----- !:: 1-: --- .- . - -t--- -.:-

1 2 * 31 I - l- 4y 5j . ! 17 f I 910'il 15 20 s0

417--Z17~~ ~ ~ ~ ~~~~~~~- AUGUiST

30s .. . ,. 1 - - - : 1 i i I. I .! - T i~~~~~~~~~~~~|-- ~~~ ~ ; - ---- j1. --- :: i | i !-I I ii :

2 .. -S-}-- -X 7ret.i--- -r -i w " jtj----ait--'9* I bl !y7_ i4 !T-- + l 10 E t- - . - t -1--i < -i~ -- l-l l -- X --

Q6-t-?-1 2 3-,:i-|--i|l4 56 7- 91: 0|-:' |5 20 -i r~~~~ -AV1/-- ! I'M. h=F*- n- APPE;NDIX 4 Figre 12c

RAINFALL - DURATION - C URVES PERIOD i934-I9 69 STATION CHITTA6ONG SEPTEMBER

A ~ ~ ~ A

LL4U~~~~~~-7-~

-X-;:-7]T-:--t:1:-i-1' -

1D~~~~~~~~~~~~~~~~~ A Y s

.127TZ. z17::l ::::::ij§::I -:L 4t -:---.2q I-- ---t----l -. -- - 4-t---7 17F t0 4z t jrt4-1 t jz t j 5

¶ ~~ ~~23 4 5 6 7 8 910' 15 20 30

20 - TuI4

t--H-.-Li-.4:--k-t-m-v- nl: D;1-1 - -t- i-It--:t-

K ~~~~~~~~~~-

'-44: _- 7

24 - L -4 i7_

E' Hl ' tI *__L|--

1 2 3 5 6 7 8 9 10 2 0 0

ID j;' 0 LT ; 2L -'^ Z t w y g l: z4~~~ ~ N 4x--- 2 i t- ,- 1---1--r! < ,'I - I-I' ,

W. ~~~~~~~~~~X- 2La H0 _ ;141 Tt-;t _ ; i <'a! 4e|i p.- -- 1--$ 5 cs ' I ,f, O O 0D XD rv 90 In ~~~~~~~~~~~~~~~~~~tt l

cn ~ ~ ~ ~ 5jO I N lVJI' 31 N l lV N V APPENDI 4 Figure 13b

RAI NFALL - DURATION - CURVES PE RI OD 1934 -t959 STATION COMILLA . :IULY

0-I.10LAd vii: -- ' 1' ' lI i2, :::I1:

_ _v____ t_ _ t _\-r ¢';!;'7--:'l i: ~ :~:- -~ 710 _ .:: : i V:: !: I, i-, <- 4t,Fj j.7 20+--=.~ ~ -i..o->;.i,,~ F-l ? ......

--ii.i-I .~- v P -t -- ; - - -- :1-1 .--.- ,jii-11 Z- ,-,|IT - __I----+---- i~- I: .:i.'1f . t., , I . i :1 ' - .::..... ' ..1. .. El __.. _

1 2, 3 8' : I0 '. _0 - '______to ! ,, _ _ _ P_ ' _ F:_ _._ _ _---_ iL

~~~~~~1~~~-

<~~~~~2H ~.- .- - - I--:I ...... ---.-- + .., ... !I....t...... -t t 1 , I::::-!:::l:I::::!:.!-- -

J4->~z ''_z i':T--sT-.T-L . ti4 t T - 4-i - 7 -i-4--:1-j----- : .!:: ,-:i-. : :----zi-_z...... I,...... ,...... ,.. ., .. ,..;F

6-j~ ~ ~ ~t-j4W i-t-Ii~~~~~~~~~T,-1

1 + -2 3 4 5 6 7 8 9 10- 15 20 !- APPENDIX 4 Fig -lre 1 s3

RAINFALL- DURATION -tURVES PERIOD 1934-i969 STATION COMILLA SEPTEMBER

20 d-I,------:ft-_ jIjL --- _-- 4z. . I

2t)tM ~ H3'

- T.7- 1 -- -:--W=4 -- jll -__ 7t>_ 1 _ ~~~~~~~-: . _w--...... -1.:::.:s 1 ...... -. n-

: -':.- -:1-1:-::: I .1 -- 'I.I:: t-:' - I- : - :1 - 4~~~~~~~~-4- 2 7 7 t1 _ -tI1c7YiFIiL 7U j1'-:itLi 1-. fl-tA - t -tVKt-w tK I- - ±- HkI-T-:

yv4f ---- , TI7-r _. _ V.: t:-.

1 D4, = _ ' 3 4 SA<.':.2F5 6 7 8 : to..l-'I4 ' iS 2o0 t. Z--- J---1n2 : SAYSDl ______t, i

10.

____r___ f * j--1--- ,-R -iF .l.j i- __,_1 ______| 1$ -- - - E -- _7 - - - 4 1 ' 3! 4 , 7 -2 o 1 0 jlL -, --I:!:.-1.--1h.1 t :- -T "j A :---j

t - rtFm-r-2 t 3 4 - 6 -. t l t- 1 20 so1 11 - :,_ 4 201---~~~~wLmF-II I: nFi|-17 1- X

APPENDIX IL Figure 14L

RAINFA! !- DURIPAT!AON - CURVES PER IO D 1954 -1969 STATION DACCA MAY

o -..-._ , _.,-: t:_ -- . - . -. _ . -~~~~~~~~~~~~~~~~~~._...... - _ ._ .-._ _

_ 7 _ -;:;::_= .. .. _~ -.. _-,:: f_2A,'- -, _.=.i. -= ri I~~~~~~~~~~~~~~~~~~~~~~~~~

1:T=I:1-'1'1 q IL'' I I 4.2-RlI._,II -.

2r- {_..p;. .o..J.. 1. 1.- ... A T.l-.7.-T7.l..- 1--

1 1 "'3 i 4 1 - :-7 1 18 129 10 15 20 50

I J .. 7. 7__

4 - -- ,--.--...... -- . -..- ..4a . .. .

ii~~~sN 3 _ -l'g .. l .. ..1_'.... NIMAFs ....nrf ...t , )v'.... i...l _{.... ! t+t '| l, _ s t--:L:"W:--l: -:'-l ::i:1 Hid-:::1 -- :il1--' :i-t

-4 1 2 3 4 S 6 7 8 9 10' 15 20 !o

-~fa ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ - -t tt L ~~~~~~~~~~~~~. : : I -t-A[-- -- 7dHJ-1 't-2-t

.. , L-I!-'.--'tul I I I1-'1i,.,:

1 -: 2 - 41 5 6 e7- S 9 10 15 . i- 5

S , ~~~~~~~~ii?.Afl - V--5_ _F APPENDIX h Figure iI4D

RAINFALL - DURATION - CURVES PE R IO D i934 -1969 STATION DACCA JULY

-laXit i : 3 -- f - -- ! ...... -I f- zit': ui T |- i I ': 20 LI I| . l l-'Jl.- 1 ...7i-j .0 ...... ---l _ ~-t..l t_h _.ti1-4. . --t-!.-~- l,-__-I__i =-*t_ 1-t-1 H_W .t. 1P - .9::HX t9[-t.77 f._1 IV, -7

. . . . r . s ..s ' vr I . .| - I . I

28 . I -=tf .. :i r~~~~~~~~~~~~~:t L 7 7

l 4 f1 i : ~~~~~1 M:,: F --D _ iA I:: ' tI' 1 I--

1 t------f- l l---iz f <3 +2 I4 6t 78910t2 so 2 t I l ^ ; ft Ll z~i1: . . :I.:-: .i : 12- !l -

AUGU ST

_. --I .d1-- * ' - -' 4 I t .-- .

A-1w -t- al~ ~~A6f's

30-- f -.- --f- - 1 j f- - I 1 I--i - :IIX4 6 1 42 2 - 3 ! 4 5 6 78 910' 15 20 I50 r I~ ~~ ~ ~~~~~I

20-~~~~~~~- | - - 3l -- 4{-! -4 6- t a 9 -t t

X . T-X- -;t ---fF MUM9FQ n -DA-so

.1M.A.. .Fu r.. FtI 4...>AK 1-1 T4YKr. APPENDIX 4 ~- 1

RAINFALL - DURATION - CURVES PERIOD 1934- J969 STATION DACCA SEPTEMBER 4 VI ~~ §'4-k4~~+.4". 1434.

~~~~~~A~~~~~~rm

10 -t- L4 i'-

__0.b...... 1 i4-'-42=.~ __- _ . :.I :j:- IIjI-+ I~~~~~~~~- 14

______ii'1_K5_. P4 _H A. : - _ . -.- - ~ ~ ~ ~ [~~A 50 -r 1 ~tT1i- Til F - -

in i 4I I Lfl1=jr~~f i LullI4 I7_ 'I- HI'z ...P7 h.±2i -oI

2-- 3 t 5-_ 7 . _3 Is 20 50

10 i-, ' X; H'- .. 1 +i44Iii._ _-+-tI J 4 =l ->lf.. t .tt,-l-,: 'i-. ..- 't-~~~~~~~~~~~~~~~~~~~~~Lr---,I HTw 4 - 207t --- ' ~ g 4r8 ,i t_ ,

NUM4~ ~ 5 S 8 I? lo . 1 20-f ->X~~~~~~~~~ --- t__ p- ----. A-T-~~ --.- L-T--.- . 1..,-:

- I ...... ' ...... I ...... - -...... - , H.I '

.~~~~~~~~~~~tt~~~~~~~~~

El~~~L~~~

Ca IT~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~C

I I~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Ii, I~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~T

Fr'LIfL--- 1.4AA 0 1-0

. IJds3VNINIlVNV a~~~~~~~~~~~~~~~~;3W rL4

-- IiLiA- ..

I I - V - T ' C r A. ; -TXTI 7 '1

=>1S\f23 00 -0 '~~~~~~~~I- 1- Tl- K,\, 71F1L

=Oz z A a t ;: 14 T

u-~~~~~~~ L2iL 5FON T 3N I 11 ViNl'VY 5 3 WONI Nl IV-.h>1 1 .4

S 3 43N i N i I IVANi'Vl1 ' W4N I N I 11IV4NIV t: APPENDIX 4 Figure 1'c

RAINFALL - DURATION - C URVES PER IO D 1934 - 1969 STATION KHULNA 'EPTE!BER

_ AnL2te5 :.::x=-| 1 t:----- (-- i _ _ _ :7-

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APPENDIX 4 Figure l6a

RAINFALL - DUPATION - CUPVES PER IOD 1934 -19b9 STATION MYMENSINGH MAY

I - I I

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RAINFALL - DURATION - CURVES PE R IO D 1934 -1969 STATION MYMENSIN6H JULY 5J-0 i-:-::: - ::::_1.-.::::-':i -- .-- ::: - 7 i i~~~~~~~~~J t-7 j::j::4:::-:1::: .- -- :::-::::-::i:J S i- -- - 20

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RAINFALL - DURATION - C UR VES PE R I0 D 1934 -1969 STATION NYMENJSiNGih SEPTEM5ER 30 _. =.I t _

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APPENDIX 4 Figurei 17a

RAINFALL- DURATION -CURVES PERIUD 1934-1969 STATION RASISHAHI MAY

20-

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RAINFALL- DURATION - CURVES PFRIOD 1934 4969 STATION PAJSHAHI JULY

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9 6i 7 . 9 0 ' 4* 20 -. N B" |__---__.- ;_ _ _:Y______ij, APPENDIX 4 4h.r,AJ.e CL Xf

RAINFALL- DURATION -CURVES PERIOD 1934-1969 STATION PAJSHAHI SEPTEMBER 30 -_ f . l -s ; -l-4D l tJ7lj-

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RAINFALL - DUR'PAT ONC R E PERIUD fS354-4969 STATION RPAIIGPUP SEPTEMBER

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ll * 172<,<;>RV,)> i 7BANGLADESH

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%x ,-' .> %t ~R,%N G IP U . . | 01, ,.-; +

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IRBD-10010 r j \ >; 89O z w ~~~~~~~~~~~~~~~~~~~~~~May 1972 11Els 5>-X'-4---l,lstl |BANGLADESH

11 ,% 7iR !1 tt ' " .... '.f. 8 j .... ~~Plate 2 z::>)/ -+\, blt a,'t ,X,Vs tWATER BALANCE STUDY r (/ \ )-)\ \-- t v, '<<'SURFACE WATER SUPPLY -26;fto zN>^J U gx tu 1.0 <;;. + 6OAVERAGE MONTHLY INFLOW

I I ,1 . i |-. t ,,, ti, o Is0 ~~~~~0s°40 30 40 f 0 70 s0 o 90 10 MItLIs

~~~~~~~~~~~~~~~~~~~~~~~~19 21

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| | J

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IBRD-10011i Na-8 W ~1972|!0{1My --1°2 ^f-':X t '*.- 0BANGLADESH

,>Y; | \^EX j ~~~~~~~~~~Plate3 <> , T[]nV ~~f I ...... ,WATERRA =Ml qNF VVATER SUPPLY ;<~~~ ik)k}) X,\j ,,_. SURFACE ~~~~~~~~~~AVERAGE MONTHLY INFLOW

ZO 30 40 so hO 70 so 90 loO1<|NILERS | 5§ n . / ,_, 4 t \ 1\ l\ 0 O ~~~~~~~10

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IBRD-10012 1972 | r__RR' \l tD\ t'- lMy

|tX 0;13> g$!t q BANGLADESH

.< t A %0v -.X < ,\ .;.-ct's.SURFAE WATER SUPPLY _ro 5t >--xa'!,\s2 >i+y< owt gAVERAGE MONTHLY INFLOW

i j i O ~~~~~~~~~~~~~~~~~~~~~~1020 30 .0 S. 60 70 80 90 100MILES

SC 12KltOMETERS tXXs \ 01\ t t A 0~~~~~~~~~~~~~~~~20 2_03 40 69 70 80 90 IQO11

10 ,3" &/ffi i l i t r-^X9'2kta e ( '" :/'-X-i';;33 "f 10 I

25~~~ 18 25- " " L 3w~~~~~~~lo7 - f-

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--- Bonare~~~~~~~~ STEMFO~~~Ditrc U R- STEMFO FRO | PE2°4 EFFLUENT~~~~~EGRUDAE

I BRD-10013 F 72i n taj t°a°I ~~~~~~~~~~~~~~~~May1972| p)1 ' ,' 6426 4 i 0BANGLADESH

p - i XT20 -X X < j ~~~~~~~~~~~Plate5 >_.,\ 'tahx,yJ liR,' \ ,, ;.CEWATERBANC STUPPY -26°.'5vgR-u<;gCt;'* ;- .. .26=AVERAGE MONTHLY INFLOW

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IBRD-10014 -88. ' Kj i 9 !g 9° i ay 1972Z -0 *<, L R q ~~BANGLADESH

5 ,-4 / << j ~~~~~~~~~~~~~~~Plate 6 { \X>\:XrJ 'l >:,\ -WATER BALANCE STUDY ,. t -- CV \t< ytX¢>

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J > [ g / +X \ > | | '2 k~~~~~~~~~~~~~~~~SALE

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| ~ ~ R J S111 I, I __ | H EET\fi / | : ~ / _ :,_, _ j 90-X jv Lca . t E '> t99 6.1~~~~~~~ 3-r - -

|~~~~k LEENA |1 \N ----- hRoads Ralrad 100CS410CFL0-A i tY~~~~~~~ ,37 MILO CEFE ?jMILO CEFE ; --- District Boundaries STREAMFLOWSTREAMFLOWFROMt~~~~~~1 EFFLUENT GROUNDWATER 920~1.1

IBRD-10017 IQQO ,¢ \] W 89° R 9001 ~~~~~~~~~~~~~~May 1972

1~~~~~~6 41X,E BANGLADESH,,2U%A

I V3 1*.N - .->\S S1 A X U/~~tAA TC D D AI A lUPC C'rTlrInVI

11 A< z,)t1\uy > .9 ,> ^NC 4 AVERAGE MONTHLY INFLOW| [zo i N, JPSeptember

1 02 : i i 2 2~~~~~~~~~~~~~~~~340 So m 70 1MIL90so KLEERS

k ' ~ ~ ~ -22D~ u VT C2 _0 10 49 5/ KL6 ETERS

J 1 FYE A W S} ; 1 1~~~...... 92 : 0 s ti - ~ '' i-n'--;'-"'f%

I~~~~~~~~~~~~~~~~~~~4-1t\ Euahl\ ;kjX\ iEa09 4.44l1l

| -14 ;|9; - t

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| EFFLUEN~~~~~~~~~~~~~~~TGROUNWATE 92° I IBRD-10018 IM° .;5o t) Xr;z / -^^o Mav 1972 z <. -2,.,01 *. ,'a}0 ...... 'BANGLADESH

W 5_.G- > > < 8 <,, WATER BA~~~~~~~Plate M1C0ETD t %j-.i9a \vN\ tL ;.-;>'c | SR'F~A"C'EWATER SUPPLY ,,1 92 +,5 \ 4 -. 5,<.t*-i-@ ' ,AVERAGE MONTHLY INFLOW

0,,0 ,R D.+Nr G\ " X W <) 26° ~~October

!> 1 vt < / | o lo 02 =Ao~~~~~~~~~~~10 40=50 E0 70 so S0 -ILOIES

1-2f--'~~ ~)<@P ~ ~ ~L t { \/ S=X_S't1 030O 400 60 70 S0 90 IQO 110 I2 K.LO.ETERS|

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---- ~~~~~~~~~~~~~~~ --- --.L, Roads

_~~~~~~~~~e Ialod 6D 100CS Ao KF A- L 1

EFFLUENT~~~GRUNWAE 920G

IBRD-10019 I w° . 8{3 i ~~~~~~~~~~~~~~~~~~~~May 1972| p '"* ~~~~21 BANGLADESH

t 71. -f .-. . ..4.: ~~~~~~~~~Plate11 t /J. < * \ W~~~IAIATER BALANCESTD g t ) 5i- SURF~~~~~s`ACE WATER SUPPLY ''' WJ9 '!, \|. , :,,',rAVERAGE MONTHLY INFLOW 2f-2'.D I NtbJ\ Li R >\e' 26° , November

| \t ' > ' \i R A N G PU R

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~~~~~~~~~~~~~~~~ia ...------~ r 5>->1

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230~ ~ ~~~~~ A/ 8 ' \* ;

i 49 \ . o ,.;, , .j..; , W 5 t. ,' . t. , I i'J it )/ ' ! -{ X& -r 30

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--- Dstric BounariesSTREAFLOW TREAMLOW FOM __.47[' ._ ,"J~~~~EfUNGONWAEs2 .

IBRD-10020

||) *vs.84 ,- t u J/-| 4BANGLADESH

| ¢\| 3g~~~~~~~~X < ~~~~~~Platej 12 swV_+%\ t 1-. )\la ;x<<4;6 URFACE WATER SUPPLY

-; D I5NC'J\ U- PRA.l a26, December

11t; QWatE1881 so~~~~~~~~~~~~~~~~1_ 50 Is7esoULES t /-5 ° \ ,, Fm, XI ~~~~~~~~~~~~~~~2 _ AO 70 S --90-4tiR

;~~~~~~~~~~~~~~~~~~~md --'-;----- 5 |4 X< f t t; WA<; _n'#i 0 X'~~~~~~~~~~~~~~~~~

2~~~~ ~ 5' 5 I EI > , 25~,11

| id LEGEND l \ v F '<,No, Rods .' ; |

RajMi~lrod 67 100 CF L 00CSr l, - 1 P 3ZMLINACEFEliMLINAREFE \ --- DistrictSTREAMFLOW 80undaries STREAMFLOW FROM _. _ ,, t;' _~~~~~ | EFFLUENTGROUNDWATER 9~~~~~~~~~~~~~~~~~~~~~~~~~2°

IBRD-10026 r° ^t > v < 0O -gr ~~~~~~~~~~~~~~~~~~~~~May11972 | tt* <1t!5799 g t BANGLADESH

|%;W*WA , ;r< i < | ~~~~~~~13| ~~ t/4 ~~Plate VVi.N{ATER BALANCE\\iis %ot Jt' -- !X STUDY SURFACE WATER . LOWER QUARTILE INFLOW /5tH S 26 ~~~~~~~~~~~~March

k / X < \ i 1 X ~~~~~~0 l\ r X -| 1l_°20 3 40 ~~~~~ 50 wi 7080 160so 2 ERS-ILMe

0Xe~~~~'-- ' 15

j v , ~~\ 1 S .' 9 j '' S~~9~~

~~89IL _ ...... _..! ----- 2 ,V(,h,~~

~~R oad~~~~~~~~~~~~~~~~~~~~~s Halod . . JILO 00CS4 ~ ~~~2)~ R~~~~~ ~ 37 ACEFE lO CS_ MLINAR FE \| ,. 1 --- Ditrict SREAMFLoursdries W STR AMFLOW FROM L ,0 f6 02 L E TG O ND AE~~

~~IBRD-10025 < , < ~~~~~~~~~~~~~~~~~~~~~~~~~~~May 1972| t 9 ' ; *...... 60<=wy 0...BANGLADESH~~

~~i0 '. -f-~~W sXrJ'\ \. 4ty j ~~~~Plate14 '^ VV T'- RA A\>.rF 4ZTi -- \t'Ar: :,dl... _____...T...... _,_ _, ..~~

~~026'°~ 0,1DI Y a J,P U | w , j: 26' A_:~~

~~k r 7; t_ <, Q~~~~~~~~~~~~~~~~~ 10 20 30 40 50 _ 70 90 IO IlLES~~

~~( ~ ~ ~ ~~~~~~~ ~~~~~~~~~~~~~~'' /0 20 30 40 60 70 89 9010010-E'R~~

~~) Ao/ ) s^/>> ' titV --R^^^t * ~~~~ ~ ~~~~~91°92°~~

~~|- ,; X-- r . << , 1 t I L 4 t 1 ^,A------6~~

~~|1 f | ; l 12'1*1 I| \ W\ ' -~~

~~j Qt 11. ; ~/ laZlaL3;i !' I, e :"t13os~~

~~.wi||-^"S4 k J\qq~~

~~89 I i ( - f l sA~~

~~LEGEND , \g.j F 4~~~~~~~7 *------Roads l *\ \59 l l~~~~~~~~~~~~~~~~~~~Af 7alod 00F 00F \^ -1 7 ML!NC RE FET.12MLIOAR FE ' DititBunais SREMLWSREMLWFOM| l\; 53 ~ FLETGOUDAE 2~~

~~15RD-10030 8. S ~~-~' _ !- | . May 1972~~

~~k - - BANGLADES H~~

~~_ [ - ' _ I __ <_-r_ . Plate 15 j4; * | -n ~1 |- | LINES OF EQUAL SAILINITY K-25f. ' "1-1-- *>' -~ ' NOVEMBER-MAY 1968~~

t j , S{ g-. --- _1 l-uslJ *~~~~~.n~~~~~~~0 j 2 1~ 1 1 ~~~~SCALE ~~~~~- ! 0 '0 00 90 00 50 0_0 7Q0 50 n01000IiE0 -.",, * ' a 00 00 l 30 40 s0 00 70 00 sn0r,o10iO iiIOOiItCiLi> . U I _ ~~~~~~~~~~~~~~~~~~~~~~~~~9,... -I - -- '--'- < l - - ;=---1 ; SCALE~~~~~~~~~~~~~~~~~~~~~~~~~~------

~~K ' ,4 ' I' 25~~

~~Q ' -1l 1 ,! t rl;~~~~~E.o ..t2, zl 2 - r n I *i=|I _1 _L,-~~

~~!~~~' _ . - , - - _ !- -_,____LL-~~

~~~|~ -~ ~~~~I 'Ij- -- jt s - - - Ii - - - -,~~

~~__ I . - .If .;.. ~ '.r' .~~~

~~J . ~ ~ s~~

~~I .;1 --| E'- ' -t f I _-__ --- __~ ~ ~ ~ ~ ~ T~~

~~_SOnDS''.~~

~~7I 'is-~~

~~I ;-l ,.;t . ' i iI I ; | I ,-~~

~~' h,' I6 t --_ C)' (--N,--' -1---- -; S''i~~

~~. _ _ _ I d N_I_ , 8 91__,yyh_-. I 1 -t _iit ~ _ _ _I.SALINITY MOVEMENT of m* | _ _2_,. -\|C-~~

~~B_ B 1Line__ of equal salinity incuion-E.C. of 2W000 micromhos/cmi as2-C.ontintskof months-hown. 1t \~~

~~Estimated I mi of salinity inorsion-EC hS0J micromhos / cm' as 25'C i - 1~~

~~_ _Limit of salinsityloom Coastal Embanomoent Psoincoreport by l.E Co. loSt.~~

1. LinEsOf equal salinity on this sheenaro thoono los Ohs -. Stationand Number n poriod Novembor-Maymheno nliorty is mooino snlotS of Salinity Samplo -9_2 . from tho Bay of Bongal Soeshent 16 tor ushor monhth. 2. Limos6re hasodon roadinfo takon on:e nach month durnng the period Janosny toot through aoe 1007.

~~IBRD-10031~~

~~-fd -- 2 _ _ _ _ _,oo May 1972~~

~~BANGLADESH~~

~~>-,;-- ,, _-l,-,j---Ir---i -;Ir.- ~~~~~Pfate16 --j <-; 3 ' tj C!, ^' X | ; --;i LINES OF EQUAL SALIINITY JUNE-OCTOBER 1968~~

~~'pa' l 1 , |SCALE~~

~~/< 0 1 10_ - 20| | tO . 40o ae50 60 70 80 90 Oionl,IS l., -. 0 1020-30405060700000100510;or lso2120KILOMETERS~~

~~-X-!--- X i -- -~~

~~(KA . hT I.-E~~

~~'2 ~ Aannat' 2~~

~~/~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

~~------" I- X PJIet -lv!tLf|2rBAl\ x~~

~~4 _I i g I : - - joar_. K_ ,,_ JoIh :~~

~~2 I~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~2 _ it. _ __; !~~

~~1 j J 4 I ___-I I ~ ~~ ~ 60 >~s'/u 7~~

~~~~~-----ncofeqa SALINITYIaint MOVEMENT iJcrinECo ___ _ri.,.iS'rl I ______~~~~~~~~~~~~mcomo I is f ot_son_t\&___t25C_n~~

~~Li.n of equal salinity in,cursion-E.G. of 2000 micromhos fewm' at 25WC.oni first of month shown.~~

~~Estimated limit of salinity incursion-E.G. 500 micromhos / cmr at 25WC.~~

Limit of salinity from Coastal Embankment NOTES Project report by I.E. Co. 1961. 1. Lines of equal salinity on this sheet are shown for the ii?9 Station and Number period June-October when salinity is moving toward of Salinity Sample 92 nheBay of Bengal. Seesheet 15 for other months. 2. Lines are basedon readings taken once eachmonth during the period January 1966 through June 1967.

~~IBRD-10027~~

~~' - I~~~~~~~~~~~~~~~~~~A-.4-lI~ 1 1{=E°. ,;%Ww . | s~~~~~ar, .vay 17 I ws,'r t : BANGLADESH~~

~~| i p A t"X- - >- ;--) -* 1 ~~~~~~~~Plate17| || ,'J ' -I-W--.a-> >wi Ixs.jMJOR HYDROGEOLOGIC REGIONS i6r-0 INNyP;/ P U Ri~. r|, ^ Z* 260~~

~~| . ! . i ., ~~~~RAN G. . i~~

~~W ~ 't W tt~pgTurJI SCALE~~

~~7Di."pur a A .t . -- T_ 2 6001101 KILOMETEFS~~

~~L: s.. -g1025~~

~~f~~~~ 4~~

~~!t 'i2%4 W2i2T ¶R $~~

~~P~~P A I~ ~~~ I3t< u >~~

~~A - TheTistT 241-.]~~

~~RE"' .. a{l- a # Middle MenhnaGood annodpgamat20n-.Jne2-3 C - Upper GangrX;150-200 Floodplain 2-3 Good ---- D~~~~~SaintictyBFfriesh wae~~

I', - 910~~~~~~~~1 IPOTENTIAL .... t.W SUITABILITY Q,~~~~~~f(L K REGIONSREQUIRED GROUNDWATER YIELD FOR TUBEWELL F~~~~~~~~~~~ii H -GeologicallycomplexN Data aleas No Data Uknown Source: Groundwater Tabesucf EtPai3n'npbshd WELL F/SEC.EPTH IN DEVEOPMENCUIC Roas Bazr.-7

~~C- Flodpaippe Gage 15-2 23 God -- Ditrct Boundarie I R 02-~~~~~~~~~~~V -1od-2LoeJmralu2n15-0 E- Syihet~ Basin ~ & ~ ~ ~ ~ ~ ~ ~ ~ _4Pauahai. SouthernMehnaB in N DaaN at nnwnBudr~~

E~~~Svhe - & F -olOlder ltoqra) Alluvium 100-150 Iwest &$asinlA.$2-3 Good~~~~~~J. yrlgca einM Southern8:iin~ ~ No Dat\ MerihnNoDt\nnwnBudr F~ ~ lbtotBqa~ ~~y-i Ole 001023 NoData Data N Unnownod| Soure: "Groudwater Reources o i?s~t {q-'7lPkistanI .upbihd Olderof Daccalcoastal Alluvium 600-1,200200-300 area(North complee area0.5-12-3 PoorGood byA ce IntrainlIc,17 L..j.. ~~~~~~~~~~~~~~~

~~IBRD-10024 I _ 4 I= _., 1072~~

~~-H.-i_2--j----- ,i: __BANGLADESH._~~

~~Plate l8 I . ! t ' _ i,, | |TIDAL VOLUMES I t ' I _,,, 4- Ebb and Flooa Spir.gilqies FebruarV -Maicd., 19S5~~

~~2 _ r _o;- l1 /S=~~

~~-,1 I,, __i,i,, I;- ' ,,; :,~~

~~- I | -\i '~ _I ._ TJk ' | | . ,~~

~~!t', | | I, -- i- | - -- i | | | -|7| I-~ ~~ ~ ~ ~~~~~~~~I T~~

~~- i- I !,--- I 'rr]- s I i a ...d.i I I .1FLO-Oi I a ml,~~

~~_ _ - | t iS - ,; . EB VLUM! -RO-. . I~~

~~R-, ds I NEDECO;IVVTA,_ _ V.I. ,19 6~~

~~I t J. u,s¢- - l- I ' I=P--.~~

~~J-I [ 1 tit: '4~~~_|4 | a | ;1 I ' S ,I-i * - r4~~

~~l 1 __ '1 ' ! t s1 I , ! |.I ,s , e- ;i I- -- _'.---- ,, I =.l-I|'~~

~~L _ltl-.e ni . 1--- .1, S Ii j.',l___,,,,l,,\,,3,°*,.>.5 <-~~

~~~~~~~~~~~~~~~~~~~~~~~~~~~~--'' I ------I -~~

~~a. ~EGN ,* r ' -'~~

~~I- Dititona ies ~ 5*1.0 ABVs4 E n1M._,4 _~~

~~Dsri o undrie l o FLOure DVOUEC-W A Vo.II.16 __ , ,~~

~~IBRD-10021 tn ' w= ' ~~~~~~~~~ ~~~-' n^° ~~~~May 1972 Aij...... 's 0 ' jBANGLADESH|~~

~~.. S \ 4' .N9\, 4 ...... t->,,Plate 1 pr t1 ~\N\fi\B.^ P/F*-'GROUND WATER ISOPACH MAP SHOWING 1!966 , 9'\t'si%" ' ':'v'29}.;DIFFERENCE MAX. &MIN. LEVELS I' 726°J': First Preliminary Mapping~~

~~<; tt AL X0~~~~~~~~~~~~~~~SCL~~

~~LEGEND~~~~~~~2 20 An( rg I MesuemntaknfomS"anTueWl WM: 2~~

~~Pakis-tan,-Drese Cap an Mc 196Ie~~

~~--- District Boundaries Li'S-4-~~~~~~~~~~~~~~~~~- ,- IX~~~~~~~~~~~~~~~~~~~~~~~~~~~------j,~~

~~IBRD-10022~~

~~May 1972 | |189~ ' ,' ' <-oo^R 89 0 ' srl~~

~~I,-2 : II BANGLADESH 2 j0y7kjC1< .) - " \-; >v-t .Plate I g>' X; \ik u 1 xE ' t5'-MAXIMUM DEPTH TO GROUND WATER AS MEASURED FROM Z Y \t ; \,'Nm ;- GROUND SURFACE DURING CALENDAR YEAR 1966~~

~~an~~~SCALE 700901UIE WRANG:uRi,~~~~~~~~~~~~

~~0 (,0 . ' 200 30 SO 50 6 0 70 gm go IC MILES~~

~~| 00 0 80 90 100'I 110 KILOUETERC~~

~~$7 Dr(~ : t ) Z\ /:--gD97~~

~~2 25t j11X> '~~~~~~~~~~~~~~~~~~~~~~~~9W k~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~5~2 25"\~~

~~1 240y< 4 < > / mKHITtAG 24311~~

~~r S '- RE? I TRA, T~~

~~- . IL \ TRACts ~ ' F , ¢< Khut t A.$ '@61L , ; -,J,)~~

~~McKee, 19B8 | 89 94( Pakistan, Camp, Dressier and .~~

~~'_--_'_I 890_0__ _~~

~~...... ~~EGENRoads Contour interval 4 feet a2roa's 11 Dataon theProvince of Eas n Source: Groundwater~~