Of Indus River at Darband

Home , Ayub Bridge, Haro River, Indus Basin Project, Kunhar River, Lake Manchar, Mahandri

RESTRICTED For official use only Not for . UNN42 Vol. 6

Public Disclosure Authorized REPORT TO THE PRESIDENT OF THF, INTERNATIONAL BANK FOR RECONSTRUCTION AND DEVELOPMENT AS ADMINISTRATOR OF THE INDUS BASIN DEVELOPMENT FUND

STUDY OF THIE WATER AND POWER RESOURCES OF WEST PAKISI AN

Public Disclosure Authorized VOLUME III

Program for the Development of Surface Water Storage Public Disclosure Authorized Prepared by a Group of the World Barnk Staff

Headed by

Dr. P. Lieftinck

July 28, 1967 Public Disclosure Authorized i R0C FPU-F ClJRRENCY EQUIVALENTS

4.76 rupees = U.S. $1.00 1 rupee = U.S. $0. 21 1 millior rupees = U. S. $210, 000 TABLE OF CONTENTS Page No.

I, INTRODUCTION 11...... -

II-.. SURFACE. WATER HYDROLOGY. .3 .. . .. , 3

Meteorological and GeographicalI Factors, ...... 3 Discharge- Measurement and River. F-lows- ...... ,44... Sediment-.Movement ..... v...... 8...... 8. Floods-.JO,:,. ,10:

III.. HISTORICAL. USE OF SURFACE WATER, . . . . 12

Development of- the. System ...... 12

IV.. THE IACA APPROACH ..... 17

Method- of Analysis...... v.. 17 Surface. Water Re.quirements;...... r19. Integration, of.Surface and Groundwater Supplies' .. 22

Storable. Water. . 23 Balancng- of Irrigation and Power..-Requi:rements.. 25 Future. River Regime ...... 27 Accuracy- of Basic. Data ...... , ,,.. . 27

Vt., IDENTIFICATION OF DAM'SITES AND, COMPARISON OF. PROJECTS' 29:

S'cope of-the Studies ... 29. A. The Valley of the Indus,...... 31 Suitability of the- Valley, for: Reservoir' Storagel 31

A(l.) The Middle Indus-...... -.. 31

Tarbela.Projject- ...... 32 Side Valley- ProjS'ectsi Associatedt w-ith Tar.bela ... 36

The Gariala' Site...... 36

The. Dhok Pathan S.te ...... 39

The Sanjwal-Akhori S'ites -.- , ... 40-

The Attock Site ...... ,41 Kalabagh Project-. .-... .- ... ., 41. Side Valley Projects- Associated with, Kalabagh i .... 43

Makhad Pumped Storage .4.. . 144

Gariala Pumped- Storage...... 44

Dhok. Abakka Pumped Storage . 44,

Summary of Middle' Indus- Sites; .v.._....r..... 44

A(2) Upper- Indus- Sites'...... 145

Skardu . . 45 Other Upper Indus Sites . .47 TABLE-OF CONTENTS (Cont'd) Page No.

A(3) Sites in the Plains ...... 47

Indus Plains Reservoir ...... 47. Chasma Project ...... 49 Sehwan-Manchar Project ...... 50

Summary of Upper Indus Sites and of Sites in the Plains ...... 51

B. The Jhelum River Basin ...... 51 Project for Raising Mangla ...... 52 Rohtas Side Valley Storage ...... 54 The Rajdhani and Kanshi Sites ...... 54 Kunhar River Project ...... 54 Summary of Storage Potentials on the Jhelum .... 55

C. The Chenab River Basin ...... 56

D. The Kabul River Basin ...... 56 The Kabul River Sites ...... 56 The Chitral River ...... 57 The Swat River ...... 57 A Project at Ambahar ...... 57 Associated Projects ...... 58 Warsak Diversion Plan ...... 58 Chitral Diversion Plan ...... 59 Summary of Sites in Kabul River Basin ...... 59

VI. FACTORS IN THE OPERATION OF SURFACE WATER STORAGE RESERVOIRS ...... 63

Coordination of Power and Irrigation Requirements .. 63 The Drawdown Level at Mangla - Up to 1975 ...... 64 The Drawdown Level at Mangla - After 1975 ...... 66 The Drawdown Level at Mangla - Bank Group Studies .. 66 Raising Mangla for Power ...... 66 The Sediment Problem at Tarbela ...... 69 The Tarbela Drawdown Problem ...... 70 The Operational Problem of Gariala ...... 74 Operational Problems at Kalabagh ...... 75 Kalabagh with Sediment Sluicing ...... 76 Kalabagh without Sediment Sluicing ...... 77

VII. THE SEQUENCE OF PROJECTS FOR DEVELOPING SURFACE WATER STORAGE ...... 81

First Stage Storage ...... 82 Alternatives for Period to 1975 ...... 84 Slow Growth ...... 86 High Growth ...... 86 Post-Tarbela ...... 87 Sehwan-Manchar ...... 88 TABLE OF CONTENTS (Cont'd) Page No.

Raised Mangla ...... 90 Kalabagh ...... 90 Swat ...... 91 Gariala ...... 91 Other Projec-ts ...... 91 Conclusions ...... 94

VIII. PROGRAM FOR INVESTIGATIONS ...... 95

Past Experience ...... 95 Basis for Programming ...... 96 Type of Investigations ...... 96 Detailed Program ...... 97 Sehwan-Manchar ...... 99 Raised Mangla ...... 99 Indus Plains ...... 99 Kalabagh ...... 99 Gariala ..... 100 Skardu ...... 101 Ambahar ..... 102 General Considerations and Conclusions ...... 102

IX. FINANCIAL REQUIREMENTS AND COST COMPARISONS ...... 105

Requirements Outside IACA Range of Growth Rates .... 110 IACA Requirements ...... 111

X. FINDINGS AND CONCLUSIONS ...... 112

Chas. T. Main's Recommended Program ...... 113 Tarbela ...... 114 Benefits ...... 115 Post-Tarbela ...... 116 Sehwan-Manchar ...... 117 Raised Mangla ...... 117 Kalabagh ...... 117 Swat ...... 118 Gariala ...... 118 Skardu ...... 119 Investigations ...... 119 Financial Requirements ...... 120

ARTIST'S SKETCH: Tarbela Dam Project ...... Frontispiece

MAPS Following Page No.

III.1 Development Plan for the Indus River System ...... 4

III.2 Gross Commanded Areas of the Indus & Jhelum-Cum-Chenab Rivers ...... 18 TABLE OF CONTENTS (Cont 'd) Following Page No.

III.3 Dam Sites of the Indus Basin ...... 32

III.4 Tarbela and Kalabagh with Associated Side Valley Storage Schemes ...... 32

FIGURES

1. Mean Monthly Discharge: Indus, Jhelum and Chenab Rivers ...... 6

2. Estimated Average Sediment Transport of Indus River at Darband ...... 10

3. Historical Usage of Available Surface Water in the Indus River Basin of West Pakistan ...... 14

4. Projected Usage of Available Surface Water in the Indus River Basin of West Pakistan ...... 20

5. IACA's Estimate of the Mean-year Demand for Stored Water on the Jhelum and Indus Rivers .. 24

6. Average Annual Yield and Efficiency of Storage Capacity on the Indus and Jhelum Rivers ... 26

7. Schematic Plan of the Tarbela Dam Project ... 34

8. Schematic Plan of the Dhok Pathan Dam Project . 40

9. Schematic Plan of the Kalabagh Dam Project 42

10. Schematic Plan of the Skardu Dam Project ... 46

11. Development Program for the Jhelum River ... 66

12. Possible Dam Sites in West Pakistan ... 82

13. Tarbela as First Stage Development on the Indus River .82

14. Kalabagh as First Stage Development on the Indus River .84

15. Alternative Growth Rates of the Total Mean-year Demand for Stored Water on the Jhelum and Indus Rivers .86

16. IACA's Estimate of the Total Mean-year Demand for Stored Water on the Jhelum and Indus Rivers .88 TABLE OF CONTENTS (Cont') Following Page No.

17. Kalabagh as Second Stage Development on the Indus River ...... 90

18. Gariala as Second Stage Development on the Indus River ...... 92

APPENDIX

Terms of Reference and Guidelines for Dam Site Consultant

ANNEXES

1 TARBELA PROJECT

2 KALABAGH PROJECT

3 GARIALA PROJECT

4 SKARDU PROJECT

5 AMBAHAR PROJECT

6 KUNHAR PROJECT

7 MANGLA/RAISED MANGLA PROJECT

8 CHASMA PROJECT

9 SEHWAN -MANCHAR AND CHOTIARI PROJECTS

ARTIST'S SKETCH TARBELA DAM PROJ ECT

MAY 1967 SOURCE: TIPPETfS ABBETr - McCARTHY STRATTON, CONSULTING ENGINEERS FOR WAPDA. I,BRD 1952R

I. IFTRODUCTION

1.01 This volume of the report is chiefly devoted to identifying potential surface storage projects in West Pakistan and to establishing a program for construction which will best meet the probable needs of the province in the future. The most promising projects for early development are evaluated in some detail. This is in accordance with the terms of reference for the Bank Group. Specifically it was stinulated that its study was to be so planned and executed as to determine which of the several potential water and power projects would be feasible of execution during the next two Five Year Plans (1965-70 and 1970 75) and to take account of and serve as a useful guide to the possible future development of water and power projects beyond 1975.

1.02 At the time the Bank Group embarked on its study one major storage project, namely the Mangla Dam on the Jhelum River 9 was already under execution. This project is expected to be completed in 1967. On the basis of preliminary investigations the opinion had developed that for the next major storage project a site on the Indus River near Tarbela was best qualified and a decision in respect of this project was considered to be urgent. This explains why the Group's terms of reference required that as a first step toward a comprehensive study of the water and power resources of West Pakistan a separate report on the technical feasibility, the cost; and benefit of the Tarbela Project should be prepared and given priority. This first part of the study. which also covered a discussion of possib:Le alternatives for Tarbela, was completed early in 1965. (Study of the lWater and Power Resources of West Pakistan, Part I, Report on a Dam on the Indus at Tarbela. February 159 1965.)

1.03 The presen-t report comprises the results of the Bank Group's subsequent studies on dam sites in West Pakistan with updated information on the field covered earlier. Because of their size and their contribution to the surface water supply, the two projects mentioned in the preceding paragraph - assuming that the execution of the Tarbela Project will start in 1967/68 as recommended - will dominate the program for the Third and Fourth Plan periods and additional projects of secondary size only have been considered for that ten-year period in more detail. For those quali- fying for early development their most suitable timing has been indicated. For the period beyond 1975, although the Bank Group sets forth in line with its terms of reference a general order of priorities for the further construction of storage facilities, the Group has considered it impracti- cal to develop a detailed plan for the development of projects extending so far in the future. In view of the many uncertainties that prevail in the project data presently available and the margin of error inherent in such very long--term projections as the next half century, any resulting prognostications would be unreliable and of limited usefulness. l.o4 The Bank Group's work on surface storage development is based on the substantial data assembled and the analysis carried out by the firm of Chas. T. Main International, Inc., of Boston, Massachusetts. The findings of Chas. T. Main are presented in a two-volume report on Tarbela dated November 1964 and a six-volume Comprehensive Report entitled t'Program for Development of Surface Storage in the Indus Basin and Else- where within West Pakistan," dated August 1966. This part of the Bank Group's report reproduces those sections of the Chas. T. Main reports which are necessary to an understanding of the conclusions and recommendations presented herein. The power aspects of this report have been based on the work of Stone & Webster Overseas Consultants Inc. (Stone & Webster) of New York. The estimated surface water needs insofar as they were basic for the storage program were developed as part of the irrigation and agriculture studies carried out for the Bank Group by the following consultant firms: Sir Alexander Gibb & Partners, London; International Land Development Consultants N.V., (ILACO), Arnhem, Holland: and Hunting Technical Services Limited, (HTS), London, who formed the Irrigation and Agriculture Consultants Association (IACA), under the general coordination of Sir Alexander Gibb & Partners.

1.05 Because of the importance of giving guidance to the Bank's consultant, Chas. T. Main, as to which of the potential projects appear sufficiently promising for more thorough examination, an advisory committee was established early in the study. This Dam Sites Committee consisted of a chairman and one other member from the Bank Study Group and two members representing the Government of Pakistan. The Committee held eight meetings, five in Lahore, two in Boston and one in Washington. At these meetings intensive discussions took place and guidance was given to Chas. T. Main, who attended each of the sessions and provided the staff work necessary for the Committee's deliberations. In addition to the selection of the order of priority of projects for investigation, the Committee, on the basis of the Chas. T. Main recommendations, decided a number of issues concerning the treatment of various aspects of water- storage sites and ensured coordination in the consideration of available information. - 3 -

EI. SURFACE WATER HYDROLOGY

2.01 An analysis of the hydrological factors affecting the Indus Basin produces one inescapable conclusion: control of the Indus River itself will ultimately be essential to control of the surface water supply. This follows from the simple observation that the Indus River carries 63 percent of the total surface water that is available to West Pakistan for development under the terms of the Indus Waters Treaty 1960 and that 72 percent of its flow occurs during the four-month period, June to September. Without storage, some large proportion of Indus water must inevitably run waste to the sea.

Meteorological and Geographical Factors

2.02 The hydrology of the Indus River's system as a whole, as well as that of the Indus itself with its large floods and seasonal fluctuations, results from the annual meteorological cycle. This cycle is characterized by four periods.

(1) October to November: - Following the humid summer heat a persistent high pressure system gradually develops over the Ind.us Plains. It is generally a period of settled fine weather.

(2) December to March: - By mid-winter, areas of low pressure from the Mediterranean occasionally gain sufficient strength to carry over the land masses and mountains to the west, forming a steady procession of secondary lows. These give rise in the northern part of the country to overcast conditions with steady mild rain for several days at a time. The southern part of the country remains clear.

(3) April to June: - The principal meteorological disturbances are local convective thunderstorms. Few of them, however, produce rain and then only in small widely scattered areas.

(4) July to September: - A persistent area of low pressure develops over the northern central plains and humidity rises. The monsoon rains occur during this season. The southeast monsoon moves up the Indo-Gangetic Plain from the southeast, but by the time it reaches the Punjab Plains it is nearing the end of its travel and is consequently unpredictable as to the amount of rain it may produce. The southwest monsoon, which moves up the lower Indus Valley is more reliable, but weaker at its source. Occasionally, moist air masses from both sources converge over the Punjab and the headwaters of the Indus system. This results in intense and sometimes prolonged rainfall. - 4 -

2.03 It is in this last period, the July to September monsoon period, that most of the annual precipitation occurs. Torrential rains may produce a third of the year's rainfall in a day. (The mean annual precipitation on the plains ranges from less than 4 inches in parts of the Sind in the South to more than 30 inches at the foothills of the mountains.)

2.04 The hydrological character of the Indus River's system is also influenced by the fact that the Indus and its principal tributaries, the Kabul, Jhelum, Chenab, Ravi, Beas and Sutlej, (as shown on Map III.1) all have their sources at elevations exceeding 15,000 feet. 1/ Precipitation on the mountain ranges accumulates in the form of snow, particularly during the winter. The snowmelt, resulting from the rising temperatures in spring, causes an early rise in the flow of the rivers, and accounts for a considerable proportion of their annual discharge. A study of the hydrographs of the Indus at Darband has led to the tentative conclusion that about half of the total annual flowJ is derived from snowmelt.

2.05 The runoff from the monsoon rain is superimposed on the basic flows derived from snowmelt. This results in high discharges on all rivers during July, August and early September.

Discharge Measurement and River Flows

2.o6 These river flows have fortunately been measured over a considerable period of time. The first records of gauge height were made on the Indus at Attock in 1868; the next were on the Chenab at Alexandria Bridge in 1879. Regular discharge measurements were undertaken later by the Irri- gation Department at the various barrages on the plains as they were completed. The most important gauging stations for which extensive records exist, are the so-called "rim"? stations, where the rivers leave the hills and enter the plains. These records have been studied by the Bank's consultants, who have concluded that the discharge figures prior to 1922 are probably less accurate than those for subsequent years. Therefore, for purposes of this study the years 1922 through 1963 have been used. 2/ This 41-year period is considered to be adequate as a basis for planning purposes. The network of gauging stations is being rapidly extended, 61 new stations having been installed since 1960, so that valuable information on the secondary rivers will become available in due course.

2.07 On the basis of the rim station measurements the average annual discharge of the rivers is shown in Table 1. Also showm are the maximnum and minimum yearly flows of record.

1/ All levels are in feet above Standard Pakistan Datum (SPD) which is based on mean sea level, Karachi. 2/ Unless otherwise noted, hydrological years, which extend from October 1 to September 30 of the following year, have been used.

VOL. 111 MAP I

U S S R

ALIAB AM U C

) je/ARADoS t , \~~~~~~SKA

t~~~~~~~~~~~~~~d SWA GORAWLEND-

+ / -# V hAWI~~~~~ ~ ~~~~~~~~~Ar9H P ~~AMBAGHA-

- ~ ~ ~w LMYALLPU) -.

( erOPJ$O -t ~ ~ ~~~~~~~~~~~~~zI M¢AADMo ~~GAILIgtwomeHt SA1 r STUd O T WATER aRESORCEA POWER,a I-.- -. esLN

PESHAWAR toA WS PA S T HMO

1jit~~~~~~~~~~~~~n. Tf

SEHWAN/LAKENANCHAR INDUS RIVERASYSTEM

oJocobobcd~ ~ ~ ~ ~~~l~ rBARRAN0 LIN EORN C T O ACHOTIARI~~~~~~~~A . LIN. CANAL

I~~~~~~~~~~~~~~~~~~~~~~~~SD> TAiNSA / MA COMPRKEHESVHIWJ'>fRoEPORT / UNDE CORTUCIO

i ~ ~ ~MAYove ~ 1967~ ~ ~ ~ EEOMN PLAI ! FOR IBRB-.THEALI

PJNSA LIN A POSBALEL TRG IE

No rs) j ~~~~~~~~~~STUDYOF THE WATER AND POWER RESOURCES

\;$ ,J . 4 ~~~~~~~~~~~~~~~~~~COMP RE HE NS I VE R EP OR T A | ts ~~~~DEVELOPMENT PLAN FOR THE

eEHwAN/LAKE NANCHOTARI LINK CANALS

\ ACHOTIARI( ~~~~~~BARRAGEAND HEADWORKS COMPLETED OR c*oJcy~UNDER 5 ~~~~~~~~} CONSTRUCTION

R~~~~~~~ fo~~~~~~~HYDERABAD *DAMS COMPLETED OR UNDER CONSTRUCTION

[ 1/* \'i t ~~~~~~~~~~~~~POSSIBLESTORAGE SITES

KARA MII

: - ,>! ~~~~~~~~~~~~~~~~~~~~~~010 20 3040 50 100OE 150 200

MAY 1967 IBRD -1921R2

- 5 -

Table 1

Annual Discharge of the Indus, Jhelum. Chenab Rivers (I¢AF) a/ Discharge River Location Mean Minimuim Maximum

Indus Attock 93 72 110 JheLum Mangla 23 -15 33 Chenab Marala 2 19 37

1)42 a/ Million acre-feet.

2.08 Hydrographs of the mean monthily discharges of the Indus, Jhelum and Chenab Rivers over the years 1922-63 are shown in Figure 1, plotted from the figures of Table 2. The high :summer flows are the result of a combination of snowmelt and monsoon rainfall. The Indus shows a bigger difference between winter and summer fl-ows on account of a stronger influence of both snowmelt and monsoon effects.

2.09 There is considerable year to year variation in discharge since the monsoon rainfall :is very variable.. The Indus has a higher proportion Qf snowmelt runoff than the Jhelum and Chenab has less variation in annual yield. It is important to notice, however, that, whatever the deviations from mean may be, a very large proportion of the annual flow of the Indus occurs in the four months June to September. In-the mean-year case as noted at the outset, this is 7? percent, representing approximately 67 MAF (out of 93 MAF recorded at Attock).

2.10 The hydrographs of the Jhelum and Chenab are smoother, with 31 MAF or 64 percent of the annual total of 49 MAF occurring in the peak four months. A notabLe difference between the rivers is that the rise in flow of the Jhelum/?henab occurs about a month earlier than on the Indus. This characteristic is of particular importance to the system from the operational-point of view. - 6 -

Table 2

Monthly Discharges of the Indus, Jhelum.and Chenab (MIAF)

Indus at Attock Jhelum at Mangla Chenab at Marala Highest Lowest Highest Lowest Highest Lowest Mean Recorded Recorded Mean Recorded Recorded Mlean Recorded Recorded

Jan. 1.71 2.78 1.33 0.53 1.06 0.34 0.53 1.25 0.27 Feb. 1.62 2.58 1.18 0.73 1.94 0.33 o.66 1.90 0.29 Mar. 2.45 5.58 1.33 1.56 2.99 o.68 1.06 3.12 0.51 Apr. 4.30 9.91 1.94 2.58 3.93 1.55 1.36 2.45 0.73 May 8.38 15.31 4.46 3.61 5.45 1.76 2.23 4.51' 1.14 Jun. 15.49 23.98 8.20 3.69 5.99 2.22 3.55 5.18 1.75 Jul. 22.57,-32.24 11.68 3.79 7.85 1.85 .5,.68 -8.03 3.67 Aug. 19.81 31.54 12.47 2.97 5.22 .1.54 5.61 8.56 3.68 Sep. 8.65 12.42 5.31 1.60 3.52 0.72 2.94 6.92 1.70 Oct. 3.62- 6.47 2.21 0.85 1.78 0o49 1.o4 3.28 0.54 Nov. 2.14 4.28 1.62 0.54 1.57 0.34 0.52 1.46 .0.35 Dec. 1.87 3.37 1.42 o.48. 1i64 0.32 o.46 1.18 0.28

Total 92.61 22.93 25.64

2.11 The Indus measurements at Attock, shown in Tables 1 and 2, in'clude the flow of the Kabul River and other upper tributaries. They do not, however, provide information as to the degree of that contribution. Though neither the Indus nor the Kabul River has been gauged at a point upstream of and adjacent to their confluence,-regular readings of,the- Indus at Darband, some 50 miles 'upstream of the confluence were started in 1954. These readings, which have been used to assess the flows at Tarbela, comprise'stage records from 1954 to 1958 and discharge measurements since 1960. (No readings were taken between 1958 and 1960.) Cor- relation of these readings with concurrent flow data of.the Indus below Attock-have permitted the computation of synthetic records for the two rivers independently, as shown in Tables 3 and 4. VOLUME m FIGURE I MEAN MONTHLY DISCHARGE: INDUS, JHELUM AND CHENAB RIVERS* (AVERAGE MONTHLY DISCHARGE-MAF) 25 I I I I I W I 25

20 20

INDUS AT ATTOCK

CHENAB AT MARALA

5 / 5

..... 1'.t......

JHELUM AT MANGLA

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MEAN YEAR

* Based on the period 1922-1963 (R)IBRD-3220

-7-

Table 3

Derivation of Mean Indus Discharge at Tarbela (MAF)

Indus at Darband a/ Siran b/ Indus at Tarbela

Jan. 1.07 .04 1.11 Feb, 1.02 .04 1.o6 Mar. 1.42 .o8 1.50 Apr. 2.02 .09 2.11 May 4.36 .07 4.43 Jun. 10.22 .03 10.25 Jul. 16.70 .10 16.8o Aug, 15.85 .11 15.96 Sep. 6.66 .09 6.75 Oct. 2.71 .03 2.74 Nov. 1.54 .03 1.57 Dec. 1.24 .03 1.27

Total 64.81 _.74 65.55 a/ Calcuiated from the Indus flows at Attock for the period 1922 to 1963, by application of the Attock/Darband ratios during concurrent period of record 1954-58 and 1960-64. b/ Based on records 1959-64.

Table 4

Indus Discharge Above and Below Attock (MAF)

Indus at Tarbela Kabul above Attock a/ Indus at Attock

Jan.. 1.11 0.60 1.71 Feb. 1.06 0.56 1.62 Mar. 1.50 0.95 2.45 Apr. 2.11 2.19 4.30 May 4.43 3.95 8.38 Jun. 10.25 5.24 15.49 Jul. 16.80 5.77 22.57 Aug. 15.96 3.85 19.81 Sep. 6.15 1.90 8.65 Oct. 2.J74 o.88 3.62 Nov. 1.57 0.57 2.14 Dec. 1.27 o.6o 1.87

Total 65.55 27.06 92.61

a! Obtained from difference between Indus flows At Attock and Tarbela. - 8 -

2.12 Rounding off the figures of -Tables 2, 3 and 4, the estimated annual contribution of each of the rivers to the surface water supplies of the Indus Basin in West Pakistan is -as follows:

Table 5

Average Annual Contribution of Principal Rivers

Contribution (MAF) (percent)

Indus above Attock 66 45 Kabul above Attock 27 18 Total Indus below Attock 93 63 Jhelium at Mangla 23 16- Chenab at Marala 26 18 Others 5 3

147 100

It follows that the main stem of the Indus must be considered a principal supplier in any plan for the development of surface water storage in West Pakistan.

Sediment Movement

2.13 Any plan for the constructiQn of reservoirs in Pakistan must include serious consideration of the problem of sedimentation. This is particularly true if a reservoir on the-Indus is envisaged. For out of approximately 700 million tons of sediment transported by the river system, to (or through) the plains each year, the Indus River itself carries nearly 540 million. (This compares with the estimated load of the Missouri River at Kansas City of 131 million tons a year, and of the Mississippi River below New Orleans of 600 million tons a year.) Given this fact, it must be recognized that a large loss of useful capacity by sedimentation will occur in any reservoir on the Indus. It must also be recognized that only a continuing program of silt measurement can serve to determine the precise dimensions of this problem and provide a basis for its solution.

2.14 Because the rate of sedimentation will have such a profound effect on the life of any Indus reservoir it has been necessary to make the most of all available data, hoping thereby to establish a basis for a defensible judgment about the useful life of Tarbela as well as other possible reservoirs of the system. Following is a brief analysis of the situation as it is known and a summary of the broad conclusions that can be drawn from it.

2.15 The information used dates from 1960. Before then, records of sediment measurements are considered unreliable because of-the sampling' techniques which were employed. Since 1960, howeyer, a fairly extensive network of sampling stations has been established; on the Indus River in particular, at Darband, 5,000 samples of water have been taken using - 9 - up-to-date methods. IThe results of this field work are shown in Figure 2, and summarized in Table 6, which together clearly indicate the rapid rise in rate of sediment transported with increase in flow.

Table 6

Estimated Average Sediment Transport of Indus River at Darband

Flow Suspended Sediment (Cusecs) a! (1000 tons/day) b/

100,000 400 150,000 1,200 200,000 2,400 300,000 6,600 400o000 13,000 500,000 23,000 600,000 36,ooo a/ Cubic feet per second. b/ Sediment measurements for different flows vary considerably; for example, at a flow of 300,000 cusecs the range is from 3.2 million to 13 million tons per day.

2.16 Since the sediment load varies with discharge, seasonal differences occur in one as in the other. It is estimated that about 90 percent of the total aanual sediment load is carried by the river during the period between the middle of June to the middle of August.

2.17 The average annual sediment transport of the Indus at Darband has been estimated at 440 million tons a year. Sediment deposited in Tarbela Reservoir is expected to consolidate to a final density of about 85 pounds per cubic foot. This rather high value is estimated because of the predominance (about 60 percent) of fine sand in the suspended sediment and the absence of clay. At 85 pounds per cubic foot, 440 million tons is equivalent in volume to 238,000 acre-feet. On the basis of these estimates, Tarbela Reservoir may be expected to silt up at the rate of approximately 2 percent per annum. In 50 years the live storage capacity would be reduced to about 1 M4AF.

2.18 Table 7 gives estimates of annual average sediment transport for the other rivers of the system. Though sediment sampling on the rivers other than the Indus has not been carried out so systematically and estimates of quantities carried by them are therefore subject to even greater uncertainty, in very rough terms, the relative importance of sediment in the Indus as opposed to the other rivers stands out clearly. - 10 -

Table 7

Estimated Sediment Transport a/

River Location Sediment Transport (million tons/year) Indus Partab Bridge 177 Indus Darband 440 Indus Kalabagh 540 Kabul Attock 88.5 Swat Chakdara 1.4 Haro Sanjwal 7.1 Soan Rawalpindi 4.4 Jhelum Mangla 72 a/ All figures are for suspended sediment with the exception of Darband and Kalabagh which include bed load estimated to be 5 percent of the total. Table based on data obtained during period 1960 to 1964.

2.19 It should also be noted that, in the case of the Indus, variations in the total suspended sediment load have occurred. These variations may have been caused in part by erratic geomorphic processes resulting from heavy rainfall, landslides and avalanches. The statis- tically random nature of these occurrences gives rise to the possibility that sediment actually deposited in a reservoir at Tarbela could, over a number of years, vary substantially from that assumed in the studies which are based upon a rating curve, as shown in Figure 2. Should there be a succession of years in which geomorphic processes were particularly active, the usable volume of the reservoir could be depleted at a much faster rate than has been assumed.

2.20 One further reservation which must be made relates to bed load. No reliable methods are available for measuring bed load and in the case of the Indus opinions differ as to its importance. For the purposes of the study, it is estimated at 5 percent of the suspended load. Any errors resulting from this probably will be small compared with those resulting from the possible vagaries of nature.

Floods

2.21 The Indus and its tributaries are subject to severe floods. These generally result from rainfall of high intensity sometimes combined with snowmelt. They may also be caused or aggravated by the breaching of natural dams formed by glaciers or landslides.

2.22 The control of floods in the Indus Plains, and associated drainage problems, are covered in Volume II of this report. In this volume they have to be considered only as they affect the design of dam and spillway structures. In the case of both Mangla and Tarbela adequate spillway capacity is essential because of the catastrophic consequences in terms of damage and loss of life which would result from a failure of the earth and rock fill dams in the event of their being overtopped during a massive flood. ESTIMATED AVERAGE SEDIMENT TRANSPORT OF INDUS RIVER AT DARBAND*

. ~~I 80C

U.)

4~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~r 0~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 0 w 1,00 10 fr 60 -___

90so on th yea 135 by et 19215. IFfre Fro IeslmTAM dmsn 15Y0 ()8D 40

LOGARITHMIC SCALES I0 I_ _II_ 1 2 3 4 5 6 7 8910 20 40 60 80100 200 400 600 1,000 2,000 4,000 10,000 20,000 40,000 100,000

SUSPENDED SEDIMENT LOAD IN THOUSAND TONS/DAY

*Based on the year 1961 as conifirmed by measurements 1962-1964 From TAMS drawing 15NY500

(R)IBRD -3221' nr.

- 11 -

2.23 For both the Jhelum and the Indus, therefore, detailed meteorological investigations were undertaken to ascertain what might be the maximum probable flood arising from the most adverse conditions. In the case of the Indus River, allowance was made for superposition of a storm run-off (1,173,000 cusecs) upon a base flow of 600,000 cusecs (from snowmelt) and the possible breach of a natural dam at the same time (354,000 cusecs). While a combination of the first two is quite probable, the concurrence of all three is extremely unlikely. Additional spillways may contribute as much as $100 million to the cost of a dam on the Indus, but prudence dic- tates the acceptance of the possibility of an exceptional flood. The design floods for the Indus and Jhelum Rivers are shown in Table 8.

Table 8

Indus and Jhelum River Peak Floods (Cusecs)

Indus at Tarbela Jhelum at Mangla

Maximum flood of record 875,000 a/ 1,100,000 b/ Maximum flood assumed for design purposes 2,127,000 2,600,000 a/ Estimated peak flow at Attock, August 1929. b/ August 1929.

2.24 The studies at Tarbela were used as a base for determining likely flood flows at other points on the Indus River, Skardu upstream and Kalabagh downstream. The latter site is the one farthest downstream from the Kabul confluence, still within the Indus Gorge. Possible peak flood flows were established as: 1,100,000 cusecs at Skardu and 2,530,000 cusecs at Kalabagh. Estimates of peak flows in the Haro and Soan Rivers, tributaries of the Indus, were made by the irrigation consultants, IACA, on meager data. The figures of 386,000 cusecs and 555,000 cusecs are considered, however, to be adequate for the purposes of this study. - 12 -

III. HISTORICAL USE 07 SURFACE WATER

3.01 It has been indicated that the chief characteristic of the Indus is a very high seasonal variation of flow. Approximately 67 MAF, or 72 percent of the total flow, occurs in the four months from June to September. The principal opportunity for future development of surface storage lies in the conservation of this kharif 1/ flood, a large part of which flows at present to the sea. Another way of expressing this is to point out that present diversions of water from rivers into the canal systems average 79 MAF per year. WThen the headwaters of the Ravi, Beas and Sutlej are diverted by India, the total amount of water in the rivers in West Pakistan in a mean year will be 142 MAF, excluding 5 M4AF in the lesser tributaries. However, the total amount of water in the rivers in the critical period between the beginning of October and the end of April in a mean year is only 31 MAF, and that amount is almost entirely used up by present diversions. It follows that unless the canal system is modified or unless supplies are redistributed with respect to time of year, a limit to the volume of water which may be diverted has been reached.

3.02 IACA, as will be shown in Chapter IV of this volume, envisages both a modification of the canal system through enlargement of the diversion capacity and a redistribution of supplies with respect to time through the provision of surface storage. IACA also envisages the extensive development of groundwater. To the extent that the IACA approach has to take note of the historical pattern of surface water development, it is important to have some idea of what that pattern has been.

Development of the System

3.03 The present irrigation system of the Indus Plains, commanding a gross area of about 38 million acres, is large by any measure of comparison. Evidence from archaeological sites shows that some lands near the main rivers were cultivated by flood irrigation over 3,000 years ago. The first canals were constructed some five or six centuries ago and were extended under the great Moghul emperors. These early canals were inundation channels which delivered water to the fields when rivers were high in summer, but they were rather unpredictable in operation and were subject both to frequent breaches and to serious siltation problems. In the riverain areas and in some depressions outside the river belt there has long existed another type of flood-dependent cropping, sailaba, whereby crops were grown on residual soil moisture following the recession of the summer floods. The canal system as it is seen today, with a culturable commanded area (CCA) of 33-1/2 million acres of which 25 million acres receive surface water, was started in the nineteenth century. Weirs and barrages were constructed so that the supply of irrigation water would be no longer dependent on the natural variation of the river level. New canals were cut and old inundation channels were incorporated into these systems and given much better regulated supplies. Since independence in

1/ Summer crop season (mid-April to mid-October). - 13 -

1947, Pakistan has continued the extension of the canal system and almost all the areas previously served from inundation channels are now served from river barrages. The increase in the withdrawals of surface water over the years is showm in Figure 3. The withdrawals for the early periods include large discharges into the old inundation canals during the summer flood. Not all these withdrawals were used effectively. It can be seen from Table 9 that, historically, canal head diversions, having increased very substantially during the 1920's from some 38 MAF delivered annually to about 53 MAF, continued to increase to the present level of around 79 MAF. The equivalent increases in watercourse deliveries have been from 30 MAF to 40 MAF and to 58 MAF respectively. With the present additional use each year of about 10 MAF from groundwater sources, some 68 MAF of irrigation water is now available annually to the farms. This amounts to an increase of 125 percent in a little over 40 years.

Table 9

Estimated Annual Canal-Head Diversions (IfAF)

Period Average Annual Diversion

1921-1926 38 1926-1931 53 1931-1946 64 1952-1963 78 1965 79

In addition to surface and groundwater supplies. effective rainfall con- tributes about 6 MAF in canal commands. This is equivalent to a watercourse delivery of about 10 MAF before deduction of watercourse and field losses.

3.o4 Up to the present there has been virtually no provision for reservoir storage to regulate river flows. The only dam of consequential size is at Warsak on the Kabul River, and this serves primarily as a regulator for hydroelectric generation. Its capacity Qf 23,500 acre-feet is almost negligible for agricultural purposes. The commissioning in 1967 of Mangla Dam on the Jhelum River with an initial live capacity of 5.22 MAF (with an assumed minimum drawdovm level of 1040 feet, and including 0.28 MAF in the Jari arm below the level of Mirpur saddle) will complete the first major storage project in West Pakistan. Its main purpose, however, is to provide replacement water for rabi flows to be diverted from the Ravi and Sutlej Rivers under the Indus Basin Settlement Plan. It will not, therefore, go far toward meeting the needs of growth, although it will have considerable value in regulating the flow.

3.05 The historical increases in available surface water, as noted in Table 9, were not achieved easily. The allocation of additional water, as successive canal projects were introduced over the past 100 years, has been - 14 - the subject of a long series of controversies and agreements. The fundamental issue has been the problem of water shortages, particularly in the rabi cropping season 1/ and early and late kharif.

3.o6 The early inundation canals from the Indus and its tributaries took such supplies as the river levels permitted, but withdrawals thereby comprised a small portion of the total supplies available. The introduction of barrage-controlled canals in the nineteenth century enabled supplies to be withdrawn throughout the year. During rabi. when river discharges are low, the barrage-controlled canal withdrawals, even in the period immediately after the First World War, became a significant proportion of the total river supplies. By the late 1920's a situation had been reached wherein large areas of the Sutlej Valley Project were found to be seriously short of water because of their dependence on rivers-uncertain in themselves, which had been tapped for irrigation at upstream points. Monthly withdrawals by some of the canals of the Sutlej Valley varied from mean levels by more than 30 percent. Large areas of the CCA were abandoned.

3.07 By the mid-1930's the whole problem of water allocation to the existing and projected canal system had been and continued to be the subject of extensive discussion and investigation. The complaints of the Sutlej Valley could not be taken in isolation but had to be seen in the context of the whole river and canal system. Thus the Sind had to be assured that its Sukkur Barrage Project would not suffer from the simultaneous sanctioning and construction of the Sutlej Valley Project. Its inundation canals had to be protected from the effects of Punjab withdrawals - hence the recommendation for the construction of barrages at Gudu and Ghulam Mohammed. Finally, in 1945, a comprehensive agreement was drawn up by the Chief Engi- neers of the Sind and Punjab, but had not been ratified before negotiations stopped on Independence. This agreement, known as a Draft Agreement Be- tween the Punjab and Sind Regarding the Sharing of the Waters of the Indus and Five Punjab Rivers, took account of the prior rights of old canals with established supplies and also made allowance for equitable apportionment to canals which were still new or projected in 1945. When Pakistan became independent in 1947, the procedures based on the Draft Agreement continued to be applied as a means of allocating natural river flows.

3.08 These effects may be described briefly as follows: (See Maps 6 and 7, Volume II).

(1) Allocations on the main stem of the Indus continue to be based on historical precedent. The Thal Canal at Jinnah Barrage, the canals at Sukkur Barrage, and certain channels which previously received supplies from old inundation systems came to share first priority, and deliveries to the areas served by these canals are now maintained at fairly consistent levels. The newer canals at Taunsa, Gudu and Ghulam Mohammed-Barrages have relatively low priority.

1/ Winter cropping season (mid-October to mid-April). VOLUME m FIGURE 3 HISTORICAL USAGE OF AVAILABLE SURFACE WATER IN THE INDUS RIVER BASIN OF WEST PAKISTAN (FLOWS, WITHDRAWALS - MAF) 40 1 i I a I 1 i 1 1 40

- COMPOSITE HYDROGRAPH OF INDUS RIVER SYSTEM PRIOR TO DIVERSION OF THE THREE EASTERN RIVERS. BASED ON THE PERIOD 1952-1963 HISTORICAL WITHDRAWALS :1952-1963 AVERAGE 35 - HISTORICAL WITHDRAWALS 1931-1946 AVERAGE 35 HISTORICAL WITHDRAWALS- 1926-1931 AVERAGE ...... HISTORICAL WITHDRAWALS 1921 - 1926 AVERAGE

3 0 30

25 25

20 20

15 15

10 10

...... 0 I I I I I I I I I I I 0 OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP MEAN YEAR

(R)IBRD- 3222A

- 15 -

(2) First right to the flows of the Jhelum and Chenab Rivers is given equally to the Upper and Lower Jhelum, the Upper and Lower Chenab and the Lower Bari Doab Canals (generally known as the five linked canals) whLch together supply the whole CCA of Chaj Doab, 95 percent of the CCA of Rechna Doab and 27 percent of the CCA of Bari Doab.

(3) Canals on both sides of the Sutlej Valley are primarily dependent on the uncertain flows of the Sutlej River for their supplies. Priorities are technically equal among these canals although within the canal system the design generally favors the perennial areas.

(4) Trimmu Barrage and Panjnad Barrage, the latter of which was actually constructed as part of the Sutlej Valley Project, receive river supplies only after priority requirements of the five linked canals mentioned above (viz. UJC, LJC, UCC, LCC and LBDC) have been met in full. The Rangpur, Haveli9 Sidhnai in part, Abbasia and Panjnad Canals, which are served from these barrages, suffer accordingly from frequent shortages which can become quite severe in the rabi cropping season.

3.09 One result of the operation of these procedures is that a significant part of the canal deliveries, nearly 45 percent in fact, is passed to the Lower Indus and the Sind. This will continue to be the case if the IACA program is carried out, as may be seen from Table 10.

Table 10

IACA's Projected Mean Annual Canal-Head Withdrawals for Internal Uses of Regions - 1965, 1975, 1985, 2000 Conditions (MAF/Year)

Region 1965 1975 1985 2000

Vale of Peshawar 2.2 2.3 2.0 1.9 Thal Doab and Indus Right Bank 7.8 7.3 8.6 10.8 Chaj Doab 4.2 3.8 5.3 5.5 Rechna Doab 9.0 9.6 10.1 12.2 Bari Doab 12.5 15.8 17.7 20.1 Sutlej and Panjnad Left, Bank 9.3 10.8 13.4 18.5 Lower Indus 34.0 35.3 44.3 54.7

Total of Principal Canal Commands 79.0 84.9 101.4 123.7

3.10 But this similarity between IACA's program and what obtains at the present as far as the division of waters between North and South is concerned does not result from adhering rigidly to past and present practices. Indeed, to a great extent, what is being proposed in the irrigation and agricultural part of this report (see Volume II) is based on a recognition that the present allocation methods have been rendered - 16 - obsolete by developments since independence. The present allocating procedures, for example, relate onlv to natural river flows and make no allowance for storage or for the development of groundwater resources under the public programs which were started in 1959, and which will undoubtedly continue over the next two decades.

3.11 By departing from the old procedures for distribution, the IACA program will be able to meet, in very rough and aggregated terms, the present and foreseeable demands. Nothing less than a radical departure from those old concepts could compensate for the combination of a severe shortage of surface water in the rabi season plus the loss of the Ravi and Sutlej River flows to India (an event not foreseen in past Punjab-Sind agreements) and at the same time meet the legitimate demands of growth and development. - 17 -

IV. THE IACA APPROACH

Method of Analysis

4.01 The most important constraints on the present system of water supply and distribution are that the system was designed to support a -lower cropping intensity than is required in the future and that the seasonal canal -deliveries are variable and inadequate in rabi and in late and early kharif. Over the next 30 years, IACA expect these constraints to be removed by three major changes which are the regulation of river supplies by surface water storage reservoirs, the full development of usable groundwater resources and the enlargement of many of the existing canals.

4.02 The function of irrigation planning is both to forecast the demand for irrigation water and to determine the best methods of meeting the 'demand. At the outset it was necessary to determine the size and type of unit to be adopted for analystis. The-units had to be suitable for studies of surface water distribution, groundwater pumping and agricultural developments, small enough to provide sufficient detail, but not so-small-as to result in an unmanageable number of units.

4.03 The basic Unlit adopted by IACA was the,canal command, subdivided where necessary to take into account the further aspects of surface water distribution and groundwater supply. and combined where two commands are served from the same headworks and share the same characteristics. The adjustments led to the 42 principal canal commands being studied in IACA's basin an,alysis as 61 divided canal comimand units.

4.o4 The analysis adopts as basin constraints the availability of water and the feasible rates of installing tubewells, enlarging canals and constructing surface water projects. Within each command, apart from the individual applications of these basin constraints, there are important agricultural constraints, which are related to the present status and potential development of individual areas. In the analysis, finance is considered a constraint in the private:sector only. As a basis for the analysis IACA took decisions on a number of factors, including the quality of water usable for irrigation, the desirable depth to the water table and the techniques for developing water resources and the irrigation system.

4.05 The starting point for the analysis of canal commands is the crop water requirements and the cropping patterns. The crop water requirements, which already allow for precipitation, can be met either by surface water deliveries throuigh the canal system or by groundwater pumped by tubewells, or by a combination of the two. A computer program was developed by IACA to make the calculations for water supply in the 61 divided canal command units. The physical characteristics and constraints of these units were used-as input for the program and the-attainable intensities and monthly water budgets represented the output. - 18 -

4.o6 The water demand in the individual canal command units was then examined by IACA in terms of the river flows and the requirements for storage and link canals. A second comnuter program was developed for this purpose. The results of these water studies, combined with econQmic criteria and agricultural factors form the basis for IACA's development program.

4.07 1 IACA's approach is to meet the rabi watercourse requirements from three sources: with groundwater, with the river flow and with storage releases. The quantity of the last has been calculated by IACA as a residual demand and in consequence is most sensitive to change.

4.08 The use of groundwater is not in itself a new concept. As early as 1890, 75 percent of the 4 million acres of land in the Punjab under irrigation was supplied with some water from Persian wheels. In recent years exploitation has been made of this resource by the use of tubewells. But IACA's program provides a formal recognition of the economic value to West Pakistan of a vast underground aquifer, whose volume is now estimated at no less than 300 MAF of recoverable water. The groundwater reservoir would be pumped on average up to the amount of recharge of the aquifer. It would also serve as a balancing reservoir to make up the shortfalls in years of less than normal rainfall.

4. og In the use of river flows, IACA anticipate, among other things a "transfer out" of water from surplus areas (taking ground and surface supplies together) into deficit areas. One of the factors which will make this possible is the physical transfer of river supplies. Ever since the construction of the Triple Canals Project early this century transfer. (from west to east) has been a feature of the irrigation system. In the years following Independence the Marala-Ravi, Bambanwala-Ravi-Bedian- Dipalpur and Balloki Suleimanke Links were constructed. As the major works of the Indus Basin Project are completed, transfers will become increasingly feasible. The Jhelum and Chenab Rivers- are presently connected by the Upper Jhelum Canal and will be further connected by the Rasul- Qadirabad Link, which will continue as the Qadirabad-Balloki Link to the Ravi. The Trimmu-Sidhnai-Mailsi-Bahawal Link gives the system another interconnection. When the Chasma-Jhelum Canal, scheduled to be completed in 1971, goes into operation, waters of the Indus River also will become available to the irrigated areas presently served by the Jhelum/Chenab Rivers downstream from the Trimmu-Sidhnai-Mailsi.-Bahawal Link. Completion of the Taunsa-Panjnad Link in 1969 will enable water from the Indus to be transferred to areas comnanded by the Panjnad Headworks. The irrigated areas that may in future be served from each river are shown in Map II1.2.

4.10 In the integrated system proposed by IACA, those water requirements which cannot be met by groundwater or by natural river flows must be met by surface water storage. The efficient operation of such a system will require the employment of electronic devices and adoption of the most advanced techniques of control and forecasting. Regular estimates of field requirements in each area of the basin must be compared continuously with

VOL III MAP 2

H I N A

N 0 . B

r EHW~S o R \ A S H hl I R

I~~~~~~~~~~~~~~~~~~~~~~~~\,) t ) ~~RAWALPIND9 QJ

+ ~~~ ~~~r Tnlabn#i

C, ~~ ~ ~~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ B

/~~~~~~~~~~~~~/

5~~~ FN ~~~~~~~~~~~~~~ D I a

OSul / -

t x 4K~~h-ip-r STUDY OF THE WATER AND POWER RESOURCES \ ' g g ~~~~~~~~~~~~~OF WEST PAKISTAN S ' g gt ~~~~~~COMPREHENSIVE REPORT

)4 t s - ~~~GROSS COMMANDED AREAS § t t i ~~~~~OFTHE INDUS & X W X E t} ~~JHELUM-CUM-CHENAB RIVERS

W } -n ~~~~~~~~~///xINDUS COMMAND)

s_- 9 ^ {t g t < ~~~~~~~~~~~~~~~JHELUM-CUM-CHENAB COMMAND

.- 6 2 22 g } t t ~~~~~~~~~COMBINEDCOMMANDS

^ 64, , v 1 xW } ol 1~~~~~01020 304|050 100 1510 200

APRIL 1967 IaRD - 1922R

- 19 -

the'current annual hydrological conditions. -Keeping in mind the electric power requirements of the-grid system as well as pumping demands, decisions wi'll have to be taken as to the,optimum method of operating the surface and underground reservoirs. fOperation of such -an integrated water system wTill -require both an effective management and extensive system analysis as a guide for the optimum use of the water resources..

Surface Water Requirements

4.11 The analyses carried out by IACA gave the results presented in Table 11.

Table 11 I I

Estimated Irrigat;ion Requirements at the Watercourses during the Kharif and -Rabi.Seasons at Present and as Projected by IACA (MAF)

Present Conditions Khari'f Season (Mean 'Year) 1975 1985

May 5.8 7.1 9.0 June 8.5 10.7 13.4 July 9.5 10.3 13.0 August 9.1 11.5 15.5 September 8.2 10.5 14.3 Subtotal 41.1 50.1 65.2

Rabi Season

October .1 9.4 11.2 November 4.2 4.5 5.7 December 3.3 3.7 4.7 January 2.6 4_4 5.6 February 3.3 7.1 8.5 March 4., 7.6 8.7 April 4,.1 53 6.9 Subtotal ,27.6 2.0 51.3

Total 68.7 92.1 116.5

4.12 n'I'Tab'le-12,a 'simmary 'of 'IACA's projected watercourse deliveries to meet t-hese rxtr,atl-on req,u'Irements 'isg'iven for three key years: 1975, which is the enrd 6o-fthe ftierst- 10-year action period; 1985, the end of the perspective Plan.- erd,athsand s alysis assumes, the ultimate sztage ofdevel§opment wi'll Jhave 'been achieved. Table 12 breaks down projected watercouurse Ideliveries -into the separate components of groundwater andzsurface%water, and presents.estimates of the total diversion of surface water required at canal head. The projected withdrawals for the three key years are shown in Pigure 4. - 20 -

Table 12

Projected Water Deliveries in the Canal Commanded Areas (Mean Year) (MAF)

Total Diversion Projected Watercourse Deliveries of Surface lWater Groundwater Surface Water Total at Canal Head a/

Present 10 58 68 7'9 1975 30 63 93 85 1985 4o 77 117 101 2000 b/ 44 91 135 124 a/ The difference between diversion at canal head and watercourse delivery is accounted for by losses in the conveyance system. b/ The fiaures for the year 2000 are an expression of what is believed may be the position at the ultimate stage of development and are not to.be taken as an estimate of the actual position in the year 2000.

4.13 These aggregate figures for surface water deliveries are broken down in Table 13 with estimated monthly deliveries at canal heads. The comparison of river flows with demand gives no more than a general impres- sion of the periods when water should be stored and when it should be released from storage. Apart from the complex matter of limitations in regional distribution from the individual river sources and distribution losses in the rivers and link canals, it is also necessary to make allowance for variations from the mean flow conditions. VOLUME m FIGURE 4 PROJECTED USAGE OF AVAILABLE SURFACE WATER IN THE INDUS RIVER BASIN OF WEST PAKISTAN (FLOWS, WITHDRAWALS - MAF) 40 lI E1 1 1I I 40

- COMPOSITE HYDROGRAPH OF INDUS RIVER SYSTEM AF rER DIVERSION OF THE THREE EASTERN RIVERS BASED ON THE PERIOD 1922-1963 -- - PROJECTED WITHDRAWALS 2000 CONDITIONS

35 - PROJECTED WITHDRAWALS 1985 CONDITIONS 35 ---- PROJECTED WITHDRAWALS 1975 CONDITIONS

30 30

25 25

20 20

15 15

10 ,, /*\ 10

5 5

0 ~~~~~~~~~~~~~~0 OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP MEAN YEAR

(R) IBRD-32231

- 21 -

Table 13

Estimated Mean-Year Total Monthly River Flows and IACA's Present and Projected Surface Water Use at Canal Heads (MAF)

Reservoir River Estimated Projected Projected Projected Filling Flows a/ Present Use Use Use Period (Mean Year) Use b/ 1975 1985 2000

May 14.22 7.0 7.1 8.3 10.3 June 22.73 10.0 10.4 13.2 16.4 July 32.04 11.1 11.0 13.6 16.9 August 28.39 10.7 11.2 14.0 17.4 September 13.19 9.6 9.9 12.1 15.3 Subtotal 110.57 T___ 4-9.6 2 76.3

Reservoir Drawdown Period

October 5.51 7.0 7.5 8.2 9.9 November 3.20 4.6 3.7 4.4 5.5 December 2.81 3.6 3.5 3.9 4.6 January 2.77 2.9 4.0 4.5 5.2 February 3.01 3.8 5.9 6.4 7.3 March 5.07 4.5 5.6 6.1 6.9 April 8.24 4.8 5.1 6.7 8.o Subtotal 30.61 31.2 35.3 4o.2 47.4

Total 141.1,3 79.6 84.9 101.4 123.7

a/ Figures exclude flows from the head reaches of the Ravi and Sutlej, which will be diverted by India. b/ Figures are larger in some months than river flows owing to current use from the Ravi/Sutlej and to time lags between rim station and canal head.

4.14 The preceding tables show that under the IACA program, during the period 1965 to 1975=the use of groundwater would increase by 200 percent, from 10 to--3Q_MAF. This would necessitate the development of some 18,000 additional public tubewells coupled with the anticipated development of private tubewells. In the same period, the use of surface water at the watercourse would increase by some 10 percent, from 58 to 63 MAF. During the=second decade, the projected use of groundwater would increase by 10 MAF, while the use of surface water would increase by 14 MAF. By the year200Q0, the projected use of surface water at the watercourse would increase:to-91 MAF, implying a total diversion at canal head of nearly 125 MAF. A part of this increase would be achieved by canal remodeling to--allow for the greater use of natural river flows. - 22 -

4.15 Despite the improvement that would result from canal remodeling, a substantial increase by other means is essential. Only one means can be found to meet figures of the magnitude involved, and the finding is confirmed in the comprehensive and detailed reports prepared by both IACA and Chas. T. Main. Throughout all their reports, there is evidence of a great need to develop storage capacity on the Indus River and its tributaries in order to meet the needs of irrigation as formulated by IACA.

Integration of Surface and Groundwater Supplies

4.16 The IACA plan is based on a close integration of surface and groundwater supplies, the groundwater aquifer being assigned the roles of both seasonal and over-year storage. Thus, to project the demand for surface water storage, the mean-year flows were used. The importance of this use of the groundwater reservoir for over-year storage, from the point of view of minimizing the requirement for surface storage, is indicated in Table 14.

Table 14

IACA's Present and Projected Groundwater and Surface Water Availabilities at Watercourses during the Kharif and Rabi Seasons (MAF)

Estimated Present Condition 1985 Kharif Ground- Surface Available Ground- Surface Available Season water Water Irr. Water water Water Irr. Water

May o.6 5.2 5.8 1.9 7.1 9.0 June 0.8 7.7 8.5 3.4 10.0 13.4 July o.6 8.8 9.4 3.7 9.3 13.0 August 0.7 8.4 9.1 5.3 10.2 15.5 September 0.9 7.4 8.3 5.3 9.0 14.3 Subtotal 3 37.5 41.1 19_.6 65.2

Rabi Season

October 1.1 4.4 5.5 5.1 6.1 11.2 November 0.9 2.6 3.5 2.9 2.7 5.6 December 0.8 2.1 2.9 2.1 2.6 4.7 January 0.7 1.6 2.3 2.7 2.9 5.6 February 0.9 2.1 3.0 4.5 4.1 8.6 March 0.8 3.2 4.o 3.9 4.8 8.7 April 0.7 3.4 4.1 1.3 5.6 6.9 Subtotal 5.9 19.4 25.3 22.5 28.8 51.3

Total 9.5 56.9 66.4 42.1 74.4 116.5 - 23' -

4.17 Table 15 shows that,. without groundvater5'the amount of reservoir storage required would be greatly increased. If -itwere decided to adopt a system design-standard for meeting- requirements three years in four, it would be necessary to increase surface storage by about 30,percent to 50 percent. The projections are based upon a comparison of the monthly discharge requirements at,,the rim stations for irrigation purposes, with the mean-year historical i'low-of'the two rivers ('see Figure 5).

Table 15

IACArs Estimate of'Storage Requirements on the Indus and Jhelum Rivers (MAF)

1975 I,1985- 2000 Indus Jhelum Total Indus, Jhelum Total Indus Jhelum Total

Mean 5.0 4-.3 9.3- 8'.8 4.5 13.3 (15.5 a/ 6.0 a/ 21.5 a/ (I9.0,b/ 7.5 b/ 26.5 b/ MIedian 5.' 5.r4 11l1 9.7 5.6 15.3 - - - 3 years, i,n 4 6.9 6.o 12'.9 12.1 6.2 18.3 - - - a/ Lower limit. b/ Upper limit.

4.18 With the development of storage at a rate necessary to meet mean- year requirements, it is estimated that a shortage of surface water may occur in one year out. of two, creating- a demand for additional pumping in those years. An.attempt was made to examine via a computer analysis (S'equential Analysis of'Sir Alexander Gibb. & Partners,, September 1966) the effect of deviations, from the- assumption of mean-year water conditions (see Volume II)'. It was, found,, using a historical sequence of flow conditions rather than the mean year, that-prior to 1975'there is evidence of irrigation shortages- in the sE.rstem during rabi which are offset by a small overdraft on the aquifer restricted to areas of'public tubewell development in the IACA program. This- condit-ion is' relieved when Tarbela water becomes. available and no shortages are indicated' until around 1980 when the system becomes short. of' water again in rabi. By 1985-, the total overdraft on the- aquifer- is-indicated ta be about 8 MAF'in the mean-year sequence as compared;to about 16 MAR on the historic sequences. In other words', this sequential study, which' essentially simulated the operation of the entire irrigation' system under conditions. of- the proposed development program', provided a check on the internal consistency of the IACA program and demonstrated that it would operate successfully over a range of river inflows- taken, over' a sequence' of years.

Storable Water..

4.19' The amount of surface- water available for storage' will vary as the irrigation system d'evelops;. The' impounding season for reservoirs on the Tndus- and Jhe'lum extends, from- May throughX Septemler- of each year. - 24 -

IACA's projections of the irrigation requirements in these months have been deducted from the mean river flows, to ascertain the amount of water in the rivers that may be surnlus and available for storage. This is shown in Tables 16 and 17, the figures of which reveal a marked drop in the water available for storage between the years 1985 and 2000. This results from the increasing need for irrigation water during the impounding season and has an important bearing on future reservoir canacities.

Table 16

Mean-Year Storable Surplus Based on IACA's Projected Program: Jhelum River at Mangla (MAF)

1985 Full Development M4ean Flow Irrigation Storable Irrigation Storable Mdonth at Mangla a/ Requirements b/ Surplus Requirements b/ Surplus

May 3.6 o.8 2.8 2.1 1.5 June 3.7 0.7 3.0 1.8 1.9 July - 3.8 o.6 3.2 1.1 2.7 Aug. 3.0 o.8 2.2 1.6 1.4 Storage Sep. 1.6 1.0 o.6 2.0 Release

Total 15.7 3.9 11.8 8.6 7.5 a/ 41-year period. 1922-63. b/ After full allowance is made for use of flows from the Chenab River.

Table 17

Mean-Year Storable Surplus Based on IACA's Projected Program: Indus River at Tarbela (T4AF)

1985 Full Development Mean Flow Irrigation Storable Irrigation Storable Month at Tarbela a/ Requirements b/ Surplus Requirements b/ Surplus

May 4.4 3.1 1.3 6.o Storage Release June 10.2 5.0 5.2 9.4 0.8 July 16.8 1.5 15.3 5.7 11.1 Aug. 16.0 2.4 13.6 6.1 9.9 Sep. 6.8 _4.5 2.3 6.6 0.2

Total 54.2 16.5 37.7 33.8 22.0 a/ l--year period, 1922-63. b/ After full allowance is made for use of flows from the Kabul River. VOLUME m FIGURE 5 IACA'S ESTIMATE OF THE MEAN-YEAR DEMAND FOR STORED WATER ON THE JHELUM AND INDUS RIVERS (MAF STORAGE) 15 i 1 1 1 I IF21 F rFF 15 JHELUM RIVER

10 10

Storage to meet surface water demand in 3 years out of 4 UPPER LIMIT I I Some for I year out of 2

5 5

LOWER LIMIT

oMEAN-YEAR STORAGE DEMAND

20 -i- -i- r I mI I I w rI ImI I 20 INDUS RIVER

UPPER LIMIT

15 15

Storage to meet surfoce water demand in 3 years out of 4

Same for I year out of 2

t / . / ~~~~LOWERLIMIT 10 10

5 5

. / MEAN-YEAR STORAGE DEMAND

1965 1970 1975 1980 1985 1990 1995 2000 (2R)IBRD-3225A

- 25 -

4.20 A more complete picture of the potential of the two rivers for storage development is presented by Figure 6 and Table 18. These show the average annual quantity of surplus water that may be stored, for various assumed reservoir capacities. The figures are derived from an analysis of the monthly discharge records of the two rivers over the impounding season for the 41-year period, 1922-63, and take account of the required mean irrigation releases implied in IACA's program during these months at the ultimate stage of development. The figures in Table 18 emphasize the necessity for basing further storage development plans on the Indus rather than on the Jhelum River. The efficiency of reservoirs, measured as a ratio of mean annual storage yield to storage capacity available, falls off noticeably on the Jhelum River at figures above 6 MAF, whereas it remains at 100 percent up to nearly 20 MAF on the Indus.

Table 18

Average Annual Yield and Efficiency of Storage Capacity on the Indus and Jhelum Rivers at the Ultimate Stage of Development a/

Storage Average Annual Efficiency of Capacity Yield Storage Capacity

(MAF) - (MAF) (percent)

Indus at Jhelum at Indus at Jhelum at Darband Mangla Darband Mangla

1 1.0 1.0 100 100 2 2.0 2.0 100 100 3 3.0 2.9 100 97 4 4.0 3.8 100 95 5 5.0 4.6 100 92 6 6.o 5.4 100 90 7 7.0 5.9 100 84 8 8.0 6.4 100 80 9 9.0 6.6 100 73 10 10.0 6.7 100 67 15 15.0 b/ 100 b/ 20 19.5 b 98 b 25 21.8 b/ 87 30 22.5 b/ 75 35 22.6 b/ 64 b a/ Assuming the year 2000 mean-year irrigation requirements as estimated by IACA continue to be met during the impounding season. b/ Not physically feasible to provide capacity of this size on the Jhelum.

Balancing of Irrigation and Power Requirements

4.21 The relationship between irrigation and power requirements is discussed in detail in Chapter VI of this volume: Factors in the Operation of Surface Water Storaae Reservoirs. Therefore, only the broad approach need be described here. IACA has translated the estimated monthly discharge - 26 - requirements into a very preliminary set of "rule curves" for the drawdown of reservoirs on the Jhelum and Indus. Water released from storage in accordance with these curves, which are expressed in percentage figures in Table 19, would, combined with the actual monthly flows of the rivers, provide water to the irrigation areas generally in accordance with requirements. In times of shortfall, the actual water deliveries would be supplemented by overpumping from the groundwater reserves noted above.

Table 19

Pattern of Reservoir Operation as set forth by IACA on the Indus and Jhelum Rivers (in percent of useful storage capacity)

( - = release) ( + = storage)

Month Jhelum at Mangla Indus at Tarbela

September 0 0 October - 23 0 November - 15 - 8 December - 10 - 11 January - 10 - 21 February - 24 - 26 March - 18 - 19 April 0 - 10 May + 24 - 5 June + 36 + 45 July + 31 + 55 August + 9 0

4.22 The above operational schedules as worked out by IACA for the two specific reservoirs, Mangla and Tarbela, besides meeting irrigation requirements, also take account of the desirability of effecting impoundment each season as quickly as possible in order to increase the head available for hydroelectric power generation. Completion of impoundment on the Indus could be delayed, however, until August should other considerations prove more important (see Chapter VI of this volume). Also, when two or more reservoirs have been constructed on the Indus, both the impounding and release patterns for individual reservoirs could vary from that shown, providing the overall pattern of releases remains similar to that set out in Table 19.

4.23 These operating schedules, established after a study of the pattern of storage release requirements during years of mean, median and critical supply, represent a first approximation of an optimum pattern under varying conditions. Actual operational experience and acquisition of additional hydrological data will serve to improve the scheduling of releases and the efficiency of the reservoirs. The difference in time between the periods of maximum reservoir drawdown on the two rivers VOLUME m FIGURE 6 AVERAGE ANNUAL YIELD AND EFFICIENCY OF STORAGE CAPACITY ON THE INDUS AND JHELUM RIVERS*

25 YIELD

20 a | 5 _ X <~~~~~~~--lNU AT DARBAND U-

z 5 5 > z w 5 JHELUM AT MANGLA

I E oo0 0 E C5 10 15 20 25 30 35 STORAGE CAPACITY (MAF)

110__ _ EFFICIENCY

June through August for the Indus nd May thr August for thNDUS AT DARBAND 90 w

4 ~~~~~~~~JHELUMAT MANGLA z z < 70 *0 Bosed_ ontepno_92i63_sumg___00 odton,zpudigpr z w 60

0 5 10 15 20 25 30 35

STORAGE CAPACITY (MAF)

*Based on the period 1922-1963, assuming year 2000 conditions, impounding period June through August for the Indus and May through August for the Jhelum (2R) IBRD-3224

- 27 -

(April on the Jhelum, May on the Indus) is of particular importance to power generation. The patterns in Table 19 show that in general projects on the Jhelum and Indus may be so operated as to avoid coincidence in time of minimum hydropower potential, although some overlap of minimum level could well occur.

Future River Regime

4.24 The construction of reservoirs on the Indus and its tributaries will have a considerable effect on the future flows of the rivers both as to downstream flooding and sediment carried. Of first importance will be a reduction in the frequency and magnitude of floods on the Indus Plains during June and July, early in the impounding season. The maximum flood peaks, particularly those that occur late in the season when the reservoirs are full, will not be affected, since the reservoirs' capabilities for flood absorption will be comparatively small. Consequently, the spillways and ancillary works have been designed to pass the maximum probable flood through the reservoirs with only slight attenuation of the flood peak.

4.25 Settlement of the major portion of the sediment load in the repervoirs will result in a restoration of load carrying capacity to the released water. Downstream, therefore, the river will pick up sediment from its bed and banks until energy balance has been reestablished. Opin- ions differ as to the extent and rate of erosion that may take place under varying conditions in different streams. Principal effects may be felt along the dikes and at the abutments and piers of structures that have been built across the rivers, and in the canals of the irrigation system. Additional maintenance costs will undoubtedly be incurred but they are not expected to be unusually great.

Accuracy of Basic Data

4.26 As noted in Chapter II of this volume, the hydrological records available for the rim stations cover an unusually long period, and appear to be reliable. Because of their extensiveness it has been possible in certain instances to use them as a base for the derivation of synthetic discharge data. InforTmation on sediment flow, on the other hand, is of short duration and subject to various interpretations. Any error of estimation, where the rate of sedimentation is concerned, will obviously affect the rate at which new reservoir storage must be provided.

4.27 Indeed, this question of the accuracy of basic data appears in many aspects of the program. The forecasts of storage requirements, being based upon both a plan for agricultural development and a large groundwater program, are subject to their achievement. This will be difficult because considerable ef'fort will be required as well as large investments in many associated fields. If the needed investments are not obtained, the plan will fall short of achievement and the predicted increase of need for water may fail, to develop to the extent expected. The rather general lack of factual data related to many of the projects, particularly with respect to subsurface conditions, introduces another element of uncertainty that will be resolved only by extensive investigations. - 28 -

4.28 Nevertheless, while the existence of doubt in many matters is acknowledged, and the shortage of basic data is realized, the Bank Group is of the opinion that the information used in the preparation of this report is the best presently available. It also believes that this information is adequate to formulate a considered judgment on the next and subsequent steps that should be taken to effect beneficial control of the surface water supplies of West Pakistan. - 29 -

V. IDENTIFICATION OF DAM SITES AND COMPARISON OF PROJECTS

Scope of the Studies

5.01 A large number of potential surface water storage projects were reviewed by Chas. T. Main, as consultant for dam sites. The assignment required that studies be made of specific sites designated by the Dam Sites Committee (see Para. 1.05) and that preliminary cost estimates be made of dams appropriate to those locations. In addition, an appraisal of other likely sites was required as a means of determining how each might fit into plans separately considered for development of the rivers individually and the system as a whole. Cost estimates, essential to economic evaluations, were made in a number of cases from preliminary designs worked up for the purpose. Finally, comparisons were made of projects considered both in isolation and in combinations.

5.02 For purposes of economic analysis and to facilitate comparisons, the dam site consultant's terms of reference specified that project cost estimates should exclude all Pakistan duties and taxes and interest during construction and should be based upon the prices generally prevailing in 1965. The cost estimates do not therefore, unless it is so stated, represent an assessment of the financial resources that may be required for realistic construction programs.

5.03 The data available to the consultant, on which he had to base his findings, varied considerably among projects. For some, such as Tarbela and Mangla, there was no lack of relevant information and comprehensive studies in depth were possible. In other cases, reliable data were limited, and some sites could not even be visited within the consultant's program for the time available. Variations of this kind have made it extremely difficult to compare dam sites fairly as to the probable costs. The Bank Group and the consultant concur that until projects can be compared on an equal basis it is only prudent to add an appropriate uncertainty factor to those projects which have not been studied in detail. The consultant has felt that his buildup of the cost estimates used in his report makes sufficient provision to cover the worst conditions that may be encountered. While not challenging this judgment the Bank Group, with a mind to future financing problems, has chosen for itself a more conservative position as stated below.

5.o4 In developing preliminary designs for cost estimating purposes, the consultant frequently found it necessary to rely on judgment as no facts were available. In such cases his assumptions regarding physical conditions have -been stated. Future field exploration and subsurface investigations could, of course, reveal different conditions. These might affect not onl-y the cost figures, but even the physical feasibility of the structures conceived to be practicable. For this reason, although his estimates are based on the judgment of experience and include a contingency item to cover unforeseen physical conditions, the Bank Group has considered it advisable to indicate a possible cost range for each project - 30 - about which there is incomplete information, cautioning at the same time that the higher figure of these ranges should not be taken as a firm ceiling. The upper figure of the range was arrived at by independent methods, the fj;fst of which applied a judgment factor to the total estimated cost. This was checked by an analysis involving the utilization of weighted uncertainty factors. While the cost range was introduced primarily to identify and emphasize the uncertainty relating to each project considered, it also serves to establish a reasonable degree of preference, in the present state of knowledge, for those projects which have been more thoroughly investigated. The salient facts pertaining to the various storage sites which are reviewed in this,part of the report, are summarized in Table 33.

5.05 The discussion which follows has for convenience been divided into sections dealing first with potential projects on the Indus and then on the rivers Jhelum, Chenab, Kabul, Chitral and Swat. The presentation is as follows:

Section A: Paras. 5.06-5.76: The Valley of the Indus.

Section A(l): Paras. 5.08-5.51: Middle Indus.

Paras. 5.09-5.19: Tarbela.

Paras. 5.20-5.35: Side valley projects associated with Tarbela.

Para. 5.36: Attock.

Paras. 5.37-5.43: Kalabagh.

Paras. 5.44-5.47: Side valley projects associated with Kalabagh.

Section A(2): Paras. 5.52-5.59: Upper IEndus.

Paras. 5.52-5.58: Skardu.

Section A(3): Paras. 5.60-5.76: Indus Plains.

Paras. 5.61-5.68: Indus Plains Reservoir.

Paras. 5.69-5.72: Chasma.

Paras. 5.73-5.74: Sehwan--Manchar.

Section B: Paras. 5.77-5.90: Jhelum River Basin.

Paras. 5. 7 9 -5.8 4 : Mangla.

Paras. 5.87-5.89: Kunhar. - 31 -

Section C: Para. 5.91: Chenab River Basin.

Section D: Paras. 5.92-5.107: Kabul River Basin.

Para. 5.95: The Chitral.

Paras. 5.96--5.106: The Swat.

It will be noted that t,he principal emphasis of this material is on the Indus River itself. The hydrological factors which are relevant in this connection were presented and analyzed in Chapter II of this volume.

A. The Valley of the Indus

5.o6 The Indus rises in the highlands of Tibet and flows nearly 2,000 miles to the Arabian Sea. In its upper reaches it is surrounded by mountains that rise to 28,000 feet in height, and its valley is inaccessible for practical engineering purposes for a distance of nearly 500 miles. The river then traverses a basin, in which the village of Skardu is located, before entering a deep gorge which extends for another 300 miles. This gorge terminates about six miles above the village of Tarbela, below which the valley widens. Some 32 miles doamstream from Tarbela the Indus is joined by the Kabul. Then at Attock, it enters another series of gorges through which it flows for a distance of nearly 100 miles before reaching the broad flat plains of West Pakistan near Kalabagh. Beyond that point the river pursues a braided course through the alluvium of the plain for 950 miles on an average direct gradient of about one foot per mile before entering the sea near Karachi. The annual discharge of the Indus at Attock, where it has been gauged since 1868 averages about 93 MAF. Up- stream, above the confluence of the Kabul, at Darband, its average annual discharge has been computed at 66 MAF on the basis of correlation with the Attock records.

Suitability of the Valley for Reservoir Storage

5.07 The uppermost site for a dam on the main stem of the Indus River, for which access may be considered reasonably easy, is at Tarbela (see Map III.3). Some 80 miles north of that general area the mountains rise abruptly and the river flows through deep and narrow gorges. While these gorges may provide opporttunities for the construction of high dams with considerable power potential, the number of potential storage sites appears very limited. Furthermore-, the area has been subject to little exploration and the developments of aeccess routes could rival in cost the building of the projects. FrQm--TarEiela south to Kalabagh the valley is relatively open, but either its-width is such as to preclude the economic construction of a dam or, as at-Attock, such valuable land and properties would be submerged as to make--thel-proje-ct unifeasible.

A(M) The Middle Indus-

5.08 In the first part of this study, Report on a Dam on the Indus, dated February 1965, which was specifically concerned with Tarbela, - 32 -

detailed comparisons were drawn between the construction of a dam at Tarbela and at Kalabagh. In the course of this second and comprehensive phase of the study, the dam sites consultant has made a substantially more detailed examination of a possible project at Kalabagh. In the following pages, the previous studies of Tarbela will be sumlmarized and more detailed attention will be given to Kalabagh on the basis of the consultant's supple- mentary studies. An annex on each project is attached to this report. After discussion of those two projects, consideration will be given to Upper Indus and Indus Plain sites in that order. Although a number of good potential sites can be found on the so-called middle reach of the Indus, where Tarbela is located, all of them would be considered alternative to Tarbela or Kalabagh and in that context those mentioned will be discussed only briefly.

Tarbela Project

5.09 The Indus River, between the villages of Bara and Kirpalian (M4ap III.4), has been thoroughly investigated since 1959 to ascertain the most advantageous reservoir site on this promising 17-mile stretch of river. In 1962, WAPDA's consulting engineers, Tippetts-Abbett-McCarthy- Stratton International Corp. (TANIS) of New York, submitted a report in which it was concluded that the Bara site (essentially the Tarbela site and hereinafter referred to as Tarbela) would afford the best location for a dam on the Indus in that general area. The Bara site was compared to two alternatives, one at Kirpalian, the other at Kiara. The choice of Bara was based on the following facts and observations:

(i) The Kirpalian site, 17 miles upstream of Tarbela, was judged to have a maximum practical gross storage potential of 4.3 MAF. An additional 1.3 MAF of gross storage could be added by diverting water by gravity flow from the Kirpalian reservoir, through a conveyance canal, to a reservoir formed by a dam to be constructed at Thapla on the Siran River. The estimated cost per acre-foot of usable storage at the Kirpalian site was found to be greater than the comparable storage at the Tarbela site. The cost of the conveyance system and the Thapla dam would further increase the overall average cost of storage at Kirpalian in comparison to that at Tarbela.

(ii) The Kiara site, only two miles upstream of Tarbela, has a storage potential about 10 percent less than that of Tarbela. Also, the physical attributes of the site are not as favorable as those of Tarbela. The estimated cost of storage at Kiara is more than that at Tarbela.

(iii) The Bara site (Tarbela) proved the most promising of the three, primarily because of a geologically ancient stream bed at the left abutment of the proposed dam, which would facilitate the construction of a spillway. VOL. III MAP 3

}/ ,._ ~ Siudy of the Water and Power Resources

.-..-..--- o~~~~~~~~~f'West Pakistan

COMPREHENSIVE REPORT DAM SITES OF THE INDUS BASIN

Dams completed or A under construction

( ,0 9/r ~ v (> A Possible storage sites

ChitralLGIT 20

MAY 1967 IBRD - 1'3Ch;/es ^FH^H0$T^ 449 tw7 , ,

FwE <9<-tr;tS/k/n [X>r, ,A.m r <\- <~~~~~~~~~~~

$ -" - ~~~PESHAWAR"Nowshera y _ /\\

X f) W AttAkhori ISLA $ * a A S H Mo I R

| > \ J ~~~~~~~~~~RAWAPNI/:c

) - s X 4 ~~~~~~ ~ ~~AbbakieJEU

X t 7 o~~~~~~~~~~SARGODH^7OGUJRANWALA

0 20 40 60 80 100MILES

IBRD -1475R3 MAY 1967

VOL [11 MA'P 4

STUDY OF THE WATER AND POWER RESOURCES OF WEST PAKISTAN COMPREHENSIVE REPORT TARBELA AND KALABAGH WITH ASSOCIATED SIDE VALLEY STORAGE SCHEMES spollonZ' 1 O S 10 5

TARBELA K.., dl DAM-

NOWSHERA i I MA

04j CA IVA I

- t ~~~~~~~SA N JWA L X GARIALA DAMA _m g uA;L SITEt

* / ¢ t ,Da @| ~~~~~~~~SLAMABAID

s '* '-- ' AKHORI LiD DAMS R BAHTAR WI

DA.

A 4 4Z4 UA I

. ,/ 4, i~~~~~ARSELASCAN {$v

Id~~~~~~~~~~~~~

Ye, 5 ~ ~ ~ ~ P ~ PN '

6 HOK ABBAKI GLA 4 _ DAM> ,SITE M

3 / ~~~~~~~~DiIOKPATHAN , " C ( DAM

COHO-PArHIA N - CANAL 3 KALABAGH - MAKHAD DAM- DAM,

APRIL 1967 1B4D - 1932R

- 33 -

5.10 Cost estimates in the TAMS' report revealed the following comparative cost per acre-foot of live storage capacity.

Table 20

The Comparative Cost per Acre-foot of Live Storage Capacity at Sites Alternative to Tarbela

Percentage of Cost of Bara Site

Kirpalian site 149 Kirpalian including Thapla dam and conveyance structure 168 Kiara 111 Tarbela (Bara site) 100

All sites listed as alternatives to Tarbela would equally permit gravity diversion of Indus water to the side valley storage on the Haro and Soan Rivers (see Paras. 5.20 to 5.35 below).

5.11 Between 1959 and 1965 more than $19.5 million were spent on site investigations, preliminary works and design for the Tarbela Project. Sub- surface investigations include 560 bore holes, totaling about 100,000 feet, more than 25,000 feet of adits (tunnels); and 4,184 feet of trenches, varying in depth from 10 to 80 feet. In addition, more than 1,000 test pits have been dug. Design has now been completed, with the aid of extensive model tests, and bid documents have been prepared and checked. Estimates of cost, therefore, can be considered much more reliable than for any of the other projects evaluated in this report. It should be noted, however, that the estimates of the Bank Group, though based on the best engineering studies, are not intencded for the same purpose as those of the consultant who will evaluate bids received for the project.

5.12 The project, as presently conceived, consists of a rockfill dan across the Indus River, 485 feet high and 9,000 feet long at its crest. This dam will be flanked by two auxiliary embankments on the left abutment (Figure 7). All told, the three embankments will contain 179,000,000 cubic yards of fill materials. With a crest elevation of 1565 feet, the embankments are designed to imipound 11.1 MAF of water to a normal operating level of 1550 feet. (For-a moire detailed description see Annex 1.) The designed maximum drawdown level is 1300 feet, which would provide initially 9.3 MAF of live storage,_but-f-ri- the purposes of this study a maximum drawdown level of 1332 feet providing initially 8.6 MAF live storage has been adopted (see Chapter VI, Paras. 6.22 to 6.31).

5.13 Two spillways with a combined discharge capacity of 1,670,000 cusecs are to be-p-prov-idced at the left abutment to handle a flood inflow of 2,127,000 cusecs, with a rise of 6.8 feet in the water level of the reservoir above the normal operating elevation. The service and auxiliary spillways are designed for seven and nine radial gates, respectively, each 50 feet by 58 feet in size. - 34 -

5.14 Four concrete lined tunnels, each 45 feet in diameter at the upstream end, are planned in the right abutment to divert the flow of the river during construction. Each tunnel will be equipped with emergency closure gates about halfway along its length. Downstream of the gate chambers all tunnels will be steel lined and the diameters will be reduced to 43.5 feet for Nos. 1, 2 and 3, and to 36 feet for No. 4. Tunnels Nos. 1, 2 and 3 are designed to serve subsequently as power intakes and to be equipped when necessary, with penstock manifolds at their downstream ends in such a way that each will be able to supply four generating units. Tunnel No. 4 is designed as a permanent irrigation water release outlet, its discharge being controlled by two radial gates at the downstream end. Until such time as Tunnel No. 3 may be required for power purposes, it can also be used to release irrigation water.

5.15 The designs presently envisage that the Tarbela power plant when completed will have 12 generating units each rated at 175,000 kw with a capability range up to 183,000 kw under full head and low tailwater conditions.

5.16 The cost of the project, as estimated during the first part of the study, including the first eight generating units, at 1964 prices and excluding Pakistan duties and taxes, was the equivalent of $739 million. Although minor changes may affect individual items, the Bank Group sees no reason as this is written to alter the estimate, which was as follows:

Table 21

Estimated Cost of the Tarbela Project a/ (US$ million equivalent)

Reservoir Works Total Foreign Exchange

Precontract Costs b/ 16.5 4.7 Net Contract Costs 414.4 284.0 Contingencies (20%) 86.2 57.7 Engineering and Administration 36.2 30.0 Insurance and Miscellaneous 9.0 9.0 Performance Bond 4.o 4.o Land Acquisition and Resettlement 59.0 - 625.3 389.4 Power Facilities (Units 1 to 8 inclusive)

Civil Engineering Works 55.1 35.7 Contingencies (20%) 11.0 7.1 Mechanical and Electrical Equipment 35.6 31.7 Contingencies (10%) 3.6 3.2 105.3 77.7 Engineering and Administration 8.4 7.0

Total units 1 to 8 113.7 84.7

(Table 21 continued on page 35; see footnotes on page 35). VOLUME III FIGURE 7

IRRIGATION OUTLET

\/~??X CA\ - ) POWER PLANT 12 -175 MW A WA \ )>"-:\. NGENERATING UNITS iSCHEMCATICM DIVERSION, POWER S IRRIGATION TUNNELS

OPIJLETA GATED DIVERSION CHANNEL DAMESTRUCTURE

DIERSION CHANNEL

DAM~ 2 ~ ~ ~ ABLADMPRJC

MAY 1967 IBRO - 1927R~~SPILWA

MAYLIA-SERVICEI P N OF T

CONSULTINGREPRODUCEDENGINEERSST CHA';. TCO.REHENSIEFOR WAPDA,AS REPn.

- 35 -

Table 21 (Cont'd)

Total Foreign Exchange

Reservoir Works 625.3 389.4

Power Facilities 113.7 84.7

Estimated total project cost including first 8 units 739.0 474.1 a/ As stated in Para. 5.02, the costs are for the purposes of economic analysis and comparison and exclude provision for inflation, financial contingencies, Pakistan duties and taxes and interest during construction, etc. They do not, therefore, represent a full assessment of the financial resources that might be required to carry out the project (see Chapter IX). b/ Excluding costs incurred prior to January 1965.

5.17 The project is physically adaptable to construction in more than one stage. The following estimates relating to a two-stage project, assuming that the dam would be constructed initially to impound water to an elevation of 1500 feet and would be raised subsequently to permit impounding to elevation 1550 feet, are based on information obtained from TANS by the dam site consultant.

Table 22

Estimated Cost of Phased Construction of the Tarbela Project: Reservoir Features Only (US!) million equivalent)

Cost of initial Tarbela, F.S.L. 1500 588 Cost of subsequent raising for F.S.L. 1550 64 Cost of two stage Tarbela 652

Cost of single stage Tarbela 625

As will be indicated in Chapter VII of this volume, the construction of Tarbela by stages would( not be economically viable on the basis of the rate of growth of the Tmean-year demand for stored water projected by IACA. 5.18 In Tab-le- -7 (-.§e-e Para. 2.18, Chapter II), it is estimated that the most probabie1sedfim ent inflow into Tarbela Reservoir will run to about 440 milliont'ons- a year. On this basis it is estimated that about 240,000 acre-.feet of' storage volume will be lost each year by sedimentation. Thus, in 50 years the live storage capacity will be reduced to about 1 MAF. A large loss of useful capacity by sedimentation will occur in any reservoir on the Indus. It is., therefore, a subject for prime consideration, not only - 36 -

during planning stages, but continuall,y in the future. Action that should be taken includes field investigations and research aimed to determine quantities of silt carried in suspension and material moved as bed load, correlating these with river discharges at critical points. Programs for watershed improvement and management to reduce erosion should be instigated, and studies made of the possible effects of check dams and other upstream structures.

5.19 As noted in paragraph 5.11, design of the project is now complete and bidding documents have been prepared. The plan is to complete construction to the stage where impounding could commence in a period of seven years. Thus, should the construction contract be awarded before the end of 1967, the project might be ready to store water towards the end of the summer of 1974 but not to full reservoir capacity.

Side Valley Projects Associated with Tarbela

5.20 In recognition of the high rate of depletion of storage capacity at Tarbela, various proposals have been put forward by the Pakistan authorities for auxiliary (side valley storage) reservoirs on the Haro and Soan Rivers which would be filled by the diversion of Indus River waters through canals from Tarbela Reservoir. It has been indicated that the potential capacity of reservoirs on these rivers is in excess of 30 MAF. A study of the proposals. however, suggests that the costs of dams, considered in connection with the cost of conveyance canals, would make construction of side valley storage projects as expensive as reservoirs on the main stem of the Indus.

5.21 For any such undertakings Tarbela would have to be built to elevation 1565 feet in order to facilitate the transference of water across the divide. Also, because diversions would be possible only when the Tarbela Reservoir might be full or nearly full, it would be necessary to fill Tarbela as soon as possible each flood season. This would provide sufficient time to fill the side valley reservoirs before drawdowns for irrigation. Three potential side valley projects, Gariala, Dhok Pathan and Sanjwal-Akhori, were studied in detail by the dam site consultant and discussed in his earlier Tarbela Report. A summary of the results is described in the following paragraphs.

The Gariala Site

5.22 For side valley storage on the Haro River the dam site consultant came to a conclusion that an earth dam at the Gariala site would provide the most suitable solution. (For a more detailed description see Annex 3.) Such a dam would be about 375 feet high and have a crest length of 40,000 feet. It would contain about 189,000,000 cubic yards of embankment materials. The normal high water elevation behind the dam would be 1250 feet and with a minimum drawdown level of 1020 feet, would provide a live reservoir capacity of 8.0 MAF. This would be filled in a mean year by diverting 7.6 MAF from Tarbela Reservoir, the Haro River itself contributing 0.4 MAF to storage. - '37 -

L5,.23 TTP Scpnvey ithe I-ndus .water from Tarbela to tGarla-la, ,a tcanal some -1iy g iles long,, ~witth ,a capacity of '76,000 c-usec.s, woxuld 'be :constructed 4f-rom ,the S4i$ran sarm .of'the ;Tar,bel-a Reserv.oixr to -the Jabba Kas 'River, a -tgj-itut.ary ofo-the Hiaro :(.see Map '1I..'4',). -ew -details -are 1known -of the g9,?92lgy Q9f itkhi Arkea thro-ugh which the .canal would pass *but the entire !APgth -i6 exp,eet.ed to .be in ieasiJy 'excavated, water-,deposited silt dand ssand3 ,,it 1bedxppk :generTaly ,w.ell bellow invert rgrade. .A control and drop atr-u^e'r,e ,t th ,eind of the teanal xwoiild 'be .required -to -regulate the *re- le,asgs of water -into -the ,ffabba Kas , .own 'which -it -woud :fldow to the ,ar-,i,,laR.,e.srv,oir,

§.2.4 'F9ur reinforced concrete conduits,.26 feet-in diameter, used to di-vert -the -fljow, of -the Haro River duri'ng construction.,-would provide the ,nece9qa,y w,at,er release capacity for ,oeration -of the reservoir. These !con,duits would be the only water release structures and would, when oper- ,ating a,t full d-ischarge, be used in conjunction -wiith the capacity of the -reser-voir betw,ee -f,ull supply level and the design-flood freeboard on the da,m,-to .deal with -the assumed peak flood inflow .of 386,000 cusecs.. An se,,rg,PP9y §3pillway would b.e provided. The consultant's studies indicate th,t t,-i, arrangement would be the most economical.

The -inatallation of turbines at the downstream end of the release ptrqctures would permit the generation of power, but only during the tvqrage release period. Because there would be no discharge for several pToiyths of t,he y,a,r-, -t-he dam site consultant did not carry out detailed sPtudies to determine what the Qptimum installation might be, but as a mWatter- f- Judgment decided that three of the four release tunnels might each serve two, generating units. Each unit would have a rating of 85 mw 4th aL,capability for sustained overload of 15 percent. Since the main que,s,tion is w,hether any installation could be justified, further studies do, not. appear war-ranted at this time.

5.,26 Basic dat-a for- the preparation of feasibility designs and cost estimates are pres,ently limited. Information available to the consultant has consisted of- l l5 00Q scale topographic maps. G.T. sheets of the area at a scale of- one- ineh to. one mnle,, air photographs and one generalized, u.ve.y,Ze,, geolog-ical. cross-section of the dam site. No subsurface ex- pqorations;, bgae been mladle or detailed mapping carried out to date.

The dam s-ite consultant, on the basis of a desk study, estimated th,,a, ajpr-ajec,t o-f the, scale. env-ispaged would cost the equivalent of $651 million+, made. up, as fqllows.s - 38 -

Table 23

Possible Cost of a Dam at Gariala a/ with Conveyance Canals (US$ million equivalent)

Conveyance System Total Foreign Exchange

Precontract Costs 3.5 2.4 Net Contract Costs 86.o 59.7 Contingencies 26.6 18.8 Engineering and Administration 9.2 6.5 Insurance and Miscellaneous 1.9 1.9 Performance Bond 0.9 0.9 Land Acquisition and Resettlement o.4 -

Subtotal 128.5 90.2

Gariala Dam

Precontract Costs 11.9 8.7 Net Contract Costs 295.5 212.9 Contingencies 91.5 66.8 Engineering and Administration 31.7 23.1 Insurance and Miscellaneous 6.6 6.6 Performance Bond 3.0 3.0

Land Acquisition and Resettlement b/ 82.4 _

Subtotal 522.6 321.1

Total 651.1 411.3 a/ Excluding power facilities. b/ The town of Campbellpore, site of a large military cantonment would be inundated by the reservoir: the cost of relocation of the facilities and resettlement of tho peonle. as estimated by WAPDA. is included.

5.28 The estimate given is the best that can be prepared at this time. In view, however, of the lack of necessary engineering data it indicates no more than an order of magnitude. For reasons previously stated the Bank Group has assumed that although the consultant's cost estimate of about $650 million was a reasonable start for planning purposes, should unforeseen difficulties and serious problems arise, the costs could rise to the order of $975 million.

5.29 The consultant appraised the feasibility of phasing the construction at Gariala, based on an initial live storage of 4.6 MAF, increased subsequently to 8.0 MAF by raising the dam. Two-stage development, however, would cost some $28.6 million more than construction under a single contract. The reduction in initial investment cost was estimated to be $54.9 million. - 39 -

The Dhok Pathan Site

5.30 In the course of the earlier Tarbela investigations, as an alternative to side valley storage on the Haro River, consideration was given to storage on the Soan River and, for this, a site at Dhok Pathan appeared particularly attractive (see Map III.4). The project envisaged is shown in Figure 8, although the canal and pumping/power plant indicated relate to a pumped storage project which might be associated with the Kalabagh Project (see Para. 5.37). Study was also made of an alternative site at Dhok Abbaki with the possibility of a similar development in mind (see Para. 5.47). Details are incorporated in the report on the first part of the study and a summary of the results is described in subsequent paragraphs. The Makhad dam site (see Para. 5.45), some 30 miles downstream from Dhok Pathan, would be inundated by the possible future development of a reservoir at Kalabagh.

5.31 The dam at I)hok Pathan envisaged by the consultant would be an earth and rockfill structure5 some 275 feet high, with a crest length of about 12,000 feet, containing about 38,000,000 cubic yards of fill material. The normal top water level of the reservoir would be at elevation 1225 feet which, with a minimum drawdown to 1110 feet, would provide a usable live storage capacity of about 7.5 M4AF. Two 30--foot diameter conduits, to be used for diversion during construction, would be provided at the right abutment to serve as water release outlets. The conduits could also be used as power penstocks in the event that the installation of generating units became justified. The design flood of 560,000 cusecs, with a total inflow of 1.66 MAF and outlets discharging to full capacity, would raise the reservoir level by 14 feet. Since the provision of this freeboard would be cheaper than a service spillway, the consultant concluded that only an emergency spillway would be needed to prevent overtopping in the event of a catastrophic flood.

5.32 To convey water from Tarbela to Dhok Pathan Reservoir, three parallel canals each about 70 miles long, with a combined capacity of 76,000 cusecs, would be required along with ancillary structures, including dams, syphons, aqueducts and culverts. The canals would traverse several different types of terrain, including sandy, silty alluvium, limestone, sandstone and shales. The most important ancillary structure would be a dam at Bahtar, where the canal alignment crosses the Nandna Kas. This dam would add about 0.8 MAF of useful storage to the project and involve about 44 million cubic yards of fill. The operation of the conveyance system would be complicated by the fact that it would be empty for some nine months in each year. Maintenance costs would be particularly heavy. Further studies would appear essential to confirm operational feasibility.

5.33 The engineering and geological data available to the dam site consultant for study of the project was very scant, consisting of a prefeasibility report dated 1957, a geological map to a scale of 1:4,800 based on field investigations carried out in 1960 supplemented by two boreholes, and a geological report dated 1964. Special topographic maps of the area of the proposed reservoir and canal routes thereto at a scale of 1:15,000 and contour intervals of ten feet were made for the study to - 4o - aid in preliminary design. The consultant's order of magnitude estimate of cost (Table 24) has been prepared on the same basis as the estimate for Gariala and in the light of the present very limited knowledge of the two sites it appears that Dhok Pathan would cost considerably more than Gariala.

Table 24

Possible Cost of a Project as Described at Dhok Pathan (US$ million equivalent)

Conveyance Structure Total Foreign Exchange

Precontract Costs 14 Construction Costs a/ 700 Land Acquisition and Resettlement 8

Subtotal 722 476

Bahtar Dan

Precontract Costs 3 Construction Costs a/ 135 Land Acquisition and Resettlement 3

Subtotal 141 92

Dhok Pathan Dam

Precontract Costs 5 Construction Costs a/ 218 Land Acquisition and Resettlement 45

Subtotal 268 149

Total Project Costs 1,131 717 a/ Including an allowance of 30 percent for contingencies and 8 percent for engineering and administration.

5.34 The power output of a development at Dhok Pathan would be negligible for a considerable period of the year when no releases of stored water could be made. It was the opinion of the consultant that an installation of six9 75-mw units might be possible, provided the storage release patterns were found compatible with the pattern of electrical demand.

The Sanjwal-Akhori Sites

5.35 To check whether a project involving a dam at each of these two locations on the Haro River and its tributary, the Nandna Kas, might be developed to serve as an alternative to a high dam at Gariala or perhaps

COF WEST PAKLSTAN SCHEMATIC PLAN OF THE ' ' \1tX1/, 0 ( DHOK PATHAN DAM PROJECT co' a

SOURCECHAS T MAINORAWING

KAY 1967 IBRD - 1928R

- 41 -

to supplement the storage created by a low dam at the same place, the consultant made a preliminary study of structures that would impound 3.3 MAF of water (see Map IIIh). A detailed discussion of this project was also incorporated in the earlier Tarbela Report. In the course of that evaluation it became evident that an inordinate amount of earth moving would be involved and that serious foundation problems would be encountered at each site. Cutoff grouting would be required along the axis of Sanjwal Dam, the embankment of which would be 12.5 miles long, and extensive treatment would also be required at Akhori. In view of this and other considerations, the project was deemed less favorable than Gariala.

The Attock Site

5.36 A dam on the Indus River across the gorge near Attock would create a large reservoir and, if carried to a high level, could impound as much as 30 MAF (see Map III.3). The river at this point has an average annual discharge of about 93 MAF compared with about 66 MAF above its confluence with the Kabul. Serious consideration of such a scheme is ruled out, however, by the fact that it would inundate a major part of the Peshawar Valley as well as the cities of Peshawar and Nowshera. Aside from the problems that would be caused by displacing such a large popula- tion, acquisition of the property would be very costly and economic loss to the area would be great.

Kalabagh Project

5.37 The last dam site in the gorge before the Indus River reaches the plains is at Kalabagh some 12 miles upstream of the Jinnah Barrage (see Map III.4). A project at Kalabagh was studied in the course of the preparation of the earlier Tarbela Report. Additional studies have been made and are incorporated in the discussion that follows. A report on studies of the site, based on designs for an earth and rockfill dam with an abutment overflow spillway, was prepared in 1956 for the Pakistan Government. For preparation of that report limited subsurface investigations were carried out, including 15 drill holes, 150 to 300 feet in depth, and 55 test pits. Foundation rocks at the proposed dam site are sandstones and shales of the Siwalik series, overlain by up to 60 feet or more of alluvium in the river channel. Since then, further reports have been prepared by WAPDA and its consultants, but no additional exploratory work has been undertaken.

5.38 In the course of his Tarbela Report the dam site consultant evaluated several possibilities for a dam at Kalabagh. At that time he favored a concrete dam of a multiple arch type. Since then, from the meager data available, he has prepared a preliminary study of several possible alternative -schemes. He concluded that the best, from a number of different points of view, would be a central earth and rockfill dam, flanked by a concrete buttress sluiceway/spillway structure on the right bank (see Figure 9). The project as envisaged would involve a dam of - 42 - about 300 feet in height impounding water to a normal operating level of 925 feet which, with a minimum drawdown to 825 feet, would create a reservoir with a live storage capacity of 6.4 MAF. The bed level assumed at the dam site is at elevation 670 feet. The cost of the structure would be about $540 million and seven years are estimated as necessary for its construction. (For a detailed review of the Kalabagh Project see Annex 2.)

5.39 The right bank concrete sluiceway/spillway structure would require the placing of about 2.7 million cubic yards of concrete. The ad- joining dikes would take about 13 million cubic yards of fill. The concrete buttress spillway would be controlled by 25 radial gates, each 40 feet wide by 28 feet high. In addition, 25 low-level sluice gates would be provided to control the outflow through an equal number of outlets, each 16 feet wide by 24 feet high, situated in the buttress section. At reservoir level of 943 feet, the maximum outflow over the spillway would be 1,550,000 cusecs. This capacity would accommodate the maximum expected flood inflow of 2,600,OOQ cusecs with an 18-foot surcharge.

5.40 Three, 40-foot diameter, concrete and steel lined tunnels, as well as the concrete sluiceways, would be needed for diversion of the river during construction. At a later date, each tunnel would be connected to three, 23-foot diameter penstocks, thus making it possible to serve a total of nine generating units, each rated at 125 m'.'.The power station, with a total installed capacity of 1,125 mw, would be located at the left abutment of the dam.

5.41 A crucial aspect of the project that received special study was the backwater effect of the dam above the gorge, and the area of land that might be inundated as a result of its construction. From a detailed study of hydrographic data from surveys carried out by the Pakistan authorities at the request of the Bank Group, the dam site consultant concluded that the restriction of the Attock Gorge is the primary cause of flooding upstream to Nowshera. The consultant concluded, therefore, that construction of a dam at Kalabagh, as proposed, would have little effect on flood levels above Attock. He also concluded, however, that the gradual deposition of sediment in the head reaches of the reservoir might cause some flooding in addition to that occuring in the Nowshera area under present conditions. Extensive study of these aspects would be essential to determine the full extent of potential damage.

5.42 It has been estimated that the sediment load of the Indus at Kalabagh is in the order of 540 million tons a year. If this were all deposited in the reservoir its capacity would be reduced at a rate of approximately 300,000 acre-feet each year. Only part of this volume would be deposited in the upper levels to affect live storage, but sometime, between 23 and 33 years after construction, the capacity of the reservoir would dwindle to about 1.0 MAF. Sediment flow-through and sluicing were proposed by the consultant as a possible means of extending the useful life of the reservoir. Lli~~i

DIVERSION,~ -~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~~BRO

- - -~~~-

/, X t/8' / - SCHEMATIC PLAN OF THE o ' 8 .- / /,-' ~~~~~~KALABAGH DAM PROJECT / GENERAL PLAN

- too 0 100 hoo z o' ('< EARTH DAM WITH BUTTRESS SPILLWAY 1

.~~ac ~~~ PE~,1 ,- jOF WlEST PAKISTAN fliE3 . ~~~~~~~~~~~~~~~~~,,C \ 'COMPREHENS IVE REPORT v|

_ 'at / x >t ~~~~~~~~~~~~~~~~~~~~~~~~~CHAS I. MAINDRAWING_ ~ ~ ~~~~~~~~~SOURCE: IBRD-1925RI JUNE 1967

- 43 -

5.43 The Kalabagh Project as tentatively designed by Chas. T. Main would cost roughly as indicated in Table 25 below. These costs do not include taxes, duties, levies, or interest during construction. The total cost is estimated at $540 million of which $212 million would be in foreign exchange. The power plant of nine generating units having a total capacity of 1,125 mw is estimated to cost about $140 million. As discussed in Annex 2, in view of the gross uncertainties involved, the lack of information leading to serious questions as to the technical feasibility of the project as proposed, the Bank Group feels that a cost range of $540 million to $700 million should be adopted as a clearer indication of the possible total cost. The example is cited in the annex of the possibility that a conventional spillway might be the only structure feasible, and in that case the costs would rise greatly.

Table 25

Possible Cost of Chas. T. Main's Recommended Scheme for Kalabagh (US$ million equivalent)

Reservoir Total Foreign Exchange

Precontract Costs 8.9 5.7 Net Contract Costs 228.3 147.2 Contingencies (30%) 68.5 44.2 Engineering and Administration (8%) 23.8 15.3 Land Acquisition and Resettlement 210.8 -

540.3 212.4

Power Facilities a/

Construction Cost 100.0 76.2 Contingencies (30%) 30.0 22.8 Engineering and Administration 10.0 8.0

140.0 107.0 a/ Nine units installed in equally priced groups of three.

Side Valley Projects Associated with Kalabagh

5.44 The dam site consultant studied proposals for extending the useful life of the Kalabagh Reservoir, or for augmenting its capacity by the development of storage projects in side valleys similar to those for Tarbela, described in paragraphs 5.20 to 5.35. Three of these are summarized below. - 44 -

Makhad Pumped Storage

5.45 The Makhad site on the Soan River is about 30 miles downstream from Dhok Pathan and about eight miles above the confluence of the Soan and Indus Rivers (see Map III.4). The river bed at the site is at about elevation 700, and a dam impounding to elevation 1000 would provide a reservoir of about 6 MAF capacity. Previous reports had suggested that this project be undertaken in conjunction with a dam at Kalabagh having a high water elevation of 825 feet, which would largely submerge Makhad dam site. Kalabagh Dam in this case would have negligible storage and serve primarily as a source of power, to pump water into Makhad Reservoir. The consultant concluded that such a project is unrealistic.

Gariala Pumped Storage

5.46 It would be feasible to pump water from Kalabagh Reservoir into Gariala but diversion by gravity from Tarbela appears less costly. The consultant, therefore, dropped Gariala pumped storage from detailed consideration.

Dhok Abakki Pumped Storage

5.47 This project would be similar in many respects to a Dhok Pathan development which has been discussed in detail in the early Tarbela Report and is summarized in paragraphs 5.30 to 5.34, except that the reservoir would be filled by pumping from Kalabagh instead of by gravity diversion from Tarbela (see Map III.4). Deepening of the Soan River channel would be required, however, to convey the water from Kalabagh Reservoir to the foot of the dam, and, by siting the dam at Dhok Abakki rather than at Dhok Pathan, about 7-1/2 miles of channel excavation would be saved. Dams at the two sites would be quite similar. The intake-outlet structure would consist of four, 30-foot diameter conduits, each branching into four, 18- foot diameter penstocks connected to reversible pump-turbine units. These units would have an approximate pumping capacity of 2,000 mw and would produce 1,900 mw on generation cycle. By comparing sketch layouts of the project with those for Dhok Pathan, the consultant estimated its probable cost to be about $634 million, which includes the pumping/generating plant. This figure should be considered as an order of magnitude estimate. As development of this project could only take place after the construction of Kalabagh, detailed investigations do not appear to be warranted until Kalabagh itself has been studied more fully.

Summary of Middle Indus Sites

5.48 Dam sites at Tarbela and Kalabagh provide favorable opportunities for storage on the Middle Indus. Both have advantages and both present problems. Sedimentation and its probable effects must be given thorough consideration at the two sites. - 45 -

5.49 The Tarbela Project has been extensively studied, more than $19 million having been spent on site investigations and engineering studies. Physical feasiblity of the project has been established. Its economic cost, excluding generating facilities, is reliably estimated at $625 million. If the program can be carried out as envisaged by the Pakistan authorities, who contemplate awarding a construction contract in 1967, it is probable that the dam could be completed in time to begin storing water in 1974.

5.50 Feasibility of the Kalabagh Project, as described, has not been established. Field data are limited and much more exploratory work is required to obtain necessary geologic and topographic data and to confirm the physical feasibility of a high concrete buttress structure as proposed by the consultant. The consultant has estimated its cost to be somewhat less than Tarbela but so many uncertainties exist and so much engineering information is required that a realistic comparison is extremely difficult. It would take approximately four years of intensive investigation and study to bring the Kalabagh Project to the present stage of Tarbela. The consultant has estimated that the earliest possible completion of a project at Kalabagh would be about 1979.

5.51 Both reservoirs would be liable to very rapid depletion by the deposition of sediment. Kalabagh, however, would have a shorter useful life because the river's silt load at that point is about 25 percent greater than at TarbeLa. The feasibility of operating the Kalabagh Reser- voir in such a manner as to minimize sediment deposition is discussed later in this volume. Although it may be within the range of possibility to pass a large part of the sediment load, it should be kept in mind that operating for passing sediment would completely eliminate any firm power potential. Side valley storage could be developed from either reservoir but only at considerable cost.

A(2) Upper Indus Sites

Skardu

5.52 The most promising reservoir basin of the Upper Indus is the Skardu Valley at an elevation of about 7000 feet (see Map III.3). Access to the area is extremely difficult as it is separated from the rest of West Pakistan by high mountain ranges. The present access rcute is through Balakot and Bunji over the Babu-Sar Pass at an elevation of 13,000 feet. Available data, consisting mainly of reconnaissance reports prepared by WAPDA and its consultants, supplemented by aerial photographs and 1:15,000 contour maps prepared at the request of the Bank Group by the Pakistan authorities, were studied and provide the basis for the preliminary findings expressed below.

5.53 To compare the merits of storage in the Skardu Valley with other possibilities on the lndus, the consultant carried out a desk study of a possible dam in the gorge immediately downstream from the principal basin. The site selected was at Kandore, about two miles above Ayub Bridge. (For a detailed description see Annex 4.) - 46 -

5.54 No discharge measurements of the Indus at Skardu are available. A study, however, of downstream flow measurements at Partab Bridge, carried out for a single year, and data on regime of the Gilgit, a tributary of the Indus some 100 miles downstream, led the consultant to estimate that the annual discharge of the river at the dam site might be in the order of 35 IMAF. He concluded also that the monthly distribution of flow is such that, allowing for the necessary direct releases to meet downstream re- quirements9 a reservoir of about 8 M5AF capacity could probably be filled in an average year. No records of sediment discharge of the river at Skardu are available. From meager information obtained at Partab Bridge supplemented by judgment, the consultant concluded that the reservoir capacity might be depleted at a rate of about 0.1 MAF a year.

5.55 An earth and rockfill dam, abutting a concrete gravity spillway and reservoir outlet structure on the right bank was conceived by the consultant as the most promising possibility. Two heights of dam were considered, one of 260 feet to impound 5.2 MAF of water, the other of 310 feet to impound 8.0 MAF. The spillway in either case would be provided with thirteen 58 feet by 50 feet radial control gates to permit discharge of a design flood of 1,100,000 cusecs. Sluiceways at river level, through the concrete dam, could be used for diversion during construction and subsequently for releasing water from storage (see Figure 10).

5.56 Existing roads into the Skardu region are inadequate for any means of transportation except small, four-wheel-drive vehicles and pack animals. In this rugged mountainous region the building of access roads would present many problems. The cost of adequate access might rival the cost of the structures facilitated by it. Also, the creation of a reservoir of 5.2 MAF or 8.0 MAF capacity would displace a considerable number of people living in the valley.

5.57 The dam site consultant estimated the cost of the projected undertaking to lie between $427 million and $510 million for a 5.2 MAF reservoir and between $498 million and $588 million for an 8.0 MAF reservoir. All figures would include the cost of an access road. While these estimates are the best that can be made at present, they should be re- garded as indicative only of a probable order of magnitude of the cost of such a project, and the Bank Group feels that a figure of $900 million might be taken as an upper limit if extreme and unforeseen difficulties should be encountered.

5.58 In view of the above, a dam at or near Skardu is generally attractive and the development of the site is potentially promising. Access will continue to present a formidable problem, and considerable further investigations will be required before any specific proposals can be formulated for a development in this area. Since investigations will be difficult, they need to be started as soon as possible. SHIGARTHANG DIKE

MV~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~- -d~~~~~~~- W ~~~~~~~~~~~~~~~~~~~~~~ I: j ~~~~~~~~~~ /7*~ ~ ~ ~~FFRA

400 0 400 600

SCALE IN FEET STUDY OF THE WATER AND POWER RESOURCES OF WEST PAKISTAN COMPREHENSIVEREPORT SCHEMATIC PLAN OF THE ;7, C= CZ SKARDU DAM PROJECT mm SOURCECHAS T MAIMDRAWIH6G

UNE 1967 IBRD-1926RI

- 47 -

Other Upper Indus Sites

5.59 Two other sites at Bunji and Chilas, 100 and 140 miles respectively downstream from Skardu, have been proposed as suitable for the development of hydroelectric projects (see Map III.3). Situated as they are in the confines of the Indus Gorge where the river flows on a steep gradient, the storage potential of any reservoirs created by them would be small. Therefore, even as power projects, it would appear that their development will depend on the construction at some future date of an upstream storage reservoir, such as Skardu, which would serve to regulate the river flows for firm power generation. A third alternate site is at Khapalu, in a narrow gorge of the Shyok River about 50 miles from Skardu (see Map III.3). Few data are available as to features of the site and the area is even less accessible than the Skardu Valley.

A(3) Sites in the Plains

5.60 Below Kalabagh, the river enters the Indus Plains, where the terrain and subsurface conditions do not lend themselves easily to the development of large storage reservoirs. However, WAPDA's consultants for regional planning in the Northern Indus Plains, Tipton and Kalmbach, Inc., (T & K) of Denver, Colorado, have recently produced a scheme for a large reservoir. There are, in addition, a number of smaller projects possible and these are also described below.

Indus Plains Reservoir

5.61 In February 1967, after the Bank's consultants had submitted their reports and when the Bank Group's own report was already in draft form, T & K, as consultants to WAPDA, issued their Regional Plan for the Northern Indus Plains. The plan covers the development and use of the water resources of the Indus Basin and includes a proposal for a large reservoir in the Indus Plains to provide off-channel storage for the Indus River runoff.

5.62 The scheme provides for a great semicircular reservoir in the Thal Doab, created by an encircling embankment, swinging southward in an arc between the Indus and Jhelum Rivers. This site lies to the south and east of the present Thal Project and the reservoir, when full with a top water level at elevation 600, would extend to within about 15 miles of Adhi Kot on the Chasma-Jhelum Link. The gross storage capacity would be 21 MAF and the live storage about 20 MAF.

5.63 The reservoir would be filled by diversion from the Indus River at a new barrage sited some 35 miles south of Chasma. An inlet channel approximately 12 miles long with a capacity of 80,000 cusecs would be required. Filling would also be assisted by a feeder canal of 20,000 cusecs capacity offtaking from the Chasma-Jhelum Link.

5.64 The embankment - or dam - would have a length of 115 miles, a maximum height of 70 feet, an average height of 50 feet, and would involve 300 million cubic yards of fill. The embankment, as proposed by - 48 -

T & K, would be constructed with the alluvium of the doab, compacted in layers with a puddled core. Near the southernmost corner of the reservoir outlet conduits, equipped with control gates, would convey water to an outlet canal to deliver releases to the Jhelum River upstream of Trimmu. The capacity of the outlet would be of the order of 50,000 cusecs. A head of 50 feet between the minimum pool level and the Jhelum River might justify the installation of power generating facilities, but this aspect was not studied in detail by T & K.

5.65 It is recognized by T & K that such a reservoir would suffer a considerable loss from evaporation and from leakage, possibly of the order of 5 MAF a year. However, some of the leakage would be recovered from the groundwater or from regeneration and the net annual loss might be about 3.7 MAF. Thus even in a year of minimum flow the yield of the reservoir would be about 12 MAF or with full use of Tarbela regulation, between 14 and 15 MAF.

5.66 The costs of the scheme as estimated by T & K are shown in the following table.

Table 26

Estimated Cost of the Indus Plains Reservoir (Us$ million equivalent)

Barrage and inlet channel 142 Feeder canal from Chasma-Jhelum Link 22 Embankment (dam) 424 588 T & K estimate the cost of a similar, but smaller, development to provide live storage of 10 MAF to be about $400 million equivalent.

5.67 Associated with this scheme T & K propose a new link system taking off from Kalabagh Barrage to convey water from the Indus River to the lower portions of existing canal systems in the Lower Chaj and Rechna Doabs. This link system, with a maximum capacity of about 10,000 cusecs and a total length of 235 miles, would involve new barrages on the Jhelum and Chenab Rivers and is estimated by T & K to cost in the order of $260 million equivalent.

5.68 The concept evolved by T & K appears to contain a number of attractive features. As off-channel storage the rate of sedimentation should be low. T & K anticipate a 50 to 75 percent increase in rabi supplies to the Sind and believe that with the reservoir in being it would be possible to en- hance greatly the firm power capability and energy generation at Tarbela. Yet the scheme in itself would produce no significant quantity of hydroelectric power. While reservoirs of the type described by T & K are commonly constructed on a much smaller scale, anything on the scale proposed for the Indus Plains Reservoir would be unique. There are many features which - 49 - the Bank Group feel will require careful and possibly prolonged investigation before final conclusions can be drawn. To name only a few: evaporation, seepage and siltation rates, optimum reservoir size in relation to water availability, reservoir capacity based on detailed surveys, foundation conditions and suitability of local materials for embankment construction. Any or all of these items could have a pronounced effect on costs. An operational disadvantage is that unrecoverable water losses would be very high. These losses may be relatively unimportant for the next 10-20 years, but would be a serious matter when towards the end of the century the flow of the Indus and its tributaries becomes fully committed. (As pointed out in Volume II it is water and not land that represents the ultimate constraint on irrigation development.) However, in view of the late stage at which information was made available to the Bank Group, a study has not been possible, either by the Group or by the Bank's consultants. T & K's assessment, bearing in mind that detailed operational studies have not been undertaken, is that the regional irrigation requirements of the northern Indus Plains may not necessitate the scheme until 1990, although the requirements of the Sind for rabi supplies may force earlier consideration. The Bank Group is of the opinion that before consideration can be given to assigning the scheme a place in the development program considerable investigation, which might well take five years or more to complete, must be carried out. In the circunstances tho Bank Group, while taking cognizance of the scheme, has not sought to integrate it into the program, but as stated in Chapter VIII, recommends an early start on preliminary investigation.

Chasma Project

5.69 A large storage project was considered during the study at Chasma (see Map III.3). However, foundation problems were discovered to be so severe that the Dam Sites Committee after receiving the recommendations of Chas. T. Main determined that further investigation of this site would not be fruitful. Some investigation was made of possible additional storage at the nearby Chasma Barrage. (For a more detailed description see Annex 8.) The construction of Chasma Barrage, 35 miles downstream from the Jinnah Barrage, commenced early in 1967. It will serve to divert water from the Indus River to the Jhelum River, through the Chasma-Jhelum link canal. As originally designed, the barrage would operate under normal conditions with a head pond elevation of 640 feet with provisions to handle an additional three feet in flood. Subsequent studies by the consultants for the project and others indicated the feasibility of raising the barrage structure by six feet, to provide more useful storage in the head pond. This change in design was effected and it was also decided to raise the invert of the Chasma-Jhelum link by two feet.

5.70 The central concrete section of the barrage will be 4,200 feet long, and will be flanked on each end by closure bunds, totaling 33,000 feet. The central concrete section will be provided with 41 normal sluiceways, 60 feet wide, and with 11 sediment sluiceways adjacent to the canal head regulators on either side of the barrage. The discharge capacity of the sluices will be 950,000 cusecs. - 50 -

5.71 The water level behind the barrage will probably be held at or below elevation 642 feet from May to August. Subsequently, as flood flows of the Indus recede and the sediment content of the water falls off, the water level will be raised to a maximum storage elevation of 649 feet. Considerable quantities of sediment will therefore be deposited in the head pond below elevation 642 feet. Above that level deposition should not be significant. The dam site consultant has estimated that the storage capacity of the head pond will be essentially permanent at about the following values:

Table 27

Chasma Barrage: Capacity of Head Pond (MAF)

Elevation Range Capacity

645-642 0.18 649-642 0.51 649-645 0.33

Seepage losses and evaporation will reduce the usable volume in each range by about 14 percent.

5.72 The cost of raising the pond level of the barrage by six feet less the savings in cost of raising the canal invert by two feet has been estimated by WAPDA's consultants as follows:

Table 28

Estimated Cost of Incremental Storage at Chasma (Us$ million equivalent)

Total Foreign Exchange

Incremental cost of raising structures 18.3 9.0 Land Acquisition and Resettlement 13.3 -

31.6 9.0

Sehwan-Manchar Project

5.73 The capacities of the Rohri and Nara canals are inadequate to meet the future demands for water in the areas they serve. Construction of a barrage at Sehwan has therefore been proposed by WAPDA's consultants (see Map III.1). Such a barrage would divert Indus water into a new feeder canal to serve the southern Rohri Command and the main Nara Command. This would avoid remodeling long lengths of the Rohri and Nara canals. Along with this, it is proposed to develop additional storage by taking advantage of the head created by the barrage to divert flood waters into Manchar Lake. Water would be released from the lake when the water level behind the barrage has fallen. The storage capacity available in the head pond and lake - 51 - is estimated at 1.8 MAF, after allowing for evaporation losses and seepage. Later, additional storage of about 0.9 MAF would be provided in Chotiari Lake located close to the junction of the Sehwan Feeder and Nara Canal. (Further details on this project are provided in Annex 9.)

5.74 The estimated cost of the construction of the new barrage, feeder canal and the works associated with storage in Manchar Lake, but excluding works related to Chotiari Lake storage, is about $177 million. WAPDA's consultants have estimated that the project would save nearly $150 million which would otherwise be spent on remodeling the Rohri and Nara canals. On that basis the incremental cost of developing storage at Manchar Lake would be only about $27 million. However, IACA studies indicate that considerable development is possible in the usable groundwater area of Rohri North and Rohri South by tubewells alone without recourse to canal remodeling. Furthermore, remodeling in the saline areas would necessitate the installation of drainage tubewells. It may therefore be prudent for the purposes of analyses to allocate the full cost of the Sehwan-Manchar Project to water storage and the Bank Group has adopted a range of between $177 million and $221 million.

Summary of Upper Indus Sites and of Sites in the Plains

5.75 To sum up, an apparently promising site for the development of a storage reservoir on the Upper Indus is the gorge immediately downstream from the Skardu Valley. Construction of a dam here to regulate the river might warrant the development of power projects at either Bunji or Chilas, or at both sites. The area is presently difficult of access and considerable additional exploratory work would be necessary before any project could be defined. It follouYs nonetheless, that development of the Upper Indus Valley for power and water storage is worthy of serious consideration as part of the long-range plans of West Pakistan.

5.76 In summary, it can also be said that the potential for developing storage reservoirs in the plains is limited to the possible site suggested in the Thal Doab, which has not yet been fully explored, and the site at Sehwan and two off-stream reservoirs served from it, namely, at Manchar and Chotiari.

B. The Jhelum River Basin

5.77 The basin of the Jhelum River lies in the north central part of West Pakistan. The principal tributaries embraced by it are the Kishanganga, the Kunhar and the Poonch Rivers (see Map III.3). The average annual discharge of the Jhelum at Mangla, where it has been gauged since 1922, is estimated at 22.93 MAF. This will be the inflow to Mangla Dam, presently under construction and scheduled to store water in the summer of 1967 and to be completed in 1968. Any plans for the further control and use of the waters of the Jhelum must therefore be built around the Mangla Project.

5.78 Several projects in the Jhelum Basin that have been studied by WAPDA were reviewed by the dam site consultant. With the exception of the - 52 -

Kunhar Project, which is primarily for power, all the schemes reviewed relate to the problems of compensating for storage lost in Mangla Reservoir by sediment deposition and of increasing its capacity. Dam sites other than those studied are undoubtedly available 9 but few, if any, deserve consideration except for the development of power.

Project for Raising Mangla

5.79 Mangla Dam, now in final stages of construction is part of the Indus Basin Project. The dam will impound 5.9 MAF of water at elevation 1202 feet. Live storage between that elevation and drawdown level of 1040 feet will be 5.22 MAF. This includes 0.28 MAF in the Jari arm below Mirpur saddle. (For a more detailed description see Annex 7.)

5.80 Principal features of the Mangla Project as it is now being constructed are three large earth dams, containing more than 120 million cubic yards of fill. Mangla Dam, the largest of these, spans the Jhelum River and is 11,000 feet long at crest. Its maximum height is 380 feet. Sukian Dyke, 17,000 feet long, closes gaps in the reservoir rim immediately to the east of the main dam. Jari Dam. 5,700 feet long, spanning the Jari Nullah, is some 12 miles east of the main dam. Two spillways, service and emergency, with a combined capacity of 1,300,000 cusecs, are designed to control the expected maximum inflow of 2,600,000 cusecs, with a surcharge of 26 feet over the normal operating water level of the reservoir. Five tunnels, each 1,940 feet long, served for diversion during construction. Four of these are lined with steel to an internal diameter of 26 feet to serve the needs of power and irrigation. The fifth tunnel is closed with a steel bulkhead, but could be commissioned later if required for irrigation or power. A powerhouse at the discharge end of the tunnels is initially provided with three generating units, each with continuous capability of 100 mw, and a fourth unit has been ordered. Two generating units can be connected to each penstock, thus permitting an ultimate installation of up to ten units. Each turbine will be linked with a companion bypass valve so connected as to maintain a uniform water release regardless of variations in load on the turbine. At present, eight irrigation release valves are being provided, thereby providing the required discharge capacity for irrigation purposes at minimum drawdown. Because Jari Dam had to be constructed downstream from the Mirpur saddle for technical reasons, it has been necessary to provide a 7-foot, concrete-lined tunnel on its right abutment to carry the trapped water (0.4 MAF) to the Upper Jhelum Canal. A decision has been taken to excavate a trench through the Mirpur saddle to enable 0.28 MAF of this water to be diverted into the main reservoir and thus through the power plant.

5.81 The cost of the Mangla Project, including the first three generating units only, is $534 million equivalent, of which $18 million is for the generating units and $12 million for specific features included in the basic design to permit future raising of the reservoir operating level (see Paras. 5.83 and 5.84 below). The following table is based upon actual expenditures to December 1966 and estimates to complete the work: - 53 -

Table 29

Cost of the Mangla Project (US$ million equivalent)

Total Foreign Exchange

Preliminary Works 10.5 2.5 Construction Costs 433.3 297.0 Contingencies 16.8 10.9 Engineering and Administration 22.1 11.3 Land Acquisition and Resettlement 51.8 -

534.5 321.7

Estimated cost of Units Nos. 4, 5 and 6 13.6 11.6 Estimated cost of Units Nos. 7 and 8 11.6 9.7

5.82 It has been stated that the probable average annual sediment load of the Jhelum River at Mangla is 72 million tons. Considering the distribution pattern of sediment deposits in the reservoir, the dam site consultant estimated that the live storage capacity of the reservoir would decrease at a nominal rate of 0.02 MAF per year for the first 27 years of its life and thereafter at 0.04 MAF per year until, after more than 100 years, the usable capacity would be reduced to about 1.0 MAF. Improved watershed management would decrease erosion and prolong the life of the reservoir. Nevertheless, as with most other storage projects on the main stream of rivers in West Pakistan, the loss of reservoir capacity by sedimentation will always constitute a serious problem.

5.83 All impounding structures presently under construction at Mangla are designed to permit raising the normal operating level of the reservoir from elevation 1202 to 1250 feet. This raising would add 3.5 MAF to the live storage capacity of the reservoir and thus increase its useful life although the rate of sedimentation would be unaffected. The three earth dams can be raised without interference to the operation of the reservoir by adding material on their downstream slopes and crests, except for Sukian Dyke where material would be added upstream at a time when the reservoir level is low. The spiliways can be structurally altered at certain seasons of the year without interference to the operation of the project. The impellers of the turbines installed under the initial contract are suitable for the higher heads anid would not require changing.

5.84 The most recent estimate, prepared by WAPDA and their consultants, of the cost of increasing the capacity of the reservoir is as follows: - 54 -

Table 30

Estimated Cost of Raising Mangla (USt million equivalent)

Total Foreign Exchange

Construction Cost 152.5 99.2 Contingencies 15.2 9.9 Escalation a/ 16.8 10.9 Engineering and Administration b/ 18.3 9.8 Land Acquisition and Resettlement c/ 13.7 -

216.5 129.8

a/ The estimate is based, where appropriate, on present Mangla contract rates, escalation of 10 percent is to allow for rise in prices from date of original tender which was November 1961. b/ Taken from information by WAPDA's consultants. c/ Probably estimated too low. Land estimate is based Rs. 1,850 per acre.

Rohtas Side Valley Storage

5.85 The Rohtas Dam site is on the Kahan River, seven miles west of the Jhelum (see Map III.3). The reservoir would be filled by diverting water from Mangla Reservoir through a canal. WAPDA's consultants, after studying the project, decided that a storage capacity of about 5.75 MAF could be provided by this scheme for about the same cost as the Mangla Project. Depletion of the reservoir would be very slow, because the sediment load of the Kahan River with a catchment area of 390 square miles would be small in comparison to the volume of the reservoir. Also, the amount of sediment brought in from Mangla would be small. These factors suggest that the project may be suitable for consideration in connection with some later stage of long-term development: however, the shortage of water in the Jhelum River would appear to limit its usefulness to over-year storage.

The Rajdhani and Kanshi Sites

5.86 Reservoirs created by dams at these two sites would serve as silt traps on the Poonch and Kanshi River arms of the Mangla Reservoir (see Map III.3). Studies to date indicate that in proportion to Mangla, they would add little to the storage capacity available on the Jhelum. In view of the additional capacity that may be obtained by raising Mangla, it is unlikely that they can ever be justified.

Kunhar River Project

5.87 This project on the Kunhar River, between 30 and 70 miles upstream of its confluence with the Jhelum River, would be primarily for power, but would add an estimated 0.378 MAF of storage capacity in the Jhelum Basin. - 55 -

The project would develop power from a drop of more than 4,000 feet over a 35-mile reach of river. (For a more detailed description see Annex 6.)

5.88 The project would consist initially of a concrete, gravity dam, 530 feet high, at Suki Kinari (see Map III.3). A 16-foot diameter, concrete-lined tunnel, eight miles long, would carry the water from the Suki Kinari Reservoir under the mountains, across a loop in the river, to steel penstocks terminating in a powerhouse at Paras. The installation in the Paras Power Station would operate under a head of about 3,000 feet and would consist of two generating units each rated at 122 MVA at 0.90 p.f.

5.89 The second stage of the project would consist of the construction of a concrete gravity dam, 410 feet high, at Naran on the Kunhar River upstream of the Suki Kinari Reservoir to improve regulation of discharge and permit the addition of two generating units to the Paras Power Plant. In the ultimate stage of development, a 14-foot diameter, concrete-lined tunnel, about seven mi:Les long, would be built to convey water from the Naran Dam to a power plant situated at the upstream end of the Suki Kinari Reservoir and containing three generating units each rated at 44.5 MVA continuous. The estimated cost of the project (prepared by WAPDA's consultants in 1961) is shown in the following table with other relevant data.

Table 31

Kunhar River Project

Ultimate Development Stage I (Stages I, II &_III)

Firm Capability (total) mw 198 500 Annual Energy million kwh 1,014 2,545 Live Storage Capacity MAF 0.128 0.378 Estimated Cost a/ US$ mil. equiv. 110 195 a/ 1961 price levels. The cost of an 80-mile transmission line to Wah is included. The cost estimates have not been updated for the purposes of this report.

Summary of Storage Potentials on the Jhelum

5.90 Mangla Dam will provide a live storage capacity of 5.22 MAF on the Jhelum River. Raising the dam would increase its capacity by 3.5 MAF and a side valley storage reservoir with a dam at Rohtas would provide further storage capacity. As pointed out in paragraph 4.20, however, the development of storage capacity in excess of 6.7 MAF on the Jhelum would appear to be of limited use unless some water of abundant years is to be held in the reservoir for release in subsequent dry years. Raising of Mangla appears to represent a reasonable addition to the program for future development of the Jhelum River. The Kunhar River Project offers a promising power development. - 56 -

C. The Chenab River Basin

5.91 The most promising storage sites on the Chenab are situated in Jammu and Kashmir beyond the cease-fire line. Their development for the benefit of Pakistan would involve considerations beyond the scope of this study, and they have therefore not been evaluated. Within West Pakistan the only site with known storage potential is at Chiniot (see Map III.3) some 110 miles downstream of Marala, where an offstream reservoir of 1.4 MAF capacity might be created in an abandoned channel of the river by the construction of extensive earth dikes. The reservoir would be connected to the river by a canal and filled with surplus flood flows for subsequent release. It could also be used to regulate minor differences between river flows in the Chenab and irrigation demands on the canal which takes off from it. The relatively small amount of storage involved in this project and the substantial uncertainties presented by the lack of data, plus its apparent high cost, running to between $100 million and $150 million, makes it appear of doubtful economic value.

D. The Kabul River Basin

5.92 The Kabul River rises in the mountains of Afghanistan, where lies the major part of its catchment area. Before entering West Pakistan it is joined by the Kunar River which in its upper reaches (in West Pakistan) is known as the Chitral. The Swat River, a second tributary of the Kabul, lies wholly in Pakistan. The average annual discharge of the Kabul at Attock (where it joins the Indus) is estimated at 27 MAF. At Warsak, some 75 miles above Attock, its discharge has been gauged at 17 MAF for an average year, the difference being accounted for principally by contributions of the Swat and two minor tributaries, namely, the Bara and Kalpani Rivers. Of these the Swat is the most important, with an average annual discharge of about 7 MAAF.

5.93 Apart from the Peshawar Valley, information relevant to the basin is scant. The terrain is generally mountainous, and difficult of access, also political considerations have discouraged methodical explorations. The river gorges were not visited by the Bank's consultant during the course of his studies and his findings have, of necessity, been based on a review of existing reports and such other data as have been obtainable from the Pakistan authorities.

The Kabul River Sites

5.94 From a study of small-scale maps, WAPDA had come to the conclusion that a suitable site can be found for a dam in the gorge of the Kabul River, adjacent to or on the Pakistan border, which would serve to impound a large reservoir. The reservoir, however, would be almost entirely in Afghanistan. Within Pakistan, the major development on the Kabul is the Warsak multipurpose project which was completed in 1960 (see Map III.3). This consists of a dam and power station with an installed capacity of 160 mw in four generating units. The addition of two more 40-mw units is planned. This increase in capacity would be principally for peaking purposes and was - 57 - anticipated to require the construction of a re-regulating dam doymstream from the power station to even out the river flow and protect downstream irrigation interests. It now appears that the installation of the two extra units may go ahead without the re-regulating reservoir. The capacity of the reservoir has been greatly reduced by the deposition of sediment and still greater reduction is anticipated. Downstream from Warsak additional irrigation canals draw their water from the Kabul River to irrigate the fertile valley surrounding Peshawar.

The Chitral River

5.95 The valley of the Chitral River is remote, generally narrow and steep, and is not suited to the development of large storage projects. The power potential of the river could be exploited if there should develop a sufficient demand to justify the cost of long-distance transmission. It is unlikely that a local market for power in significant quantities will develop in the foreseeable future.

The Swat River

5.96 Existing developments on the Swat River include the Upper Swat irrigation scheme, based on the Amandara headwrorks, and the Lower Swat system of canals which draw their water from the Munda headworks. It has been estimated by the Bank's agricultural consultants that at full development these projects will utilize in an average year all but 4.75 MAF of the Swat River flow. Of this, only about 2.0 MAF would be "untimely" and therefore available for storage.

5.97 A review of available data and reports indicates that there are several alternative dam sites in the basin suitable for the development of large storage reservoirs. Basic data necessary to the preparation of preliminary designs are totally lacking, however, so, to assess the merits and possible potential of a storage reservoir on the Swat River, the dam site consultant prepared a desk study of a dam at Ambahar in the Lower Swat Gorge, about 13 miles upstream from the Munda headworks and less than two miles downstream from the mouth of the Ambahar River (see Map III.3).

A Project at Ambahar

5.98 This proposition, as studied by the consultant, envisages a rockfill dam about 710 feet high, creating a reservoir with a gross storage capacity of 2.8 MAF of which 2.0 MAF would be live. Records of sediment in the Swat River are not available. It is believed, however, to be so low that the capacity of the reservoir would not be adversely affected to any great degree. (For a more detailed description see Annex 5.)

5.99 An overflow spillway at the left abutment of the dam would be provided with twelve 40--foot by 40-foot radial gates, to pass a total discharge of 310,000 cusecs, which is equivalent to the maximum probable flood inflow. On completion of the dam, two 34 -foot diameter, concrete- lined tunnels, each 5,700 feet long, used for diversion of the river during construction, would be provided with steel linings and used as - 58 -

water release conduits or power penstocks. No detailed studies of the power aspects of the project were made by the consultant, but assuming the installation of six units, each rated at 75 mw, calculations indicated a firm power potential of 20 mw and an annual energy potential of 1,900 million kwh.

5.100 The consultant estimated the cost of the project allocable to storage at $145 million equivalent, broken down as follows on the 1964 price basis:

Table 32

Estimated Cost of Ambahar Project (uS$ million equivalent)

Total Foreign Exchange

Precontract Costs 6.o 4.2 Contract Costs a/ 111.8 67.0 Engineering and Administration 9.2 6.4 Land Acquisition and Resettlement 18.0 -

145.0 77.6

a/ Including 30 percent contingencies.

5.101 A considerable period would be required for predesign investigation and for the construction of an access road and preliminary works. Thereafter, the project would require at least six years to design and construct. A program of field investigation of the storage potential of the Swat River is believed warranted.

Associated Projects

5.102 Two schemes for making increased use of the storage sites on the Swat River were reviewed by the consultant. Both schemes are based on the diversion to the Swat of water from other rivers (the Kabul and Chitral) which have poor storage potentials. Either would involve raising the Ambahar Dam to provide additional reservoir capacity.

Warsak Diversion Plan

5.103 Water from the Kabul River would be diverted from the Warsak Dam through a 2.5-mile tunnel and a 16-mile long canal to the Swat River. The water, which would be relatively silt free, would then be raised by pumps to a reservoir on the Swat, created by a dam at Munda headworks. The Munda Reservoir would extend up the river to the foot of the Ambahar Dam. A set of reversible pump-turbine units, would then raise the water more than 800 feet into the Ambahar Reservoir, which for the purpose of this project would be 90 feet higher than the project previously described, The capacity of this higher reservoir would be in the neighborhood of 8 MAF. - 59 -

5.104 To implement the project, a 3,200-.mT pumping plant would be needed at Ambahar and the installation at Munda would have to be of about 450 mw capacity. Because of the very large power demand of these pumping installations, such a project does not appear realistic at this stage of power and resource development.

Chitral Diversion Plan

5.105 A dam could be built in the upper reaches of the Chitral about 12 miles upstream from the Afghanistan border. Such a dam would be about 400 feet high and its impoundment would run to about 0.58 MAF. A tunnel, 23 miles long, would convey the water to the Panjkora River, a tributary of the Swat. To pass an average of 4 MAF a year, the tunnel would have to be 42 feet in diameter, because of the short season during which transference of water would be feasible.

5.106 Available reports suggest that considerable power development could be associated with the project, but the problems associated with the transmission of power to the grid would be great, and the local demand for power is likely to remain small for some time. Also, a major proportion of the power capacity would be unfirm, because the capability of the plant would be restricted to that period of the year during which diversion takes place. The consultant did not prepare a cost estimate of the project, because the magnitude of the structures involved appeared to preclude it from comparison with other storage projects on the Indus or its tributaries.

Summary of Sites in Kabul River Basin

5.107 There would appear to be a basis for the development of hydro power in the Kabul Basin sometime in the future. A limited amount of storage on the Swat River may be feasible. Extensive investigations will be necessary, however, for the development of a comprehensive basin plan. - 6o -

Table 33

Study of the Water and Power Resources of West Pakistan Summary Statement of Principal Potential Storage Projects

Live Cost a/ River Location Capacity Range - omments (MAF) (US$ millions)

Middle Tarbela 8.6 625 Extensively studied. Indus Feasible of completion by 1975. Useful life limited to 50 years, due to siltation.

Attock - Cannot be considered feasible, due to number of people and land affected by reservoir inundation.

Kalabagh 6.4 (54o to 700 Limited field data. Ex- (non-sluicing) ( tensive further investi- Kalabagh 8.0 ( gation required to con- (sluicing) ( firm feasibility and ( cost. Could not be ( completed by 1975.

Side Valley

Haro Gariala (High) 8.o (651 to 975 Side valley storage (Low) 4.6 (596 to 800 scheme associated with Tarbela. Very little ( field data. Long-term ( project.

Sanjwal Akhori 3.3 490 to 735 Side valley storage scheme associated with Tarbela. Very little field data. Not com- petitive with Gariala.

Soan Dhok Pathan 8.3 (1,000 to Side valley storage ( 1,500 scheme associated with ( Tarbela. Very little ( field data. Not com- petitive with Gariala.

Table 33 continued on pages 61 and 62; see footnotes on page 62. - 61 -

Table 33 (cont'd)

Live Cost River Location Capacity Range -/ Comments (MAF) (US$ millions)

Upper Skardu 8.0 588 to 900 Reconnaissance data only. Indus Not feasible of execution in foreseeable future.

Bunji - - Power project not feasible of execution in foreseeable future.

Chilas - - - Same as above -

Indus Chasma 0.5 32 b/ Construction of barrage Plains (incremental due to commence 1967 with storage) completion scheduled 1971. Storage features being provided as an addition to basic design.

IT Sehwan/Manchar 1.8 177 to 221 Feasible timing of execution dependent on canal remodeling in Lower Sind; possible completion date 1982.

Indus Plains Uncertain Uncertain Off-channel storage. (Thal Doab) Only very preliminary study. Long-term project.

Jhelum Mangla 5.2 534 b/ Under construction. Com- pletion scheduled 1968.

Raised Mangla 3.5 216 b/ Project would involve raising Mangla Dam.

Rohtas 5.8 - Side valley storage scheme associated with Mangla. Very little field data.

Chenab Chiniot 1.4 100 to 125 Need for storage on Chenab questionable.

Table 33 continued on page 62; see footnotes on page 62. .- 62 -

Table 33 (cont'd)

Live Cost a/ River Location Capacity Range - Comments (MAF) (us$ millions)

Kabul- Ambahar 2.0 145 to 215 No field data available. Swat Representative of developments on Swat River. Capa- city limited by water availability.

Warsak Diversion - - Project to increase water availability in Swat Basin for storage therein by pumping from the Kabul. Would require 3,600 mw of installed pumping capacity. Doubtful feasibility.

if Chitral Diver- - - Project to increase water sion availability in Swat Basin for storage therein by pumping Kabul. Doubtful feasibility. a/ Economic costs, without provision for inflation or financial contingencies. b/ Includes income tax on contractors' profits. - 63 -

VI. FACTORS IN THE OPERATION OF SURFACE WATER STORAGE RESERVOIRS

Coordination of Power and Irrigation Requirements 6.01 The emphasis of this volume up to this point has been upon the necessity of developing surface water storage in order to meet agricultural requirements. It was briefly noted in Chapter IV, The IACA Approach, that IACA had had to bear in mind the necessity for an intimate coordination of the needs of both power and agriculture. A case in point is the "overpumping' concept, use of mean year flows being justified on the grounds that tubewells would make up the deficit in below--average years. Meeting the deficit in this way reduced the surface storage needs but equally affected the power consultant's load forecasts. Reference was also made to the desirability in the interests of power of filling the reservoirs as quickly as possible each season in order to increase the available head on the machines. The differences in time between the periods of maximum drawdown on the Indus and Jhelum Rivers was noted. Furthermore, while possible energy available from the hydroelectric projects was determined by mean-year hydrology, a critical water-year was taken for the analysis of the firm capability of projects thus ensuring the provision of sufficient back up thermal generating capacity for critical year conditions. 6.02 The power consultant's integrated (hydro and thermal) generating program envisages the installation of units at the Mangla and Tarbela Projects in accordance with the schedule shown in Table 34.

Table 34 Power Consultant's Program for Installation of Generating Units at Mangla and Tarbela

Mangla ._.____ Tarbela Cumulative Cumulative Cumulative Cumulative Installed Firm Capa- Date of Installed Firm Capa- Date of Unit Capacity city a/ Instal- / Capacity city b/ Instal-, No. (mw) _ (mw) lation _(mw) _ mw) lation - 1 100 65 1968 175 81 1975 2 200 131 1968 350 162 1975 3 300 197 1969 525 243 1976 4 400 262 1971 700 324 1976 5 500 328 1972 875 399 1977 6 600 394 1972 1050 473 1977 7 700 464 1981 1225 536 1978 8 800 533 1981 1400 598 1978 9 _ 1575 661 1982 10 _ 1750 723 1982 11 - 1925 791 1983 12 - 2100 859 1983

a/ 1075 feet drawdown. b/ 1332 feet drawdown. c/ Units assumed to be in commercial operation by January 1 of year designated. - 64 -

These dates have become the starting point for analyzing the varying effects that may be obtained by control of reservoir operations, with reference to certain specific problems.

The Drawdown Level at Mangla_- Up to 1975

6.03 Though the power studies carried out by the Bank Group's consultant assumed a minimum drawdown of Mangla Reservoir to 1075 feet, on the basis of preliminary data on the relative value of water to agriculture and power, the adoption of 1040 feet as the minimum figure was anticipated by the consultant before their reports were completed. The Bank Group feels that it would be prudent to accept a 1040-foot drawdown level at least for the period to 1975 as a tentative decision pending further operational studies. This conclusion resulted from a comparison of the permanent loss to power with the gain to agriculture which would result from using the lower drawdown level.

6.o4 The permanent loss to power results from the fact that, at the low level of 1040 feet the capacity of the generating units would be seriously reduced. Also, because of limited discharge possible through the turbines at lesser head, a part of the essential irrigation releases would have to bypass the electrical units with a consequential loss of useful energy. That permanent loss to power assuming 1985 conditions is quanti- fied in Table 35. By using a drawdown level of 1040 feet as opposed to 1075 feet in a critical water-year, the firm capability of the probable ultimate installation (eight units) would be 381 mw against 504 mw. Ex- pressed in terms of energy, the loss to power would be 327 million kwh. Table 35

Mangla Project: Effect on Power of Change in Drawdown Level (eight units installed)

Drawdown Live Storage Firm Power Capability a/ Annual Energy Level Cat)acity Maximum Peaking Generation -/ (feet) (1AF) (mw) (million kwhY

1075 4.8 504 5,760 1040 5.2 381 5,433

o.4 123 327

a/ Critical water-year. Assuming 1985 conditions. b/ Mean water-year.

6.05 The costs of replacing this lost hydro power by power derived from alternative sources as estimated by Stone & Webster are expressed in Table 36. It will be seen that to make good these 120 mw some $17.5 million would have to be spent on thermal facilities and an additional $3.8 million on extra transmission which would be needed at some time before 1975. The additional annual costs in operation, maintenance and fuel (assuming a cost - 65 - of 30 cents/million Btu) through the use of alternative thermal generation would be approximately $700,000. The present value of what is lost by drawing Mangla down to 1040 feet (at a discount rate of 8 percent to 1965) would, therefore, be approximately $9 million, or equivalent to nearly $23 per acre-foot of annual storage.

Table 36

Mangla Project: Power Costs Incurred by Change in Reservoir Drawdown Level a/

US$ rMillion Capital Costs Equivalent

Equivalent thermal generating plant (120 mw) 17.5 Required transmission 3.8

Annual Costs

Plant @ 8.58% 1.50 Transmission @ 8.174% 0.32 Operation and Maintenance 0.23 Fuel @ US¢ 30 per million Btu b/ o.48

Total Annual Costs 2.53 a/ The basic data used to develop the cost figures set out in this table are contained in Volume IV of this report. b/ If a fuel cost of US¢ 12 per million Btu is assumed, as pointed out by Stone & Webster, the total annual cost figure becomes $2.24 million.

6.o6 In spite of the magnitude of this estimate of the value of this water for power, the Bank Group feels that - at least for this early period - the gain to agriculture of 0.4 MAF of stored water must be decisive.

6.07 This judgment, is influenced by three considerations. First, the sequential analysis undertaken by IACA and Harza (Harza Engineering Company International of Chicago) has indicated that there may be difficult surface water problems before 1975. To maximize the water available during the dry season, the reservoir would have to be emptied every year. To do this, the water would have to be drawn down to elevation 1040 feet. Second) Stone & Webster have indicated that not all of the additional 327 million kwh would be of use in the grid system by 1980, indeed, they have estimated that even by 1985 only 150 million kwh approximately could be absorbed. Third, it has been noted that, except for Chasma Barrage, Mangla will constitute the only large storage project on the Indus system until about 1975. Until such time as other storage projects are completed, any storage on the Jhelum, surplus to requirements of the Jhelum Command, would be helpful in meeting the growing demand for stored water in the Indus Command. - 66 -

The Drawdowm Level at Mangla - After 1975

6.o8 The sequential analysis shows that during the 10-year period, 1975-85, the reservoir could be operated temporarily to a drawdown level of 1075 without affecting irrigation interests. Figure 11 compares the useful live storage capacity of Mangla with IACA's projected mean-year requirements for stored water on the Jhelum. This shows that on a mean*- year basis the full capacity of Mangla Reservoir may not be needed to meet the mean---year storage requirements on the Jhelum River until about 1990. The surpluses, of course, only begin in 1975 when Mangla's obligations to the Indus Command are met by Tarbela. At this point a reduction of 0.4 MAF in the usable capacity by working with a 1075 drawdown level, might be feasible. For the period 1985-2000 the irrigation needs of the basin as a whole (and, after 1990, of the Jhelum Command just by itself) seem once more to call for the lower drawdown level.

The Drawdot-m Level at Mangla - Bank Group Studies

6.og Studies undertaken by the Bank Group largely confirm these conclusions. They indicate that there are very large benefits attached to releasing the last 0.4 MAF of water (between drawdown levels of 1040 feet and 1075 feet) from Mangla for irrigation purposes over the period 1968-75. These benefits have a present worth value at 8 percent of about $20 million. After 1975, when Tarbela is on the system, the marginal value of these benefits would be much smaller; the present worth of agricultural benefits from releasing this water for agriculture every year between 1975 and 1985 is estimated at about $2 million or $8 million, the lower value applying if further storage is built in the form of Sehwan-Manchar about 1980. Power benefits from maintenance of the higher drawdown level have been assessed for the whole period 1968-85 at about $19 million in present worth terms - which is clearly less than the sum of the benefits to agriculture from releasing the water over the two periods. Nevertheless, as discussed more fully in Volume IV of this report, the value of the maintenance of any particular drawdown level to both agriculture and power will fluctuate considerably over the years as a result of hydrology, the degree of adequacy of power and irrigation supplies obtaining in any year, and the additions to the power system and the irrigation system that are in prospect. Therefore, the question of the correct drawdown level should be frequently reassessed, and considered in the light of the conditions that may obtain in the particular year in question. It is likely that the correct drawdown level will be different in different years.

Raising Mangla for Power

6.10 As indicated earlier, provision has been made for raising the crest of Mangla Dam from 1234 feet to 1274 feet to allow for raising the top water level by 48 feet from 1202 feet to 1250 feet. This will increase live storage capacity by about 3.5 MAF. Thus, with Raised Mangla, a higher head for power could be maintained without having to reduce releases from storage. Table 37 shows this clearly for 1985 conditions. With Low Mangla and a drawdown level of 1040 feet, storage releases of 4.58 MAF may be made. With Raised Mangla and a drawdowm level of 1183 feet, storage releases of DEVELOPMENT PROGRAM FOR THE JHELUM RIVER (MAF STORAGE) 25 I I 25

o cnz a. F

209 20

10~~ 15 15

LL --iL WE II

10 10 STORAGE CAPACITY AEANNUAIL YIELD

5 ------_

I ~~ ~ ~ '~~~MEAN-YEAR STORAGE DEMAND

0 1 I I I I II lo 1965 1970 1975 1980 1985 1990 1995 2000<

(3R)IBRD-3226-

- 67 -

4.58 MAF are still possible, while the firm capacity of the power plant with eight units installed would be increased bv more than 600 mw. An additional 2,000 million kwh could be generated in an average year.

Table 37

Comparison of Power Characteristics. Low Mangla and Raised Mangla Operated for Maximum Power Benefits (1985 conditions, eight units installed)

Low Mangla Raised Mangla Difference

Drawdown Level (feet SPD) 1040 1183 143 Annual Energy Generation (mill. kwh) a/ 5,433 7,429 1,996 Firm Capability b/ limited peaking c/ (mw) 381 780 399 maximum peaking d/ (mw) 395 1,025 630 Storage Release (MAF) 4.58 4.58 0 a/ Mean water-year. b/ Critical water-year. c/ Assuming restriction on the hourly variation in water releases and plant factor not to fall below 80 percent. d/ Assuming 100 percent load factor on at least two to three machines to maintain a constant flow in the Upper Jhelum Canal, the remaining units operated to maximum peak capacity.

6.11 In the previous section, it was argued that by 1985 the demands of the system as a whole may once more necessitate the 1040 feet drawdown level and that by 1990 the demands of the Jhelum Command alone will certainly do this. IACA envisage that some time after 1985 Mangla will be raised for irrigation purposes.

6.12 Given the facts as presented in Table 37, the Bank Group had to examine the question of raising Mangla for power earlier than, say, 1990; i.e., earlier than would be the case under the Bank consultants' program. They found that the picture presented in Table 37 had to be integrated to take account of two points.

6.13 First: It -had to be realized that raising the dam to obtain an additional 3.5 MAF-of usefu1 capacity would not result in an equivalent increase in average annual yield, because surplus flows in the Jhelum available for-storage-wtuld not be adequate in all years to fill the larger reservoir. Gen-ally, the reservoir would be emptied in April so that impounding could-difm6mence in all probability no earlier than May with completi-on in Septe,mber. A review of 41 years of historical record (1922-63) shows -that=, ?allowing for IACA's projected irrigation releases required during the impounding months, Raised Mangla might yield the following amounts of stored water: - 68 -

Table 38

Raised Mangla: Stored Water Yields Under Conditions of IACA's Projected Irrigation IJses Year Year 1985 2000 Conditions Conditions Number of years out of 41 in which the reservoir would not have been filled 7 25

Average annual storage yield duxring 41-year period (IMAF) 8.3 6.8

Minimum storage yield in 41-year period (M4AF) 5.7 2.3

6.14 Second: An examination of alternative methods of operating Raised Mangla showed that the extraction of 6.75 MAF or 7.72 MAF, under IACA's 1985 irrigation conditions 9 caused a reduction in the firm capability of the power installation in May and June during critical years because of the necessity of limiting flow through the turbines to fill the larger reservoir. The loss of power capability, however, was very small.

6.15 Bearing both these points in mind, the Bank Group made some calculations comparing the possibility of raising Mangla for power purposes with the Kunhar Project and with a thermal alternative. It also considered the possibility of raising Mangla and simultaneously installing units 9 and 10 there. The figures underlying the Bank Group's calculations, which differ slightly from those used by Stone and Webster, are presented in full in Volume IV, Annex 8 and summarized here.

Table 39

Increase in Power Output Obtainable by Raising Mangla Compared with Kunhar Power Output (mean year) Increase due to Raising Mangla, Increase due to adding Units 9 Raising Mangla and 10 and Kunhar Project and Drawing Dovm Drawing Down Capability and to 1175 feet to 1175 feet Energy-Output_ Capacity in Critical Period (mw) April 1 - 10 592 840 524

Energy-Output (mil. kwh) June-September 459 589 1,170 October-May 1,516 1,696 19734

Total 1,975 2,285 2,904 - 69 -

6.16 Maintenance of a minimum reservoir level at Raised Mangla of 1175 feet, as opposed to 1040 feet, would result in an increase of about 600 mw in the firm capability of the power plant, while installation of a further two units would increase this firm capability by an additional 240 mw. Raising Mangla and drawing down to 1175 feet would also result in a very substantial addition to energy.output in the critical period of the year, when it would be fully usable. In both these senses, raising Mangla would be more attractive than Kunhar. However, Kunhar would produce more energy over the year as a whole and also over the winter season as a whole. By the early 1980's Tarbela will probably still be capable of producing more energy than can be absorbed in the summer, but there will be energy shortages in the winter.

6.17 The Bank Group's rough calculations suggest that raising Mangla for power purposes a few years before it is required to meet irrigation needs does not seem attractive from the present perspective. The Bank Group used the project costs shown in the following table.

Table 4o

Comparative Costs of Raising Mangla and of Kunhar (US$ million equivalent)

Raise Mangla 217 Raise MIangla and Install Units 9 & 10 235 Kunhar 204

It should be borne in mind that the Raised Mangla cost estimate is very recent (1966) whereas the Kunhar estimate dates from 1961. The Bank Group found that raising Mangla would be preferable to gas-fired thermal units in the early 198 0's only if the gas price were in the neighborhood of 65 US¢ per million Btu, while Kunhar was slightly more attractive being preferable to gas.fired thermal plants at a gas price of about 58 US} per million Btu. These calculations were made taking account of the fact that additional energy produced in the summer in the early 1980's would not generally be usable. These gas prices are substantially above those foreseen by the-Bank Group for this period (see Volume IV, Annex 5) and so it was concluded that neither raising Mangla for power nor Kunhar appeared likely, from the present perspective, to be attractive until about 1990 when more of their energy could be absorbed and gas would be more scarce.

The Sediment Problem at Tarbela

6.18 Because-the -sediment inflow to Tarbela Reservoir will be very high, (around 440 milli6nttons a-year) the dam site consultant investigated the feasibility of pr@vid-i-h-g sluiceways to pass the heavily charged waters of the monsoon season-, pricf_i ipally during June and July when over 50 percent of the annual load is carried. It is clear that sluicing would serve to increase the useful life of the reservoir, otherwise estimated at 50 years, to some indeterminable degree. Three schemes were studied in detail, one based on the present design and two on modifications. - 70 -

6.19 The dam site consultant concluded, however, that effective sluicing at Tarbela is precluded by the nature of the site. Owing to the broad valley and the great depth of alluvium underlying the dam, enough outlets cannot be provided. The four tunnels included in the present design appeared to be the maximum practicable for installation. Sluicing through these tunnels during the critical months of June and July as the head increased would be hazardous because of the high resultant tunnel velocities,. some of which are indicated in the following table.

Table 41

Tarbela: Velocity in Tunnels if Used for Sediment Sluicing (mean-year conditions)

Mean Inflow Reservoir Velocity in at Tarbela Elevation Tunnels (cusecs) (feet SPD) (feet/second)

June 1 - 10 147,000 1185 23 11 - 20 188,000 1230 30 21 - 30 204,000 1245 32

July 1 - 10 252,000 1310 40 11 - 20 270,000 1335 43 21 - 31 280,000 1350 44

6.20 The generally accepted design practice for large steel lined conduits carrying substantial quantities of sediment is to limit velocities to something less than 20 feet/second to avoid excessive damage by abrasion. It follows that any plan involving tunnel velocities of more than twice the safe figure would be unacceptable.

6.21 While this would seem to constitute a sufficient reason in itself for discarding any hope of profitable sediment sluicing at Tarbela, the detrimental effects on power production confirm the conclusion. Power generation caoabilities would be eliminated for upwards of 60 days each year. For both reasons, therefore, the dam site consultant concluded that sluicing would be impracticable. The Bank Group concurs in this view.

The Tarbela Drawdown Problem

6.22 WAPDA's planning is based on a 1300 feet SPD drawdown level for Tarbela. The IACA program assumes that Tarbela Reservoir would be drawm down to a level of 1332 feet SPD each year about the middle of May and that the natural river flow will then be passed downstream until about the middle of June. At this time flow in the Indus will begin to exceed irrigation requirements, and impounding will begin.

6.23 These irrigation requirements (for the months of June, July and August) are presented in Table 42. Requirements for 1985 are given, and also for the year of ultimate development. - 71 -

Table 42

Tarbela: Average Monthly Irrigation Release Requirements During Impounding Period (cusecs)

1985 Ultimate Development (2000)

June 84,ooo 156,000 July 24,000 92,000 August 39,000 99,000

6.24 As indicated in paragraph 6.02, the program developed by the power consultants for the integration of hydroelectric and thermal generating capacity into the grid system includes 12 generating units to be installed at Tarbela by 1985. The discharge capacity of the outlet structures with these units installed would be as follows:

Table 43

Tarbela: Discharge Capacity of Outlet Structures

Reservoir 1 Irrigation 12 Turbines Elevation Release Tunnel (3 Power Tunnels) Total (feet SPD) (cusecs) (cusecs) (cusecs)

1300 64,o0o 43,000 107,000 1332 69,000 49o000 118,000 1350 70,000 54,000 124,000 1400 78,000 65,000 143,000 1500 92,000 81,000 173,000

6.25 The inference that must be drawn from inspection of Tables 42 and 43 implies some modification of the basic IACA program described in paragraph 6.24. For, while the minimum drawdown level of 1332 feet will be sufficient to meet the irrigation releases of 84,000 cusecs that will be required in June of 1985, only a reservoir level cf about 1450 feet will be sufficient to meet the irrigation releases of 156,000 cusecs that will be required in June of 2000.

6.26 This is a situation which involves both the power and the agricultural benefits.

6.27 The advantages for power may be seen from an inspection of Tables 44 and 45 which- show the effect of different minimum reserve levels on the power capability-and energy availability. - 72 -

Table 44

Tarbela: Effect of Different Drawdown Levels on Firm Capability (1985 conditions: 12 units installed) Minimum Reservoir Level - feet 1300 1332 1350 Water Released from Storage - M4AF 7.9 7.3 6.9 Difference from Minimum Level (1300) 0 o.6 1.0 Capability at Critical Period - mw 487 730 896 Increment 0 243 409 Annual Energy Available - million kwh 11,694 11,944 12,221 Useful Energy a! - million kwh 6,833 7,063 7,294 Gain in energy - million kwh 0 230 461 a/ During July, August and September9 the amount of usable energy is the same for all cases. If the potential energy generated in those months is omitted, it is estimated that the amounts which remain could all be used in the system. Table 45

Tarbela: Evaluation of Power Benefits from Different Drawdown Levels (US$ million equivalent) Drawdown Level - feet 1332 1350 Incremental Gain in Capability (mw) over 1300 drawdown 243 409 Capital Construction Costs: alternative thermal generating plant 23.1 56.7 alternative transmission 5.0 12.4 Annual Costs: plant @ 8.58% 2.0 4.8 transmission @ 8.174% o.4 1.0 operation and maintenance 0.3 o.6 fuel @ US¢ 30 per million Btu 0.8 1.5

Total Annual Value 3.5 7.9

Quantity of Water Retained in the Reservoir between 1300 feet and Drawdown Level (MAF) o.6 1.0 Value of Power per acre--foot of Water Retained in the Reservoir $5.8 $7.9

This rough calculation indicates that the value to power of water retained in the reservoir is around $6 per acre-foot at the 1332 feet level and around $8 per acre-foot at the 1350 level. IACA has estimated the net addition to agricultural production attributable to Tarbela over the life of the project and discounted this agricultural benefit at 8 percent to 1965. The resultant estimate of net production value per acre-foot of water stored in the project over its life is $17. This is clearly substantially greater than the figure for power estimated above. However, the IACA figure is an average value and does not indicate the marginal benefits attributable to the release, for irrigation purposes each year, of the 0.6/0.7 MAF lying between 1332 feet and 1300 feet. 73 -

6.28 The Bank Group has attempted to measure the marginal value for power and for agriculture for the period 1975-85 of the 0.6/0.7 MAF lying between 1332 feet and 1300 feet, and these analyses show quite clearly that advantage lies on the side of retaining the higher drawdowm level at least during the first ten years of the life of Tarbela. The benefits to power of maintaining the higher drawdown level arise largely in the form of postponement of the need for further additions to generating capacity. Some benefit also arises in the form of reduced fuel costs due to the greater energy output of Tarbela in the critical period at the higher drawdown level. On the basis of its systems analysis the Bank Group finds that the savings to power which result from maintenance of the higher drawdown level over the period 1975-85 have a present worth value at 8 percent in the neighborhood of $19 million. The exact size of this figure depends on a number of things, in particular the price attrib- uted to thermal fuel in this period; since the Bank Group feels that present prices tend to underestimate the true scarcity value of fuel that looks likely to prevail in the period 1975-85 it considers the $19 million a minimum estimate. The Bank Group's linear programming analysis of agricultural investment suggests that the net benefits to agriculture that would arise from providing over the period 1975--85, o.6/o.7 MAF of rabi irrigation water in addition to that available from Tarbela with a drawdown level of 1332 feet also have a present worth value of the order of about $19 million. This makes the marginal value of small amounts of Tarbela water for agriculture and for power seem very close. However, in contrast to the power figure, the agricultural benefit figure must be considered a maximum. The value of an additional 0.6/0.7 HAF of rabi supplies in this period should really be consiclered in terms of the costs of making this water available by other means. By 1975 very substantial tubewell fields will be in existence and so large amounts of water could be made available by overpumping. Valued in these terms, i.e., the alternative cost of producing the same quantity of irrigation suipplies over the period 1975-85, the water lying between 1300 feet and 1332 feet has a present worth value of about $11-15 million. Since it will take some years after completion of Tarbela to achieve high agricultural benefits on marginal additions to the 7--8 I'AF that will be available from Tarbela drawn down to 1332 feet and since, especially in the later years, there will be large possibilities of adding to irrigation supplies by temporary overpumping., the Bank Group feels strongly that present evidence recommends a 1332 foot drawdown level at Tarbela over the period 1975-85.

6.29 Over the longer terms the relative merits of different drawdown levels will depend-greatly on what additions to the power system and the surface storage system have been made or are in prospect. The loss of water to agriculture resulting from maintenance of a higher rather than a lower drawdown level will in-fact fall considerably over the years as a result of sedimentation filling--up-part of the storage capacity at lower levels in the reservoir. For instairce, it is estimated that by the year 2000 the loss of winter irrigation supplies resulting from maintenance of a drawdown level of 1350 feet rather than 1300 feet would be of the order of only 0.2 MAF (see Table 46). - 74 -

Table 46

Tarbela: Storage Capacity in MAF Useful Storage Capacity above Year _ Level 1975 1985 2000

1300 9.3 7.9 5-6 1332 8.6 7.3 5.5 1350 8.2 6.9 5.4 1400 6.7 6.1 5.0 1500 2.7 2.5 2.4

6.30 The fact that additions to irrigation supplies resulting from maintenance of a lower rather than a higher drawdown will decline over the long run may mean that the use of Tarbela storage capacity for agricultural purposes should be reduced more rapidly than it will physically have to be reduced as the direct result of sediment depleting the live storage capacity of the reservoir.

6.31 It may, in addition, become necessary over the years to maintain a higher minimum reservoir level, say up to 1450 feet, in order to permit adequate discharge through the outlet structures during the month of June. The Bank Group has therefore concluded that a gradual raising of the minimum drawdown level at Tarbela from 1332 feet to perhaps 1350 feet or higher may very well yield substantial economic benefit, taking power and the value to agriculture of full June irrigation releases together, than operation at a permissible level of, say, 1300 feet. The Bank Group would recommend that this preliminary conclusion be subjected to further detailed investigation.

The Operational Problem of Gariala

6.32 The conclusion noted in paragraph 6.31 above, namely that a relatively high reservoir level, perhaps 1350 feet or even more, at Tarbela should be maintained, would be strengthened by any decision to construct Gariala as a side valley storage project in association with Tarbela.

6.33 The purpose of the Gariala Project would be to offset the loss of useful storage at Tarbela. With loss of storage capacity in Tarbela reservoir by siltation, Gariala would achieve a progressively higher annual yield of stored water. By the time the live storage capacity at Tarbela had fallen to 1 MAF, Gariala would have achieved an average annual yield of nearly 8 MAF.

6.34 Yields of this order, as noted in paragraph 5.27 involve, however, costly conveyance and control structures, quite apart from the cost of the storage project itself. Since the diversion period would end when it became necessary to begin seasonal drawdown at Tarbela, the conveyance canals would have to be unusually large in order to carry the available water in a limited period of time. The capacity of the canal at Gariala would have to be 76,000 cusecs. - 75 -

6.35 Operating Tarbela to a higher than minimum drawdown level would extend the period of time available for the filling of Gariala.

6.36 The release pattern of Gariala Reservoir is expected to follow the pattern established for Indus Reservoir at Tarbela (see Table 19). The reservoir would be drawn down to its lowest level in May, after which no further releases from storage would be made until October. With the period of minimum capability occurring at the same time as for main river projects and extending for more than four months it is difficult, if not impossible, to justify the installation of power facilities in the project. However, this disadvantage would be partially offset by the higher capability obtainable at Tarbela with the higher drawdown level assumed. It is therefore concludecL that Gariala would provide useful storage but would not be justified for power development.

Operational Problems at Kalabagh

6.37 The dam site consultant has stated his belief, subject to further investigation, that an earth and rockfill dam with a concrete buttress sluiceway/spillway structure can be built at Kalabagh to impound water to a level of 925 feet. The bed level is assumed to be at elevation 670 feet. He believes, further, as described in subsequent paragraphs of this chapter, that the dam could be designed and operated in such a way as to pass a large proportion of the river's sediment load.

6.38 The Bank Group, however, believes that insufficient facts are known at this time to justify the firm conclusion that a high, concrete buttress can be built at the Kalabagh site, with sluicing capabilities, at a cost commensurate with the benefits that may be derived. As indicated earlier, only fragmentary information is available with respect to geological conditions and explorations have been limited. Before design could be undertaken it would be necessary to carry out extensive subsurface investigations involving borings, test pits and tunnels. Detailed studies would then be required to evaluate the foundation conditions and determine treatments necessary or precautionary features to be included in the design. If it should develop that an overflow or submerged orifice spillway (as suggested by WAPDA's consultants) is the only type of structure appropriate for the site, it would not be possible to provide for sluicing except to a very limited extent through irrigation sluices and power tunnels and furthermore it would pose considerable problems in dealing with river flow during construction.

6.39 Pending the results of these further investigations, which it wholeheartedly recommends, the Bank Group feels that it would be useful to set forth here some of the advantages and disadvantages that would attach to the two different types of dams (viz. sluicing or non-sluicing) or to different modes of operating the same dam. - 76 -

Kalabagh with Sediment Sluicing

6.40 The chief advantage that attaches to Kalabagh with sluicing lies in the extension of the dam's useful storage life. Table 47 shows the mean-year monthly discharge of the Indus at Kalabagh and the estimated monthly sediment movement. The figures include contributions of the Kabul River, which joins the [ndus at Attock between Tarbela and Kalabagh.

Table 47

Kalabagh: Mean-Year Water and Estimated Sediment Discharge of the Indus River

Mean Flow Estimated Sediment Discharge Month (1,000 cusecs) (MAF) (million tons/day)

January 28 1.71 Negligible February 29 1.62 It March 40 2.45 " April 72 4.30 " May 135 8.38 o.6 June 258 15.49 3.7 July 364 22.57 7.3 August 320 19.81 5.5 September 144 8.65 o.8 October 58 3.62 Negligible November 36 2.14 " December 30 1.87

Total 540 million tons or 0.292 MAF (@ 85 lbs. per cu. foot)

6.41 The dam site consultant proposes that Kalabagh Reservoir, if operated for sediment flow-through and sluicing, would be drawn down to near elevation 700 feet SPD in M4ay and, in years of mean flow, all the Indus water would be allowed to pass through the low level sluices essentially unrestricted until near the end of July. Impounding would be achieved in late July and August. Thus, the sediment carried by the river in June and July (more than 60 percent of the annual total) would be passed through the reservoir without detention. During seasons of particularly high flow, with the reservoir empty, some of the sediment previously retained in the river channel might be scoured out. The initial useful storage capacity of the reservoir between elevations 700 feet and 925 feet SPD would be 8.0 MAF. With sluicing, this capacity would decrease after 50 years to 6.6 MAF. Without sluicing an initial live storage capacity of 6.4 MAF would decrease, in less than 50 years, to a negligible amount (see Table 48). - 77 --

Table 48

Kalabagh: Estimated Depletion of Live Storage Capacity

Year After Live Storage Capacity Project Completion With Sluicing Without Sluicing (MAF) (MAF) 0 8.0 6.4 5 7.9 5.7 10 7.7 5.0 15 7.6 4.0 20 7.4 2.9 25 7.3 1.5 30 7.1 1.0 50 6.6 Negligible 100 (state of equilibrium) 5.2 Megligible

6.42 The chief disadvantage that attaches to Kalabagh with sluicing lies in the fact that passage of maximum sediment would eliminate power generation for three to four months a year when the reservoir level would be some 90 feet below that required for turbine operation.

6.43 It has been estimated that during the remainder of a mean water- year the nine-unit power installation suggested by the consultant might generate 4,300 million kwh. According to very rough calculation, the value of this energy, translated to the cost of thermal fuel (see following table), even if it were valued at primary energy, would hardly justify the cost of the hydroelectric installation.

Table 49

Kalabagh: Evaluation of Energy from Sluicing Scheme US$ Millions Annual Energy Production 4,300 million kwh Equivalent value of fuel savings @ ¢30 per million Btu 12.9 Capital cost of hydroelectric plant 140.0 Annual Costs Plant @ 8.455 11.8 Operation and Maintenance 1.4

13.2

Kalabagh without Sediment Sluicing

6.44 The advantages of Kalabagh without sediment sluicing lie primarily in its power potential. Its capability during a critical water year and its energy potential during a mean water-year would be about as shown in Table 50, the figures of which are based on gradual impoundment during the months of June and July, with final filling occurring late in August. - 78 -

Table 50

Kalabagh: Power Potential if Operated without Sluicing

Initial Operation 1979 1985 2000

Units installed (No.) 9 9 9 Maximum Capability for Peaking (mw) 1,125 1,125 1,125 Minimum Capability (mw) 350 350 720 Annual Energy Generation (kwh millions) 6,000 6,100 6,400 Useful Storage Capacity (MAF) 6.4 5.4 2.4

6.45 A secondary advantage lies in the operation of the Dhok Abbaki Project, as a side valley project in association with Kalabagh.

6.46 The Dhok Abbaki Project would involve pumping water each season from Kalabagh Reservoir to a storage reservoir on the Soan River after Kalabagh had been filled. To provide a maximum period for pumping, thereby keeping the capacity of the pumping installation to a minimum, Kalabagh would have to be filled as soon as possible each season. Under these terms, operation of the project for reduction of sediment retention would be impossible.

6.47 This secondary advantage is, however, dependent on the amount of surplus hydro energy in the system. About 1,750 mw would be needed to provide power for a period of 60 days' pumping into Dhok Abbaki. Kalabagh's projected power potential, as can be seen from Table 50, is 1,125 mw at maximum capability. Detailed study might reveal that a greater installed capacity was justified. For the pumping period, therefore, Kalabagh would impose upon the system a net demand of about 600 mw. This might not rule out the project if large amounts of surplus hydro power were available at other dams such as Tarbela during these months.

6.48 The chief disadvantage that attaches to Kalabagh without sluicing lies in its loss of useful storage capacity (see Table 48). But this disadvantage must be qualified by a consideration of the function of Tarbela.

6.49 The construction of Tarbela would have a marked effect on the sediment problem at Kalabagh by sharply reducing the amount of sediment reaching the reservoir. Table 51 below presents a preliminary assessment of this effect. - 79 -

Table 51

Kalabagh: Effect of Construction of Tarbela on Sediment Inflow (MAF/year) Average Annual Sediment Inflow Without Tarbela With Tarbela

Sediment load of Indus at Darband 0.238 0.238 Less: sediment trapped by Tarbela - 0.200 0.238 0.038

Sediment picked up by Indus between Darband and Attock, say - 0.030 a/ 0.238 0.068

Sediment load of Kabul at Attock 0.054 0.054

Total: Sediment inflow to Kalabagh Reservoir 0.292 0.122 a/ The water released from Tarbela will be relatively free of sediment and charged with energy. This will enable it to lift loose materials from the river in the process of achieving a more stable regime. The extent of gain in sediment load between Tarbela and Kalabagh is impossible to predict with any accuracy. The allowance of 0.030 MAF/year is solely indicative of the state of inequilibrium of the water.

6.50 With the two reservoirs in existence, Tarbela would presumably have to be filled first each season, in June and July, and water would then be passed over the spillways in July and August to fill Kalabagh.

6.51 A secondary disadvantage lies in the danger of flooding. Oper- ating Kalabagh for optimum power benefits would require that the reservoir be filled as rapidly as possible in the monsoon period and, once full, be maintained at that level throughout the remainder of the flood season. Such a regime, however, would not only result in the maximum accumulation of sediment but would also threaten valuable lands in the upper reaches of the reservoir, should high river discharges occur in August with the reservoir already full.

6.52 These, then, are some of the issues involved in the construction of any dam at Kalabagh. As noted in paragraph 6.38, they cannot be resolved until further intensive investigations of the site have been undertaken. On the available evidence, the Bank Group has reached the very tentative and preliminary conclusion that, should detailed investigation and study confirm that it is feasible to build and operate a dam for sluicing and sediment flow-through, such a dam should be built. The tentative long-term surface water program has thus included Kalabagh as the next major storage development after Tarbela. This would permit a flexible approach to this whole question of sluicing and non-sluicing. It might be, for example, that while Tarbela acted as a silt trap the value of power would call for o80 - the operation of Kalabagh without sediment sluicing. On the other hand, as the live storage capacity at Tarbela declined, so - unless further upstream storage reservoirs were constructed on the main stem of the Indus - the natural sediment regime would be re-established and 0.292 MAF of deposits would reach Kalabagh every year. It might then be clear that Kalabagh should be operated with sediment sluicing. The problems of flooding and of the role of Dhok Abbaki would meanwhile have been explored in much greater detail. - 81 -

VII. THE SEQUENCE OF PROJECTS FOR DEVELOPING SURFACE WATER STORAGE

7.01 The comprehensive development of water resources in Pakistan as outlined in the work of the Bank's consultants and in Volume I of this report has emphasized the intimate link between the development of surface storage with the exploitation of groundwater. Irrigation for agriculture is already largely dependent upon the supplies of surface water with 85 percent of water used on crops coming from that source. Although groundwater will be an important part of the development program for the next several decades, the river system will according to the program of the Bank's consultants still supply 67 percent of the total crop requirements at the stage of ultimate development. To evolve a fully effective water development plan sufficiently flexible that it may be adapted to the changing conditions and growth patterns in future years, it has been necessary to study the river system and the influences of nature upon it, all in relation to projected needs. To this end, an inventory was made of some 100 apparent dam sites on the Indus and Jhelum Rivers and those tributaries from which significant discharges may be expected (see Figure 12).

7.02 Then, in conjunction with the Dam Sites Advisory Committee, 14 dam sites at the more promising locations were selected for study. These were compared with each other from the standpoints of capacity and cost, and were finally tested from the standpoint of overall operational effectiveness. Eleven of these sites, including ongoing projects, were adopted by the consultant responsible for the identification and appraisal of surface water storage projects.

7.03 This program is summarized below, and will henceforth be known as the '`Chas. T. Main recommended program'.

Table 52 Initial Live Project In^Service Water-Year Storage Volume (MAF)

Mangla a/ 1968 5.22 c/ Chasma a/ 1972 0.51 Tarbela 1975 8.60 Sehwan-Manchar b/ 1982 1.80 Raised Mangla 1986 3.55 d/ Chotiari b/ 1990 0.90 Kalabagh (with power) 1992 6.40 Swat 2002 2.00 Low Gariala 2011 4.60 Skardu After 2020 8.oo a/ Ongoing projects. b/ Timing decided by irrigation planning. c/ Volume recoverable through main outlet works and power plant, assuming cut through Mirpur saddle to release 0.28 M4AF from Jari arm. d/ Raised to maximum height now contemplated. - 82 -

The Chas. T. Main recommended program may be characterized in one sentence. It is designed to meet reasonably the anticipated needs of surface water storage with maximum economy and effectiveness.

7.04 The program has been evolved by Chas. T. Main to meet IACA's Lower Limit" (see Table 15), although in practice it is likely to do better, depending on the pattern of agriculture that may eventually develop and other factors. The program is, therefore, designed to meet a requirement of 9.3 MAF in 1975, 13.3 MAF in 1985 and 21.5 MAF in 2000 (these figures assume that the IACA program of canal remodeling takes place). The Bank Group agrees with this approach. It believes it is reasonable to plan the sequence of projects on the basis of IACA's projected requirements of surface water.

7.05 Nevertheless, the Bank Group realizes that the ultimate demands on storage as indicated by IACA are determinable only within certain assumed limits. It follows that any sequential planning undertaken at this time will require review from time to time in the light of actual development. The longer the period of time under consideration the greater the variations required may be. The effects of such variations will be noted, when appropriate, and alternative sequences of projects will have to be discussed.

First Stage Storage

7.o6 The Bank Group believes that Chas. T. Main's recommendations for the period up to 1975 should have the status of an "action program". Since both Mangla and Chasma are ongoing projects fixed in time, this is tantamount to saying that Tarbela must be built by 1975. Chas. T. Main has indicated that if the estimated need for stored water on the Indus in 1975 is to be met there is no alternative to Tarbela (see Figure 13).

7.07 Chas. T. Main has taken into account the fact that storage at Mangla, where impounding began in February 1967, will provide 5.22 MAF live capacity if the reservoir is drawn down to 1040 feet and if use is made of the water trapped in the Jari arm behind the Mirpur saddle. This water would meet the demand for stored surface water until 1970. But in that year India will exercise its rights to divert for its use the waters of the Ravi and Sutlej Rivers. In certain circumstances India is entitled to divert water before 1970.

7.08 Chas. T. Main has also taken into account the fact that Chasma Barrage has been included as from 1971 and will add about 0.5 MAF storage to the system.

7.09 But, in spite of these contributions from Mangla and Chasma, the surface water supply is expected to become increasingly insufficient until, by 1974, the annual shortage calculated on the basis of mean-year flows in the rivers and tubewell pumping of groundwater up to balanced recharge, will be running at about 5 MAF.

7.10 On the basis of the 1964/65 reports of the consultants, Chas. T. Main, and of the Bank Group itself, it was concluded that the VOLUMESITI

POSSIBLE)AM SITES IN WESTPAKISTAN

IEOEND: ZONE, N - NORTH;S - SOUTH TYPE: E -EARTHFILL; R ROCKFILL,G - INANITY; A - ARCH PURPOSEsI- IRRIGATION,P- POWER;N - MULTIPURPOSE;W - WATERSUPPLY NR RIVERREGULATION; F - FWOODCONTROL; S - SEDIINETCONTROL PURESENTSTAVE. 0- IN OPERATION;C - UNDUROIRSTRUCYION; P - IR PIANNING; F- FORFUTURE; S - SUPERSEDUDORABANDONED

LO0C A TIO0N C HAR AC TE RI ST IC S NAMEOF DAM GROSSCAPACITY POVERCAPACITY (ffW PRESENT lONE REGION BASIN NEARESTCITY TYPE HEIGUT IENGTH OFRESERVOIR PURPOSEINITIAL OR SiTS- ROTES STATE (Fr.) (FT.) (MAP) INSTALLED MATE Ada" Ect N West Side Tributaries GO-1a D.I. Khan See Ehajsri Each P Ah-ei Ta,,gi. (or Ahsi Ei-li) N West Side Tributaries Task D.I. EKesn Super.eded by Hissnis Tangi I Akhcrl B East Side Tributaries Nandna Attach N 250 15,850 3.6 I Superseded by Garisla S tae Aktr Eili N West Side Tributaries Zbhb Port Sa.decaa by Khjuri Each S Asbahar N Kabul Riser Ssit Peshawar N 920 850 7.9 I P 1,270 P Anaab.ar S Ea... i Plains Asuabar Sibi N 80 2,600 0.055 F p Aittnk N Upper Indus Indus Attack 5 30 I F Superseded by Klalbagh S Babar~ East I S Eaechi Plains Sangasn SIbi N 180 40O 0.715 IP F 15 P EKhar BHaterKeah II S KEa.ohi Plaies Beji Sibi. R 120 Abandoned V Badis CAL N West Side Tributaries Zhob Pert Sandecsn Superseded by ihajuri Kash S Bahtar N East Side Tributaries Nandna Rawalpisdi N 235 7,500 0.9 I p Kee Bakhuwala N East Side Tributaries Taba Kae Rawalpindi. U HO 2,500 I p Bandagal N Kabul Riser Panjkora Saidu Sharif P F Band, Said. N East Side Tributaries Siras Mansabre G 210 500 0.003 I BasdaTasda N West Side Tributarl,,s Kohat ¶bi Kohat 5 115 2,340 0.078 I See Tends Sam C Bare N Kabul Niver Hera Pesbawar See Miri Khel Hera Tassa N West Side Tributaries Rarsan Bases See Bares Barahotar N East Side Tributaries Soss Ielasabad 150 0.007 P WN Superseded by Chariot S Bare N West Side Tr,ibutaries Beras Banns 120 3,475 0.098 I 0 Basund N Fast Side Tributaries Sirss Mansehra 271 750 0.075 I P Basargal B Kabul Siere Swai Pashawa E R 960 H.O N 1,140 P Beji Di"erisn S Kacchi Plains Hajil Sibi B 120 750 P P Biaun N East Side Tribustaries Stag Rawalpindi. K N 206 2,050 0.026 I p Bhugarsang N East Side Tributarieas SIrea Mucaffarabad Boles S Eacchi Pletas Bolan Sibi E 0.06 I 0 Boya Post B West Side Tributaries Toshi Bssnu 300 0.28 See To.hi. Busts. I N Jheluza Busts Jhelus 2.H BaustsII B Jhslue Bushs Jhelue 250 6.6 Bunji N Upper Indus Indus Gigit p 2,000 p Burn Cs N West Side Tritutarirs9 Darsgan D.I. Khan E 168 0.171 I P 1.8 p Butte N East Side Tributariss Nsndn Attach Kas Chasiot N East Side Tributaries Sees Islassabd G 176 675 O.0095 P W 1,536 P Chapter Rift B KE..chi Plains Khost Sibi lBS 0.079 5 W 1 F Cherub N East Side Tributaries Soas leIeanbd 0 175 832 0.067 I W P Che.= Barrage N Upper Indus Indus Miansali 0:051 I 0 Cheudhee las N West Bide Tributarics CheudmanD.I. Kh E 262 0.150 I P 2.24 5.1 P Ohisboli Pass N West Side Tributaries ChisbhNi.Kalabagh Abandoned Ohilas N Upper Endue Indus Chilaw F F Chiutet B Cheab Cbhaob Chisist 1.4 I P Chitral. N Kabul River Chitral Chitral. P F Chati N Wastaide Tributaries - D0.G.KOhe Chutietan N Kabul Riv- Panjkcca Saidu Sharif P 12 F Dabar N Kabul River Swat Saidu Sharif F Dadar N East Bide Tributaries Sires Nuzaffarabad 0 260 1,620 0.028 I PW 4 F Regarel N West Side Tributaries Techi Base 230 0.10 I Uhuatour B East Side Trbutaries Bar Abbettehd 225 780 0.027 IPWN 15 F Oars Tang N West Side Tributaries Karras Niasali 130 6,500 F DerabesZas N West Side Tributaries Harshen D.I. Khan 10o/175 0.03/0.5 I Sea Rurj las F Darasinda N West Side Tributaries Iaraban D.I. Khen Superseded by Hun las B Iarwat S South Tributaries Baran Hyderabad 110 0.073 I Infeasible Date Khel N West Side Tribs,taries Kaitu Beans 200 0.35 I Boa Tschi la S taecbi Plains Barrn Sibi Dheebi B East Side Tributaries Ghabhcsir Rawalpindi 77 0.01.2 I Dhaisgrah B Chenab Chesab BaleS P F Dteryal weir N East Side Tributaries Sixen Macsabre 42 9,20 I Dthk Abb.ki N Fast Bids Tributeries Sees Kalabagh N N 295 24,000 9.0 p 105 P Stab Bus N East Side Tributarie Askr Kwe alabghb a 131 700 0.013 I F Ithk Nil. (PF..er Plent) N East Side Tributariec Ind-c - Kaabagh P 1,200 P -oanB n. ShahPathan N East Side Tributariea Stae -EKlabegh E R 275 312,12) 6.5 I P Dtoh Sial N East SideoTributaries SDhrab Ea2abagh a 72 360 0.012 I P Strati N East Side Tributaisnis Shebh:Lr Kelabgh N 77 985 0.02 I p Se,sanda N West Side Tributaries CheudhwenD.I. Khse Urn CheudhueZen Crash N Kabul Ri-er Chit,.1 Chitrel 300 1,700 p F Dultel B East Side Tribtatri-a Dulihl ftRassalpindi 70 3,000D Fort Sandanasn N West Side Tributariec Ronal D.I. Khas See Khajwri Each Ostixat N Kabul Rive - Chitrml Chitral e- .100 F F Oaj (Gaja Na2i) S South Tributaries SBj eDscb 300 3120 0.150 I F F Gasdbila N West Side Tributariev OasisLi Base I F Gandelat TangWeir S Eanshi Plai.s Sukle.Ii Kalst 10 Gariale N East Bids Tributerien Bars Attach K 375 40,000 8.2 I US1 F Ghatti Bridge S Ea.. i Flaies ~ Beji Sibi Shasiabad N East Side Tributaries HaAeo- Attach Infeasible- Gidder Fur N East Side Tributaries Sires anAsebra N 52 1,134 0.004 I nasal lea N West Bide-Tributaries _ioona D.I. Ethn See Ethj=r Each Basal las Weir (urtase) N West Side Tributaries5 Goal D.1I. Stan See Mi- RN- Oal Each N West Bide Tributaries Baoml B.I. Khen 0 1.95 0.50 I F F Narasbar N West Side Tributaries-Sasgrah D.0. Ehen -BlaNa (Lani) Hacalias B East Side Tributaiesle Siren Abbottabed E 173 6,600 0.018 C Bienis Tengi N West Side Tributaries Task D.I. Sthn 236 0.68 C P 0.015 F But S Marrm Cmeat- - - HBu Karachi K 153 22,900 0.606 20 C

Jar N Kabul Ricer -- Swat Saida SharSf 0 350 .lathapet N Jbelvan h.lblu Rewalpindi 2.7 Superseded by Mangle S Jheluxa B Jtelus Jtelue Sh.lu

VSI)LIMC-III PICURC12 PArE 2

LOC A T IO0N CNHA R AC T AR I T IC 1 GRiOSSCAP. POWRCAPACITY (MW4) PIlRIST NAMlEOF DAM ZONE REGION BASIN NEARESTCITY TYPE NSTGNTLUIGTH OF NESERVOIR PURPOSEINITIAL OR SLTI-j NOTES STATE (Fr.) (FTP.) (RAP) IROTALLED MATE

Eahas N West Side Tributaries Kahu D.0. Khsa Kalab.gh N Uppe, Indss Indus Eaaba9h E A 085 6,900 8.0 I P 1,125 p Kai.. N Kabu1 Riser Seat Said,. Sharif 480 0.363 I P US0 F Kalungai N Kabul River Swat Said- Sharif G/N R 580 6.5 I P 750 F Kassl- Each S Es..ahi Plains Lahin Sibi N 200 I F P Ka-hi N jbsil, Eswahi Jhel1s 270 1.1 5 P Khiari Murat N East Side Tribstarios Sil Rawulplndi K 220 0.021 I P Khjsrt Keach N West Ride Tribstarins Gomeal D.I. Kiss A/'O 500 630 2.15 I P 127 p Khajsrl Past N West Side TrIbutaries Tochi Races 150 0.130 Kh-spur 0 East Side Tributaries Ners Islasabad E 137 1,310 0.059 C P 8 C Ehapuls N Upper Indus Shyok Shards 600 10 IPPFA 600 PP Eharika KC.s N East Sid. Tribtiarics Khaika- Kalabegh N 230 9,750 0.13 Kea Eh.sana N Kabul River Panjkora Raid. Sharif E N 520 3.0 N 170 P Khirgi Weair N West Side Tributaries Task D.I. Kiss P P Kh.shaldsairh N Upper Indus Indus Kalabagh. N Superseded by KEalaagh Kswaja Ksizar N West Side Tributaries Kohat TeL Kahat E/t 100 000 0.110 I See Yoarar lirpalian N Upper IrdaN InAse Attack I P Superseded by Tarbel. S Kess N Kabul River Chitral Chitrul p P tat Fateh N East Ride TributariEs Sil K.N Rawelpindi E 00 8,000 0.016 I p Kotkai N Upper Indus Induse Abbottabad N Superseded by Tarnela S Kotli N Jihise Punch Rawalpiedi K 320 0.3 I P 2 20 Eud 5 Marren Caset Kud Kaedrach 0.047 E P Esebat N Kabul River Chitral Chitmal P P Eurree Gsrhi N West Side Tributaries Kurrn, Races I P 0 0 Kurrac Tango N West Side Tribut-i-e Earran, Ranes K 300 1.50 I FPPP ladee S Kacchi Plaice Khatac Sibi 80 P Leoh Rhir N East Side Tribda.rics Kurang Isisabaad Lehar Gslo N Jhelse Eunhar Mzcaffanabad 0 530 0.8 I PP Laser Tabs Eas N East Side Tritataries Tabs KeasRawalpindi 170 4,000 Main Swat N Kabul River Swat Saids Sharif 500 I P P Nabbed N East Side Tributaries Scan Kalabagh 280 6.0 I P 700 Superseded by KslabeEh I Macgla N Aih s J1lu Jhele E/N 380 11,000 5.88 N i00 1400 C K.stuj-LA,tkho N Kabul River Chitasi Chitral 200 P P Miaccur N West Ride Tributaries Gocal S.!. Kban K 77 3,060 0.089 I P P mile 46 N West Side Tributaries Chsudhwss D.I. Riac Superseded by Dccsd. 5 Rica Bacar N West Side Tributaries Ziab Fart Sanderac 90 660 Superseded by Khajuril Kech S Mirabandl N KEst Ride Tributrues Rirns M.caffarabad 375 2.30 I Miri Khe1 N Kabul River Rars Peshawar F Mlrkhani N Kabul River Chitral Chitral 000 0.58 MerEah Weir N East Side Tribut-rtsa Sm.c Rawalpindi 0 09 0.016 I P Mued. N Kabul River RSwt Pesawasr K N 660 2.0 I P 370 760 Ip Murta.a Weis N WesWtSide Tributaries G.ceal D.I. Khac I P 8 Superseded by Mase N-r S Nacel N East Side Tributaries GOclarNullah Yiecuali 0 85 153 0.022 PI5 WC Xu4 Raise S saechi Plains Balsa Sibi j K 6A 1,750 0.325 5 P C Naa S liaise Easier MNasaffarabad 0 (.10 1,360 0.28 5 P 50 P Naulasg S Eacchi Plinec Mule Sibi N 185 0.306 E p N-a-a- N Jhelu. Jheluc lslacabad 650 2.6 Supersededby Macgls S Naearai N West Side Tributaroes Zhah Fart Sacdece Superseded by ths,uri Each S ROSS.Each N Wect Side Tributaries Gceal D.I. Ehac K 77 0.01.8 I P Pek-Afghss N Kabul River Kabul Peshawar I PR F Peejar N Jhel-s bhela Islacabed 3.0 P 1,500 Papid N Beast Side Tributaries Wadala K-Raspuinldi ER 100 300 0.053 I P Parse N Jhelia Kunher Nucaffarabad Infeasible- Pasbhtkand (Raika) IS Kacehi Plaids Huola Kalat 190 0.244 Superseded by Haulacg S PAshi N West Side Tributaries Vlder D.0. Kiss Parali S Marrec Cmsat Parali Kacdrch R.Jdh.si N Jhelas Punch Rawalpiddi K 325 0.86 I P (.0 Superseded by Macgle S R-es N Jbeis ihelus, Jhel1e 10.0 I P 300 Spap-sded by Eacgla S Newel N Beast Side Tftjitarie. KOracg Isl1cbad G 80 700 0.0075 I W o R.btas N Jholsa KaSes Jhelsa 25 1.90 I P 60 P Sagger tea N Easat Side Tint.utare Sil Kas Kalabugh K 230 9,500 0.77 1 P P Saciwal N East Side Tributaries Rare Atbach R 165 5,800 0.177 2,250 Superseded by CarteSs S Sapiala Kas N East Side Tributarie 5 Sepiald asa Rawalpindi 130 7,00 Sawa- S Ma-se Caset Sawawan, Kandrech Schuss, Barrage S Scuth Tributaries Indus Dads 3,500 0.8 (2.7) I P Shadi Ear iS Marae lust Shedi Kead-he Shah BAlcsal IN East Ride Tributries Sabhir KaInbagh K 73 1,300 0.021 i p Shah Par 8 East Side. Tributarie, Shab PurEes Rawalpindi Shakdeta NaSa N East Ride Tributaries Shakiete Noai Attcak K 187 11,900 6.25 Sheikh Raider Zas, N West Side Tributerie-, Sc..an 0.I. Kiss E 188 0.0687 P Sheikh Nela N West Side Tributaries Alidngai Ibis S.I. Kiss Superceded by Docmnde S Shinkci Past N West Side Trsbutariest Tachi Races 250 0.23 I Sieg.r N Kabu1 Niver Chitral Chitral P F Ridly N East Side Tribu,taries aSs, 1sl1-bad K 215 900 0.020 W C Skardu N Upper Indus Iedas Shardu N 310 3,700 8.0 N P Spin Eases S Interier Baluchiista Ner Murder Quette N 70 2,090 0.0055 I P W Spli Toi N West Side Tributaries Slhabr Ibis D.I. Khee Superseded b2 Hinisc Tesgi S Tank Suki Kiseri (Pawe Plast) N ibeiIs Kuahar Musaffarahad P 500 P Surg.1-Chbeebl N West Side Tributaries Kahat Tat Kahat Superseded by Tend.s Takeni EilA N West Side Tributarie,s Zhab Pert Sandec,ae See Khajuri. Each Tallt Tangi S Eacchi P:lass bla.i(Chalar) SARi 0 195 150 0.a385 I F P Twacd N West Side Tributaries Kohat Toi Kohat K 137 2,150 0.079 I o Tarbela N Upper Indus Indus Attack K N 465 8,700 11.1 IP R 800 2,500 NC Theian N East Side Tributariec 55l Kas Nawalpindi Thapla N Epper Ieda Sires Abbottabad 210 0.27 I P Superseded by Tarbel. S Tochi N West Side Tribstari-c YTht Race See beta Khsel Tarder M Kabul River Chitral Chitrdl P F TYatl Bela M East Side Trlbutariec, Total MeSa Attack K 108 104,500 6.25 I P F Tang S KXachiPlaids Neji Sibi TongS N West Side Trlbutariezc Tobhi Races I P Turac Chim N West Ride Tributarie. NShhur S.I. EKhc Superseded by Niecin Teegi I Nul. (Taek) Upper Sukleji S Keachi Plaice Suhieji Kalat See sandalat Tang Upper labs Keas N East Side Tributariee Tabs Kas RE..alpledi 60 2,000 See Gaedalat Tang Wadela N East Side Tributarien h&dala KweRawalpiddi Walt Tacgi B Interimr Beluchistan Wali Tang. Quetta N 75 700 0.0000 F 0 Warsak, N Kabul River Kabul Peshawar 0 250 650 N 160 2400 Wuaha Sesta N West Side Tributaries Chsud1huanD.I. Ekes K I Superseded by DOcada P laser N West Side Tributaries Kfdet Te Kohat K/N 100 000 0.10 I p Zhair Naral Chise N West Side Tributariesa Zhsb Pert Sandeasn Superssded by Ehajui Each S

TARBELA AS FIRST STAGE DEVELOPMENT ON THE INDUS RIVER (MAF STORAGE) 25 E I I E I I I I I I I F I I I I 25

4 4 4 Z4

0. 0

20 20

15 15

. / / ~~~~~~LOWERLIMIT

10 10

_ _ -- _ _ _ __ "~EHWA/L,4KExC ~~ *~-

MEAN-YEAR -___ STORAGE DEMAND _ _ 5

TARBELA

1965 1970 1975 1980 1985 1990 1995 2000 mnr

mM (2R) IBRD-3227

- 83 -

Tarbela Project, as envisaged by TAMS (consultants to WAPDA), was technically feasible. It was also concluded that the Tarbela Project compared favorably with other potential projects for the storage of water on the Indus River. The dam site consultant has stressed, moreover, that Tarbela is the only large-volume storage project that can be completed by 1975 to meet projected stored water requirements. Tarbela's power yields have been demonstrated by the Bank's power consultant.

7.11 This conclusion with regard to Tarbela as first stage storage is firmly supported not only by the analysis in this volume, but also by the discussion in Volume II. The dam site consultant, having in hand plans which have now been drawn up by WAPDA and their consultants, has reconfirmed that the project is technically feasible. The return on the project, considered as a separate comDonent of a development plan for the Indus Plains, is by the latest calculations of Sir Alexander Gibb & Partners, 13.3 percent. The consultants stress that this figure assumes however, that a full supporting program of agricultural inputs is implemented; otherwise the increase in production will be less and the return on the project will be reduced.

7.12 The Bank Group has made its own evaluation of the return on the Tarbela Project. Though a somewhat lower return may be indicated (see Volume II), it has no hesitation in concluding that Tarbela should be executed as scheduled.

7.13 The Bank Group, in drawing this conclusion, emphasizes in Volume II, that the Tarbela Project will make a major contribution to the projected incremental rabi crop production of the Indus Plains by regulating the natural river flows and by supplying additional water. Of the total future increment in rabi water deliveries to the farmers, from both ground and surface sources, Tarbela will by 1985 contribute almost one-quarter.

7.14 The Bank7s estimate of the power benefits from the project in Volume IV, indicates that they will be substantial and almost as important as benefits accruing to agriculture. A study of the integration of Tarbela into the power system of West Pakistan, carried out by the power consultant, indicates that the 12,000 million kwh of electric energy, which it would be capable of generating annually would be absorbed relatively quickly into the system (see Volume IV). In a situation where the present known gas reserves may soon become fully committed, Tarbela will provide a badly needed supplement to potential hydro and thermal power through 1985. Its firm capability during the critical period of the year would, of course, depend on the drawdown level assumed. For example, at 1300 feet drawdown the firm capacity would be 487 mw and at 1396 feet it would be 1047 mw, an increase of 560 mw. With reduction of the useful storage capacity of the Tarbela Reservoir by sediment deposition, its firm power capability, and hence its usefulness to the power system, would gradually increase.

7.15 The Bank Group is of the opinion that there are no alternative major surface projects or sequence of projects that appear to offer net advantages over the program recommended in this report which embodies - 84 -

Tarbela for operation in the year I975.. Quite apart-from- the merits of the project in itself, it must be recogni'zed that there is-a degree of interdependence between the current;program of ongoing and of early future irrigation works on the one-hand and Tarbela on the other. Tarbela has for some: time- now formed part of Government planning-. Thifs interdependence may-be chiefly seen in the-newly developing areas along the main Indus st-em and in the Chasma-Jhelux and Taunsa-Panjnad Links, now under construction-, which are designed to convey stored Indus water from west to east across the northern plains.

7.16 The-re- is also an interdependence between Tarbela and. the irrigation or agriculture: program of development recommended in this- report. Tarbela is a major component of'that program. Without- TarbeIla, many aspects would need to be revised incIuding, for- example., the priorities for tubewell projects and canal eylargement-s.

7.17 Chas. T. Main reviewed the possibility of two--stage development of the Tarbela Project and based on figures obtained from TAMAS, found that while there would be an initial saving of $37 million over single- stage development, the ultimate cost would be $27 million more. Thus, at an 8 percent rate of interest, two-stage development would be economical only if the second stage were required more than seven years after completion of the firgt stage. IACA's projections of the mean year demand for stored water-indincate that the second stage would be required within five years after completion of the- ftrst stage, and therefore the conclusion is that two-stage development is mot warranted.

Alternatives for Ferid tod1975

7-.18 Though the Bank Group firm-ly believes and has so stated, that T'ambelIa ghould be built by 1975, for purposes of analysis there are set out here some alternative ways of meeting, or attemptting to meet the surface water requirements of I975.

7.19' Of all the proSects studied, Kalabagh (according to Chas. T. Main) i' the only project of comparable size that can be considered as an alterna- tfi've to Tarbela for near-term development. However, at least three, and m-or-e likely four ytsrs. would be required to explore the problems which are associated with the proJect. Another seveu or eight years would be required for designing, financing and constructing it. Even under an aggressive program of development, Kalabagh FroJect could not be completed and available for service before water-year 1979. Such a program is shown in Figure 14.

7.20 On this basis, with the need for stored water growing at the rate estimated, an additional cumulative shortage of surface water supply of about 14.6 MAF would occur between 1975 and 1979. The annual shortages could amount to as much as 9 MAF per year by 1979. The available groundwater pumping facilities would not be able to make up the additional shortage from an already lowered groundwater level, owing to limitations in pumping capacity and to factors of geographical distribution. KALABAGH AS FIRST STAGE DEVELOPMENT ON THE INDUS RIVER (MAF STORAGE) 25 I I I1 I I1 I I I I I 25

" 'D1 ~ ~~~~~

20 20

15~~ LIPPER~~~~~~~~ LIMIT / 1

WITH SLUICING AT KALABAGH

*--'--'- * *' '@ j 1 _ ~~~~WITHOUT SLUICIG AT KALABAGH| MEAN-YEAR *. STORAGE, DEMAND EH /L KE A.AI;7/

* ~~~~~~KALABAGH

___/ -.. I-_-______--

0 0 1965 1970 1975 1980 1985 1990 1995 2000 cnr

(2R) IBRD-3228 4

- 85 -

7.21 Besides the water shortages which would result from any program that involved the substitution of Kalabagh for Tarbela, there would be a serious effect on power. In the first place, other sources would be needed prior to 1979 to supply large quantities of power if Tarbela were deferred. This is a factor which might actually aggravate the water shortages as power for pumping would be in short supply as well. Secondly,, even with Kalabagh built, operation for sediment flow through would cause generation of power to be discontinued at the project when the reservoir level dropped below elevation 825 feet. rPhis would be expected to occur during the latter part of March and would continue until about July 20 each year in years of mean flow in the river.

7.22 If economic necessity required power to be generated at Kalabagh in its early years of operation, a greatly curtailed life of the reservoir would result.

7.23 There might. admittedly, be a cost advantage to Kalabagh over Tarbela. Chas. T. Main's estimated cost of the water storage project (US$541 million) is $84 million less than the estimated (economic) cost of Tarbela. There seems, especially, to be a saving in the foreign currency component. But Chas. T. Main recognize that this cost estimate is based on insufficient and incomplete data. They have concluded that these differences in the estimated costs should not be a controllin,g factor in any decision concerning the immediate construction of Tarbela. The loss to West Pakistan, in terms of irrigation and power, caused by deferring Tarbela might far exceed any savings that might be made in the initial investment.

7.24 Another alternative examined both by Chas. T. Main and IACA involved raising Mangla Dam with completion in 1972 and earlier construction of Sehwan-Manchar. If the enlarged Mangla Reservoir could be counted on to produce an annual firm yield of 7.5 MIAF of water during the period immediately following 1972 for use on lands commanded by both the Indus and Jhelum Rivers, construction of Tarbela might be deferred to about 1979 by overdrawing from the groundwater and somewThat later if Sehwan- Manchar is available. IACA indicated, however, that the possibility of a series of below-normal runoff years on the Jhelum during the deferral period might make such a solution risky.

7.25 Raising Mangla with completion in 1972 would not have the advantage of dividing storage between the Indus and the Jhelum, which could permit diverse reservoir filling schedules, because of the different flow patterns of the two rivers. Furthermore,, the power potential at Tarbela now being counted on would be unavailable for the four years Tarbela was deferred and another source of power, not now in the program, would be required to meet the system load.

7.26 A third way of meeting 1975 requirements involved raising Mangla with completion in 1972 and building Tarbela with completion in 1975. This alternative was rejected because it was felt that while according to the sequential analysis (see Para. 4.18) shortfalls in surface water deliveries are possible in two of the years between 1967 and 1975, the surface water deficiencies themselves are so small and there are so many other complica- ting factors, that no adequate basis was available for a decision involving - 86 - such a very large expenditure. It was indicated clearly that the proper operation of groundwater projects could alleviate demands on Mangla. Therefore, to raise Mangla before the mid-1980's would be prior to its being essential for irrigation purposes and would involve a waste of scarce economic and administrative resources. Furthermore, there is some doubt about whether Raised Mangla will fill in a sufficient number of years to make it worthwhile for irrigation purposes (see Para. 4.20).

Slow Growth

7.27 One factor which might involve a departure from the action program as envisaged for this early period to 1975 would be the assumption of a growth rate of surface water storage requirements lower than is believed probable by IACA (see Figure 15). Such a growth rate is most unlikely and lies outside all projections made, but Table 53 has been prepared to show some alternative project sequences under this assumption.

Table 53

Alternative Project Sequences with Slow Growth of Surface Water Requirements (in-serice water-years)

Low Tarbela 1975 Low Tarbela 1986 Low Tarbela 1995

Mangla 1968 Mangla 1968 Mangla 1968 Chasma 1972 Chasma 1972 Chasma 1972 Low Tarbela 1975 Swat 1979 Swat 1979 Sehwan- Sehwan- Sehwan- Manchar 1982 Manchar 1982 Manchar 1982 Chotiari 1990 Low Tarbela 1986 Raise Mangla 1986 Raise Mangla 1990 Chotiari 1990 Chotiari 1990 Raise Tarbela 1997 Raise Mangla 1990 Low Tarbela 1995 Kalabagh 2001 Raise Tarbela 2003 Raise Tarbela 2004 Low Gariala 2010 Kalabagh 2007 Kalabagh 2009

7.28 This slow growth sequence implies a total surface water requirement of only about 5 MAF for 1975, 8.5 MAF in 1985, and about 15 MAF in 2000. This requirement is so low that it could be met until about 1985 without Tarbela. Projects such as Raised Chasma, Sehwan-Manchar and Swat would be sufficient (as shown in the last two columns in Table 53). Alter- natively, Low Tarbela could replace Swat (as shown in the first column of Table 53).

High Growth

7.29 Another factor which might involve a departure from the action program up till 1975 as recommended would be the assumption of a growth rate in surface water storage requirements higher than IACA believed necessary (see Figure 15). Table 54 shows some alternative project sequences under this assumption. VOLUME [ FIGURE 15 ALTERNATIVE GROWTH RATES OF THE TOTAL MEAN-YEAR DEMAND FOR STORED WATER ON THE JHELUM AND INDUS RIVERS (MAF STORAGE) 35 1 m m - -vr-i- i- - - -- v-i- i w i 35

30 30

2 5 ; I /~FST GROWTH ALER NAT VE _ > 25 25

20 2 0

/ / v z ~~~~~~LOWERLIMIT 15 15

10 10

SLOW GROWTH ALTERNATIVE

5 5

1965. 1970 1975 1980 1985 1990 1995 2000

(R)IBRD-3225C

- 87 -

Table 54

Alternative Project Sequences with High Growth Rate of Surface Water Requirements (in--service water-years)

Tarbela/Sluicing Kalabagh Tarbela/Kalabagh with Power

Mangla 1968 Mangla 1968 Chasma 1972 Chasma 1972 Raise Mangla 1972 Tarbela 1975 Tarbela 1975 Kalabagh 1979 Kalabagh 1979 Sehwan-Manchar 1982 Sehwan-Manchar 1982 Raise Mangla 1984 Chotiari 1990 High Gariala 1988 Low Gariala 1992 Chotiari 1990 Raise Gariala 2006 Swat 2015 Swat 2022 Skardu 2023

7.30 The rapid growth rate of surface water requirements is projected for the purpose of this analysis at 13.5 MAF in 1975 and 21.5 MAF in 1985. One of the sequences would involve raising Mangla in 1972 as well as building Tarbela by 1975. Both sequences would place a further strain on imple- mentation capacity because, with Kalabagh scheduled for 1979, construction of that project would have to begin before Tarbela was completed. All solutions to meeting the requirements of such a growth rate would appear to be infeasible.

7.31 It is also worth pointing out here that, whatever assumption is made about the growth rate in the demand for stored water and regardless of whether Tarbela or another project on the Indus is constructed first, Tarbela would be required at some point. Furthermore, Figure 16 indicates that regardless of when Tarbela is comnleted, it will have to be followed by a second-stage project by the end of the century.

Post-Tarbela

7.32 The alternative approaches to the pre-1975 period, which the Bank Group does not recommend, have been expounded here because they demonstrate a variety of solutions which will become possible and require serious consideration once Tarbela is constructed. The high and the low growth rate assumptions may be rirled out, for one reason or another, for the early period. But they-shourld not necessarily be ruled out forever. Indeed, the Bank Group feels that the investigation of projects for execution after Tarbela should in any case be carried out with a sense of urgency.

7.33 Nevertheless, as has been already stated, the Bank Group adopts IACA's requiremen-ts as a basis for planning, though it may make a different recommendation about the basis for investigations. The various components of the Chas. T. Main recommended program post-Tarbela, will therefore be summarized briefly in turn, together with some other possibilities. Certain important points must be noted as a preface to that discussion. - 88 -

7.34 All projects after Tarbela, with the exception to a certain extent of Raised Mangla, are, in different degrees, at an early stage of investigation. Unknown or little known subsurface conditions at all sites made it necessary to rely in varying degrees on judgment where the design of the dam was concerned. Actual conditions, affecting design, may differ considerably from those estimated to exist. This difference could result in lesser as well as in greater cost. Thus, the costs which are shown here are used for the purpose of comparing very tentatively the relative feasibility of projects and for evaluating in general terms the price of a long- range surface storage program. Except for Tarbela, Raised Mangla and Chasma, the cost estimates for projects incorporated into this report, although deemed sufficiently accurate for comparative purposes in preliminary analysis, are not considered accurate enough to state with any precision the financial provision that would have to be made for them. Even in the case of Raised Mangla, some reservations should be made. Though information at hand is adequate to provide the assurance that the project structures can be increased in height by 40 feet at a later date, though the details of design, the sources of materials, etc. are generally known, absolute accuracy is still not possible.

7.35 Certain exceptions to the generalization contained in paragraph 7.34 above must be made, in particular respects. For example, Kalabagh and Dhok Pathan were investigated previously in the field and prefeasibility reports prepared. Supplemental factual data on both sites were prepared subsequent to the reports and further field data for backwater studies and on land costs at Kalabagh were prepared specifically for the present report. These are considered reliable for the purposes of this analysis.

Sehwan-Manchar

7.36 Following Tarbela, development of storage volume at Sehwan Bar- rage and Lake Manchar in 1982 is expected to fill some of the needs for surface water supply during the early 1980's. IACA assumed that Sehwan and Manchar would be developed concurrently for completion in 1982. A barrage would be constructed across the Lower Indus near Sehwan town to raise water to the level of a new canal on the left side of the river and thereby feed both the main Nara Canal and the southern Rohri Canal Command area. (The new feeder canal would also be connected at its eastern end to Chotiari Lake, where additional storage could be developed later.) The barrage storage would be connected to Lake Manchar on the right side of the river through the Aral-Manchar Channel. The proposed barrage would be 3,500 feet long, with marginal bunds on the right and left banks to protect the right bank outfall drain and the Sehwan Feeder, respectively. The barrage would raise the water level in the Indus 30 feet. A new head regulator would be required and an enlarged channel (some 20,000 cusecs capacity) for both filling and emptying Lake Manchar. The bunds around Lake Manchar would have to be raised above their present level. This project excluding development at Chotiari Lake could result in total storage of up to 1.8 MAF at a cost between US$177 million and US$221 million. However, such a project might reduce the cost of remodeling the upper end of the Nara and Rohri Canals making the net cost for storage relatively low. VOLUME m FIGURE 16 IACA'S ESTIMATE OF THE TOTAL MEAN-YEAR DEMAND FOR STORED WATER ON THE JHELUM AND INDUS RIVERS (MAF STORAGE) F5 r 35 w 35

o Z 4 ~ _j

30 30

25 25

UPPER Li IT

200 20 Storage to meet surface witer demand in 3 years out of 4

Same for I year out of 2

10 to~~~~~~~~~~~~~~~~~~~~~~~~~~0

15 -1~~~~~~~~~~~~~~5

MEAN-YEARNSTORAGE DEANDNETFRSABEPOCS

0 -s' .- W5.JL .~± L....L .4

1965 1970 1975 1980 1985 1990 1995 2000

(2R)IBRD-3225B

- 89 -

7.37 Though the Sehwan-Manchar storage scheme has been programmed as noted above, because of its relatively small size, it can be fitted com- fortably to any sequential planning, and its position would have no significant effect on other Indus projects except possibly in their timing. Equally, other small projects which will serve local irrigation schemes and water supply projects are not of significant importance to the overall development plans.

7.38 On the Chas. T. Main recommended program, Mangla would be raised in 1986, Kalabagh would be built in 1992, and Low Gariala in 2011. This program, as stated earLier, would meet IACA's projected requirements (see Table 15). But this particular sequence of Raised Mangla, Kalabagh and Low Gariala is not the only one which can meet these IACA requirements. Table 55 makes a comparison between the recommended program and an alternative program.

Table 55

Recommended Alternative Tarbela/Kalabagh 1992 Tarbela/Gariala 1992

Mangla 1968 Mangla 1968 Chasma 1972 Chasma 1972 Tarbela 1975 Tarbela 1975 Sehwan-Manchar 1982 Sehwan-Manchar 1982 Raise Mangla 1986 Raise Mangla 1986 Chotiari 1990 Chotiari 1990 Kalabagh 1992 High Gariala 1992 Swat 2002 Swat 2012 Low Gariala 2011 Kalabagh 2020

Total useful storage (MAF) 62.1 63.2 Cost of program a/ (.¢millions) $548 $547 Cost of useful water ($ per acre.-foot) 8.8 8.7 a! Present worth as of January 1, 1965, at 8 percent discount rate. Costs of Mangla',-Chasma, Sehwan-Manchar and Chotiari excluded.

7.39 The similarity between these two programs leads to the conclusion that more detailed consi-deration needs to be given to the relative orders of Raised Mangla, Kalab-agh or other second-stage storage. Sufficient information must be'established about all projects to permit the preparation of reasonably detai-ed plans, including assessments of power potentials, and cost estimates_ for~their construction. This emphasizes once more the need to initiate at tlie' ear=liest possible date a comprehensive program for investigation of the e-'second-stage storage sites. At this stage the order of development of the projects and the dates of development, particularly those towards the end of this century and into the next century must be treated as indicative only. Pending the establishment of data on which - 9o - more precise decisions can be taken, the Bank Group feels it is useful to present here some of the considerations which have led it to approve, as a basis for planning, the sequence of projects as recommended by Chas. T. Main.

Raised Mangla

7.40 As noted earlier in this report (see Para. 6.11), Raised Mangla will be needed for irrigation purposes on the Jhelum Command by 1990. While storage on the Jhelum River cannot substitute wholly for storage on the Indus, or vice versa, because of transference limitations, as discussed before (see Map III.2), it is of practical significance to combine the demands on the two rivers in a single chart as shown in Figure 16. Further- more, there appears to be some power advantage in having Raised Mangla after Tarbela. On this basis it appears reasonable to advance the construction of Raised Mangla to 1986, as proposed by Chas. T. Main.

Kalabagh

7.41 At the present state of knowledge, Kalabagh appears to be the most attractive choice for development of major storage after Tarbela (see Figure 17). Tarbela will protect the project for many years from large sediment input. Moreover, further development of storage on the Middle and Upper Indus following Kalabagh will reduce to a negligible amount the opportunity for passing sediment through the reservoir. It seems possible, therefore, that sluicing at Kalabagh would have only limited advantage during the life of Tarbela. The construction of Kalabagh for operation without sluicing would on the other hand have great power advantages. For, while it would be difficult to justify the installation of generating facilities at Kalabagh if it were to be operated as a sluicing project, a preliminary study of the power capabilities of Kalabagh without sluicing indicates that it could generate 6,100 million kwh of energy during a mean year and have a firm capability of 350 mw (see Para. 6.44).

7.42 Nevertheless, in view of the limited knowledge about sedimentation rates and the effect of upstream storage upon them, serious study must still be given to the operation of Kalabagh as a second stage sluicing project.

7.43 The assumption that promising potential exists at Kalabagh must, however, be tempered by the main uncertainty of the competence of the foundation for the type of outlet works structure tentatively designed for the site. The effects of the proposed project on potential flooding, and hence land costs, in the Nowshera area are better understood than heretofore but knowledge is still insufficient for drawing unqualified conclusions. Land for the reservoir is one of the more expensive items of the cost of the project. Studies by Chas. T. Main of the backwater effects of Kalabagh Reservoir, made after additional field data were obtained by WAPDA, have added to the understanding of the situation. Additional field data and further analyses are required before the backwater effects can be defined conclusively. Completion of those later studies will be necessary before the optimum operating level of Kalabagh Reservoir can be fixed. KALABAGH AS SECOND STAGE DEVELOPMENT ON THE INDUS RIVER (MAF STORAGE) 2 5 1 1 1 1 1 1 1 1 1 1 1 WI I I I I I I I I I I I I 2-5 w 25 w m~~~~w

20 I- I~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~cn; 20

zWITH SLUIC ING AT KALABAGH ______

WITHOUT SLUICING ~~~AT ~~ I KAL ABAGH I...... Is~~~~~~~~~~~~~~.----t--. *...z----@@ *-_.I_ 15 .'-----% i -- 15 * *******... . ft.

UPPER LIMIT *. *-/LOWER LIMIT

KALABAGH

10 10

SE__N/L4KE MANCHAR --

MEAN-YEAR __ - STORAGE DEMAND_ _

TAR BE LA

0 IIS 7 7- o r------__ CHSA.______.______O 1965 1970 1975 1980 1985 1990 1995 2000 < C '

(3R)IBRD-3229 s p

- 91 -

Swat

7.44 Studies of the Swat River Valley may indicate possible dam sites of some promise. These studies have not yet been undertaken, but if by 1976 investigations can be begun, it may become apparent that large volume storage on the Swat River (at Ambahar) can be accomplished only by constructing a very high dam. The runoff of the river, however, is small. The average storable surplus estimated on the basis of present irrigation requirements would be about 2 MAF and large variations in storable runoff could be expected from year to year. There are possibilities that imported additional water could be brought from the Kabul for storage at Ambahar but the cost would be very high. The high head available would generate a considerable amount of firm power in proportion to the relatively small flows available. The project would have considerable value for generating peaking power in the low flow season, although the transmission distances would be substantial.

Gariala

7.45 The recommended program has Low Gariala in 2011. In the case of Gariala, the growth rate assumed is of particular importance. Stage construction of Gariala is economical if the growth rate in storage demand is such that the initial 4.6 MAF in the first stage development will fill the needs for water for at least eight to ten years after the in-service date of the project.

7.46 The Gariala Project appears to be logical for detailed study for offstream storage from Tarbela. The major drawback is that its cost appears at least as much as the cost of Tarbela. And it might well be more. A sequence of development with the construction of Gariala following as the second major development after Tarbela is shown in Figure 18. Subsurface geologic conditions for most of the length of Gariala Dam are completely unknown. The foundation treatment required for the dam structure could be drastically different from that estimated for the design presented by Chas. T. Main. The estimated cost of Gariala Project made after data are available for more accurate design might make what is expected to be an expensive project prohibitively costly.

7.47 Gariala would have a long life because of the low rate of sediment flow in the river relative to its size. However, the water conveyance system required to fill Gariala would be extremely large. Furthermore, power could be generated at the site only about eight months each year, and thus power generation at Gariala does not appear economically feasible.

Other Projects

7.48 The site for a dam in the vicinity of Skardu was selected by Chas. T. Main with the thought that the reservoir created by it would serve to regulate the entire flow of the Indus River at that point. The sediment transport rate at the site should be less than at Tarbela because of its upstream location (although no records are available to verify this) so a reservoir of similar size should have relatively longer life than Tarbela. The project as proposed would be in a remote area, at present - 92 - inaccessible for construction and the cost of providing access would be of such magnitude as to prejudice seriously the economic feasibility of any proposal. The long distances over rugged inaccessible terrain to power markets would make power development at the site impracticable in the foreseeable future. Floods created by landslides and/or glacial action are potential hazards of unknown proportions to the safety and life of the project.

7.49 Foundation conditions at Skardu are unknown. That a suitable foundation, as adopted for designs for this report does exist is strictly an assumption, for Skardu site was not visited in the course of the present studies and previously has not been studied in any detail. Therefore, even though two widely varying assumed conditions were used in arriving at the designs for estimating costs, little reliance can be assigned to the adequacy of the estimated costs. The access route to the area has not been determined nor have the policies on allocation of costs of access to the storage site been defined.

7.50 A potential project at Sanjwal-Akhori was considered by Chas. T. Main as an alternative to Gariala for side valley storage from Tarbela on the Haro River. A dam at this site does not have the potential of Gariala and would be relatively more costly. The site is suitable for a small development but such a project would be inundated by the Gariala Reservoir.

7.51 Another side valley possibility at Dhok Pathan or at the Dhok Abakki site on the Soan River could be filled by gravity diversions from the upper levels of Tarbela Reservoir through a conveyance system 70 miles long. Because of the short period that will be available for filling any offstream reservoir as the water resources approach full development, the conveyance system would require extraordinarily large capacity. The costs and problems of operating such a conveyance system make these projects relatively unattractive.

7.52 Water could also be stored on the Soan at Dhok Abakki or at Dhok Pathan by pumping from the Kalabagh Reservoir. Such a scheme could not be carried out in conjunction with sediment sluicing. Because of the short season when storable water would be available, large pumping facilities would be required. To meet the pumping load, the power system would need additional capacity which makes this project of questionable value. Fur- thermore, power could only be generated at either Dhok Pathan or Dhok Abakki for about eight months each year.

7.53 As indicated in this report Raised Mangla would probably provide all the storage feasible on the Chenab-Jhelum River to supply seasonal water requirements. Some storage on the Chenab River may be useful to regulate heavy flood flows and to reduce sediment loads which now force the canals to be shut down on occasion. A dam at a potential offstream storage site, near the city of Chiniot, is the only known feasible location for storing water on the Chenab River in West Pakistan. A reservoir at this site could store 1.4 MAF of water but Chas. T. Main indicates it would have to be released from storage by November, because of the permeable nature of the reservoir floor and the danger of waterlogging GARIALA AS SECOND STAGE DEVELOPMENT ON THE INDUS RIVER (MAF STORAGE) 25 l l l I 25

w LU 4

r <

20 -, //WUP LIMIT 20 ___~~.______--. ___ _-_ _ __

1O | k _ G~~~~~~~~~~~~~~~~~~ARIALALll

MEAN-IYEAR STORAGE DEMAND---, 5 5

TARBELA

I---.

0 , .______-I5Xr I I I .______.____I I-__ 1965 1970 1975 1980 1985 1990 1995 2000

RR-

- 93 - surrounding farmlands. The costs would be high at over $80 million. Such a project would have no effect on water or sediment flows on the Chenab to benefit operation of the canals because of its location downstream of several of the major canals. The project would also have negligible effect for attenuating flood flows to benefit canals farther downstream. Experience in operating the link canal system may, however, demonstrate a need for canal regulatory storage at the Chiniot site to avoid wastage of water.

7.54 There are, of course, a large number of potential hydro power projects. In the gorge between Skardu and Tarbela there are numerous possibilities for the construction of dams suited to the development of hydroelectric power; they would, however, all have limited storage capacities. The two most promising are at Bunji and Chilas. The Bunji site is about 100 miles below Skardu, just upstream of the confluence of the Gilgit River. Reconnaissance studies only have been made; no detailed surveys or investigations have been carried out. Maps are not available. The site would appear to have considerable potential for power but little for storage. Forty miles below Bunji, at Chilas, indications are that a site exists for a dam approximately 600 feet high, which would have a gross storage of about 3.0 MAF. These figures are based upon reconnaissance visits only and no detailed studies have been carried out. The site is not attractive for storage purposes.

7.55 A power project with incidental storage benefits has been discussed (see Paras. 5.87 to 5.89) for the Kunhar River. This hydroelectric scheme was studied in 1959/60 by Chas. T. Main for WAPDA. The full project would develop about 500 mw of power. The feasibility of the project and the project's potential -have been established. Chas. T. Main studies proposed that the first stage of the development for a firm capability of 198 mw would be completed in five years in a program extending over a nine-year period to bring the project to full development. The program for developing the entire project could be compressed to about five years if the need arose. The project would consist of two reservoirs and two power plants with power tunnels for conveying water from the reservoirs to the power plants. The cost of this scheme would be about $200 million which would indicate moderately expensive power but not beyond the limit of economic possibility.

7.56 The Kunhar River Project investigations are at the feasibility stage. Both prefeasibility and feasibility stage reports are available. Sufficient field investigations and design studies were made to assure that the project is feasible. Considerable detailed field investigations at the sites remain to be done in order to develop definite locations for and designs of the structures. The quantities of work and materials for construction then will become more definitely known and more refined estimates of costs can be prepared. - 94 -

Conclusions

7.57 The development of an optimum sequence of surface storage projects will be costly in both money and effort. It will take considerable time and tax heavily the technical capabilities that may be available. For these reasons plans should be prepared early and schedules established that will lead to the obtainment of information necessary. The requirements are described in some detail in the next chapter. - 95 -

VIII. PROGRAM FOR INVESTIGATIONS

8.o0 It became apparent early in their study that many of the data required by Chas, T. Main for the evaluation of various storage sites were lacking. In order to obtain the data necessary to evaluate a particular storage site in relation to others and to provide a basis for constructing and operating a system of reservoirs in the Indus Basin, it is necessary to embark on an organized program of investigations.

Past Experience

8.02 When considering a timetable for the investigation of possible future developments in West Pakistan, it is useful to note the experience already gained during the planning for Tarbela. The agreement between WAPDA and their consultants (TAMIS) for engineering became effective in January 1960. Initial studies covered a stretch of river extending over nearly 20 miles. Three locations for a dam were considered and in May 1961 the consultants recommended adoption of the Bara site, which is the site accepted.

8.03 By January ].962 investigations and designs were sufficiently advanced for the preparation of a project planning report covering the preliminary phases. At this stage many of the features of the scheme were of a tentative nature and subject to further exploratory work on site. Towards the end of the year, in November 1962, a supplement to the project planning report was issued. This supplement, while still based on the adoption of the Bara site, showed considerable changes in concept of the dam, both in alignment and in design. The report further brought out that a number of additional points required investigation on site before the designs could be finalized. At this stage in the investigations, after nearly three years of work, the cost amounted to $9.9 million, of which $3.4 million was in foreign exchange. From that time, until September 1965, in the course of definite project planning, a further $9.6 million was expended, of which $3.7 million was in foreign exchange. The estimated cost of a continued program of exploratory work, detailed design and preparation of tender documents over the period extending from November 1965 until the end of 1967 is about $8.8 million, including $4.2 million in foreign exchange. All the cost figures include provision for the necessary support work, such as temporary access and camps, power supplies, etc., but do not include preliminary works, such as permanent road and rail access and housing required for construction of the project.

8.o4 Thus for Tarbela, it took a year to fix the site, two more years to establish project feasibility with reasonable certainty, three more years to prepare definite plans and another two years to reach the stage when construction might start. Even then the problem of siltation and its effect on the useful life of the reservoir remained unresolved. If the rate is unchecked storage capacity will be reduced to about 1 MAF in 50 years. If means can be found to reduce the rate by even a half the cost of investigations leading thereto will be repaid manifold. - 96 -

With this example in mind, it makes sense to continue a program of investigations that will get to the roots of the basic problems of river flow at the same time determining the facts necessary for planning specific future projects.

Basis for Programming

8.05 The program for future investigations should be such that whatever the rate of growth of demand for stored water, timely decisions can be taken based on a knowledge of as many of the relevant facts as possible. For this reason the program should be related to a high growth rate, rather than to the projected growth anticipated by IACA.

8.o6 Each year the program should be reviewed in the light of the rate of growth of demand achieved and suitable adjustments should be made in the circumstances prevailing. This review would be quite separate from, and additional to, the continuing process of reassess- ment of the probable sequence of projects as further technical facts became known.

Type of Investigations

8.07 The investigations to be undertaken fall into two broad categories: first, the acquisition of hydrological data and the conduct of a general research program, and second, the mapping of promising localities and subsurface exploration of possible sites. The first part of the program is essentially broad in its approach. It is directed to learning more about the Indus River system as a whole. Although some of the sites selected for regular observations will be chosen with possible projects in mind, the information that will be gained is intended to form the basis on which many schemes can be considered in the future. Although there have been instances where major dams have been designed and constructed with the benefit of very limited information about the hydrology of the river concerned, it can be an expensive or even a dangerous course. If because of lack of data a design which proves overconservative is adopted, money is wasted. If the flood potential is underestimated, damage may occur and in extreme circumstances the project may be destroyed.

8.o8 For these reasons no time should be lost in the acquisition of complete hydrological and meteorological knowledge. Gauging stations must be established without delay and systems developed for obtaining accurate and consistent readings over as long a period as possible. Fifty or a hundred years of records are not too long, when costly schemes are envisaged. Topographic surveys should be made over extensive areas, both upstream and downstream of anticipated sites. In some cases, time can be saved by carrying out an initial reconnaissance by air, and in nearly every case it will be desirable to make a thorough inspection of the ground before initiating a costly program of mapping. After the contours of the ground and the visible surface geology have become known, a limited program of subsurface exploration should be undertaken to establish foundation conditions that will have a controlling effect on the type of structure. - 97 -

8.og Thereafter, it should be possible to establish which of several alternate sites should be chosen for detailed exploration. In the case of two apparently equal sites, it may be necessary to continue investigating both in more detail. Apart from direct cost comparisons, other factors such as accessibility, may influence the choice.

8.10 Once a site has been selected a full program of investigations will be required, in conjunction with definitive design of the project. Work involved will comprise boreholes, shafts, adits, seismic and/or resistivity surveys., jacking and in situ shear tests, soil tests for embankments and possibly some trial grouting.

Detailed Program

8.11 The program of investigation and research should include the collection of data on temperature, precipitation, runoff, infiltration and percolation, evapotranspiration, sediment discharge and sediment input, effects of snowmelt and glacial movements, fragmentation of rock by temperature changes, and the determination of all other facts relating to or affecting the river regime. To this end, the following field observation stations should be established as proposed by WAPDA and endorsed by IACA:

Sarrori Khawar near Kuza Banda

Nandihar Khawar at Batgrar

Panjkora River near Banda Gai

Shyok River at Yuga Village

Indus River below Shigar Confluence

Gilgit River at Alam Bridge

Hunza River at Mouth

Mastunj River near Dhok Muligram

Dir Nallah near Confluence

Shewa Khawar near Wach

Shewa Khawar near Chakdara

Kurram River near Sulaimani Chowki

Kurram River at Kurram Tangi

Kurram River at Dara Tank

Kaihi River at Data Khel - 98 -

Tochi River near Dand Kili

Tochi River near Boya

Tochi River near Seria Gambila

Jhelum River near Chinari

Jbelum River near Mangla

Nanda Kas near Akhori

Sil Kas near Kot Fateh

Wadala Kas near Papur

Nili Nadi at Bunr

Manur Nallah at Mahandri

Indus River at Kalabagh

8.12 The frequency of measurement at existing stations should also be increased. Studies should then be extended to the laboratory for determination of the quantities and characteristics of sediment transported, the critical velocities and depths for its entrainmentmovement in suspension and deposition, and finally by models to determine appropriate works for its retention, bypassing, side casting, or other means of disposal. In addition, the rates of sedimentation in existing and future reservoirs should be measured.

8.13 Bearing in mind that the program of investigations should provide data suitable as a basis for decisions necessary to meet a high growth development, it appears that the following schemes require initial investigation:

a) Sehwan-Manchar

b) Raised Mangla

c) Indus Plains

d) Kalabagh

e) Gariala

Furthermore, in view of the fact that virtually nothing is known about the possibilities of development in the vicinity of Skardu or on the Swat River, it will be desirable to carry out a modest exploration program to determine conclusively whether either scheme is likelv to compete with the other projects named for investigation. - 99 -

8.14 The types of investigations to be undertaken at the various sites, as recommended by WAPDA and/or the Bank's consultants are described in the following paragraphs. The list for each site is not exhaustive.

Sehwan-Manchar

8.15 Lower Indus Project (LIP) suggested that the study started at Kalri Lake on sedimentation be continued and that a similar program be undertaken at Manchar Lake. They also suggested that investigations on reservoir evaporation should continue. Topographic and hydrographic surveys, climatological observations will- be required and subsurfac-e investigations will have to be carried out.

Raised Mangla

8.16 Much of the preliminary design work for Raised Mangla has already been done in the interests of ensuring that the project as now being built can be raised as economically as possible in the future. It will, however, be necessary to review the various readings which will be taken regularly as the reservoir comes into operation, to determine whether any changes in design are desirable. Sources of fill must also be identified.

Indus Plains

8.17 The proposal by Tipton & Kalmbach for a large reservoir in the Indus Plains was received too late for study by the Bank's consultants and consideration by the Bank Group. As a project alternate to Kalabagh or Gariala - and following Tarbela and Raised Mangla, it may have merit. Considerable investigation, however, will be necessary before it is possible to plan with complete confidence in the feasibility and likely cost. The evaporation, seepage and siltation rates will have a profound effect and study, possibly by the construction of a small pilot project, will be required. The optimum reservoir size needs to be established, taking account of water availability, distribution and use. An aerial survey of the reservoir area with suitable ground control must be made to establish capacity for different pond levels. The foundations must be investigated along the suggested alignment of the embankment and the local materials should be tested for suitability for the construction of the embankment. The effects of wind on a reservoir of the size proposed and on the embankment itself will have -to be considered. Investigations along these lines should be introduced into the program at a fairly early date.

Kalabagh

8.18 In the Chas. T. Main proposals much of the economy of construction and value of long life of usable storage volume at Kalabagh is to be achieved by incorporating large outlet capacity at low reservoir levels in a buttress-type sluiceway/spillway dam. Intensive investigations of the physical properties of the foundation rock are needed for design of this structure. These investigations should include exploration for the posi- tions of massive sandstone beds throughout the foundation area. The locations of bedding zones. clayshale or silstone partings need to be - 100 - examined in detail. Large diameter holes permitting entry by persons for direct examination of the foundation structure may be necessary. Labora- tory and in-place tests of the rocks should be made. The depth and nature of the overburden in the river channel must be thoroughly explored for the design of the earth embankment. Sources of materials must be identified and explored in sufficient detail to learn their physical properties for design and the adequacy of quantity for construction.

8.19 Backwater effects and, hence, the land acquisition problem, must be studied in considerable detail. Some work in this respect was carried out in the course of this study by the establishment of gauge posts and measuring of cross-sections. Additional cross-sections of the river should be measured at strategic points. Establishment of staff gauges and observation of stage levels on a systematic basis at the existing as well as newly-established sections are needed. These cross-sections and staff gauges must be tied together through their own level network and tied to the Survey of Pakistan datum. More detailed mapping, particularly in the upper reaches of the reservoir is needed.

8.20 The problem of sediment transport through the proposed reservoir needs to be intensively investigated. Detailed mapping of the reservoir on a large scale would be of great assistance in these studies. Systematic measurements of sediment concentrations in the river at various stations at the head of the proposed reservoir and along in the reservoir area should be made and recorded. When Tarbela comes into operation the behavior of the sediment movement in the lower river will change. The results of measurements of sediment concentration in the river discharge at Attock and downstream and of sediment deposited in Tarbela when the time comes will enable forecasting more accurately the likely behavior of sediment movement through Kalabagh Reservoir.

8.21 Measurements of water surface levels at the dam site and for a few miles downstream are needed for design of the outlet works, spillway discharge and power plant discharge characteristics. These readings should be correlated with water levels and operations at Jinnah Barrage.

Gariala

8.22 Chas. T. Main recommends that the feasibility of the Gariala Project should be confirmed through a limited program of field investigation followed by preliminary design work and preparation of cost estimates.

8.23 Initially, about 20 exploratory holes should be drilled along the axis of the dam. Fifteen of the holes should be in the foundation of the main dam and the remainder should be along the line of the long right abutment dike spaced at about one mile intervals. The holes under the proposed main dam section should each penetrate about 150 feet into bedrock, while the holes along the proposed dike should be carried at least 25 feet into bedrock. An angle boring is proposed in the limestone of the left abutment, to determine most effectively the characteristics of the formations that outcrop there. Total depth of holes required in the initial program is estimated to be 3,200 linear feet. - 101 -

8.24 About 18 test pits along the axis of the dam and dike totaling about 900 feet in depth, should be dug to sample and test the foundation soils. Six of the holes should be in the main dam area and the remainder would be spaced at half-mile intervals along the line of the dike.

8.25 The findings from the above minimum exploratory program will suggest the need for and location of additional subsurface explorations.

8.26 Standard tests, such as triaxial shear, unconfined compression, and modulus of elasticity should be performed on representative undisturbed clay and shale samples of the bedrock formations in both the saturated and unsaturated states. The samples can be selected from drill cores and from the test pits. Porosity and permeability of bedrock and overburden should be determined. Where possible, pressure tests should be made in the boreholes, in both overburden and rock. Load bearing tests, especially along the outlet conduit fotmdations, are recommended. The minimum test loads should be several kips greater than the ultimate design loads.

Skardu

8.27 Before the feasibility of Skardu Project can be determined and the designs and estimates of costs prepared with any greater reliability than the present ones, a great amount of field investigation work is required.

8.28 The gauging station at Skardu is particularly needed to gather data useful for determining the size of reservoir for the Skardu Project and to learn the sediment transport characteristics of the river at that locality. In connection with sediment, the input and output of glacial debris in the Shigar, Shyok and Indus Rivers should be studied in considerable detail to ascertain over a long period of time the mechanics of sediment movement in the valleys of those glacial streams. Snow courses should be established for correlating snow pack with runoff. Full knowledge of the hydrologic and hydrometeorologic aspects of the upper basin will be invaluable for successful operation of Skardu as well as the entire storage system when full developments of the water resources of the river basin are approached.

8.29 Other dam sites should be investigated to the extent necessary to identify those justifying further exploration. In every case, however, before the site itself is studied in detail, and certainly before any considerable program of subsurface exploration is commenced, it will be desirable to give thorough consideration to the problem of access. This will be best accomplished by a ground reconnaissance party, sent to explore the possibility of a route close to the river but above maximum flood level. If the preliminary investigation and study of alternative approaches reveal that access costs are likely to be reasonable, more detailed investigations may be justified.

8.30 Chas. T. Main has recommended that investigations be made to determine the depth and character of overburden at all dam sites selected for more detailed study. Test pits should be dug and borings made to - 102 - determine potential sources of materials for construction and to provide estimates of quantities of materials available. Detailed studies should be made of the inhabited land affected by the project, of potential lands in the area that may be developed for relocating the people affected and of the effects the project will have on the economy of the region.

Ambahar

8.31 The existing data available for studying Ambahar Project are completely inadequate for preparing designs, determining the economic size of structure and for preparing accurate cost estimates. Means of access will require special study. Chas. T. Main proposes that hydrographic work started in the river basin should be continued and expanded. The flows of the Swat River at Amandara headworks and the diversions to the Upper Swat Canal need to be known more accurately. Discharge measurements of the Panjkora River should be continued. Discharge measurements should be taken accurately and systematically at the Munda headworks and at the confluence of the Kabul and Swat Rivers. Accurate measurements of all canal diversions from the river from Amandara headworks downstream to the mouth of the Swat River are required. Systematic studies of the areas being served by the several canal commands should be made periodically to update estimated future needs for surface water when the lands are brought to full development.

8.32 Investigations should be carried out to the extent necessary to select the optimum site for storage in the Lower Swat Gorge and then that site should be investigated sufficientlv to determine its feasibility. Studies should cover the complete range of reservoir sizes likely to be needed,, including study of storage space for imported water. The preliminary investigations should include study of surface geology of the site supplemented by subsurface explorations as needed to define fully the problems of design. Sources of materials should be located. Studies should' include consideration of the site selected for various types of dam structures.

General Considerations and Conclusions

8.33 Although the proposals for investigation are considerable it is reemphasized that initially the full program for each site is not required. Sufficient should be done to confirm the immediate order of development and then the detailed program for each site should be started some four to five years before construction is scheduled to begin.

8.34 The program of general investigation, however, should be a continuing one. In particular, in the upper reaches of the Indus River and its tributaries a great deal of investigation and exploration remains to be done. The scant literature of the area and a few superficial observations suggest that some tributaries are heavily silt laden even at times of year when others flow relatively clear. These reports require confirma- tion and explanation. If some tributaries contribute a disproportionate element of the silt load of the Indus. means should be investigated to reduce the load. Any measurable reduction in the rate of siltation at Tarbela would justify considerable effort. - 103 -

8.35 As soon as it is established that a particular project is feasible and likely to be constructed in the foreseeable future, steps should be taken to curb development in the area, so that unnecessarily expensive compensation is avoided. Such arrangements would involve a notification to Government departments and other agencies that might have plans for the area, e.g., Buildings and Roads Department, West Pakistan Railway, etc., and possibly legislation to stop or at least restrict private development.

8.36 It was recommended by Chas. T. Main that WAPDA be assigned the task of collecting and analyzing the data needed to implement the development program. The Bank Group concurs in this suggestion. Specifically, the Surface Water Circle should establish the new gauging stations and intensify measurements at the existing stations. The systematic collection of other data required in the Upper Indus region, such as glacier and snow course observations, and vigilance for landslides, should begin. An engineering group should be established to develop flow forecasting procedures and to study sediment control and the operation of the present and future system of reservoirs for optimum benefits. Procedures for surveying and determing rates of sedimentation in reservoirs should be established. Investigations of proposed storage sites should be undertaken to permit the preparation of preliminary designs and cost estimates sufficient to confirm the general feasibility of the sites.

8.37 The success of the tubewell programs and the efficient operation of the irrigation systems are of paramount importance. It is worthy of note that a 3 percent improvement in the efficiency of the delivery of water at the watercourse would be equivalent to half of one major dam project. Likewise, two tubewell projects equivalent to SCARP 1 yield at the watercourse water equivalent to a major dam project. For this reason the search for improvements in operation of existing and new works must also have a place in the program.

8.38 The findings of all investigations and the conclusions of all studies will require assessment in relation to the Master Planning being conducted by WAPDA. It is recommended that this planning should continue, though once the broad framework has been established it should be fairly straightforward to take account of the results of investigations.

8.39 The cost of implementing these proposals for investigations is estimated to average over the next eight years about $2.5 million a year, of which about a third would be devoted to the general program of basic data collection planning and two--thirds to the study of specific projects. A preliminary schedule of costs is given in Table 56. It may take a year or two to recruit and train the size of staff required for the investigations, some of the work involves special skills. The preparation of records of work done is a vital part of the investigations and information must be retained in a state that will permit intelligent study by others in the future. Once the team is established it is essential to maintain the impetus and not to lose the experience gained. If promising results are obtained, particularly in such a field as sediment control in the - 104 -

Upper Indus region, it may be desirable in a few years' time to review and increase the program and consequently the cost. Expenrditure on investigations is an investment in the future, it provides greater re- turns than any other work undertaken and to defer or restrict it is to show a lack of faith in the prospects of continued development.

Table 56

Preliminary Schedule of Costs of Investigation Program for Surface Water Storage (US$ million equivalent) 1967/ 1968/ 1969/ 1970/ 1971/ 1972/ 1973/ 1974/ 1968 1969 1970 1971 1972 1973 1974 1975 Total Collection of basic data; hydrological, meteorological, etc. 0.5 0.7 0.7 0.8 o.8 o.8 o.8 o.8 5.9

Identification of Second Stage Stor- age 1.0 1.5 1.5 1.0 0.5 - - - 5.5

Detailed In- vestigation of Second Stage Stor- age - - - 0.5 1.0 2.0 2.0 2.0 7.5

Master Plan- ning o.4 0.3 0.3 0.2 0.2 0.2 0.2 0.2 2.0

1.9 2.5 2.5 2.5 2.5 3.0 3.0 3.0 20.9 - 105 -

IX. FINANCIAL REQUIREMENTS AND COST COMPARISONS

9.01 It is difficult to quantify with any degree of accuracy the investment requirements of the suggested development program for surface water storage beyond the Tarbela stage. Uncertainties with regard to cost estimates as well as price levels a decade or two away make such prognostications tentative at best. However, it is possible to give an indication of the order of magnitude of the expenditures required not only during the Third and Fourth Plan periods to 1975 but also during the decade 1975-85.

9.02 As previously noted, inasmuch as the cost estimates herein contained were prepared for the purposes of comparing the relative merits of the different projects and for economic evaluation, Pakistani duties and taxes must be added for a proper estimate of a financial program. Other factors must be included besides the allowance for the duties and taxes that would undoubtedly be paid on the goods and services required for the project. It would be most unwise to ignore entirely, when estimating the financing requirements that prices tend to rise and, not the least important, that the '3economic" cost estimates represent an assessment of the "fmost probable; cost of the project. This approach to these estimates is essential in order to present their comparison with the "most probable" value of the economic benefits. The benefits are not assessed at their "maximum value, so it would be unjustifed to use a 'maximum" estimate of the project cost for economic comparison. It is, however, considered that the commitment of financial resources to a project should be based on the maximum likely" cost of the project.

9.03 The scheduling of the investment estimates over the period 1965 to 1985 is indicated in Table 57. The total figure of around $1.35 billion (with a foreign exchange component of around $750 million) excludes duties and taxes and interest during construction. It also excludes the cost of power units. It does, however, provide for inflation at between one and one-half and two percent per annum, and for financial contingencies. It also provides for continuing preliminary investigations of potential projects even though the actual construction of these projects may take place outside the 20-year period covered by this estimate.

9.04 Table 58 shows the estimated construction cost of the storage features of the "recommended program,' viz. that designed to meet IACA's low ultimate alternative. For purposes of comparison. a sequence of projects is also shown designed to meet IACA's high ultimate alternative. It must be noted that the cost figures given, unlike the figures given in Table 57, have not been increased for inflation and financial contingency. Table 57

Estimated Annual Cost 1965/66 - 1984/85 of Chas. T. Main's Surface Water Storage Program a/b/ (US$ millions Fiscal Year Raised Sehwan Raised July 1 to Chasma Tarbela c/ Manchar Mangla d/ Chotiari Kalabagh d/ Investi- Annual Total June 30 (1972) (1975) (1982) (1986) (1990) (1992) gations e/ Expenditures f/ Total F.E. Total F.E. Total F.E. Total F.E. Total F.E. Total F.E. Total F.E. Total F.E.

1965/66 0.3 0.1 1.4 o.6 1.7 0.7 1966/67 o.6 0.2 20.4 6.9 21.0 7.1 1967/68 3.9 2.2 99.4 56.3 1.9 0.7 105.2 59.2 1968/69 5.6 2.8 103.1 64.8 2.5 0.9 111.2 68.5 1969/70 3.9 1.7 100.3 63.6 2.5 o.9 106.7 66.2 1970/71 2.7 1.1 98.8 59.6 2.5 o.9 104.0 61.6 1971/72 1.1 o.4 91.8 55.4 2.5 0.9 95.4 56.7 1972/73 86.0 52.0 3.0 1.2 89.0 53.2 1973/74 73.6 45.0 1.0 0.5 3.0 1.2 77.6 46.7 1 1974/75 65.4 39.7 3.0 1.5 3.0 1.2 71.4 42.4 0D 1975/76 53.0 31.9 6.0 2.5 3.0 1.2 62.0 35.6 H 1976/77 22.5 13.7 25.0 13.0 3.0 1.2 50.5 27.9 1977/78 35.0 18.0 3.0 1.2 38.0 19.2 1978/79 40.0 19.o 3.0 1.2 43.0 20.2 1979/80 40.0 18.0 0.5 0.3 3.0 1.2 43.5 19.5 1980/81 35.0 16.0 1.5 0.8 1.0 0.2 3.0 1.2 40.5 18.2 1981/82 26.0 12.0 5.0 2.9 3.0 0.8 3.0 1.2 37.0 16.9 1982/83 10.0 3.5 35.0 20.0 5.0 1.5 3.0 1.2 53.0 26.2 1983/84 73.0 42.0 1.0 0.2 12.0 4.5 3.0 1.2 89.0 47.9 1984/85 85.0 50.0 2.0 0.5 20.0 8.0 3.0 1.2 110.0 59.7 Totals for Period 18.1 8.5 815.7 489.5 221.0 104.0 200.0 116.0 3.0 0.7 41.0 15.0 50.9 19.9 1349.7 753.6 a/ Based on IACA's lower limit. b/ Excludes duties and taxes and interest during construction. c/ Excludes all mechanical and electrical power plant, but includes civil engineering work associated with first four generating units. d/ Based on Chas. T. Main Report figures increased for inflation and financial contingency. e/ Provides for establishing relative merits of projects following Tarbela. f/ 1966 Price levels. - 107 -

Table 58

Comparison of Chas. T. Main Recommended Sequence and Alternative Sequence for Developing Surface Water Storage Projects for Indus Plains of West Pakistan (IACA Estimated Lower and Upper Limit Requirements)

Estimated In- Estimated Con- In-Service Water Year itial Live struction Cost of Lower Limit a/ Upper Limit a/ Storage Storage Features f/ Project Alternative Alternative Volume (MAF) (US$ million equiv.)

Mangla b/ 1968 1968 5.22 d/ 534 Chasma b/ 1972 1972 0.51 32 g/ Tarbela 1975 1975 8.60 625 Sehwan-Mianchar c/ 1982 1982 1.80 177 h/ Raised Mangla 1986 1990 3.55 e/ 216 Chotiari c/ 1990 1990 0.90 12 Kalabagh 1992 1985 6.40 540 High Gariala 1995 8.00 651 Swat 2002 2014 2.00 145 Low Gariala 2011 4.60 596 Skardu After 2020 After 2020 8.00 588 a/ Table 15 shows lower and upper limits of storage requirements estimated by IACA. b/ Ongoing projects. c/ Timing decided by irrigation planning. d/ Volume recoverable through main outlet works and power plant, assuming cut through Mirpur saddle to release 0.28 MAF from Jari arm. e/ Raised to maximum height now contemplated. f/ Exclusive of Pakistan taxes, levies, import duties and interest during construction. g/ Cost is for 0.33 MAF above flood operating level in barrage pond. h/ Total estimated cost allocable to storage in Sehwan and Manchar.

9.05 Thus the figure for Tarbela is shown as $625 million. The corresponding financial requirements for Tarbela, including eight power units, are shown in Table 59. The figures are the same as those used in the Bank Group's report of February 1965. Although minor changes may affect individual items the Bank Group sees no reason as this is written to alter the estimate of total financial requirements. In Table 60 are shown the financial requirements for the project excluding all power units, but including the power house structure for the first four units. A number of minor variations in the figures have been made in the light of present knowledge and provision has been included for supervision of the project. - 108 -

Table 59

TARBELA PROJECT

Estimated Financial Requirements (including first eight generating units)

(US$ million equivalent)

Expenditures Receipts

Total Foreign Exchange

1. Precontract Costs

From January 1, 1965 16.5 h.7

2. Civil Construction:

(a) Dam and Reservoir 414.h 284.0 (b) Power facilities 55.1 b/ 35.7 b (c) Income tax a/ 61.0 El - 61.0 (d) Excise and sales taxes a/ 24.h c/ - 24.4 (e) Performance Bond 3.3 d/ 3.3 (f) Insurance and miscellaneous 7.5 e/ 7.5

Estimated bid value 565.7 330.5

3. Subtotal 582.2 335.2

4. Engineering Contingencies (20%) ll6.A 67.0 17.1 5. Subtotal 698.6 hc2.2

6. Mechanical and Electrical Plant 35.6 b/ 31.7 b/ -

7. Contingencies on line 6 (o%) 3.6 3.2

8. Subtotal 737.8 h37.1

9. Import Duties a/ h8.0 c/ 48.0

10. Engineering and Administration:

(a) Dam and Reservoir 36.2 30.0 - (b) Power facilities 8.4 7.0 -

11. Subtotal 830.h 47h.1 150.5

12. Land and Resettlement 59.o

13. Subtotal 889.4 h7h.1 150.5 11. Allowance for Inflation a/

(a) 1.5% p.a. on Foreign Exchange Costs 39.8 39.8 - (b) 2.0% p.a. on Local Currency Costs 43.h -

15. Subtotal 972.6 513.9,

16. Financial Contingency a/

(a) 5% on expenditure through 1968 14.9 9.2 (b) 10% thereafter 54.0 28.7

17. Subtotal 1,041.5 551.8

18. Expendituresbetween

No'vember 30, V962 & January 1, 1965 f/ 5.8 2.1

19. Subtotal 1,017.3 F/ 553.9 I/ 150.5

20. Less Receipts 150.5

21. TOTAL 896.8 553.9

NOTES: a/ These items have been included in the oost estimates set out above to arrive at an estimate of the financial requirements. They are excluded from the figures in Table 21 because they are not pertinent to an economic evaluation. bJ First eight units only. Excludes all transmission and distribution. I Based on figures prepared by Coopers & Lyborand. The cost of this item is given as US$4.0 million in Table 21 but is a bid item. It has therefore been reduced to US$3.3 zllion so that when contingencies are added back (20%) the total becomes uS$4 million. / This figure has been reduced from US$9.0 million to US$7.5 million for the save reason as in d/ above. In Table 21 all costs incurred prior to January 1, 1965, have been disregarded. Those incurred prior to November 30, 1962, have been met from the Indus Basin Development Fund. Makes no provision for interest during construction. - 109 -

Table 60

TARBEIA PROJECT

Estimated Financial Requirements (excluding all mechanical and electrical power plant)

(US$ million equivalent)

Expenditures Receipts

Total Foreign Exchange

1. Precontract Costs

From October 1, 1965 34.8 13.0

2. Civil Construction:

(a) Dam and Reservoir h1h.4 28h.0 (b) Power facilities 27.6 b/ 17.9 b/ (c) Income tax a/ 59.o0/ - 59.0 (d) Excise and sales taxes a/ 21.0 c- 21.0 (e) Performance Bond 3.3 3.33 (f) Insurance and miscellaneous 7.5 7.5 e/

Estimated bid value 532.8 312.7

3. Subtotal 567.6 325.7

4. Engineering Contingencies 106.2 59.6 16.0 5. Subtotal 673.8 385.3

6. Import Duties a/ 36.0 c/ 36.0

7. Engineering and Administration 36.5 30.1 -

8. Subtotal 716.3 415.1 132.0

9. Land and Resettlement 59.o - -

10. Subtotal 805.3 415.4 132.0

11. Allowance for Inflation a/ 73.2 34.1 - 12. Subtotal 878.5 1±9.5 13. Financial Contingency a/ 60.2 32.3 _

11. Subtotal 938.7 181.8

15. Supervision 9.0 7.7 -

16. Subtotal 947.7 f/ 489.5 g 132.0 17. Less Receipts 132.0 -

18. TOTAL 815.7 h89.5

NOTES: a/ These items have been included in the cost estimates set out above to arrive at an estimate of the financial requirements. They are excluded from the figures in Table 21 because they are not pertinent to an economic evaluation. b/ Civil engineering work only for first four power units. c/ Based on figures prepared by Coopers & Lybrand for February 1965 report. d/ The cost of this item is given as US$L.0 million in Table 21 but is a bid item. It has therefore been reduced to US$3.3 million so that when contingencies are added back (20%) the total becomes US$4 million. e/ This figure has been reduced from US$9.0 million to US$7.5 million for the same reason as in d/ above. I/ Makes no provision for interest during construction. - 110 -

Requirements Outside IACA Range of Growth Rates

9.o6 It is of interest to look at some of the costs of programs which adopt growth rates either higher or lower than those believed possible or necessary by IACA. In these comparisons, costs and benefits of power are not taken into account.

9.07 Table 53 set forth in detail alternative project sequences with slow growth of surface water requirements. Table 61 presents a summary of the costs of these programs.

Table 61

Alternative Project Sequences with Slow Growth of Surface Water Requirements Low Tarbela 1975 Low Tarbela 1986 Low Tarbela 1995 Usable Storage (MAF) 40.3 28.1 25.3 Cost of Program a/ ($ millions) 471 277 203 Cost of Water - New Projects ($/acre-foot) 11.7 9.9 8.o a/ Present worth as of January 1, 1965, at 8 percent discount rate. Costs of Mangla, Chasma, Sehwan-Manchar and Chotiari excluded.

As indicated, the per acre-foot cost would be $11.70 with Low Tarbela and below $10.00 with the Swat Project.

9.08 Table 54 set forth in detail alternative project sequences with high growth rate of surface water requirements. Table 62 presents a summary of the costs of these programs.

Table 62

Alternative Project Sequences with High Growth Rate of Surface Water Requirements Tarbela/Kalabagh with Power Tarbela/Sluicing Kalabagh High Gariala Total useful water available (MAF) 100.9 95.9 Cost of Program a/ ($ millions) 848 838 Cost of Water ($/acre-foot) 8.4 8.7 a/ Present worth as of January 1, 1965, at 8 percent discount rate. Costs of Mangla, Chasma, Sehwan-Manchar and Chotiari excluded. - ll -

As indicated, the per acre-foot cost of these programs would be $8.4 and $8.7 respectively.

IACA Requirements

9.09 Table 63 sets forth some alternative project sequences which would meet IACA's projected surface water requirements at their upper limit growth rate. (It will be recalled that Table 55 presented the recommended program and an alternative which would meet IACA's lower limit requirements.)

Table 63

Alternative Project Sequences with IACA's Projected Surface Water Requirements (in-service water-years)

Tarbela/Kalabagh 1990 Tarbela/Skardu 1990

Mangla 1968 Mangla 1968 Chasma 1972 Chasma 1972 Raise Mangla 1972 Raise Mangla 1972 Tarbela 1975 Tarbela 1975 Sehwan- Sehwan- Manchar 1982 Manchar 1982 Chotiari 1990 Chotiari 1990 Kalabagh 1990 Skardu 1990 Swat 2002 Swat 2005 Low Gariala 2011 Low Gariala 2011 Total useful water storage (MAF) 73.9 75.1 Cost of Program a/ ($ millions) 630 644 Cost of useful water ($/acre-foot) 8.5 8.6

a/ Present worth as of January 1, 1965, at 8 pereent discount rate. Costs of Mangla, Chasma, Sehwan-Manchar and Chotiari excluded.

9.10 The cost of a program for meeting IACA's lower limit requirements with Raised Mangla in 1972, Kalabagh in 1979 and Tarbela in 1993 would run to $470 million (present worth as of January 1, 1965 at 8 percent discount rate and excluding costs of Mangla, Chasma, Sehwan-Manchar and Chotiari) or around $7.8 per acre-foot. - 112 -

X. FINDINGS AND CONCLUSIONS

10.01 This volume focuses attention on a water storage program to meet the surface water needs of West Pakistan as forecast by IACA. This estimate of water demand is based on a detailed analysis of the crop water requirements, irrigated cropping patterns and irrigation intensities of each of the Indus Basin's canal commands. It is assumed that the water could in some cases be supplied either by pumping from the subterranean aquifer or by delivering surface water through the canal system. The surface water requirements as derived are then traced back to the rim stations in order to establish storage requirements.

10.02 In their analysis IACA meet rabi watercourse requirements from three sources: the groundwater available from the tubewell fields, the natural river flows and finally the releases from storage reservoirs. This last item, therefore, as a residual demand is especially sensitive to change in the pattern of requirements. The size of the residual demand is, in turn, influenced by the fundamental IACA assumption regarding the integration of ground and surface water supplies, as well as the distribution of cropped acreage between the rabi and kharif seasons. In IACA's program West Pakistan's vast underground aquifer, whose volume is now estimated at 300 MAF of recoverable water, is assigned the role of both seasonal and over-year storage. Thus IACA, in their calculation of the demand for surface water storage, felt able to use "mean-year" river flows. In other words, they assumed that the aquifer would serve as a balancing reservoir to make up the shortfalls in years of less than normal snowmelt and rainfall. Other more cautious assumptions, such as providing surface storage to meet the demand in three years in four, or even one year in two, would increase the cost of providing surface water storage very considerably and are not felt justified. Yet, at the same time, the concept of meeting only the mean year demand tends to minimize the storage requirement.

10.03 IACA estimated that stored surface water needed to augment the water supply to the Indus Plains in West Pakistan during the low- flow seasons would grow from an initial requirement of about 4 MAF per year in 1970 to about 9.3 MAF in 1975, about 13.3 MAF in 1985 and about 21.5 MAF in 2000. The rate of growth cannot, of course, be forecast with complete accuracy. Thus a decision on reservoir timing will affect the aggregate stored water supply at any point of time. Nevertheless, IACA's estimates of storage requirements were considered sufficiently firm to serve as a framework within which Chas. T. Main, the dam site consultant, could prepare his program for development of surface storage.

10.04 Given, then, the IACA requirements for stored water; given the operational assumptions on which those requirements are based; Chas. T. Main looked for a program or a series of programs which could meet the needs which IACA projected. The direction his work took was inevitably governed by the hydrological factors affecting the Indus Basin. Analysis of those factors produced one inescapable conclusion: control of the Indus River itself would ultimately be essential to - 113 - control of the surface water supply. The Indus River carries 63 percent of the total surface water that is available to West Pakistan for development under the terms of the Indus Waters Treaty, 1960. And 72 percent of its flow occurs during the four-month period, June to September. Without storage, some large proportion of Indus water must inevitably run waste to the sea.

10.05 The series of canals, weirs and barrages in the Indus Basin comprises the largest single irrigation system in the world. A gross area of about 38 million acres is commanded, with about 25 million acres presently receiving irrigation water. Development has been a gradual process; since the early 1920's canal-head diversions have been increased from some 38 MAF delivered annually to the present level of around 79 MAF. Recently, the Indus Basin Project has introduced a quali- tative change in the nature of surface water development. The commissioning in 1967 of Mangla Dam on the Jhelum River completes the first major storage in West Pakistan. With the waters of the three eastern rivers reserved exclus:ively to India after the transition period in accordance with the Indus Waters Treaty, and with the surplus flows of the Jhelum largely preempted by Mangla, the logic of both past and present developments (referring particularly to the main stem barrages and the IBP link canals) would seem to dictate that the next step in the orderly exploitation of the water resources of West Pakistan must be storage on the Indus.

10.06 This logic was recognized in the Bank Group's terms of reference which required that as a first step toward a comprehensive study of the water and power resources of West Pakistan a separate report on the technical feasibility, the cost and benefit of the Tarbela Project should be prepared and given priority. And it was recognized in a very practical sense when, because of the favorable conclusions in February 1965 of the study of Tarbela in isolation, Tarbela became a feature of the development plan to be devised by the dam site consultant in the comprehensive study.

Chas. T. Main's Recommended Program

10.07 The Chas. T. Main recommended program (see Table 64) may be characterized in one sentence. It is designed to meet the anticipated needs of surface water storage with maximum economy and effectiveness. As far as the period up to 1975 is concerned, the Bank Group believes that Chas. T. Main's recommendations should have the status of an "action program." Since both Mangla and Chasma are "on-going" projects fixed in time, this is tantamount to saying that Tarbela must be built by 1975. Chas. T. Main has indicated that, if the estimated need for stored water on the Indus in 1975 is to be met, there is no alternative to Tarbela. For no other storage project of a similar magnitude, which would also transfer the irrigation development to the main stem of the Indus, is advanced enough in preparation and design to compete effectively with Tarbela by :1975. - 114 -

Table 64

Chas. T. Main's Recommended Storage Program

In-Service Initial Live Project Water Year Storage Volume (MAF)

Mangla a/ 1968 5.22 c/ Chasma a! 1972 0.51 Tarbela 1975 8.60 Sehwan-Manchar b/ 1982 1.80 Raised Mangla 1986 3.55 d/ Chotiari b/ 1990 0.90 Kalabagh (with power) 1992 6.4o Swat 2002 2.00 Low Gariala 2011 4.6o Skardu After 2020 8.00 a/ On-going projects. b/ Timing decided by irrigation planning. cl Volume recoverable through main outlet works and power plant, assuming cut through Mirpur saddle to release 0.28 MAF from Jari arm. d/ Raised to maximum height now contemplated.

Tarbela

10.08 Construction of the Tarbela Dam is the main element of the action program for the further development of gravity irrigation. The Tarbela Reservoir as proposed would initially contain 11.1 MAF of gross storage with a live storage of 9.3 MAF at a minimum drawdown level of 1300 feet. For purposes of irrigation planning commersurate with the needs of power development, IACA have adopted a drawdown level of 1332 feet, resulting in an initial live storage availability of 8.6 MAF. Because of the high silt content of the Indus water and the associated sediment deposition in the reservoir the live storage would decrease rapidly over time. It is estimated that the reservoir would silt up during a period of approximately 50 years after which time the regulating capacity of the reservoir would be about 1 MAF.

10.09 The Bank Group supports and reemphasizes the conclusions already drawn in its report of February 1965, that Tarbela is both technically feasible and the clear choice as the next storage project for construction in West Pakistan. Furthermore, the analyses presented stress the fact that an immediate start is necessary, if the demands for stored water and power in the mid-1970's are to be met.

10.10 The estimated costs of Tarbela have been reexamined and confirmed. The basic economic cost, excluding power facilities, is estimated to be $625 million, including $389 million in foreign exchange. The financial requirement for the project, including the first eight - 115 -

generating units and a liberal provision for contingencies, would be about $900 million, with a foreign exchange component- of about $555 million. Without the generating units, but with a powerhouse to accommodate four units, which would be a suitable minimum starting point, the financial requireiaents would be $815 million, with a foreign exchange component of $490 million.

10.11 The program described assumes the start of construction before the end of 1967, leading to partial filling of the reservoir towards the end of the flood season of 1974 for irrigation use in 1974/75 and the production of the first power in the early summer of 1975. Any delay would result in a loss of agricultural production and a serious shortage of power.

Benefits

10.12 The Bank Group also concluded in its report of February 1965, that the return from the Tarbela Project to the economy from agriculture and power would be about 12 percent. Sir Alexander Gibb & Partners have recalculated the return on the project at 13.3 percent, in the context of IACA's comprehensive study. They stress, however, that this figure assumes that a full supporting program of agricultural inputs is implemented, otherwise the increase in production will be less and the return on the project will be reduced.

10.13 The Bank Group carried out additional studies to ascertain the return from the Tarbela Project both as an integral part of West Pakistan's power system development as a whole and as an additional source of water fully integrated in the overall agricultural production process. Though this analysis seems to indicate a somewhat lower rate of return, around 9 percent, the Bank Group still has no hesitation in concluding that Tarbela is a sound investment for Pakistan.

10.14 The Bank Group undertook a further exercise to test the costs to the West Pakistan economy of a delay in the execution of the Tarbela Project. To carry out such an exercise the Bank Group evaluated a hypothetical water program which would provide sufficient alternative rabi supplies to compensate for a 10-year postponement of Tarbela. This program was formulated in such a way as to make it possible to assume that, without alteration in the overall size of the public tubewell and canal remodeling programs as proposed by IACA, but with a degree of overpumping and a modified surface storage development based on an earlier construction of the Sehwan-Manchar scheme and Raised Mangla, West Pakistan could attain the same gross value of agricultural output in the reference years 1975 and 1985 as was projected with completion of Tarbela by 1975. The alternative program was also designed to meet Stone & Webster's forecast of system-wide basic load together with IACA's revised forecast of pumping loads. The Bank's calculations showed that, at the current exchange rate, the cost of delaying the construction of Tarbela from 1975 to 1985 would be in the order of Rs. 491 million ($103 million) in present-worth terms, and about Rs. 226 million ($48 million) if an exchange rate more nearly reflecting the scarcity of foreign exchange is used. - 116 -

10.15 While the Bank Group thinks that such a hypothetical alternative storage and power program may be technically feasible, it also believes that the program formulated around the early completion of the Tarbela Project has a degree of security that cannot be matched by any alternative. The Tarbela Project has been extremely thoroughly investigated so that the decision to complete it implies a fair degree of certainty that the reservoir's contribution to power and to irrigation supplies will indeed become available as scheduled. In sum, the Bank Group believes that the above analysis provides a reasonable indication of the savings attributable to the completion of Tarbela in 1975 rather than in 1985, except that it does not make allowance for the additional value that should be attached to the greater degree of security that attaches to the program formulated around the completion of the Tarbela Project by 1975.

10.16 Summarizing Tarbela's benefits, in purely physical terms, the Bank Group has noted that the Tarbela Project will make a major contribution both to the projected incremental scarce rabi water supplies by regulating the natural river flows and to meeting the large power needs as projected. Of the total future increment in rabi water deliveries to the farmers, from both ground and surface sources, Tarbela will by 1985 contribute almost one quarter. Most of the 12,000 million kwh of electric energy which Tarbela would be capable of generating annually, would be absorbed relatively quickly into the system. In fact, in a situation where the present known gas reserves may soon be fully committed, Tarbela will provide a badly needed supplement to potential hydro and thermal power through 1985.

Post-Tarbela

10.17 As has been indicated, the Bank Group agrees that Tarbela should be constructed as soon as possible and that Chas. T. Main's recommendations up to 1975 should have the status of an "action program." The Bank Group also approves of the consultant's tentative recommendations for the post-1975 period and is satisfied that a program based thereon would meet by and large IACA's estimate of the future demand for stored water. However, it may transpire that water requirements grow faster than IACA envisaged. In such an event, then second-stage major storage would need to be completed earlier, say by the early or mid- 1980's. In this case a firm decision would be needed on a specific project by the early or mid-1970's.

10.18 For the post-Tarbela period Chas. T. Main has presented a variety of projects and a multiplicity of orders of development because of the many still existing uncertainties connected with lack of detailed knowledge of practically every scheme that was considered. One conclusion, houever, stands out, namely, that the most attractive project at this point for second-stage storage appears to be Kalabagh. If a firm decision has to be taken by the mid-1970's, considerably more data on this project must be obtained as quickly as possible. - 117 -

10.19 In the following paragraphs a summary is given of the main information available concerning the major storage works presented in this volume, and how they fit into the "recommended program." It must be repeated here that all projects after Tarbela, with the exception of Raised Mangla, are, in different degrees, at an early stage of investigation. Conditions different from those anticipated could result in lesser or greater costs. Thus the costs shown, although based on the best engineering judgment of the facts known at this time, can only be used for comparing very provisionally the relative attractiveness of projects and for evaluating in general terms the price of a long-range surface storage program.

Sehwan-Manchar

10.20 Following Tarbela, the development of storage volume at Sehwan Barrage and at Lake Manchar could fill some of the needs for surface water supply during the late 1970's or early 198 0's. The project, excluding development at Chotiari Lake, could result in total storage of up to 1.8 MAF at a cost between $177 and $221 million. Furthermore, since such a project might also reduce the cost of remodeling the upper end of the Nara and Rohri Canals, the net cost for storage might be relatively low. For these reasons, the Bank Group has included this project in the tentative storage program in 1982.

Raised Mangla

10.21 The Bank Group would agree with Chas. T. Main's scheduling in which Raised Mangla follows Sehwan-Manchar in 1986. All impounding structures presently under construction at Mangla are designed to permit raising the normal operating level of the reservoir from elevation 1202 to 1250 feet. This raising would add 3.5 MAF to the live storage capacity of the reservoir, and also increase the permissible operating head for power during certain times of the year. The most recent estimate of cost of increasing t'he capacity of the reservoir is about $217 million, of which $130 million is in foreign exchange. There are some uncertainties with regard to this project which require further investigation. In some years -the increased capacity would not fill completely because of the shortage of kharif flows in the Jhelum. Furthermore, in Volume IV, substantial doubt has been indicated with regard to the value of power from Raised Mangla before 1990.

Kalabagh

10.22 At the present; state of knowledge, as indicated above, Kalabagh appears to be the most attractive choice for development of major storage after Tarbela. In the Chas. T. Main program, Kalabagh (with power) would follow Sehwan-Manchar and Raised Mangla and be built by 1992. The project as envisaged would create a reservoir with a live storage capacity of 6.4 MAF and incorporate nine generating units with an installed capacity of 1,125 mw. Chas. T. Main - 18 -

estimated the most realistic cost for storage facilities at $540 million, of which $212 million would be in foreign exchange. The power facilties would cost about another $140 million.

10.23 Chas. T. Main studied a number of alternative solutions at Kalabagh which would greatly affect costs. The consultant's studies indicate that storage at Kalabagh would have a life of only between 25 and 30 years. However, he also believes that a sluicing structure is possible at the site; i.e., that the dam could be designed and operated in such a way as to pass a large proportion of the river's sediment load, thus substantially lengthening the reservoir's useful life. The cost for such a dam, if feasible, would vary from a low of $526 million to a high of $734 million. The Bank Group has expressed the opinion that insufficient facts are known at this time to justify a firm conclusion that a high, concrete buttress dam can be built at the Kalabagh site, with sluicing capabilities. Studies to establish a basis for firm judgement would take several years and the earliest completion date of the project would be 1979. Furthermore, even if sluicing is possible at Kalabagh, it seems probable that it would have only limited advantage during the life of Tarbela, since Tarbela would protect the project for many years from large sediment input. In addition, if Kalabagh is operated for sluicing there would be no power output during a number of months of each year. Since a non-sluicing Kalabagh could generate some 6,100 million kwh of energy during a mean year, and have a firm capability in the low water season of 350 mw, the loss would be substantial.

Swat

10.24 Chas. T. Main have proposed that a possible surface storage development could be constructed in the Swat River Valley (at Ambahar). Detailed studies have not yet been undertaken but preliminary investigations appear to show that storage could be accomplished by constructing a very high dam. Such a project, as outlined by Chas. T. Main on the basis of relatively few data and preliminary reports, would create a reservoir with a gross storage capacity of 2.8 MAF of which 2.0 MAF would be live, at a cost of $145 million. The Bank Group has emphasized the lack of data, pointing out, for example, that records of sediment in the Swat River are not even available. Nonetheless, for illustrative purposes, this project has been included in the recommended program for the end of the century.

Gariala

10.25 A project at Gariala on the Haro River has been recommended for the end of the century or later. This project could be constructed in two stages, the first stage having a live capacity of 4.6 MAF with the possibility of a second stage adding 3.4 MAF. The power potential would probably not be great. Cost of the first stage of the project is estimated by Chas. T. Main to be $596 million. The second stage would cost an additional $84 million. If the project were carried out at one time it would cost $651 million. Gariala would be filled each year by - 119 - the diversion of water from Tarbela after its reservoir had reached its highest level. A very large canal would be required to convey the water.

10.26 The Gariala Project appears to be the logical candidate for detailed study for ofi'stream storage from Tarbela which may be essential if its life is to be extended. The major drawback is its high cost. Subsurface geologic conditions for most of the length of Gariala Dam and its large feeder canal are completely unknown. After detailed data become available. a reexamination of the costs of the Gariala Project might show it to be prohibitively costly. Again for illustrative purposes, the project has been incorporated into the late years of the program.

Skardu

10.27 The most uncertain part of the program relates to the Upper Indus. Chas. T. Main believes that, in the Skardu Valley some 315 miles to the north of Tarbela, it might be possible to construct a large reservoir to regulate the entire flow in the upper reaches of the Indus River. The consultant estimated that in very rough terms it might cost between $427 million and $510 million for a 5.2 MAF reservoir and between $498 million and $588 million for an 8.0 MAF reservoir at that location. The area is presently difficult of access and considerable exploratory work would be necessary before any project could be designed. But the Bank Group believes that development of the Upper Indus Valley for both power and water storage may be worthy of serious consideration as part of the long-range plans of West Pakistan, although considerable general investigations will be necessary before it can even be determined whether detailed study is warranted.

Investigations

10.28 The Bank Group believes that the recommended program for surface storage is a satisfactory starting point. However, whatever sequence of projects ultimately is shown to be optimum, its development will be costly in both money and effort. It will take considerable time and will tax heavily the technical capabilities that may be available. The lack of knowledge of the feasibility and cost of possible projects makes early inauguration of an extensive program of investigations imperative. The program should be designed firstly to increase basic knowledge of the topography, hydrology and meteorology of the Indus River system, particularly in the upper reaches, and secondly to identify with assurance the next major dam site from among the several possibilities. Once the site is known a full investigation of that site and design of the project should be initiated. The most rapid projection of the future demand for stored water should be used as the basis for a program of investigations. Delays in the execution of a project can be expensive but if detailed investigation has not been completed delay may be inevitable. A wrong decision in the choice of a project can also be extremely costly and only organized - 120 -

and consistent investigations, begun now and continued over the years, can provide the basis for properly timed constructive decisions in the future.

Financial Requirements

10.29 Subject to all the reservations which were noted above, regarding the tentative nature of the projects, the Bank Group has prepared estimates of the cost of the recommended 20-year program, including allowances for inflation and financial contingencies. This is shown in detail in Table 57 and summarized below in Table 65. The total figure for the 20-year period 1965-85 of around $1.35 billion (with a foreign exchange component of around $750 million) excludes duties and taxes and interest during construction.

Table 65

Estimated Cost of Chas. T. Main's Recommended Program during Period 1965-85 (US$ million equivalent)

Amount Foreign Period Total Exchange

Third Plan 1965/66 - 1969/70 345.8 201.7 Fourth Plan 1970/71 - 1974/75 437.4 260.6 Fifth Plan 1975/76 - 1979/80 237.0 122.4 Sixth Plan 1980/81 - 1984/85 329.5 168.9

Total 1,349.7 753.6 APPENDIX

TERM1S OF REFERENCE AND GUIDELINES

FOR

DAM SITE CONSULTANT

APPENDIK INDUS SPECIAL STUDY Page 1

TERMS OF REFERENCE

STUDY OF DAM SITES

June 5, 1964

The Stage II assignment will be in two parts. The first, the Tarbela Investigation, will cover the technical feasibility and construction cost estimates of the Tarbela Project 1/ ; it will also give consideration to the first stage of development of side valley storage, and to other selected schemes linked to Tarbela. The second part, the Comprehensive Report, will cover selected projects which are feasible of execution during the period 1965-1975, and will take into consideration additional selected projects which would serve as a useful guide to the possible future development of surface water storage projects beyond 1975. A draft of a final report on the Tarbela Investigation is to be completed by November 15, 1964, and the comprehensive Report by December 31, 1965.

In addition to the preparation of the reports on technical feasibility and cost estimates, the assignment will include such other assistance as may be required by the Bank and its other consultants, in connection with the determination of the economic return of the various projects.

Tarbela Investigation

1. Scope of Assignment

The work to be performed by the dam site consultant will be limited to that which is necessary for the preparation of the required report for the Bank Study, and will include the following items of work:

(a) Review existing designs prepared for the Tarbela Project, discuss with WAPDA and its consulting engineer the current designs. Detailed computations shall be undertaken only to resolve questions of doubt arising from this review. Propose and evaluate any design changes considered appropriate, having particular regard to any results of model tests.

(b) Review, in consultation with the designers and others, existing cost estimates for the construction of the dam and its appurtenances, including spillway structures, outlet works and power plant up to, but not including, the main switchyard, as now proposed, and prepare his

1/ The Tarbela Project covers the dam and its appurtenances including spillway structures, outlet works and power plant up to, but not including, the main switchyard. APPENDIX Page 2

own cost estimates of construction. Compare results of the estimates and explain major differences. These estimates should be in sufficient detail to serve as a basis for investment decision. Reliable estimates of the annual operating costs of the project shall also be provided. Indicate separately the foreign currency component of both investment and operating costs.

(c) Review present designs and cost estimates for alternative heights of the dam, and prepare as necessary other preliminary designs and cost estimates for the purpose of developing a height versus cost relationship of the dam and reservoir, including staged development.

(d) In collaboration with the Bank's electric power consultants, review and if necessary modify, after consultation with the designers, the design and cost estimates of the spillway structures, outlet works and power plant up to, but not including, the main switchyard.

(e) Review and discuss such side valley storage sites which the Advisory Committee considers appropriate for extending the useful life of the Tarbela development and estimate their cost and value.

(f) Review and study: the siltation studies carried out to date, the probable pattern of silt deposition in the reservoir, the prospects of passing some of the silt through the reservoir, the probable nature of silt input into the proposed off-stream storage sites, facilities and methods for silt control.

(g) In particular, review and prepare as far as necessary the tailrace water levels in relation to the design of the spillway stilling basin, the outlet works stilling basin, and the power house tailrace. Also prepare as necessary the backwater curves for studying the flooding effects, if any, at the head of the reservoir, for various heights of the dam.

(h) Review and study the designs and cost estimates of such other storage projects on the Indus River as may be agreed upon by the Advisory Committee, to the extent necessary to compare their contribution to the power and irrigation system of West Pakistan as it is assumed to be in 1975, with the contribution that Tarbela could make.

(i) Prepare a report on the Tarbela Project, covering the items set out in (a) to (h) above, and perform such other work, in cooperation with the Bank and its other APPENDIX Page 3

consultants, as may be necessary to ascertain the economic feasibility of the Tarbela Project.

2. Data to be Furnished by Others

To enable the dam site consultant to complete the work on Tarbela as described above, within the time limits stated, the Bank or others will endeavor:

(a) By May 25, 1964, to provide access to all reports prepared to date on Tarbela, including all back-up data and computations such as, but not limited to, hydrologic computations, hydraulic computations, stability analyses of the dam, test reports of physical properties of earth and rock construction materials, of foundation rocks and of soils, permeability and settlement characteristics of the soils and rocks of the dam foundation and proposed embankment materials, and other similar information. In those instances where further detailed study is considered necessary, arrangements will be made for reproduc- tion of the data.

(b) By June 15, 1964, to make similar arrangements related to such other projects as may be selected by the Advisory Committee as indicated under 1(h) above.

(d) By August 1, 1964, to provide final inflow hydrographs, water release patterns, power release patterns, and design flood inflow hydrograph to be used for this study.

(e) By' August 1, 1964, to provide final silt flow data, including correlation with rates of water flow, particle size distribution compared with rates of water flow, and similar data for the purposes of making sedimentation studies, density current studies, and similar studies.

(f) To make available reports and results of all model tests on the proposed diversion arrangements and spillways at Tarbela. Preliminary model tests should be completed, and reports thereon be available by October 1, 1964.

(g) To keep the consultants advised of any major changes in design and drawings.

3. Schedule for Tarbela Investigations

The dam site consultant shall commence work on the Tarbela Investigation within 10 days of receipt of notice to proceed. A draft of a final report on the Tarbela Project shall be submitted by November 15, 1964, and a final report by December 31, 1964. APPENDIX Page 4

Comprehensive Report

1. Scope of Assignment

Under the guidance of the Advisory Committee, the dam site consultant will make a survey of the potential for surface water storage in West Pakistan, and in collaboration with the other consultants of the Bank, will assist in making proposals for a program for the orderly undertaking of those projects which are agreed between the Government of Pakistan and the Bank and are feasible of execution through 1975 and would form a basis for development beyond that date. This task shall cover the following:

(a) Review existing reports and back-up data now available, or which may be prepared by others prior to October 1965, on the following projects:

(1) Tarbela

Offstream Storage Scheme

Sanjwal-Akhori (alternative to Gariala) Dhok Pathan Diversion Canal from Tarbela Makhad Others

(2) Main Indus Sites

Kalabagh Attock Chasma Chilas Skardu Khapalu Others

(3) Swat-Kabul Scheme

(4) Chenab River Storage

(5) Jhelum Sites

Re-regulating Dam at Jhelum Panjar Power Site Lohargali on Kunhar Raised Mangla

(6) Lower Indus Plain Sites

Lake Manchar Lake Hamal Polder storage along the Lower Indus Storage in dunes area east of Nara Canal APPENDIX Page 5

(b) To the extent that existing investigations are inadequate, undertake, in agreement with the Bank, a limited amount of field investigations at specific project sites selected by the Advisory Committee.

(c) After review and study of the various projects which have been agreed between the Government of Pakistan and the Bank, assist the Bank in collaboration with the Bank's other consultants in preparation of a sound program for the systematic development of the water and power resources of West Pakistan as far as needed for the Bank's Report. The degree to which each project in the program will have to be studied will depend on the adequacy of the physical data that are available or can be obtained, and will be influenced by the project's position in the program. The degree of intensity of the studies will be determined by the Bank from time to time during the course of the work on the advice of the Advisory Committee and on the recommendation of the Bank's consultants.

(d) Work with the Bank and its other consultants, as requested, in preparing the Comprehensive Report.

2. Data to be Furnished by Others

To enable the dam site consultant to accomplish his portion of the work, the Bank or others will endeavor:

(a) By May 25, 1964, to provide copies of all existing reports and such back-up data as may reasonably be required.

(b) By July 1, 1964, to provide aerial mosaics and stereo pairs as necessary for dam and reservoir sites under consideration.

(c) To provide topographic maps of dam and reservoir sites selected by the Advisory Committee. These maps will be furnished progressively in a priority to be agreed with the Bank between July 1, 1964 and January 1, 1965.

(d) To provide inflow hydrology, including silt flow, pattern of releases of water for irrigation and power generation, including peaking power patterns to be used in the Bank Study, and the estimated changes in patterns with time. These data will be furnished as available progressively between August 1, 1964 and August 1, 1965.

(e) By May 15, 1965, to provide rate of growth of stored water requirements.

(f) By May 15, 1965, to provide rate of growth of power generation requirements. APPENDIX Page 6-

3. Schedule for Comprehensive Report

The dam site consultant shall commence work on the Compre- hensive Report within 10 days after receipt of the notice to proceed, but until the end of 1964 shall give priority to the work associated with the Tarbela Investigation. The final report shall be completed by December 31, 1965. APPENDIX Page 7

Study of the Water and Power Resources of West Pakistan

Guidelines For That Part Of The Comprehensive Study To Be Undertaken By The Dam Sites Consultant March 13, 1965

1. The dam site consultant shall undertake in 1965 the work outlined for the Comprehensive Study as defined by his original Terms of Reference. The work involved in this assignment shall be considered in two separate categories: (i) a detailed study of dam sites feasible of being constructed or started by 1975, and (ii) a survey and identification of potential water storage projects for development beyond 1975. Basic to the consultant's work shall be the understanding that additional field work to include geological investigations, surveys and photography, is precluded by limitations of time and money.

2. The following guidelines are established within the framework of the Terms of Reference and shall be taken as indicative of the priorities which will control, unless changed by the Bank Group upon recommendation of the Dam Sites Advisory Committee. A basic consideration to govern the selection or identification of sites shall be that Tarbela will be built according to a general timetable evolving from the Tarbela study. Specifically the work shall be undertaken as follows:

A. The studies of sedimentation in Tarbela Reservoir shall be updated and related to the needs for side valley storage.

B. Using new maps which will be available, studies shall be made of problems relating to the diversion of flow from Tarbela to reservoirs on the Haro and Soan Rivers and all related matters including conveyance channels and dams.

C. Previous studies relating to a dam at Kalabagh shall be reviewed and expanded in the light of considering its potential usefulness for prolonging Tarbela's effectiveness either by direct storage or by permitting pump storage to another reservoir in a side valley. These studies shall include the consideration of various types of structure, including both earth and buttress, and shall result in estimates of relative costs. Back- water effects and sedimentation probabilities shall be determined. APPENDIX Page

D. The effects of Mangla Dam and its reservoir shall be studied to determine the value of additional storage and the related cost of raising the structure. Studies relating to sediment inflow shall be brought up to date, employing data now available but not at the time earlier studies were made. Effects of debris dams shall be assessed in this connection. Studies shall be made of effects to be derived from a re-regulatory' reservoir downstream from Mangla, particularly with respect to its value in permitting generation of peaking power at i4angla.

E. Studies shall be discontinued of a dam at the Chasma site and reviews only will be made of potentials existing on the Upper or Lower Indus, except as otherwise indicated. However, the feasibility or otherwise of raising pond level of Chasma Barrage for temporary storage should be studied so that the available potential at that place is not lost.

As a result of the studies undertaken, a determination shall be made of the physical data requirements for definite project reports of the future and for subsequent design programs.

3. A primary purpose of the undertaking shall be to establish a broad program for comprehensive development of the water resources of West Pakistan with particular emphasis on the Indus Basin and to this end priorities shall be established to serve as a basis for future planning.

4. In conformance with these guidelines for the study of dam sites and the potentialities for developments associated therewith, the following assumptions and basic considerations shall serve as a basis for work by the dam site consultant

a. Scope of Assignment

Make a survey of the potential for surface water storage of the Indus Basin within West Pakistan. Make proposals for a program for the development of projects through 1975 and to form a basis for development beyond.

b. Basic Assumptions

Tarbela will be completed by 1973 or 1974. Low Mangla will be completed by 1967 or 1968. Groundwater pumping will be developed to the extent practicable for (i) drainage and (ii) water supply. Hydro power is needed for growth of the country, including power for pumping groundwater. No major surface water storage additional to that listed above will be needed (or in process of construction) before 1975. APPENDDI Page 9

c. Ultimate Potential of Streams

a. Indus at Attock 91.5 MAF average gross flow (i) Indus 69+ average gross flow (ii) Kabul-Swat 23+ average gross flow

b. Jhelum at Mangla 23+ average gross flow Chenab at Marala 26+ average gross flow

5. The following dam sites will be studied and included in the Comprehensive Report.

Indus River

(a) Tarbela and Side Valley Storage Appurtenent Thereto:

(i) Update the studies on Tarbela Reservoir sedimentation as it relates to sediment input to side valley storage. These include studies of the sedimentation processes in Siran Basin; physical means for minimizing sediment input to Siran Basin, such as future debris barriers in Tarbela Reservoir and upstream of Tarbela. Consider other possible means for extending the useful life of Tarbela Reservoir.

(ii) Update and expand studies for storage on the Haro and Soan Rivers by diversion from Tarbela, using new maps now available for the diversion canals and reservoirs.

(iii) Determine sizes of canals required to fill Gariala and Dhok Pathan Reservoirs as water use grows on the Indus Plains including the evaluation of final conditions as nearly as can be estimated at this time.

(b) Kalabagh

(i) Continue and expand studies on Kalabagh as a development immediately following Tarbela and also as following side valley developments, including studies of pumping to side valley storage.

(ii) Study earth dam designs and cost estimates as alternatives to the multiple arch buttress dam studied for the Tarbela Report.

(iii) Study further the backwater effects of the reservoir and sedimentation that may be expected. APPENDIX Page 10

Additional studies of dam sites on the Indus above Tarbela will be included in the Comprehensive Report to the extent that additional reports and data may become available for review. Findings in the Tarbela Report are adequate from which to place the Upper Indus sites in their proper relationship to other developments on Indus and shall be fully presented.

(d) Chasma

Consideration of the Chasma site for a large storage dam shall be dropped for the time being. However, the possibilities of creating a temporary storage in conjunction with Chasma Barrage should be studied.

(e) Lower Indus

The potential for sizable surface storage downstream from Chasma appears limited. Although a project appears possible of development by pumping water diverted from the Indus via Lake Manchar into a reservoir on Naing Nai, so far as determinable, no studies have been made for such a proposal. Limited studies will be undertaken to ascertain the problems and value of such a project as well as other projects for which data may be available.

Jhelum River

Mangla Dam

(i) Raising of Mangla Dam shall be studied to estimate the value of additional storage on the Jhelum. Studies will include estimates of construction costs.

(ii) Sediment studies on the Jhelum shall be updated, using additional more reliable data obtained since previous reports on the subject were prepared.

(iii) Studies of means for extending the useful life of Mangla Reservoir will be updated and extended to include all reasonable possibilities.

(iv) Re-regulating reservoirs have been proposed below Mangla. A check will be made as to the possibilities. APPENDIX Page 11

Kabul-Swat Basin

Various possibilities for storage in the Kabul-Swat Basin shall be reviewed as directed by the Bank Group upon the recommendation of the Dam Sites Advisory Committee.

Chenab River

Studies of the Chiniot storage site shall be reviewed.

6. Hydro Power Sites

Investigations to date indicate the probability that additional hydroelectric power beyond that now planned or in existence will not be required in the near future. Therefore, studies relating to sites solely for electric power development shall be limited to a review of schemes already investigated.

7. Program for Implementing Project Development

The studies will determine the status of data needed to bring projects to the definite plan stage, and the Comprehensive Report will include suggestions as to programs for developing the additional data required.

ANNEX 1

TARBE,A PROJECT

ANNEX 1

LIST OF FIGURES

1. Reservoir Map

2. Tarbela Dam Project: Plan and Sections

3. Tarbela Dam Project: Outlet Rating Curves

4. Estimated Average Sediment Transport of Indus River at Darband

5. Tarbela Reservoir: Expected Storage Depletion by Sedimentation

6. Estimated Effect of Sediment Flow-through on Tarbela Reservoir Depletion

7. Tarbela Dam Project: Tentative Construction Schedule Summary

8. Tarbela Dam: Estimated Contract Costs for Economic Analysis

9. Tarbela Dam Cost Estimate for Economic Analysis

ANNEX 1 Page 1

TARBELA

Introduction

The Tarbela Dam site (see Maps III.1 and III.4) was selected by WAPDA as a result of detailed studies of three potential sites in a 17-mile stretch of the river that commenced in 1955. Investigations and engineering planning have been carried out for WAPDA by Tippetts-Abbett-McCarthy- Stratton International Corp. (TAMS) of New York.

The project comprises essentially a major earth and rockfill dam of 159 million cubic yards rising 485 feet above ground level with a crest length of about 9,000 feet and an impervious blanket extending 5,000 feet upstream; two auxiliary earth and rockfill dams; two chute spillways; four outlet tunnels each 45 feet maximum diameter; and a power station with initially four generating units rated at 175 mw each and subsequent ex- tensions for eight more units giving a total installation of 2,100 mw rated capability. The reservoir will contain initially 11.1 MAF of gross storage, giving 9.3 MAF of live storage at a minimum level of 1300 feet and 8.6 MAF of live storage at a mninimum level of 1332 feet.

The major drawback of Tarbela is that the useful life of the reservoir will be rather short - on the order of 50 years - because of rapid sedimentation. Although sluicing might conceivably be possible, the shape of the reservoir and the type of dam are not conducive to this mode of operation and, in addition, the power potential would be severely affected. Because of the overall economic effects and technical problems involved Chas. T. Main concluded that sluicing would not be practicable.

Whatever its limitations, Tarbela is the only major storage project which has been investigated thoroughly, whose technical feasibility has been firmly established, and which can be completed by the middle 1970's at which time the mean-year demand for stored water is estimated by IACA to be approximately 5 MAF. Also, its location is favorable for diversion by gravity flow to side valley reservoirs in which sedimentation would take place very slowly. Thus as Tarbela became depleted, its value to power would increase and its storage for irrigation supplies could be replaced by side valley reservoirs and/or another dam on the Indus main stem at Kalabagh which would also benefit from Tarbela's trapping of sediment.

Site

The Tarbela Dam site is situated at the downstream end of the Indus River gorge and immediately above the junction between the main Indus valley and the Vale of Peshawar. It is 6 miles downstream of Tarbela Village and about 33 miles upstream of Attock. The Indus River at this point occupies a broad flood plain some 6,000 feet wide, above which the valley sides rise steeply.

On the basis of several investigations of the 17-mile stretch of the Indus between the villages of Bara and Kirpalian, TAMS concluded that ANNEX 1 Page 2 the Bara site (which is essentially the Tarbela site referred to above) would be the best site for a dam. The considerations involved were as follows:

(i) The Kirpalian site, 17 miles upstream of Tarbela, was judged to have a maximum practical gross storage potential of 4.3 MAF. An additional 1.3 M4AF of gross storage could be added by diverting water by gravity flow from the Kirpalian Reservoir, through a conveyance canal, to a reservoir formed by a dam to be constructed at Thapla on the Siran River. The estimated cost per acre-foot of usable storage at the Kirpalian site was found to be greater than the comparable storage at the Tarbela site. The cost of the conveyance system and the Thapla Dam would further increase the overall average cost of storage at Kirpalian in comparison to that at Tarbela.

(iii) The Bara site (Tarbela) proved the most promising of the three, primarily because of a geologically ancient steam bed at the left abutment of the proposed dam, which would facilitate the construction of a spillway.

Cost estimates in the TAMS' report revealed the following comparative cost per acre-foot of live storage capacity.

Table 1

Tarbela Alternatives: Comparative Cost per Acre-Foot of Live Storage Capacity

Percentage of Cost of Bara Site

Kirpalian Site 149 Kirpalian including Thapla Dam and conveyance structure 168 Kiara 111 Tarbela (Bara site) 100

All three sites would permit gravity diversion of Indus water to the side valley storage on the Haro and Soan Rivers.

Geology

In their report, The Tarbela Project, of November 1966, Sir Alexander Gibb & Partners have the following to say about the geology of the site. ANNEX 1 Page 3

The foundations of the various structures present a variety of conditions which call for a range of foundation treatments. Foundation materials vary from hard rock to completely decomposed rock and alluvial deposits.

The rocks of the dam site are predominantly low grade metamorphic and intrusive material, and, although thought to be from the same formation, the beds on the two sides of the river differ in some respects. Those on the right bank are more strongly metamorphosed than on the left bank, and differences are observed in rock types. On the right bank the principal rock types are schists, limestones, and basic intrusives with minor beds of quartzite and gypsum. On the left bank they are predominantly metamorphosed thinly bedded marly limestones and slatey mudstones. Considerable jointing and minor faulting has occurred. The geological structure is complicated, with folding in two directions together with local doming.

An important feature of this dam site is the presence of deep pervious.alluvial filling across the river flood plain. The depth to bed rock ranges generally from 200 to 400 feet. The maximum measured at one location is nearly 600 feet. The bedrock below the alluvium has a very irregular profile and is thought to contain an inactive fault along the right side of the valley. The alluvium is predominantly boulder-gravel with elongated stones set in a sand filling.

The dam site is in a zone with occasional seismic activity for which due allowance is made in the design of both the main embankment dam and its auxiliary structures.

Hydrology

Still quoting from the aforementioned Gibb report: No records are available for the dam site itself, but a river gauge was established in 1954 near Darband about 20 miles utrstream, and stage records have been taken since then with the exception of 1959. Discharge measurements have been made since 1960, and these suggest that the rating is stable. In order to extend the period of record of river inflow, which is too short to give reliable average values, comparisons have been made between the records at Darband and Attock, where the discharge has been recorded since 1868, over the concurrent period of record 1954-58 and 1960-64. As a result the following values of the Darband - Attock ratios were established by TAMS as shown in Table 2. ANNEX 1 Page 4

Table 2

Ratio of 10-Day Flows at Darband to 10-Day Flows at Attock

Period Ratio Period Ratio

January 1-10 .63 July 1-10 .74 11-20 .63 11-20 .74 21-31 .61 21-31 .76

February 1-10 .62 August 1-10 .80 11-20 .63 11-20 .80 21-28/29 .64 21-31 .80

March 1-10 .62 September 1-10 .80 11-20 .57 11-20 .77 21-31 .55 21-30 .76

April 1-10 .49 October 1-10 .75 11-20 .46 11-20 .76 21-30 .48 21-31 .74

May 1-10 .49 November 1-10 .75 11-20 .51 11-20 .73 21-31 .57 21-30 .69

June 1-10 .65 December 1-10 .68 11-20 .68 11-20 .67 21-30 .68 21-31 .65

Using these values and the record at Attock for 1922-1963, IACA computed the average monthly flows at Darband, adding the contribution of the Siran to obtain the mean flow at Tarbela as shown in Table 3. These figures have been the subject of discussion between IACA and TAMS, but appear to be reasonably representative of discharges that may be expected in the future. Many more years will be required to establish more accurate data.

Table 3

Derivation of Mean Indus Flow at Tarbela (MAF)

(1) (2) (3) Indus at Indus at Darband Siran Tarbela Month 1922-1963 1959-1964 (1) + (2)

January 1.07 .04 1.11 February 1.02 .04 1.06 March 1.42 .08 1.50 Table 3 continued on next page. ANNEX 1 Page 5

Table 3 (Cont' )

(1) (2) (3) Indus at Indus at Darband Siran Tarbela Month 1922-1963 1959-1964 (1) + (2)

April 2.02 .09 2.11 May 4.36 .07 4.43 June 10.22 .03 10.25 July 16.70 .10 16.80 August 15.85 .11 15.96 September 6.66 .09 6.75 October 2.71 .03 2.74 November 1.54 .03 1.57 December 1.24 .03 1.27

Totals 64.81 .74 65.55

IACA estimated that, umder condition of full development, the storable surplus on the Indus at Tarbela during the impounding months of June, July and August would be as fo].lows:

Table 4

Mean Year Storable Surplus at Full Development of Indus River at Tarbela (MAF)

Mean Flow Irrigation Storable Month at Tarbela Requirements Surplus

June 10.2 9.4 o.8 July 16.8 5.7 11.1 August 16.0 6.1 9.9

Totals 43.0 21.2 21.8

It can be seen from the above that the storable surplus under mean-year conditions is twice that required to fill a reservoir the size of Tarbela.

TAMS have made a thorough study of the design flood at Tarbela, which has been derived by adding the following components:

(1) Maximum flood due to snowmelt, estimated from a study of recorded flood hydrographs to be 600,000 cusecs.

(2) Maximum flood due to monsoon rainfall, estimated from synthetic unit hydrograph and probable maximum storm ANNEX 1 Page 6

studies to be 1,080,000 cusecs (subsequently slightly revised by TAMS to 1,173,000 cusecs).

(3) Maximum flood due to the breaking of a natural dam, estimated from the flood hydrograph of August 18, and 19, 1929 when a glacial dam on the Shyok was breached, to be 354,000 cusecs.

(1) and (2), together, produce a "maximum probable flood"' of 1,773,000 cusecs and (1), (2) and (3) together give a "maximum combined flood" of 2,127,000.

Although sediment sampling was undertaken at Darband in 1959, only those measurements made since 1961, when more suitable equipment was introduced, can be relied on. The seLiment rating curve derived from these measurements is shown in Figure 4, and abbreviated in the following table.

Table 5

Estimated Sediment Transport of Indus River at Darband (19 miles above Tarbela Dam)

Approximate % Approximate % of Time Flow of Total Sediment Equalled or Suspended Transported by Flows Flow Exceeded Sediment in Range Noted (cusecs) (thousand tons per day)

0 100 0 8 100,000 31 400 5 150,000 23 1,200 9 200,000 17 2,400 39 300,000 5 6,6oo 35 400,000 0.3 13,000 4 500,000 0.02 23,000 600,000 0.00 36,000

On the basis of this curve and the synthetic record of historic flows at Darband, the average annual suspended sediment load was estimated to be about 420 million tons. The bed load is difficult to determine, but site inspection and other factors led IACA to conclude that its contribution ANNEX 1 Page 7 is small when compared with the suspended load, and of the order of 5 percent of the total. Total annual sediment transport is thus approximately 440 million tons.

The progress of reservoir sedimentation at Tarbela should be carefully observed. The use of three independent but complementary methods to measure the amount of sediment deposited in the reservoir was recommended by Chas. T. Hain. First, the change in the reservoir storage-elevation curve should be determined annually from the relation between measured changes in reservoir elevation and the corresponding volumes of water in storage computed as the difference between measured reservoir inflow and outflow. Second, direct measurements of the volume and density of the sediment deposits in the reservoir should be made periodically. Third, the unit weights of sediment deposited in or scoured from the reservoir should be regularly computed as the difference between sediment inflow and sediment outflow. At least two new water and sediment discharge measuring stations, one above and one below the reservoir, are necessary for these measurements. The one upstream of the reservoir should be established immediately. The use of air photography for monitoring sedimentation should also be considered.

Status of Project

Between 1959 and 1965, more than $19.5 million were spent on intensive site investigations, preliminary works and design for the Tarbela Project. Subsurface investigations included 560 bore holes, totaling about 100,000 feet; more than 25,000 feet of tunnels and 4,184 feet of trenches, varying in depth from 10 to 80 feet. In addition, more than 1,000 test pits have been dug.

Further investigations continue. Drilling has been carried out in the alluvial foundation for the main embankment to obtain further information regarding its structure, composition, and permeability. Immediately after the main contract has been let, deep bores will be taken to confirm more accurately the depth of alluvium overlying bedrock. The foundations for the spillway flip buckets are being explored by means of tunnels and shafts. Exploratory tunnelling is continuing in the diversion tunnel area, particularly in the vicinity of the powerhouse foundations where a gypsiferous deposit may be a potential hazard to concrete structures.

Hydraulic model tests have been made and are continuing. Natural' and distorted scale models of the Indus River in the vicinity of the Tarbela Dam site, and of the spillways and outlet works stilling basins, have been built and are being tested at the Irrigation Research Station at Nandipur, West Pakistan. Model tests of the performance of the tunnels, both under diversion and normal operating conditions and during filling of the reservoir and tunnel closure, have been conducted at the Colorado State University Hydraulic Laboratory near Fort Collins, Colorado. Further tests will be necessary to verify certain aspects and their performance.

The consultants (TAMS) for the Water and Power Development Authority of West Pakistan have completed final designs and the tender documents for the ANNEX 1 Page 8 project have been issued. This work has been reviewed by the Bank's consultants, Sir Alexander Gibb & Partners.

Design

The plan and sections of the Tarbela project are shown in Figure 2 and the major characteristics are listed in Table 6 below.

Table 6

Tarbela Project Statistics Reservoir Retention level 1550 feet SPD Drawdown level Design 1300 feet SPD Assumed for reservoir operation 1332 feet SPD Storage volume: At elevation 1550 feet 11.1 MAF At elevation 1332 feet 2.5 MAF At elevation 1300 feet 1.8 MAF Length of reservoir 48 miles Maximum width of reservoir (excluding Siran arm) 3 miles Maximum depth 450 + feet

Main Dam

Type - Earth and rockfill with impervious cores; foundation seepage control by upstream impervious blanket and downstream relief wells Crest elevation 1565 feet SPD Crest length 9000 feet Maximum height 485 feet Side slopes Upstream 1 in 2.65 Downstream 1 in 2 Volume 159 million cubic yards

Auxiliary Dam No. 1

Type - Earth and rockfill founded on alluvium with sloping impervious core and blanket extending to bedrock Crest elevation 1565 feet SPD Crest length 2340 feet Maximum height 345 feet Side slopes Upstream 1 in 2.65 Downstream 1 in 2 Volume 18 million cubic yards

Table 6 continued on pages 9 and 10. ANNEX 1 Page 9

Table 6 (Cont'd)

Auxiliary Dam No. 2

Type - Earth over rockfill founded on rock with impervious core to bedrock

Crest elevation 1565 feet SPD Crest length 860 feet Maximum height 225 feet Volume 1.7 million cubic yards

Spillways

Type - Two gated channels forming service and auxiliary spillways will be excavated in the rock on the Left bank; they will be concrete lined from their crests to flip- buckets, the remaining length of the channels to the river being unlined.

Crest level 1492 feet SPD Gates Service spillway (7) 50 feet wide by 58 feet high Auxiliary spillway (9) 50 feet wide by 58 feet high Discharge capacity at elevation 1550 feet Service spillway 615,000 cusecs Auxiliary 795,000 cusecs

Design Flood

Maximum inflow 2,127,000 cusecs Maximum outflow At elevation 1550 feet 1,410,000 cusecs At elevation 1556.8 feet 1,670,000 cusecs Maximum flood of record (August 27-30, 19,29 at Attock) 875,000 cusecs

Outlet Works

Four concrete-lined tunnels, each 45 feet diameter up to gate structures

Emergency gates - two 13.5 feet by 45 feet fixedwheel gates in each tunnel plus two bulkhead gates of same size upstream of emergency gates

Tunnels 1, 2 and 3 steel-lined downstream of gate structure 43.5 feet diameter

Table 6 continued on next page. ANNEX 1 Page 10

Table 6 (ContI'd)

Outlet Works (Cont'd)

Tunnel 4, steel-lined downstream of gate structure, 36 feet diameter

Tunnel 4 controlled for irrigation releases by two 16 feet wide by 24 feet high radial gates at downstream end. Tunnel 3 will be similarly controlled until power units 9 to 12 are installed.

Intake sill level (final construction stage) Tunnels 1 and 2 1225 feet SPD Tunnels 3 and 4 1160 feet SPD

Estimated discharge capacity of Tunnel 4 At elevation 1300 feet 62,500 cusecs At elevation 1332 feet 66,500 cusecs

Estimated discharge capacity of each of three power tunnels (controlled by four turbine-bypass valve units) At elevation 1300 feet 15,200 cusecs At elevation 1332 feet 17,200 cusecs

Release capability full development one irrigation tunnel plus 12 turbine-bypass valve units At elevation 1300 feet 107,000 cusecs At elevation 1332 feet 118,000 cusecs At elevation 1492 feet 171,000 cusecs

Power Plant

Ultimate Installation - 12 turbine generator units, 4 each on Tunnels 1, 2 and 3

Turbines - Francis type, to be designed for best efficiency at 333 feet net head and to have guaranteed outputs at 376 feet net head of 241,000 hp and at 417 feet net head of 281,000 hp.

Generators - Rated 175 mw but capable of 15 percent continuous overload.

Maximum normal tailwater elevation 1115 feet Minimum tailwater elevation (1 unit) 1100 feet Maximum net head 437 feet Minimum net head 183 feet ANNEX 1 Page 11

Embankments

The main dan with a total volume of fill amounting to 159 million cubic yards will be the most massive of its kind in the world. Seepage through the foundation of the main dam will be controlled by an impervious earth blanket covering the valley floor under the dam and extending about 5,000 feet upstream and by a system of drainage wells in the alluvium at the dowmstream toe of the dam. Two saddle dams of similar design, but with impervious membranes extending to bedrock, close two gaps in the topography of the left bank. One of these dams is in itself a large structure with a maximum height of 345 feet and volume of 18 million cubic yards. The other is a relatively small structure 225 feet in height with a volume of 1.7 million cubic yards. Each of the three dams is designed as a zoned rockfill embankment with a blended core of silt and angular gravel set within the dam section. Suitably graded filter zones are provided on each side of the impervious core. The embankments are being designed so that materials from required excavation could be moved directly to embankment sections with a minimum of rehandling..

As mentioned before, the site is located in a region of seismic activity. In view of this condition, 5 feet of the 15 feet normal freeboard on the dams has been provided as insurance against abnormal earthquake- induced subsidence. In addition, the impervious core and the adjacent filter zones will be constructed from materials that will tend to be self- healing in the event differential settlement or subsidence is sufficiently severe to cause cracking. The materials composing the impervious core will be blended during construction as necessary to assure high shear resistance and impermeability.

During construction the river would be diverted through a channel excavated on the right bank with a capacity of 750,000 cusecs. For final diversion, the outlet tunnels would be used.

Spillways

Two gated spillway structures on the left bank would discharge excess floodwaters through concrete paved chutes into a common discharge channel to be excavated along the course of a natural channel (the Dal Darra). One, the service spillway, would be o'erated every year, the other, the auxiliary spillway, would be used only in the case of unusually high floods,. The spillway gate structures and chutes are to be founded on rock throughout. Flip buckets at the downstream ends of the spillway chutes are designed to throw the water into the air clear of the concrete structures. Energy of the water, which will leave the flip buckets at velocities as high as 130 feet per second, will be dissipated partly in the air and partly by turbulent interaction with the water in the pools that will be scoured in the discharge channels to depths of some 200 feet by the falling water. Present designs envisage that the flip buckets for the service and auxiliary spillways will be about 70 and 40 feet, respectively, above the bottom of the discharge channel. The discharge channel would be constructed with its bed at a level of 1160 feet, which is about 70 feet above the bed of the river. The approximate length of this channel from the intersection of the two spillways to the river is 1-1/2 miles. ANNEX 1 Page 12

The combined discharge capacity of the spillways is:

(i) 1,410,000 cusecs at normal retention level (ii) 1,490,000 cusecs with surcharge of 2.2 feet (iii) 1,670,000 cusecs with surcharge of 6.8 feet

Flood routing studies have shown that, after allowance for a flow of 132,000 cusecs through the tunnels, (ii) is sufficient to pass the 'maximum probable flood" of 1,773,000 cusecs and (iii) the "maximum combined flood' of 2,127,000 cusecs.

The great volume of water discharged at high velocities and falling on erodible materials will cause significant maintenance problems. Some damage to the concrete chutes from cavitation and abrasion will occur, and this will increase as the reservoir volume becomes depleted and the water flowing over the spillway becomes more sediment-laden. Also, the flip bucket foundations will be exposed to erosive action and will require corrective work at some point. Careful operation will be necessary to minimize damage due to erosion and frequent inspection will be advisable to detect conditions requiring repair in their early stages.

Outlet Works

The outlet works would consist of four tunnels each 45 feet in diameter upstream of the gate shafts and 43.5 feet diameter downstream except for tunnel 4 which is 36 feet diameter downstream. These tunnels would be used for diverting the flow of the river during the later phases of constructing the embankment. One of the four tunnels is to be used permanently as an irrigation outlet. The other three will, at various stages, each be connected to four generating units.

To minimize water hammer, to permit fast response to load variations and to assure uninterrupted irrigation releases in the face of changing power loads and emergency power shutdown, a bypass valve will be installed at each generating unit with its inlet ahead of each turbine. These valves will open as the turbine gates close to maintain preset discharge rates that are independent of turbine load. Each valve will have a discharge capacity of about 3,800 cusecs when the reservoir level is at elevation 1300 feet.

The four tunnels during diversion will be capable of discharging about 430,000 cusecs with the reservoir level at elevation 1345 feet (recent model tests indicate a slightly higher figure). This discharge will be reached during diversion if the construction design inflow flood (805,000 cusecs peak), which has an estimated probability of being equalled or exceeded once in one hundred years, occurs.

Until the conversion of tunnel 3 to power, the two irrigation release tunnels will have a combined minimum release capacity of 125,000 cusecs (recent model studies indicate this may in fact be 136,ooo cusecs), and the two power tunnels could provide an additional 30,000 cusecs, all at a drawdown level of 1300 feet. ANNEX 1 Page 13

The combined outlet capacity at Tarbela will reduce to about 107,000 cusecs at reservoir elevation 1300 feet and 118,000 cusecs at elevation 1332 feet at the time 12 generating units are installed and tunnel 4 is the only irrigation tunnel. Consequences of limited outlet capacity in later years are described subsequently.

Power Installation

The powerhouse will be located on the right bank of the river at the foot of the dam. Initially, it will be built to house 4 generating units rated at 175 mw each. The ultimate installation of 12 units will provide a total ratecL capacity of 2,100 mw. Each group of 4 units will be served by one penstock tunnel. The tentative in-service schedule for the generating units is given in Table 7 below.

Table 7

Schedule for Generating Units

Scheduled for Units Commercial Operation

1 and 2 June 1975 a/ 3 and 4 April 1976 a/ 5 and 6 1978 b/ 7 and 8 1979 b/ 9, 10, 11 and 12 1980 _/

a/ TAMS' construction schedule. b/ Bank Group's schedule to meet system load.

Operation

Since the sediment inflow to Tarbela Reservoir will be very high, Chas. T. Main carried out an analysis to ascertain whether it would be feasible to operate the reservoir in such a manner as to pass a major portion of the heavily silt-laden water of the monsoon flood through the reservoir, and to commence impounding only at the tail end of the flood season. It was estimated that about 60 percent of the annual silt inflow takes place during the months of June and July, as indicated in the following table. ANNEX 1 Page 14

Table 8

Mean-Year Sediment Transport of Indus River at Tarbela During Flood Season

Approximate Percentage of Mean Flow Ratio Tarbela Mean Flow Sediment Total Annual Period Attock to Attock Flow Tarbela Load Sediment Load a/ (thousand (thousand (million Per Cumu- cusecs) cusecs) tons per Period lative day)

June

1-10 226 o.65 147 1.1 3 3 11-20 276 o.68 187 2.0 6 9 21-30 301 o.68 205 2.7 8 17

July

1-10 340 0.74 251 4.o 12 29 11-20 365 0.74 270 5.0 15 44 21-31 369 0.76 280 5.5 16 60

August

1-10 368 o.8 294 6.o 18 78 11-20 324 o.8 259 4.7 14 92 21-31 260 0.8 208 2.8 8 100

Total Sediment Flow for Period 338 100 million tons a/ May and September sediment flow and bedload, accounting for 2, 5 and 5 percent respectively of average annual sediment transport are omitted for simplifying discussion. The mean-year flow does not adequately reflect peak flows which account for disproportionate amount of sediment transport, hence, in the peak flow months, the sediment transport above is understated. Average annual sediment transport is estimated to be 440 million tons.

Three schemes were studied, one based on the present design and two on modifications. The first involved sluicing at two tunnels, the second at three tunnels, and the third at all four tunnels.

It was concluded that, in any case, the broad valley at Tarbela, the earth and rockfill type of dam, and the great depth of alluvium underlying the dam would preclude the possibility of installing sufficient ANNEX 1 Page 15

outlets to provide a feasible method of operation. The four tunnels included in the present design are considered to be the maximum practical. Additional tunnels of similar size would cost upwards of $40 million per tunnel and this cost would be greater for each tunnel added due to the greater length involved by the topography.

Sluicing through the tunnels during the critical months of June and July under increased head would be hazardous because of the high resultant tunnel velocities, some of rhich are indicated in the following table:

Table 9

Tarbela: Velocity in Tunnels if all Four Used for Sediment Sluicing (mean-year conditions)

Mean Inflow Reservoir Velocity in Period at Tarbela Elevation Tunnels (cusecs) (feet SPD) (feet/second)

June 1-10 147,000 1185 23 11-20 188,000 1230 30 21-30 204,000 1245 32

July 1-10 252,000 1310 40 11-20 270 ,000 1335 43 21- 31 280,000 1350 44

The generally accepted design practice for large steel-lined conduits carrying substantial quantities of sediment is to limit velocities to something less than 20 feet/second to avoid excessive damage by abrasion. It is therefore considered that such a scheme, entailing velocities of more than twice this figure, would involve an unacceptable safety hazard. Also, operation of the reservoir in this manner would preclude its use for diversion into side valley storage and seriously reduce the potential of the project for power generation. For some two months in the year power output would be nil. The Bank Group concurs with the consultants that planned sediment sluicing at Tarbela is not practicable.

It is planned that Tarbela Reservoir will be drawn down to its lowest level each year about the middle of May and that the natural river flow will then be passed downstream until about the middle of June when flow in the Indus will begin to exceed irrigation requirements and impounding can begin. The need for irrigation releases is expected to increase so that in about the year 1990, it may be necessary to set the drawdown level above 1300 feet in order to be able to pass the inflow straight through the reservoir and meet downstream irrigation requirements. The minimum level to which the reservoir should be drat.m down at any particular time should be determined by consideration of power demands and sediment deposition as well as irrigation release requirements. ANNEX 1 Page 16

The irrigation release requirements during the filling period as estimated by IACA are shown in Table 10.

Table 10

Tarbela: Average Monthly Irrigation Release Requirements During Impounding Period (cusecs)

Ultimate 1985 Development (2000)

June 84,ooo 156,ooo July 24,000 92,000 August 39,000 99,000

The program developed by the power consultant for the integration of hydroelectric and thermal generating capacity into the grid system envisages that 12 generating units will be installed at Tarbela by 1985. The discharge capacity of the outlet structures when these units are installed would then be as follows:

Table 11

Tarbela: Discharge Capacity of Outlet Structures

Reservoir 1 Irrigation 12 Turbines Elevation Release Tunnel (3 Power Tunnels) Total (feet SPD) (cusecs) (cusecs) (cusecs)

1300 64,000 43,000 107,000 1332 69,000 49,000 118,000 1350 70,000 54,ooo 124,000 1400 78,000 65,000 143,000 1500 92,000 81,00o 173,000

This table shows that the required irrigation releases during June (84,000 cusecs) may be achieved in 1985 when operating at a minimum drawdown level of 1300 feet, whereas to achieve the desired June discharge at the ultimate stage of development (156,000 cusecs in year 2000) would require that the reservoir be maintained at about 1450 feet. It will be noted that there would be little difficulty in achieving the desired July and August discharges.

If the reservoir were drawn down to 1,300 feet, Chas. T. Main estimated that its useful storage capacity would decrease at the rate of 0.12 MAF per year for the first 15 years of its life and then 0.17 MAF per year until the permanent value of 1 MAF storage were reached in approximately 50 years. The table below shows the estimated useful storage capacity for various elevations at the three reference years of 1975, 1985 and 2000, and Figure 5 gives a more complete description of the expected siltation effects. ANNEX 1 Page 17

Table 12

Tarbela: Storage Capacity

Useful Storage Capacity above Year Level 1975 1985 2000

1300 9.3 7.9 5.6 1332 8.6 7.3 5.5 1350 8.2 6.9 5.4 14oo 6.7 6.1 5.0 1500 2.7 2.5 2.4

In the year 2000 Tarbela could not be emptied by the middle of May. Instead the reservoir would have to be maintained at some level above the minimum, in order to permit a reasonably adequate discharge through the outlet structure in the month of June. If that level were 1350 feet the loss to agriculture would only be 0.2 MAF, that is to say the difference between 5.6 MAF which might have been released and 5.4 MAF which will actually be released. This low figure results from the fact that by the year 2000 silting will have occurred in the lower levels of the reservoir. If, however, an even higher reservoir level is maintained, say 1400 feet, the loss to agriculture would be 0.6 MAF, whereas the gain to power would be to raise the minimum capability to around 1,300 mw.

The combination of these two factors, viz., the necessity of gradual increase in the minimum drawdown level and the rate of sedimentation, will have the effect of decreasing the annual water yield of the project at a faster rate than would be achieved by sedimentation alone.

Program for Construction

The Indus Basin Fund is at present financing the foreign exchange component ($13 million) of certain preliminary work to be undertaken in the period 1965-67, the total cost of which is estimated at $34.8 million equivalent. Costs incurred by WAPDA prior to this period, principally on initial site investigations, were approximately $19.5 million equivalent, of which $7.1 million involved foreign exchange.

Work in progress in June 1967 included the following:

(i) Construction of access road and railway to the project site.

(ii) Construction of an access bridge across the Indus downstream of the dam site.

(iii) Additional quarters and offices for WAPDA personnel. ANNEX 1 Page 18

(iv) Replacement of intake works for the right bank Pehur Canal, whose present intake will be blocked by construction of the dam.

(v) Additional tunneling and core drilling on the right bank.

The project is intended to start impounding water, with a restricted retention level, towards the end of the flood season of 1974, so that a limited amount of storage may be available for the release period 1974/75. Impounding to top water level (1550 feet) is scheduled for 1975, with full use of storage during the release period 1975/76.

The main dam across the Indus will be constructed in three major stages, dictated by the river diversion problems, particularly during flood seasons. Construction work must have reached a definite point of completion of one stage for the next stage to proceed without an intolerable risk of severe damage by floods. The period of construction envisaged to the start of impounding is seven years. To complete the project, including the installation of the first four generating units, will take a further 18 months.

Stage I:

A working area on the right bank of the river will be cofferdammed, inside which the diversion channel and buttress-type closure structure will be completed, and dam and blanket construction started. Excavated material will be stock-piled for future use. Cofferdams will be built around the power station and outlet tunnel stilling basins and work on the power station and tunnels commenced. Excavation for the spillways and drilling of relief wells at the toe of the main dam will start.

This stage is scheduled to take three years, leading up to diversion of the river into the diversion channel after the flood season of 1970. In view of the large amount of work involved this part of the program is particularly critical.

Stage II:

With the river diverted, cofferdams will be constructed across the river, inside which construction of the main dam and blanket can proceed. Work on the spillways and the right bank dam and power station will continue and the tunnels will be substantially completed.

This stage is also scheduled to take three years, and will be completed after the flood season of 1973, when river flows are diverted from the diversion channel into the right bank power and irrigation tunnels. Completion of the tunnels up to the state that they can be used for river diversion is the most critical factor during this stage. ANNEX 1 Page 19

Stage III:

Following the closing of the gates in the buttress-type closure structure the downstream end of the diversion channel will be cofferdammed, and the closure of the main dam across the channel commenced. To ensure its safety during the flood season of 1974, the schedule calls for the dam to be at least at elevation 1450 feet by that time. Rapid completion of the closure section is thus essential and is the most critical factor during this stage.

The substructure and superstructure for the first four units of the power station are scheduled for completion by July 1974. The first two generating units will be ready to run when penstock connections are completed and at the same time erection of the-third and fourth units will be well advanced. If the dams have reached safe elevations and the spillways are completed by August 1, 1974, the plan is to close the two power tunnels (Nos. 1 and 2) and store water on the receding flood flow. Immediately following closure of these tunnels, tunnel No. 1 will be connected to the four units of the power station, the first two units of which are scheduled to be ready for commercial operation by June 1975-.

Cost Estimates

The estimated cost of the Tarbela Project originally prepared by Chas. T. Main was based on information supplied by TAMS and prices existing in July 1964. WAPDA supplied the figure for land and relocation. The contract cost for this estimate is shown in Figure 8. Subsequently, the Bank Group revised the estimate for its Tarbela Report of February 1965, and these modifications are indicated in Figure 9. All costs are for purposes of economic analysis and exclude provision for inflation, financial contingencies, taxes, duties, levies and interest during construction.

The estimate given below is that of the Bank's Tarbela Report and includes the estimate for the provision and installation of the first eight generating units. Although minor changes may affect individual items, the Bank Group sees no reason to alter the total. ANNEX 1 Page 20

Table 13

Estimated Cost of the Tarbela Project a/ (US$ million equivalent)

Reservoir Works Total Foreign Exchange

Power Facilities (Units 1 to 8 inclusive)

Civil Engineering Works 55.1 35.7 Contingencies (20%) 11.0 7.1 Mechanical and Electrical Equip. 35.6 31.7 Contingencies (10%) 3.6 3.2 105.3 77.7 Engineering and Administration 8.4 7.0

Total units 1 to 8 113.7 84.7 Estimated total project cost including first 8 units 739.0 474.1 a! Excluding taxes, duties, levies and interest during construction. b/ Excluding costs incurred prior to January, 1965.

The project is physically capable of being constructed in more than one stage. In the first stage, the dam would impound water to a level of 1500 feet to provide an initial gross storage volume of 8.4 MAF. Live storage would be 6.6 MAF with a drawdown level of 1300 feet and 5.9 MAF with a drawdown level of 1332 feet. In the second stage, an additional 2.7 MAF would be provided to elevation 1550 feet by raising the dams and spillways, which could be accomplished with little serious interference with reservoir operation. The dams would be raised 50 feet by the addition of earth and rock to their crest and downstream faces. Spillways would be modified by raising the concrete crests, abutments, piers and bridges, and the radial control gates 50 feet.

TAMS have prepared detailed cost estimates for various possible heights of the dam. These estimates show that because of the large basic costs that would be incurred for such items as diversion of the river and construction of the spillway, and because of the necessity of making provisions for the later raising, the reduction in cost for a lower dam are comparatively small. ANWNEX 1 Page 21

By pro-rating TAMS' estimates on the basis of the $625 million figure, Chas. T. Main determined that two-stage development would provide an initial saving of $37 million over single-stage development but ultimately would cost $27 million more. Justification for two-stage development depends on the value of the extra 2.7 MAF available initially with single-stage development, the growth of demand for stored water, and the rate of interest assumed. If no value were assigned to the extra storage and the requirement for stored water were increasing at a rate such that the second stage would be needed seven years after completion of the first stage, two-stage development would be marginal assuming an 8 percent rate of interest. If the second stage were needed sooner, single- stage development wou].d be preferred. On the basis of this analysis in the Stage 1 report, Chas. T. Main concluded and the Bank concurred that Tarbela should be constructed in a single stage.

VOLUME III ANNEX 1 FIGURE 1

~- - - -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~ ~ ~ ~

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AREA AND CAPACITYr CURVES\'-. ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ SUD O TEWAERAN, OWR ESURE ( /~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~O ETPKSA

TARBELA DAM PROJECTN~A

I,V~~~~~~~~~~~~~~~~~~~~~~~'~~-- 1 RESERVOIRA MAP

T- ~-. 1. ~ ~ ~ I I N -~~~~~~~~~~~~~~~ '~~~~~~~~"''~~~~~~~~~~~~~ o \ I 0o,~~~~~~~~~~~~~~~~~~~A~ ~ ~ I. MARCH967 IBY-197

VOLUME III ANNEX I-FIGURE 2

TARBELA DAM PROJECT SO-ROEOR 0*00 PLAN & SECTIONS DE0U0RN.100* T R T N 00000 500*00

000100100OONOLOCHCAS T MAIN INCTERNATIONCAL- NC ;, .. :- A.'I_00: ii:__~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~A..E7=- 0 LATER0_ , 000

DIVERSION I POWER TUNNEL

. IG~~~~~~~~~~~~~~~~~~~~LLO OLr O GO e F , ,. M .,,~~~~~~E IRRIGATION RELEASE TUNNEL

PLAN

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AUXILIARY SPILLWAY

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- -- - … ;,.-TCL*OOO~~~~~~~~~~~~~~~~~~~~~~~_ E. - -

SECTION OF MAIN EMBANKMENT a IMPERVIOUS BLANKET

MARCH 1967 IBRD-1971

VOLUME III ANNEX 1-FIGURE 3

_ _T _- -___

4UI,I/TS - UUT /r VNr / 11/2 Itwr 1500-- -- - N LIt

*HYDROELECTRIC _ ___ TWITH < _ X BYPASS_ _ Z I _ _ _ _ _

I IRRIGATION z 21400-- SO 1

NOTE 4 HYDROELECTRIC > -UNITS ,EACH WITH

__ A BYPASS VALVE, PER TUNNEL

: STUDYIOFTTHE WATERANDPOWERRNNES OUUNCELs

1200-- -

50IIS 100 NOTE ENTRANCE DISCHARGE IN 1000 c f s I 1T APPROXIMATE RATING CURVES FOR TUNNELS

A550

1500

1450

-j 'J 1400

U)1350 ILl STUDY OF THE WATER AND POWER RESOURCES OF WEST PAKISTAN I-~l COMPREHENSIVE REPORT

1300 3 4 5 6 8 TARBELA DAM PROJECT DISCHARGE IN 1000 cfs OUTLET RATING CURVES

APPROXIMATE RATING CURVE. CHAS TMAIN INTERNATIONAL INC

FOR ONE HYDROELECTRIC UNIT 9A0AUGUr196 .URETFIGMS. TS U -3A

MARCH 1967 I BRD-1972

ESTIMATED AVERAGE SEDIMENT TRANSPORT STUDY OF THE WATERAD POWERRESOURCES OF WEST PAKISTAN OF INDUS RIVER AT DARBAND* COMPREHENSIVE REPORT 4,000-i- 11I

2,000 {- _

I,OOC 800

,60C0------

U-

4000

C') o 0

Z .

I 2k 3 4 6890 2 40 6 800 20 40 60 1,0 2,0 4,0 00000,0 0,0 4000

I 00~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ *Bsdo8h0er161a ofre ymaurmns16-94FomTMorwn 5Y0 0~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~F

MRH167 OBRD199

VOLUME III ANNEX 1-FIGURE 5

>9t

z 0 > 4

w 0cn

I-z w w 7 IBD17 o3 ______

I -1 w 0

4 6 w 0n I,-

4W W

IIE EPR 0- ~~~ ~ ~ ~ ~ ~ ~ ~ ~ ~~~~~~ ~CMRHN

0 ______1 _ 1__5 2 _ 2 3 4 4_5

TIME IN YEARS AFTER INITIAL RESERVOIR FILLING

*ELEVATION AT MAXIMUM PROPOSED DRAWDOWN

STUDY OF THE WATER AND POWER RESOURCES OF WEST PAKISTAN COMPREHENSIVE REPORT

TARBELA RESERVOIR EXPECTED STORAGE DEPLETION BY SEDIMENTATION

CMAS T MAIN INTERNATIONAL. INC BOS5T 0N MASSACIIUSETTS U S A

r~AUGUST I1966 MARCH 1967 IBRD-1974

- VOLUME III STUDY OF THE WATER AND POWER RESOURCES ANNEX 1-FIGURE 6 OF WEST PAKISTAN COMPREHENSIVE REPORT

ESTIMATED EFFECT OF SEDIMENT FLOW-THROUGH ON TARBELA RESERVOIR DEPLETION

GROS:STSRA6EI -E NO-Ej- r.1h /U4E/Cm

\10 - ______i______- rUNN4LS W , E OPEN \ \ ^| > ; t ~~~~~~~~~~~rHROUGHJV Y w 8

L V C-I AT OUR\1 NNELIS eX * ______U +>5 7 z _ 0

S~LWICINVU AT 7T REE UVNNEtS

SL ICING AT WO rvNNEL

0 5 w PR,PEcr AS PANNED a)

0 - - -7 -

0 50 100 150 YEARS AFTER FIRST RESERVOIR FILLING

MARCH 1967 IBRD-1975

VOLUME III ANNEX 1-FIGURE 7

REMARKS WORK ITEM 1967 1968 |16 |190 |1971 |1972 19T3 19,14 1975 1976

Tqdte C_'on E I_ syg. ondet- h o o ol-Idd of,--tTAotI shoe,,oIRIVE nooo IN A_eRALC I 1 ,-/A tn,RhLOWIN Oe R,o,N cin r

I 0_ 66_ f DIt ANtR,CAf C ZeEe oRSION

ii ol Ersonno5=,t ||ln bc cc_ bo= d= zo,= TuNA L~~~~~~~sos>/croccJ _t _

DA M PR by O EC o tes o f /v r TIRE. L J g T hrr2 e1 c fho je g rl stee /S ¢E o nhe 0 0,/free d , o f nlt6Fz rk sh o n Rn Th c d l v e rs so n c /os u re

u/O lo? n5 tD nE7 9100nod 1,010 b,ern 0J tecDhl atoeled

/7toooh the tonoeco dl the dwole hesn SARBEL OAMTHPWTROJDPEECRSTRE 3. YoE/scrbhdy4neo drOosto bTUD OFcotr OHEWESTE PANDISTRREOUCE TENTATIVE CONSTRUCTION SCHEDULE 250to th do REPORTSUMR tostooy.COMPREHENSIVE 1 2

MARCH~1967 ~~ ~ ~~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~~~SUMR MARCH1967 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~IBRD-1976

STUJCY OF THE WATER AND POWER RESOURCES VOLUME I II COF WEST PAKISTAN ANX1FGR CMPREHENSIVE REPORT ANX 1FGR TA R BE LA D AM Estimated Contract Costs for Economic Analysis (No Pakistan taxes, duties, etc., included)

C U ~~~~~ ~~~~~~P R ICE ~~~~~~~~~~~UNITITEM TOTAL TOTAL WO0R K I T EM UNIT QUANTITY $ uEQUIVALENT

ODNTRACTCOSTS DIVERSION &CARE OF WATER Steei Ceiiular Cofferdams L.S. 2,32'I.100 11,157,700 Cofferdams c.y. 720,000 .7638 1.01125 5119,900 750,578 1 Excavation, Common, Channel c.y. 10,165,000 .11695 .67417 11,773,077 6,658,326 Excavation, Rock, Channel c.y. 5,936,000 1.1135 2.33411 6,610,210 13.857,0541 Concrete, Diversion Structure c.y. 325,100 15.111 55.35 11,923,639 17.995.5841 Appurtenances, Diversion Structure L.S. 8,6611,000 11.2142.800 Cofferdams c.y. 1,020,000 .7637 1.01121 779,025 1,063.319 Excavation, Conmon, Channel (plug.) c.y. 2,4129.000 .14696 .67117 1,1110,560 1.638,846 2 Excavatioon.Rock, Channel (pliigi) c.y. 3311,000 1.01111 2.2708 338,806 758,1160 Excavation, Common River Alluvium c.y. 2,200,000 .7379 1.0060 1,623,336 2,213,3541 3 Borrow Area Spoil c.y. 3.1150.000 .10110 .1560 356,800 538.200 ____ SUBTOTAL 31,975,753 611,3711,221 115.499.7419 EMBANKMENT &BLANKET Abutment &Foundation Preparation Embankment L.S. 2,090,1100 10,692.2110 1 Contact & Foundation Preparation Blanket L.S. 213,200 751,1100 Pervious Zones c.y. 11,538,000 .0390 .1170 1119,982 1,3119,9116 & Impervious Zones c.y. 1,271,000 1.1818 1.113111 1,4176,658 1,8 19,30 Transition Zones c.y. 537,000 .4810 .6630 256,297 356,031 2 Drainage Blanket c.y. 1122,000 .0390 .1170 16,1158 119.3741 Impervious Blanket c.y. 5.565,000 1.08741 1.11339 6,051.611 7,979,7118 Abutment & Foundation Preparation Embankment L.S. 2,090,1100 10,692,2110 Contact A Foundation Preparation Blanket L.S. 1,309,100 11,616.300 Pervious Zones c.y. 611,395,000 .0952 .1918 6,133,484 12,351,352 Impervious Zones c.y. 8,722,000 .9517 1.3035 8,300,987 11,369,212 Transition Zones c.y. 1.798,000 .5131 .7223 922.6S1 1,298,6841 Drainage Blanket C.D. 1,1160,000 .0390 .1170 56,9110 170.820 Impervious Blanket c.y. 17,1171,000 .7358 1.0319 12,855,160 18,029,022 3 Eoundation & Preparation Embankment L.S. 1,135,560 5,717. 110 rervious Zones C.y. 18,685,000 .5326 .7600 9,952,348 111,200.0311 Impervious Zones C.y. 2,158,000 1.0050 1.3399 2,168,853 2,744.168 Trannition Zones c.y. 5110,000 .4810 .6630 259,7110 358.020 Impervious Blanket c.y. 692,000 1.2296 1.5013 850,930 1,038,9117 Abutment Preparation Embankmeont L.S. 325,000 1,731.600 4 Pervious Zones c.y. 17,982,000 .56112 .8088 10,1116,578 141,5113,577 Impervious Zones c.y. 2,2119,000 1.1511 1.11215 2,588.935 3,197,0641 Transition Zones c.y. 350,000 .4810 .6630 168,350 232.050 Waste c.y. 1,000,000 .11955 .7527 49,6 752.700 _ ___ SUBTOTAL 70,317.182 126.0115.015 96,797.227 AUXILIARY EM4BANKMENTS Excavation, Common & Rock c.y. 7,639,000 .5922 .9276 11.5211.227 7,086,058 Abutment & Foundation Preparation L.S. 1,287,000 8.009,300 Cut-off at Upstream End Impervious Blanket L.S. 89,700 1170.600 Pervious Zones c.y. 13,088,000 .11631 .7133 6.060,528 9.335.800 Impervioun Zones c.y. 2.305,000 1.1758 1.11189 2,592,678 3,128,7811 Transition Zones c.y. 599,000 .4810- .6630 288,119 397,137 Impervious Blanket c.y. 3,380,000 .9778 1.2335 3,305,105 11,169.262 Waste c.y. 2,1110.000 .11955 .7527 1,060,,98 1_610_778 SUBTOTAL 19.207,855 311,207,719 26.3911.350 SERVICE SPILLWAY (LEFT BAN,kI Excavation Common c.y. 38,933.000 .5717 .8016 22.258,298 31,207,801 Excavation Rock c.V. 12,803,000 1.0568 2.51105 13,529,883 32,525,782 Foundation Prepuration & Nibc. Items L.S. 41.1311,000 9.328.800 Concrete c.y. 659.700 12.112 51.38 8.190.175 33,892.7117 Crest Gates and Hoist L.S. 1.561.300 1,1119,200 _ ___ SUBTOTAL 119,673,656 108.1011.330 72,3811,650 AUXILIARY SPILLWAY (LEFr BANYK) Excavation, Common c.y. 1100,000 .7072 1.01165 282,880 1118,600 Excavation, Rock c.p. 1,970,000 1.1807 2.6773 2.325,900 5.2711.378 Foundation Preparation A Misc. Items L.S. 1,821,300 11,744,900 Concrete c.y. 441,500 12.61 51.18 6,071,715 211,6113,651 Crest Gates and Hoists L.S. 2.007,200 1.1178,100 _____ SUBTOTAL 12,508,995 36,563,629 20,190.4129 DlIVERSIONAND IRRIGATION TUNNILS AND PROVISIONS FOR FUTURE POWI.R Excavation, Open Cut. Inlet, Common c.y. 199,000 .7678 .91122 152,785 187,5111 Excavation, Open Cut, Inlet. Rock c.y. 6,171,000 1.29711 2.8761 8,006,090 17,748,5311 Excavation, Open Cut, Outlet, Common c.y. 1.255,000 .7661 .939S 961 .1112 1.179.0841 Excavation. Open Cut, Outlet, Rock c.y. 3,596,000 1.2995 2.8761 11,672.929 10,3412,5277 Excavation, Tunnels c.y. 822,000 12.110 211.75 10, 193.586 20,3113,570 Excavation, Shafts, Open Cut c.y. 116,000 .7995 .99117 36.777 115,758 Excavation, Shaft c.y. 162.000 18.59 37.09 3,011,580 6,008,1118 Concrete Tunnel Lining & Shafts c.y. 541112C0 15.71 56.28 8.1199.005 30,4157,112 Concrete in Intakes c.y. 337,000 21.23 711.91 7,1541,173 25,2113,322 Concrete in Outlets and Stilling Basins c.y. 826,200 11.79 484.16 9,7111,721 110,0110,957 Steel Liners lbs. 33,1108,000 .2795 .3602 9,337,536 12,030,220 Gates and Hoists L.S. 7,697,300 6, 185,1100 Grouting and Drainage L.S. 1,560,000 9,903,1100 Foundation Preparation & Misc. Items L.S. 111.836.200 26.283. 100 _____ SUBTOTAL 85,861. 127 205,998,916 129,138,210

CONTRACT COSTS ±1269,51111.568 575,293,830 390.1104,615

Ig Contract Costs inClude a markup of 30% to cover indirect CostS (see text).july 1904 costs. prices, wage rates and general conditions assumed to prevail for duration of job.

MARCH 1961 IBRD-1977

STUDY OF THE WATER AND POWER RESOURCES VOLUME !II OF WEST PAKISTAN ANNEX I-FIGURE 9 COMPREHENSIVE REPORT TARBELA UAM COST ESTIMATE FOR ECONOMIC ANALYSIS

FOREIGN TOTAL COST EXCHANGE $ EQUIVALENT $

1. PRE-CONTRACT COSTS 4,700,000 16,490,000

2. CONTRACT COSTS 269,545,000 390,404,615

3. PRE-CONTRACT PLUS CONTRACT COSTS 274,245,000 406,894.615 (MAIN - TARBELA REPORT)

DIRECT COSTS (210,957,700) (312,995,858) INDIRECT COSTS (30% OF DIRECT) (63,287,300) (93,898,757)

4. ADJUSTED PRE-CONTRACT PLUS CONTRACT COSTS (I3RD - TARBELA REPORT)

DIRECT COSTS (MAIN) 210,957,700 312,995.858

ADDITIONAL DIRECT COSTS EXCAVATION AND FILL 5,190,000 7.700,000 CONCRETE 1,550 000 2,300,000 6,740,000 10,000,000

ADJUSTED DIRECT COSTS 217.697,700 322,995,858

INDIRECT COSTS (MAIN) 63,287,300 93,898,757 ADDITIONAL INDIRECT COSrS 9,435,900 14,000,000

ADJUSTED INDIRECT COSTS (33.4% OF DIRECT) 72,723,200 107,898,757

DIRECT PLUS INDIRECT COSTS (ADJUSTED) 290.420,900 430,894,615

USE (430,900,000)

PRE-CONTRACT COSTS (AFTER MAY 1966) 4,700,000 16,500,000 CONTRACT COSTS 284,000,000 414.400,000

5. CONTINGENCIES (20% of 4.) 57.700,000 86,200,000

6. PRE-CONTRACT COSTS, CONlRACT 346,400,000 517,100,000 COSTS AND CONTINGENCIES

7. ENGINEERING AND ADMINISlRATION (7% of 6.) 30,000,000 36,200,000

8. INSURANCE & MISCELLANEOUS PLUS PERFORMANCE BOND (2.52% of 6.) 13,000,000

INSURANCE AND MISCELLANEOUS (9.000,000) (9,000.000) PERFORMANCE BOND (4,000,000) (4.000,000)

9. LAND AND RESETTLEMENT (WAPDA) -_59,000,000

10. TOTAL ( 6 + 7 + 8 9 )389,400,000 $ $625,300,000

USE $390,000,000 $625,000,000

Note: The total cost here excludes Pakistan taxes, duties, etc., estimated to be U.S. $106.9 million, equivalent, and Interest during construction estimated at 8%, to be $215.1 million, equivalent, wIth foreign excoange component of U.S.5138.6 million, equivalent. MARCH 1967 IBRD-1978

ANNEX 2

KALABAGH PROJECT

ANNEX 2

LIST OF FIGURES

1. Schematic Plan of the Kalabagh Dam Project: General Plan: Earth Dam with Buttress Spillway

2. Kalabagh Dam P'roject: Elevations and Sections: Earth Dam with Buttress Spillway

3. Kalabagh Reservoir: Estimated Loss of Live Storage Capacity due to Sedimentation

4. Estimated Construction Costs: Kalabagh Project: Earth Dam with Buttress Spillway

ANNEX 2 Page 1

KALABAGH

Introduction

Below its confluence with the Kabul at Attock, the Indus River flows through a series of gorges for a distance of nearly 100 miles to Kalabagh, whence the river transverses the broad flat plains sloping gradually to the sea. The dam site, located 12 miles upstream of the Jinnah Barrage, thus provides the furthest downstream location for a high dam on the Indus.

A dam on the Indus at Kalabagh was proposed by Tipton and Hill, Incorporated, in a report prepared in 1956 for the Government of Pakistan. Chas. T. Main utilize the same site but propose a different type of structure and consider Kalabagh in the context of a development plan for storage of surface water along the Indus River.

Chas. T. Main suggest an earth and rockfill dam in the main stream flanked by a concrete buttress sluiceway/spillway on the right bank (Figure 1). The dam would rise 285 feet above the river bed and would have a crest length of 6,900 feet while the sluiceway/spillway, 1,260 feet long, would have a height of 310 feet above its foundation. The reservoir would have a gross storage capacity of 8.0 MAF, virtually all of which would be live storage if the project were operated as a sluicing scheme and 6.4 MAF would be live storage if it were operated for power purposes. Three 40-foot diameter tunnels would provide diversion for rabi flows during construction and could be tapped to supply a total of nine generating units, each of 125 mw capacity. The cost of the structure is estimated to be about $540 million 1/ (see Figure 4) and approximately seven years would be required for its construction.

The major feature of the Kalabagh Dam is at once its primary attraction and foremost weakness. As conceived by Chas. T. Main, the project would best be operated as a sluicing scheme to prolong the useful storage life of the reservoir. Heavily silt-laden waters of the early flood season would be permitted to pass essentially unrestricted through the reservoir and some scouring of sediment deposited in the main river channel during the previous impounding period would occur. However, this mode of operation requires a concrete buttress structure which would involve heavy pressures on the foundation rock. In view of the fact that few data are available on the site and no detailed stress analyses have been carried out, the Bank Group does not feel that the technical feasibility of the project as proposed has been firmly established. Consequently, the cost estimate prepared for it must be treated with some caution.

Geology

The Indus Gorge, for most of the distance between Attock and Kalabagh, is composed of sandstones and shales of the Siwalik Series.

1/ See section on cost estimates. ANNEX 2 Page 2

Downstream on the dam site, faulting and distortion have occurred, but do not extend to the area of the site itself. The sandstones while variable in hardness are generally only slightly cemented and relatively friable and soft. The shales are mainly compacted. It was concluded by the firm Tipton and Hill in a report made in 1956 that the foundations were sufficiently strong to support an earth and rockfill dam. Designs considered by Chas. T. Main involve structures and foundation conditions quite unlike those considered by Tipton and Hill, although Chas. T. Main's proposed design assumes reasonablefoundation pressures. Nonetheless, it was Chas. T. Main's conclusion that bearing capacities and elastic properties of the rock must be investigated thoroughly before final design.

No difficulty is expected from deterioration or leakage since neither the sandstones nor the shales contain soluble constituents, the sandstones have a low permeability, and the shales are essentially impervious.

Hydrology

The flow of the Indus has been gauged at Attock since 1868. However, the records prior to 1922 are not considered as reliable as those for subsequent years, and thus the period 1922 to 1963 has been taken as a base. The mean annual flow for the period is about 93 MAF to which can be added 2-3 MAF for the contributions of the Soan, Haro and Kohat Toi Rivers between Attock and Kalabagh. The mean monthly flows at Attock are given in Table 1.

Table 1

Mean Monthly Flow of the Indus River at Attock (MAF)

Mean Flow Month 1868-1964 1922-1963

January 1.71 1.71 February 1.59 1.62 March 2.32 2.45 April 4.23 4.30 May 8.31 8.38 June 15.94 15.49 July 22.03 22.57 August 19.40 19.81 September 8.72 8.65 October 3.48 3.62 November 2.09 2.14 December 1.77 1.87

Total 91.60 92.61

In an average year, approximately 22 MAF will be available as storable surplus on the Indus under conditions of full development ANNEX 2 Page 3

as projected by IACA, although in years of low flows the surplus will be somewhat less. Therefore, there will in general be no problem of filling reservoirs of substantial size.

Design Flood

The design flood used for Kalabagh was that derived from the one for Tarbela by increasing the ordinates of the Tarbela hydrograph by 25 percent. The design flood for Tarbela is composed of the following elements:

1) Maximurm flood due to snowmelt, estimated from a study of recorded flood hydrographs to be 600,000 cusecs.

2) Maximum flood due to monsoon rainfall, estimated from synthetic unit hydrograph and probably maximum storm studies to be 1,080,000 cusecs (subsequently revised by Tippetts-Abbett-McCarthy-Stratton International Corp. (TAMS) to be 1,173,000 cusecs).

3) Maximum flood due to the breaking of a natural dam, estimated from the flood hydrograph of August 18 and 19, 1929 when a glacial dam on the Shyok was breached, to be 354,000 cusecs.

1) plus 2) provide the "probable maximum flood" of 1,773,000 cusecs and 1), 2), and 3) together give the "'maximum combined flood" of 2,127,000 cusecs. The maximum flood of record was 820,000 cusecs at Attock in 1929, but may have been as high as 1,206,000 cusecs according to Chas. T. Main.

The project was therefore designed to accommodate a flood having a peak discharge at Attock of 2,600,000 cusecs. It is unlikely that this flow would ever be reached because there would be considerable attenuation of the flood peak between Tarbela and Kalabagh and because the peak on the Kabul tends to occur a month earlier than that on the Indus. Most likely, the maximum combined flood at Kalabagh would not greatly exceed the figure of 2,127,000 cusecs assumed for Tarbela.

Backwater Effects

Considerable effort was spent by Chas. T. Main in studying backwater effects because of the possible danger of aggravating flood conditions at Nowshera on the Kabul (see Map III.4). The tentative conclusion is that very little additional flooding would result in areas already subject to darnaging floods and no new areas would be flooded.

Cross sections were obtained from 49 stations along the Indus and Kabul Rivers and staff gauges were established at 12 of the stations.

A computer program was prepared to calculate water surface elevations; the results were compared with rating curves obtained from WAPDA for Attock and INowshera. ANNEX 2 Page 4

Water surface profiles were computed from the dam site to Attock for Indus flows ranging from 500,000 to 1,000,000 cusecs. The water surface profiles from Attock to Nowshera were computed for Kabul flows amounting to 26 percent of the Indus flows. Comparison with the observed gauge heights revealed discrepancies in certain reaches, although elevations for low flows at Attock and Nowshera were in good agreement.

The results of the study, summarized in Table 2, indicated that the backwater effects of Kalabagh would be much less serious than previously feared. Chas. T. Main suggest that prior computations were based on flows estimated by extrapolating from the Attock rating curve and, consequently, overstated the adverse effects of Kalabagh.

Table 2

Computed Backwater from Kalabagh Dam

Elevation Water Indus River Frequency (surface feet) Kabul Flow at of Indus Attock Gauge Nowshera River Kalabagh Annual Natural with a/ Natural with a/ Flow (cusecs) Peak Years Conditions Kalabagh Conditions Kalabagh (cusecs)

500,000 2 905.2 928.0 938.9 939.5 1309000 600,000 8.5 910.0 929.3 940.8 941.4 156,000 700,000 27 914.3 930.7 942.6 943.4 182,000 800,000 80 918.4 932.4 944.3 945.2 208,000 900,000 200 922.4 936.1 945.9 b/ 947.2 234,000 1,000,000 500 926.2 939.1 947.4 b/ 948.9 260,000 a/ Reservoir at dam at maximum normal water surface elevation 925 feet for all flows up to 800,000 cusecs, at 928 feet for 900,000 cusecs, and at 930 feet for 1,000,000 cusecs; the latter two elevations being those necessary to discharge the flow over the spillway. b/ Obtained by extrapolation.

It can be seen from the above table that the water level at Nowshera would be only 1.5 feet higher with a dam at Kalabagh than under natural conditions, given an extreme flow of 1,000,000 cusecs at Kalabagh.

Since the flood peak on the Kabul normally occurs about a month earlier than that on the Indus, there is little danger that the two would combine to aggravate conditions at Kalabagh. Also, the operation of the project for sediment sluicing would have the reservoir at a low level during the early part of the flood season which would help to mitigate any backwater effects.

It was concluded that the primary causes of flooding at Nowshera are the constrictions of Attock Gorge and the Kabul River channel and that the proposed dam at Kalabagh would have only a minor effect. ANNEX 2 Page 5

Available Data

In preparation of their report proposing an earth and rockfill dam with an abutment overflow spillway, Tipton and Hill carried out limited subsurface investigations. These included 15 drill holes, 2 of them in the Indus River, varying from 150 to 300 feet in depth, and 55 test pits totaling 1,300 feet in depth.

Also prepared for the report were maps of the dam site area with a scale of1:2,400 and 10-foot contour intervals, aerial photography maps of the area along the Indus with a scale of 1:12,C00, and topographic maps with a scale of 1 inch to 1 mile of the area around the reservoir,

To the present time, no further exploration of the site has been made, although Chas. T. Main made a brief inspection, and WAPDA made various measurernents at several upstream points for the study of backwater effects.

Proposed Design

In the course of their study of possible designs, Chas. T. Main gave considerable attention to the problems of handling flood flows during construction. The need for diversion capacity during construction coupled with the irrigation release capacity required for reservoir operation led to the proposal to incorporate a number of ground sluices. This arrangement suggested the concept of providing still more sluices and operating the reservoir for sediment flow-through and sluicing.

Chas. T. Main made a study of four alternative configurations for the dam. The four all involve a sluiceway mechanism, but "Sluicing Scheme A" would have a sluiceway/spillway section in the main stream flanked by dikes, "Sluicing Scheme B" would have sluiceway structure in the main stream with an overflow spillway at the right abutment, "Buttress Sluiceway Dam with Mangla-type Spillway" would be identical to "B" but would, as its name suggests, substitute a Mangla-type spillway for the conventional and, finally, "Earth Dam with Buttress Spillway," as it is called for short, would involve an earth and rockfill dam in the main stream with a sluiceway/spillway structure at the right abutment. The comparative economic costs of the alternatives are presented in Table 3 below. ANNEX 2 Page 6

Table 3

Cost Estimates of Alternative Designs for Kalabagh Project a/ (Storage facilities only; US$ million equivalent)

Sluicing Scheme A:

Buttress sluiceway/spillway dam in main river with earth dikes 526

Sluicing Scheme B:

Buttress sluiceway dam in main river with abutment spillway 640 Earth dam in main river with buttress sluiceway/spillway dam in diversion channel. b/ 541 Buttress sluiceway dam in main river with Mangla-type spillway 734

a/ Excludes taxes, duties, levies, and interest during construction. Includes investigation, construction, engineering and administration, land acquisition and resettlement, and engineering contingency costs. July 1964 costs and wage rates assumed. b/ Recommended design.

The earth dam with buttress spillway is proposed as the first choice because its cost is only 3 percent higher than the least expensive alternative, Sluicing Scheme A, and it provides a 20 percent reduction in foundation pressures under the buttress structure (8 tons per square foot versus 10) and easier handling of the river during construction.

Design details of the project are shown in Figures 1 and 2, while the major characteristics are listed in Table 4 below.

Table 4

Kalabagh Project Statistics

Reservoir

Storage Elevation 925 feet Drawdown Elevation: for power generation 825 feet no power generation 700 feet Bed Elevation 670 feet Storage Volume at Flevation 925 8.o MAF Storage Volume at Elevation 825 1.6 MAF Storage Volume at Elevation 700 0 MAF Length 95 miles Average Width 2 miles

Table 4 continued on next page. Annex 2 Page 7

Table 4 (cont' d)

Dam

Type: Earth and Rockfill with Impervious Core Crest Elevation 955 feet Maximum Height above Ground Level 285 feet Normal River Elevation 700 feet Crest Length 6,900 feet Volume of Embankment 13 million cubic Foundation Seepage Control - Impervious yards Core Extending to Bedrock

Sluiceway/Spillway

A concrete overflow buttress structure with multiple arch upstream face, pierced by diversion and outlet sluiceways between buttresses, with concrete paved hydraulic- jump stilling basin at toe. Located in excavated diversion channel at right abutment.

Height above Foundation 310 feet Length of Structure 1,260 feet Volume of Concrete 2.7 million cubic yards Outlet Works

25 low-level sluiceways between buttresses each controlled by a 16-foot wide x 24-foot high sluice gate.

Discharge Capacity: 300,000 cusecs at Reservoir Elevation 725 feet 850,000 cusecs at Reservoir Elevation 925 feet

Spillway

Crest Elevation 887 feet Effective Overflow Crest Length 1,000 feet Gates: 25 (radial) - 40 feet wide by 38 feet high i)scharge Capacity: 800,000 cusecs at Reservoir Elevation 925 feet Design Flood, Maximum Inflow 2,600,000 cusecs Design Flood, Maximum Outflow (at Reservoir Elevation 943) 1,550,000 cusecs

Table 4 continued on next page. ANNEX 2 Page 8

Table 4 (cont' d)

Power Plant

Three 23-foot diameter steel penstocks connecting each tunnel to three generating units.

Nine generating units ultimate with three tunnels but additional tunnel(s) possible.

Turbines: Francis-type, rated 150,000 hp at 200 feet net head.

Generators: Rated 107,000 kw at unity power factor, but capable of 15 percent continuous overload.

A massive low concrete weir in the right diversion channel would form the base of the sluiceway/spillway structure and provide support for the buttresses.

The 25 spillway bays with h0- by 38-foot gates would give an effective overflow crest length of 1,000 feet and permit the design flood of 2,600,000 cusecs to be handled by the spillway with a discharge of 1,550,000 cusecs and a surcharge of 18 feet over the normal maximum operating level of 925 feet. Discharge from the spillway would be calmed by a stilling basin 375 feet in length and extending the full width of the spillway structure.

The sluiceway was designed with a large discharge capacity in order to allow sediment sluicing and to permit irrigation releases required at low reservoir level under conditions of full development as projected by IACA. Thus the sluiceway would discharge 300,000 cusecs with a reservoir elevation of 725 feet, only 25 feet above river level, and 850,000 cusecs at the normal maximum of 925 feet. The latter capacity is sufficient to pass the 100-year flood on the Indus of 820,000 cusecs.

An advantage of the scheme is that it permits the passing of flood flows between the buttresses, thus facilitating diversion during construction. Maintenance of the sluiceway gates would be accomplished in the dry behind bulkhead gates. Floating cofferdams or caissons would be needed to unwater sections of the spillway and stilling basin for repair.

The power plant would be located on the left bank of the river near the outlet ends of the diversion tunnels. Each generating unit would have a capability of approximately 125 mw, giving a total of 1,125 mw for the nine units. ANNEX 2 Page 9

Operation of the Project

In general, the reservoir will be filled during the summer flood season and gradually emptied by the end of May to provide irrigation supplies for the rabi growing season. Irrigation requirements in excess of the discharge of the power works would be released through the low level sluiceway. Since the sluiceway, with its discharge capability of 850,000 cusecs, would be able to handle floods having an expected frequency of occurrence of 1 year in 100, the overflow spillway would be needed only on rare occasions.

Two primary modes of operation of the project are possible:

1) as a sediment sluicing scheme, prolonging the useful life of the reservoir but sacrificing firm power for at least two months a year; or

2) as a multipurpose project, retaining a firm power capability of about 350 mw but rapidly losing storage capacity through sedimentation.

Because the Kalabagh site is furthest downstream of all major storage sites on the Indus deserving serious consideration, the timing of its construction with respect to upstream development would have an important bearing on its operation.

Sluicing Scheme

Table 5 shows the mean-year discharge of the Indus at Attock and the estimated sediment inflow at Kalabagh.

The long narrow shape of Kalabagh Reservoir and the fact that large discharges are expected to be needed for downstream irrigation at the onset of the flood flow season on the Indus would enable large amounts of sediment to be passed through and out of the reservoir.

Operated for maximum sluicing benefits, the reservoir would be drawn down to elevation 700 feet in May and, in years of mean flow, all the Indus water would be allowed to pass through the low level sluices essentially unrestricted until near the end of July. Impounding would be achieved in August. Thus, the sediment carried by the river in June and July (more than 60 percent of the annual total) would be passed through the reservoir without retention. ANNEX 2 Page 10

Table 5

Kalabagh Project Mean-Year Water and Sediment Discharge of Indus River

Period Mean Flows at Attock Sediment at Kalabagh (1,000 cusecs) (MAF) (million tons per day)

Jan. 28 1.7 Negligible Feb. 28 1.6 Negligible March 37 2.4 Negligible April 71 4.2 Negligible

May 1 - 10 104 2.1 0.3 11 - 20 132 2.6 0.5 21 - 31 167 3.6 1.1

June 1 - 10 226 4.5 2.4 11 - 20 276 5.5 3.9 21 - 30 301 6.0 4.7

July 1 - 10 340 6.7 6.6 11 - 20 365 7.2 7.6 21 - 31 369 8.0 7.8

Aug. 1 - 10 369 7.3 7.7 11 - 20 324 6.4 5.6 21 - 31 260 5.7 3.3

Sept. 1 - 10 193 3.8 1.5 11 - 20 144 2.8 0.7 21 - 30 103 2.0 0.3

Oct. 57 3.5 Negligible Nov. 35 2.1 Negligible Dec. 30 1.8 Negligible

Total 540 million tons or 0.292 MAF (at 85 lbs. per cubic foot)

The high flows passing through the empty reservoir would also remove some of the sediment previously deposited in the river channel. The initial useful storage capacity of the reservoir would be the entire gross capacity at 925 feet of 8.0 NAF. It is estimated that the reservoir would be depleted at an average of 0.027 MAF per year by sediment deposition beyond reach of the early flood season erosion. After the reservoir is reduced to 5.2 MAF, in approximately 100 years, little further depletion would occur (see Table 6 and Figure 3). ANNEX 2 Page 11

Table 6

Kalabagh Dam Project Estimated Depletion of Live Storage Capacity (MAF)

Years Live Storage Capacity After With Without Completion Sluicing Sluicing 0 8.0 6.h 1 8.0 6.2 2 7.9 6.1 3 7.9 5.9 4 7.9 5.8 5 7.9 5.6 6 7.8 5.5 7 7.8 5.3 8 7.8 5.2 9 7.8 5.0 10 7.7 4.9 12 7.7 4.6 15 7.6 3.8 18 7.5 3.3 21 7.4 2.7 25 7.3 2.1 33 7.1 1.0 51 6.6 1.0 100 (state of equilibrium) 5.2 1.0

If Kalabagh were constructed after Tarbela, it could be operated in the manner described above although the early flood flows would be reduced in quantities and in sediment content because of the screening effect of Tarbela. It is expected that the overall effect on the rate of depletion of the Kalabagh Reservoir would not be significant.

At full development of water utilization on the Indus, a greater constraint on unrestricted flow through of sediment-laden waters would exist. If, for example, both Tarbela and Gariala were in operation, impounding at Kalabagh would have to begin during the early part of July. Tarbela would act as a sediment trap for the first 50 years of its existence, but thereafter most of the Indus sediment load would once again make its appearance at Kalabagh. The net effect of this situation would be a somewhat higher rate of depletion than indicated above in the early stages, and a further increased rate after Tarbela were filled with sediment. Gradual reduction below the "permanent" 5.2 MAF figure would occur. ANNEX 2 Page 12

This mode of operation for Kalabagh would eliminate power generation for three to four months a year when the reservoir level would be some 90 feet below that required for turbine operation. It has been estimated that during the remainder of a mean water year the power plant proposed by Chas. T. Main might generate 4,300 million kwh.

Multipurpose Project

Kalabagh, operated as a multipurpose project, would have a minimum reservoir level of 825 feet which would provide an initial live storage capacity of 6.4 MAF. Little opportunity for sluicing sediment would exist until the dead storage space below 825 feet were filled with sediment, however, and the rate of depletion of live storage capacity is estimated to be as follows: 0.15 MAF per year to 4.8 MAF live storage, then 0.21 MAF per year until the ultimate capacity of 1.0 MAF is reached (see Table 6 and Figure 3).

If the project were completed after Tarbela, Tarbela would trap much of the silt during its useful storage life, and the depletion schedule of Kalabagh in this case is estimated to be 0.027 MAF per year until Tarbela is reduced to 1.0 MAF, 0.15 MAF per year to 4.8 MAF, then 0.21 NAF per year to 1.0 MAF (see Figure 3).

A preliminary analysis indicates that the power capability of the project during a critical water year and its energy potential during a mean water year would be about as shown in Table 7, the figures of which are based on gradual impoundment during the months of June and July', with final filling late in August. This is contrary to operational procedures resulting in optimum power benefits, which would require that the reservoir be filled as rapidly as possible in the monsoon period and, once full, be maintained at that level throughout the remainder of the flood season. Such a regime, however, would threaten valuable lands in the upper reaches of the reservoir, should flooding occur in August with the reservoir already full.

Table 7

Kalabagh: Power Potential if Operated as Multipurpose Project

Initial After After Operation 5 Years 20 Years

Units Installed (number) 9 9 9 Maximum Capability for Peaking (mw) 1,125 1,125 1,125 Minimum Capability (mTw) 350 350 720 Annual Energy, Generation (kwh millions) 6,000 6,100 6, 400 Useful Storage Capacity (MAF) 6.4 5.4 2.4 ANNEX 2 Page 13

Construction Program

The construction program of approximately seven years outlined below is representative only, since several schemes would have to be studied in detail before the final design is chosen.

Excavation for the right bank diversion channel and the left bank diversion tunnels would be started simultaneously, most likely at the beginning of the first dry season.

Construction of the buttress structure would begin as soon as the foundation could be prepared. The weir and stilling basin, and the portions of the sidewalls and buttresses below flood level would be completed before any diversion around the right bank was begun, but the arches below flood level and the sluiceways would be omitted at first.

Work would proceed on the diversion tunnels and control structures which should be completed by the end of the fourth flood season. They would then be opened, and, with their 100, 000-cusec capacity, should be sufficient to accommodate the entire dry season flows, permitting work on the buttress section to be carried out in the dry.

Cofferdams would be constructed across the river to enclose the dam foundation area, the dam site unwatered, and the dam foundation prepared. Placing of the embankment would then be started and brought up to a height sufficient to prevent overtopping before the onset of the ensuing flood season, the fifth.

At this stage, flood flows would be passed through the diversion channel and tunnels, but the tunnels would continue to be utilized to pass the dry season flows in order to facilitate work on the buttress section.

The sluicegates and arches would be completed by the beginning of the sixth flood season, and the dam would reach completion by the start of the seventh flood season. At this time, the tunnel intakes would be closed, and the river flows passed through the sluiceways and/ or stored in the reservoir.

If it were decided to make an initial power installation, the downstream ends of the tunnels would be plugged, and each of the tunnels would be connected by means of the steel penstocks to three turbines. All three penstocks would be completed to the main supply tunnel before the first turbine unit of the group were placed in service. Butterfly valves at the downstream ends of the penstock connections would permit the installation of future units without unwatering the tunnels.

The first three generators could be ready for commercial operation some time during the dry season following the sixth flood season. ANNEX 2 Page 14

Cost Estimates

The cost estimates prepared by Chas. T. Main and shown in Figure 4 are for storage facilities only and do not include provision for inflation, financial contingencies, taxes, duties, levies, or interest during construction. The total cost is estimated at $540 million of which $212 million would be in foreign exchange. The power plant of nine generating units having a total capacity of 1,125 mw is estimated to cost about $140 million.

However, in view of the gross uncertainties involved, the lack of information leading to serious questions as to the technical feasibility of the project as proposed, the Bank Group feels that a cost range of $540 million to $700 million should be adopted as a clearer indication of the possible total cost. If it should develop, for example, that a dam with a high level spillway were the only' structure feasible, the costs would rise greatly.

Construction Costs

Costs shown are rough estimates at best because of the meager information available. Subsurface conditions, in particular, are almost completely unknown. A few samples of the foundation rock have been taken, and it has not been tested. Depth of the alluvium was estimated on the basis of limited borings. No sources of construction materials were specifically identified.

Cost of materials and labor as existed in West Pakistan in July 1964 were assumed.

A 30 percent contingency on construction costs was added to cover changes brought about by unforeseen conditions. This figure compares with the 20 percent contingency allowed for Tarbela.

Comprehensive field investigations and design studies are necessary before more reliable cost estimates of the project can be made.

Land and Relocation

Estimated costs were furnished by WAPDA 1/ for all land and the relocation of all residents and facilities lying below elevation 930 feet. Particularly important, and costly, are lands along the Kabul in the vicinity of Nowshera which might be inundated by the project. Since the reservoir most likely would not be filled until late in the flood season, and since flood flows in the Kabul are generally over in June, it is expected that backwater effects from the reservoir would be relatively small. In this case, flooding of land

1/ Cable from WAPDA to IBRD-, February 2, 1966. ANNEX 2 Page 15 along the Kabul would be substantially the same with or without the project. More detailed studies would be required to give a definitive answer to the problem, however, and the estimate as shown is considered the best that can be made at this point.

Additional Investigations Required

As indicated previously, information now available is so slight that the Bank Group feels that the technical feasibility of a high, concrete buttress structure at the Kalabagh site has not been indubitably established.

Extensive investigations of the foundation rock are required involving test pits, borings, and tunnels for visual inspection of the foundation structure. The physical properties of the foundation rock must be tested. Determination must be made of the depth and nature of the overburden in the channel. Sources of materials must be identified, and their physical properties and quantities ascertained.

The problem of sediment transport through the proposed reservoir must be thoroughly analyzed. Detailed, large-scale maps and systematic measurements of the sediment load of the river at various points along the reservoir will be needed. In particular, if Tarbela is constructed prior to Kalabagh, the effect of the former on the sediment load at Kalabagh needs to be determined in order to predict the behavior of sediment movement through the reservoir.

Detailed studies are necessary to develop river discharge forecasting procedures. Data on rainfall, snow pack, temperature, and other hydrometeorological characteristics must be assembled and analyzed.

Backwater effects must also be studied intensively because of the importance of lands in the Peshawar Vale which might be flooded and the land acquisition problem. Additional cross-sections of the river should be measured at strategic points. Establishment of staff gauges and observation of stage levels on a systematic basis at the existing, as well as the newly established stations are needed. More detailed mapping of the reservoir area is required. After the backwater effect has been more clearly defined, a policy should be adopted for land taking in the areas likely to be affected on infrequent occasions by flooding from Kalabagh Reservoir. One method would be for the Government to acquire the land and lease it back to the owner for farming.

The necessity for beginning investigations at an early date must be stressed. Most likely, four years will be required for explorations and analyses to be performed, a feasibility study carried out, and detailed design for the project prepared. Thus Kalabagh could not be ready to store water until the 1979 flood season. If the demand for stored water greatly exceeds IACA's projections, Kalabagh or its equivalent may be needed shortly thereafter, even with Tarbela in the system.

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CHAS T MAIN INTERNATIONAL INC

JUNE 1967 IBRD-198OR

VOLUME III ANNEX 2-FIGURE 3 STUDY OF THE WATER AND POWER RESOURCES OF WEST PAKISTAN COMPREHENSIVE REPORT KALABAGH RESERVOIR ESTIMATED LOSS OF LIVE STORAGE CAPACITY DUE TO SEDIMENTATION 8

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0 20 40 60 80 100 120 NUMBER OF YEARS RESERVOIR FILLED

PROJECT COMPLETED NO OTHER MAJOR 10 YEARS AFTER TARBELA INDUS STORAGE PROJECT

MARCH1967 IBRD-1981

STUDYOF THE WATERAND POWERRESOURCES VOLUME III OF WEST PAKISTAN COMPREHENSIVE REPORT ANNEX 2-FIGURE 4 ESTIMATED CONSTRUCTION COSTS KAILABAGH PROJECT EARTH DAM WITH BUTTRESS SPILLWAY TEN UNIT "LIANTITY UNIT ~~~~~ ~ ~~~~TOALTOT ~~~~~TOTAL TEI UI QUNTY PRICE PRUICERs Coat COSTRe COS~IT

DIVERSION & CARE OF THE RIVER

Cofferdams

DumpedRock Fill c.y. 2,300,000 0.80 2.35 1,8110,000 5,1105,000 2,976,000 ImperviousEarth Blanket c.y. 86,000 1.115 2.50 125,000 215,000 170,000 Unwatering,Pumping, Care of Watsir L.S. - - - 185,000 1113,000 215,O00 Cofferdam Removal& Disposal c.y. 1,000,000 0.75 2.10 750.000 2,100.000 1.191,000 Subtotal - Cofferdams 2,900,000 7,863,000 41,552,000

Intake & Tailrace

ChannelExcavation -Rock c.y. 5,000,000 1.25 2.85 6,250,000 111,250,000 9,2111,000 Talirace Excavation -Rock c.y. 5,300,000 1.25 2.85 6,625,000 15I05,OS,00 9,798,000 Concrete In Intake Stracture c.y. 100,000 35.00 100.00 3,500,000 10,000,000 5,600,000 Intake Gantry Crane '100T. Cap. L.S. - - - 222,000 160,000 256,000 IntakeGates - FixedWheel - 6 Reqd. lb. '4,200,000 0.55 0.110 2,310,000 1,680,000 2,663,0010 StopLogs (steel)_ lb. 500,000 0.25 0.25 125,0010 125,000 151,000 TrashRacks lb. 500,000 0.35 0.25 175,000 125,000 201,000 IntakeRoadtway &Bridge L.S. - - - 19,0 1.114111OOD 195,000 Subtotal - Intake & Tailrace 19,399,000 112,889,000 28,1108,000 Diversion Channel & Tunnels

ChannelExcavation - Rock c.y. 7,000,000 1.25 2.85 8,750,000 19,950,000 12,9411,000 TunnelExcavation - Rock c.y. 330,000 13.00 26.00 11,290,000 8,580,000 6,093,000 Concrete TunnelLining c.y.. 81,000 21.00 65.00 1,701,000 5,265,000 2,807,0010 Steel Tunnel Sets & Lagging l b. 12.700,000 0.25 0.110 3,175,000 5,080,000 41,2412,000 Tunnel Roof Bolts lb. 390,000 0.80 2.55 312,000 995,000 521,000 WoodBlocking C.f, 35,000 2.00 11.65 70,000 163,000 1041,000 Dry StonePacking - Allow - - 15.000 200,000 57.000 Subtotal - Diversion Channel 18,313,000 110,233,000 26,765,000 & Tunnels

SUB8TO TAL - DI VE RS ION &C AR E OF RI VER $410,612,000 Res110,986,000 $59,726,000 ROLLED FILL EN4BANKIVID!T Excavation for Cutoff Trench c.y. 160,000 0.60 0.90 96,000 1111,000 126,000 Rolled Sandstone Fill c.y. 10,4100,000 1.10 1.75 11.1110,000 18,20D,0OD 15,2611,000 Impervious Clay Core c.y. 1,700,000 1.35 2.25 2,295,000 3,825,000 3,099,000 FineFilter c.y. 1120,000 2.00 3.00 8110,000 1,260,000 1,105,000 CoaraeFilter c.y. 1175,000, 1.30 2.20 618,000 1,0115,000 838,000 Riprap c.y. 300,000 0.80 2.35 2110,000 705,000 388,000 RoadwayAlong Embankment Mi. I - - 111,000 178,000 81,000 Saddle Dams& Reservoir Rim Treatment (NoData Availabl eFor Inclusionof Cost)_____ Subtotal - Rolled Fill Embankment 15,573,000 25,355.000 20.901.000 SPILLWAY STRUCTURE & CHANNEL

Excavationfor Structure - Rock c.y. 6,100,000 1.20 2.85 7,320,0CC. 17,385,000 10,972,000 ChannelExcavation - Rock c.y. 12,700.000 1.20 2.85 15,2110,000 36,195,000 22,84411000 Concretein Buttress Structure c.y. 1,520,000 19.00 75.00 29,070,000 1111,750,000 53,179,000 Concrete inApron c.y. 1100,000 16.00 60.00 6,1100,000 211,000,000 I I,1112,000 Concrete inRetaining Walls c.y. 790,000 18.00 70.00 111,220,000 55,200,000 25,838,000 Joints,Seals & Drains L.S. - - - 365,000 2,310,000 850,000 SpillwayBridge L.S. - - - 1100,000 3,000,000 1,030,000 SpillwayTainter Gates 25 @110'lng. lb. 11,200,000 0.85 0.75 3,570,000 3,150,000 11,232,000 GantryCranes - 2 Reqld. L.S. - - - 1100,000 50,000 1111,0o0 SluicewayGates 25 @ 16' s211 lb. 111,200,000 0.86 0.75 12,070,000 10,650,000 14,307,000 Reinforcing Steel lb. 15,000,000 0.13 0.21 1.950,000 3,150,00 2,612,000 Subtotal - Spillway StruCture 91,005,000 269,9110,000 1117,717,000 & Channel

CONSTRUCTION COSTS 1117,190,000 386,260,000, 228,3111,000 Contingencies 30% 1114.157,000 115,8811.000 68.503.000 Total Estimated Capital Costs 191,3117,000 502,1641,O00 296,8117,000 Engineering & Admin. 8% 15,308I,000 110,173,000 23,7118,000 Pre Project Costs 3% 5,711D,000 15,065,000 8,905,000D Land Costs (Fern ished by WAPDA)- 1.003,560.000 210.832,000 Total Estimated Project Cost 212,395,000 1,560,962,001) 540,332,000 Note: The total cost here excludes Pakistan taxes, duties, etc. , estimated to be U.S. $59.4 million, equivalent, and interest during construction estimated at 6%, to be $158.4 million, equivelent, with foreign exchange component of U.S. $67.7 million, equivalent. MARCH 1967 IBRD-1982

ANNEX 3

GARIALA PROJECT

ANNEX 3

LIST OF FIGURES

1. Gariala Project: Plan and Sections

2. Gariala Project: Plan and Sections: Detail

3. Tarbela-Haro Canal: Plan, Profile and Sections

4. Tarbela-Haro Canal: Plan, Profile and Sections: Detail

5. Estimated Construction Costs: Single-Stage Construction

6. Estimated Construction Costs: Two-Stage Construction: First Stage

7. Estimated Construction Costs: Two-Stage Construction: Second Stage

8. Fstimated Construction Costs: Tarbela-Haro Canal

9. Estimated Construction Costs: Summary

ANNEX 3 Page 1

GARIALA

Introduction

The Gariala Dam site is located on the Haro River a few miles upstream of its junction with the Indus (see Map III4.). The proposed structure would consist of an earthfill dam 375 feet high with a crest length of 40,000 feet and an embankment volume of 189 million cubic yards. Live capacity of the reservoir would be 8.0 MAF, approximately 0.4 MAF of which would derive from the annual runoff of the Haro River and 7.6 MAF would be diverted from the upper levels of the Tarbela Reservoir by means of a canal 5 miles long between its Siran arm and the Jabbi Kas, the Jabbi Kas and the Haro River (see Figures 1 and 3). Only when Tarbela Reservoir is close to normal operating level of 1550 feet, would such diversion be practical. WATater from the Geriala Reservoir would be released through four outlet tunnels into the Haro River and thence to the Indus. The estimated ,construction period would extend over 10 years.

The project could also be constructed in two stages, the first stage having a live capacity of 4.6 MAF and the second stage adding 3.4 MAF.

Cost of the single-stage project is estimated by Chas. T. Main to be $651 million 1/, of which $411 million would be in foreign exchange. The initial stage of the two-stage project would cost approximately $596 million, of which $374 million in foreign exchange. N%o-stage construction would raise the total cost by $29 million.

Gariala is definitely' not a possible choice for construction now. First of all, it requires that Tarbela be completed before it can be considered. Second, even though it would have the low rate of sedimentation characteristic of side valley reservoirs, it also has the important disadvantage that its power would be available on a seasonal basis only. Power requirements in the early stages of development are likely to favor main stem projects which can provide a firm power capability the year round.

Initially, it was thought that side valley reservoirs of substantial volume could be provided at moderate cost relative to main stem projects. Studies by Chas. T. Main have revised these early impressions significantly, as indicated by the size of the proposed Gariala Dam (larger than Tarbela) and the attendant costs.

Geology

Foundations at the dam site consist mainly of overburden of aeolian and/or alluvial origin. Slightly consolidated and poorly cemented sandstones and shales of the Siwalik series constitute the

1/ See section on cost estimates. ANNEX 3 Page 2 foundation rock in the river gorge section and generally underlie the unconsolidated overburden outside the gorge at unknown depths. Jointed and weathered limestone is present high on the left abutment.

The sandstones and shales are essentially flat-lying but the limestone dips steeply. The nature of the contact between the Siwalik and limestone is not known, but it may be a fault or a disconformity. Chas. T. Main estimated that the foundation rock would support an earth dam of suitable design.

Most of the embankment would be constructed on the overburden, composed of sand, silt, and gravel, which seems to be moderately impermeable. However, the area of the dam site is subject to earthquakes, and therefore seismic forces must be taken into consideration in the design.

Since the canal route was studied on a reconniassance basis only, few details of the geology are known. The entire length is expected to be in easily excavated, water deposited aeolian silt and sand, with bedrock well below invert grade for most of the length.

Hydrology

Data on the flow of the Haro River are extremely limited. Its mean annual discharge is estimated to be 0.4 MAF. However, developments at Khanpur on the Haro River will reduce the inflow at Gariala. Evaporation from the reservoir is estimated to be in the neighborhood of 0.1 MAF. Thus the assumption was made that the conveyance system would have to be of sufficient capacity to fill the entire reservoir with water diverted from the Indus.

The design flood at Gariala was taken to have a peak inflow of 386,000 cusecs with a volume of 11.84 million cusec-hours during a period of 70 hours.

The sediment transport of the Haro River was estimated by IACA to be 10 million tons per year at the Gariala site.

Available Data

Information available on the Gariala site is extremely limited. Chas. T. Main utilized topographic maps with a scale of 1:15,000 and a 10-foot contour interval, 1 inch to 1 mile maps of the general area, air photographs, and a generalized, unsurveyed geologic cross section of the dam site. Site inspections were made by the consultants but no subsurface explorations or detailed mapping were carried out.

Proposed Design

The plan and sections of the proposed dam and conveyance system are shown in Figures 1 to 4. It should be noted that the ANNEX 3 Page 3 drawings of the canal are representative only and do not provide for the planned capacity of 76,000 cusecs. The major features of the project are listed in Table 1 below.

Table 1

Gariala Project Statistics

Reservoir

Gross Storage 8.2 MAF Normal High Water Elevation 1250 feet Minimum Operating Level (no power) 1020 feet Dead Storage Volume (no power generation) 0.2 MAF Minimum Operating Level (power generation) 1070 feet Dead Storage Volume 0.6 MAF Assumed Tailwater Level (power generation) 900 feet

Dam

Zoned-Earthfill: Height above Streambed 375 feet Crest Elevation (fuIl development) 1265 feet Length at Crest 4o,000 feet Embankment Volume 189 million cubic yards

Flood Data

Design Inflow Flood 386,000 cusecs Volume Inflow 11.84 million cusec-hours Flood Outflow (outlet conduits) 100,000 cusecs Reservoir Superstorage 7 feet Emergency Spillway Fuse-plug Crest at Elevation 1258 feet

Outlet Works Four Horseshoe-shaped free-flow Conduits 26 feet nominal diameter Length 2,150 feet Control-Cylinder Valves at Intakes of Tunnels 24 feet diameter Design Capacity 25,000 cusecs each

Conveyance System from Tarbela Reservoir

Diversion Capacity 76,000 cusecs Channel: Length 5 miles Depth 30 feet Bottom Width 800 feet Side Slopes 1 on 2 Velocity 3 + feet per second Table 1 contir.ued on next page, ANNEX 3 Page 4

Table 1 (cont'd)

Control Structure: Crest Elevation 1534 feet Gates - 10 Radial 18 feet high x 30 feet wide Control Weirs 7 overflow with stilling basins Head Dissipated in each 1 @ 60 feet 3 ( 50 feet 1 ( 40 feet 1 © 30 feet 1 @ 20 + feet

Power Plant (if justified)

Six Francis-type Turbines, each 100,000 hp at 245 feet head Water Discharge at Rated Head, each Unit 4,000 cusecs Six Generators nominal output, each (capable of 15 percent continuous overload) 85 mw Plant Capability Maximum Head (peaking) 586 mw Plant Capability Minimum Head (peaking) 230 mw Annual Energy 1,700 million kwh

Preliminary studies indicate that, because of the large size of the Gariala Reservoir relative to the expected flood flows from the Haro and Jabbi Kas, it would be less costly to absorb the floods through superstorage rather than to provide a service spillway to prevent overtopping. The shape of the reservoir is such that half the storage volume is contained in the top 70 feet of the 350-foot depth of the reservoir. Thus, the amount of freeboard required to absorb the flood flows would be small.

The design flood of 386,000 cusecs was assumed to occur when the reservoir was full. With the outlet works operating at their peak capacity of about 100,000 cusecs, the flood would be absorbed with a surcharge of 7 feet above the normal maximum reservoir level of 1250 feet. The remaining 8 feet of freeboard would be sufficient to protect the dam without a service spillway. However, an emergency spinlway on one of the abutments with a fuse-plug at 1258 feet would be provided.

The dam would be zoned earth embankment with an impervious core. Both slopes would be protected against erosion by riprap blankets. Seepage through the earth foundation would be controlled by an impervious blanket upstream and relief wells or filters downstream. Where the rock foundation lies at shallow depths, the impervious core would be constructed down to bedrock. Materials for the embankment are available from alluvial deposits near the site north of the Haro River. Materials for riprap ANNEX 3 Page 5

and graded rock structures are to be found in the limestone foundations of the nearby Kala Chitta Hills. There are also some gravel deposits in the area which are presently being developed.

The four conduits of reinforced concrete would be constructed on the riverbed for handling river flows during construction of the dam and to be used as reservoir outlets once the structure is completed.

Release of water into the conduits would be controlled by cylinder gates within intake towers at the upstream end of each conduit. The conduits would discharge into a stilling basin to achieve the necessary energy dissipation before the water passed into the river channel.

The design of the conveyance system from Tarbela Reservoir is based on water conditions expected at full development as projected by IACA, as Chas. T. Main held this to be the most practical approach. The system would consist of a canal through the Siran-Haro divide and a series of 7 check dams, 3 in the Jabbi Kas and h in the Haro River, to dissipate the energy of the flow as it falls about 300 feet from the end of the canal to the Gariala Reservoir.

The canal is designed to carry water at a normal velocity of 3 feet per second on EL slope of 1 in 17,000. Regulation of the outflows from the Tarbela Reservoir would be achieved by 10 radial gates in the first check danm at the downstream. Each of the other check dams would have an uncontrolled concrete chute spillway leading to a spillway. The nonoverflow sections of the dams would be of earthfill with impervious cores.

Power

A power installation at Gariala is unlikely to be justified. Power from the project would be available only on a seasonable basis, during the 7 months from late October to early May, and the minimum capability would occur' at about the same time as that of the main- stem projects.

In addition, the mean annual discharge through the turbines would be limited to the storage capacity of the reservoir - 8 MAF - whereas units installed on the Indus main stem would draw on a mean annual flow of 66 MAF or more. Thus the potential energy output per kilowatt of installed capacity would be a small fraction of that which could be expected from a similar installation on the Indus.

However, in case conditions warrant, Chas. T. Main suggested a plant containing six generators rated at 85 mw as the likely optimum installation.

Two units would be connected to each of three of the four outlet conduits. Since the turbines would restrict the discharge capacity, of the tunnels, other provisions would have to be made for coping with the design flood, such as adding a service spillway or raising the height of the dam or adding additional outlets. Also, ANNEX 3 Page 6 the minimum operating level would have to be raised from 1020 feet to 1070 feet to permit the turbines to operate satisfactorily, thus reducing the live storage capacity from 8.0 MAF to 7.6 MAF.

Utilizing a release pattern based on that for Tarbela, Chas. T. Main estimated that the average annual energy output would be 1,700 million kwh and the equivalent cost of generation would be approximately 0.63 cents per kwh.

Operation of the Project

Gariala Reservoir would be filled by diversion of water from the upper levels of the Tarbela Reservoir through the canal in the Siran arm to the Jabbi Kas, down the Jabbi Kas to the Haro River, and thence to the reservoir (see Map III.4). Gariala could be filled only when the Tarbela Reservoir were at or near its high water level of 1550 feet. Therefore, it would be necessary to fill Tarbela as quickly as possible each flood season to provide sufficient time for diversion to Gariala.

Since the design and operation of Gariala depend to such an extent on the operation of Tarbela, and the timing of its construction in relation to that of Tarbela, Chas. T. Main had to make a basic assumption about the place of Gariala in the development plan for surface water storage and decided that it would most likely come in the later phase. Consequently, the conveyance system was designed for water supply conditions under full development and for a situation of advanced sedimentation at Tarbela.

When the usable capacity of Tarbela has reached its permanent value of 1 MAF, there would be approximately 60 days available during July and August for diversion to Gariala. Thus the required minimum capacity of the conveyance system would be about 67,000 cusecs (evaporation was assumed to consume the mean annual runoff of the Haro River of 0.4 MAF). Chas. T. Main adopted a capacity of 76,000 cusecs for their study but suggested that detailed analysis might indicate the need for a system of greater capacity.

During the early years of Tarbela's life, it will have a large usable capacity but will be filled quickly because the irrigation requirements during the flood season will be relatively low. Should Gariala be constructed at this time, there would be no problem of filling it. Nor would there be any difficulty after Tarbela were filled with sediment. The irrigation demands would be much greater, but the usable volume of Tarbela would be close to its 1 MAF minimum.

The critical period is likely to be when sedimentation has filled about half the storage capacity of Tarbela and its live capacity is still large and the irrigation requirements have already risen to a high level. In these circumstances, by the time Tarbela has been filled, the period remaining for the filling of Gariala will be reduced so that a conveyance system of greater capacity may be required. ANNEX 3 Page 7

Since the full yield of the Gariala Reservoir will not be needed in the early years of its life, whatever its point of construction, releases from it in the first part of the flood season could be used to make up shortages on the Indus due to any inadequacy of the outlet capacity of Tarbela at low head.

As previously discussed, power could be generated on a seasonal basis from about October to May, but since an installation does not seem to be economically justified at this stage of the analysis, no detailed operational scheme was devised.

Sedimentation at Gariala is expected to proceed at a very low rate. Sediment from the Indus will be trapped in the Tarbela Reservoir for the most part, and therefore water conveyed to Gariala would be largely sediment free for the first 50 years of Tarbela's life. Depletion during this period would result primarily from sediment transported by the Haro, estimated to be 10 million tons or 0.006 NAF per year on the basis of 80 pounds per cubic foot. A striking comparison is presented by the fact that this figure represents about 2.5 percent of the Indus sediment transport at Tarbela.

The long life of useful storage capacity of the Gariala Reservoir can be illustrated by the following: if the project were constructed to its full live capacity of 8.0 MkF in 1990, 15 years after Tarbela, it would still have a usable capacity of about 6.9 MAF after 50 years and approximately 5.4 NAF after 100 years of existence.

The town of Campbellpore would be inundated by Gariala Reservoir and the costs of relocation are included in the estimate prepared by Chas. T. Main. However, it appears desirable to establish as soon as possible the feasibility of the Gariala Project and its probable place in the development plan, so that steps can be taken at the appropriate time to prevent further growth in the Campbellpore area.

Construction Program

The project would require about 10 years to complete from the time final design studies were started. However, field explorations, feasibility studies, and financing arrangements would have to be completed prior to that time.

Cost Estimates

The designs for Gariala and consequently the cost estimates are based primarily on judgment as a result of the paucity of data. The lack of hydrological data is not of great significance since diversion from the Indus would account for almost all water stored in the reservoir. However, the subsurface conditions are not known, and extensive field investigations would have to be undertaken before detailed designs and cost estimates could be prepared. Consequently, the present cost estimates are indicative only of the magnitude of the costs that might be involved. ANNEX 3 Page d

The estimates given, as prepared by Chas. T. Main, are based on world market prices and on labor and materials costs existing in West Pakistan as of July 1, 1964. The cost of relocating the town of Campbellpore, as estimated by WAPDA, is included in the allowance for land and resettlement. Fccluded from the estimates are provision for inflation, financial contingencies, taxes, duties, levies and interest during construction.

Single-Stage Construction

Chas. T. Main estimates that Gariala, constructed initially to its full live capacity of 8.0 MAF, would cost approximately $651 million, of which $411 million would be in foreign exchange (see Figures 5 and 8). Because of the great uncertainties involved, and the almost total lack of data, the Bank adopted a cost range of $650 million to $975 million.

Two-Stage Construction

Stage development of Gariala is feasible, according to Chas. T. Main, although the cost of the first stage to impound 4.8 MAF gross storage and 4.6 MAF live storage at 1200 feet full reservoir level would cost more than 90 percent of the single-stage project for the following reasons:

1) The outlet works must be constructed to full size initially.

2) While some savings could be effected by stage constructing the canal section, Chas. T. Main concluded that the most practical course would be to construct the entire conveyance system to full size initially.

3) Since the shape of the reservoir is such that half the capacity is contained in the top 70 feet of the reservoir at full height, the amount of freeboard necessary to handle the design flood is greater for the low dam than for the high dam.

In addition, stage development is always more costly because a second mobilization is necessary.

The cost of two-stage construction as prepared by Chas. T. Main is shown in Figures 6, 7 and 8 and amount to $596 million for the first stage, of which $374 million would be in foreign exchange, and $84 million for the second stage, of which $54 million in foreign exchange. The Bank Group has adopted a cost range of $596 million to $900 million for the first stage and $84 million to $125 million for the second stage. Construction of the first stage would save $55 million over single-stage construction initially, but ultimately the cost of two- stage construction would be $29 million higher (see Table 2). ANNEX 3 Page 9

Table 2

Comparison of Estimated Costs for Single-Stage and Two-Stage Construction (US$ million equivalent)

Single-Stage Construction:

Conveyance System 128 Dam (8.0 NAF) 523

-Total Single-Stage Construction 651

Two-Stage Construction:

Conveyance System 128 First-Stage Dam (4.6 MAF) 468

Total First-Stage Construction 596

Second-Stage Dam (3.4 MAF) 84

Total Two-Stage Construction 680

Total Single-Stage Construction 651

Additional Cost Two-Stage Construction 29

Justification for two-stage construction depends on the value of the extra 3.4 MAF available initially with single-stage construction, the growth of demand for stored water, and the rate of interest assumed. If no value were assigned to the extra storage and the requirement for stored water were increasing at a rate such that the second stage would be needed 6 years after completion of the first stage, two-stage develcpment would be marginal assuming an 8 percent rate of interest. If the second stage were not needed until later, two-stage development would be preferred.

Additional Investigations Required

Even though Gariala may not be needed until the last part of the century, the project should be investigated at an early date, so that its place in the development program can be determined. There- fore, Chas. T. Main outlined a limited program to determine essential details and permit the preparation of preliminary designs and cost estimates.

Twenty holes should be drilled along the dam and dike axis totaling 3200 feet in depth. An angle boring in the limestone of the left abutment is suggested to determine the characteristics of the formation. Eighteen test pits totaling 900 feet in depth should be dug along the axis to sample and test the foundation soils. ANINEX 3 Page 10

Standard tests, such as triaxial shear, unconfined compression, and modules of elasticity should be performed on representative undisturbed clay and shale samples of the bedrock formations in both the saturated and unsaturated states.

The porosity and permeability of the overburden should be determined, and, where possible, pressure tests should be made in the boreholes. In addition, load bearing tests, especially along the outlet conduit foundations, are recommended.

When more data are available, other types of canals such as lined canals with higher velocities should be investigated for possible use in the conveyance system. VOLUME III ANNEX 3-FIGURE 1

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MARCH 1967 IBRD-1984

VOLUME III ANNEX 3-FIGURE 3

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VOLUME III ANNEX 3-FIGURE 4

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0 fESE RPLAN, PROflEE R SECTITS SH 2 TYPICAL CANAL SECTION

IrASTE | 2 ;-2 |FIG1

JUNE 1967 I BRD-1986R

VOLUME III

ANNEX 4-FIGURE 1

STUDY OF THE WATER AND POWER RESOURCES OF WEST PAKISTAN COMPREHENSIVE REPORT SKARDU DAM PROJECT RESERVOIR MAP

INTERNATIONAL BANK FOR RECONSTRUCTION & DEVELOPMENT

FROM DRAWING BY: CHAS. T. MAIN INTERNATIONAL, INC.

BOSTON MASS. U.S.A. FEBRUARY 1966

5000 0 5000 10000 F e E T

8.0 Mlillion acre feet reservoir

5.2 Million acre feet reservoir Dam sites considered

Skardu airport

MAY-1967 IBRD-1992R

STUDY OF THE WATER AND POWER RESOURCES VOLUME III OF WEST PAKISTAN COMPREHENSIVE REPORT ANNEX 3-FIGURE 5 ESTIMATED CONSTRUCTION COSTS GARIALA DAM STORAGE CAPACITY 8.0 MAF ELEV. 1265

UNIT UNIT TOTAL TOTAL TOTAL I T EM UNIT QUANTITY PRICE PRICE COST COST Rs EQUIVALENT $ $ COST $ ~~~~~~~~~COST$

DIVERSIOH AND CARE OF THE RIVER Steel Sheet Pile Cells T 3,600 480. 500. 1,728,000 1,800,000 Fill for Cofferdam Cells from Excavation c.y. 25,000 1. 2.75 25,000 69,000 Concrete Cell Caps c.y. 11,000 13. 38. 143,000 418,000 Earth and Rockfill Cofferdam c.y. 1,070,000 1.50 2.50 1,605,000 2,675,000 Cofferdam Removal L.S. - - - 580,000 2,200,000 Unwatering, Pumping, Care of Water L.S. - - - 277,000 327,000 SUB TOTAL 4,358,000 7,489,000 5,931,000

INTAKES, CONDUITS, STILLING BASIN Concrete Footing Slab - Intake Towers c.y. 32,000 28. 90. 896,000 2,880,000 Concrete in Intake Structures c.y. 70,000 38. 105. 2,660,000 7,350,000 Concrete Conduits c.y. 175,000 38. 100. 6,650,000 17,500,000 Concrete in Stilling Basin & Training Walls c.y. 315,000 33. 90. 10,395,000 28,350,000 Reinforcing Steel T 31,000 280. 500. 8,680,000 15,500,000 Rock Excavation for Stilling Basin c.y. 577,000 1.25 2.85 721,000 1,644,000 Intake Bridge L.S. - - - 275,000 2,059,000 SUB TOTAL 30,277,000 75,283,000 46,093,000

MAIN EMBANKO4ENT- FARTH AND ROCKFILL Strip and Grade for Dam and Blanket c.y. 10,685,000 0.50 0.75 5,343,000 8,014,000 Excavate in Overburden for Core Trench c.y. 11,876,000 0.55 0.85 6,532,000 10,095,000 Impervious Core Material c.y. 31,172,000 1.25 2.10 38,965,000 65,461,000 Impervious Blanket Material c.y. 21,570,000 1.20 2.00 25,884,000 43,140,000 Grouting at Core Trench and Fault Zones c.f. 300,000 4.55 35.00 1,365,000 10,500,000 Transition Filters c.y. 7,747,000 1.40 2.35 10,846,000 18,205,000 Pervious Fill c.y. 75,000,000 0.75 1. 56,250,000 75,000,000 Free Draining Material - Upstream Slope c.y. 16,492,000 0.80 1. 13,194,000 16,492,000 Rock & Gravel Fill - Downstream Slope c.y. 20,504,000 1.20 2.50 24,605,000 51,260,000 Riprap Slope Protection c.y. 3,600,000 1.05 2.70 3,701,000 9,715,000 Miscellaneous Waste Fill - DownstreamBerm c.y. 12,180,000 0.10 0.20 1,218.000 2,436.000 SUB TOTAL 187,903,000 310,318,000 253,096,000

CCTRACT COSTS 222,538,000 393,090,000 305,120,000

PRECONTRACT COSTS 8,700,000 15,232,000 11,900,000

CONTINGENCIES (30) 66,800,000 117,600,000 91,506,000

PERFORMANCEBOND (3,000,000) _ (3,000,000)

U INSIRANCE (6,600,000) - (6,600,000)

ENGINEERING AND ADMINISTRATION 23,100,000 40,936,000 31,700,000

LAND AND RESErTLEMENT __- _392,2, 000 82,400,000 TOTAL CONSTRUCTION COST $321,138,000 Rs 959,082,000 $522,626,000

U Performance Bond and Insurance Costs are included in unit prices. Total amounts are shown separately for information.

NOTE: Total cost here excludes Pakistan taxes, duties, etc., and interest during construction. MARCH 1967 IBRD-1987

STUDY OF THE WATER AND POWER RESOURCES VOLUME I Il OF WEST PAKISTAN A I COMIPREMENSIVE REPORT ANNEX 3-FIGURE 6

ESTIMATED CONSTRUCTION COSTS GARIALA DAM - Two Stage Construction First Stage - 4. 6 MAF Live Storage

UNIT UNIT TOTAL TOTAL TOTAL UNIT QUANTITY PRICE PRICE COST COST EQUIVALENT I Rs S Rs COST $

DIVERSION & CARE OF THE RIVER

Steel Sheet Pile Cells T 3,600 480.00 500.00 1,728,000 1,800,000 Fill for Cofferdam Cells from Excavation e.y. 25,000 1.00 2.75 25,000 69,000 Concrete Cell\Caps c.y. 11,000 13.00 38.00 143,000 418,000 Earth A Rockfill Cofferdam c.y. 1,070,000 1.50 2.50 1,605,000 2,675,000 Cofferdam Removal L.S. - - - 580,000 2,200,000 Unwatering, Pumping, Care of Water L.S. - - - 277,000 327,000 SUB TOTAL 4,358,000 7,489,000 5,931,000

INTAKES, CONDUITS, STILLING BASIN

Concrete Footing Slab- Intake Towers c.y. 32,000 28.00 90.00 896,000 2,880,000 Concrete in Intake Structures c.y. 70,000 38.00 105.00 2,660,000 7,350,000 Concrete Conduits c.y. 175,000 38.00 100.00 6,650,000 17,500,000 Concrete in Stilling Basin & Trainingi Walls c.y. 315,000 33.00 90.00 10,395,000 28,350,000 Reinforcing Steel T 31,000 280.00 500.00 8,680,000 15,500,000 Rock Excavation for Stilling Basin c.y. 577,000 1.25 2.85 721,000 1,644,000 Intake Bridge L.S. - - - 275,000 2,059,000 SUB TOTAL 30,277,000 75,283,000 48,093,000

MAIN EMBANKMENT - EARTH & ROCKFILL

Strip i Grade for Dam &Blanket c.y. 9,925,000 0.50 0.75 4,962,500 7,443,750 Excavate in Overburden for Core Trench c.y. 11,876,000 0.55 0.85 6,531,800 10,094,600 Impervious Core Material c.y. 20,239,000 1.30 2.20 26,310,700 44,525,800 Impervious Blanket c.y. 20,498,000 1.25 2.10 25,622,500 43,045,800 Grouting at Core Trench & Fault Zones c.f. 275,000 4.80 37.00 1,320,000 10,175,000 Transition Filters c.y. 4,379,000 1.55 2.60 6,787,450 11,385,400 Pervious Fill c.y. 73,096,000 0.80 1.05 58,476,800 76,750,800 Free Draining Material -Upstream Slope c.y. 10,532,000 0.90 1.10 9,478,800 11,585,200 Rock A Gravel Fill -Downstream Slope c.y. 14,124,000 1.35 2.75 19,067,400 38,841,000 Rliprap Slope Protectlon c.y. 2,486,000 1.16 3.00 2,858,900 7,458,000 Miscellaneous Waste Fill-Toe Berms c.y. 12,180,000 0.10 0.20 1.218,000 2,436,000 SUB TOTAL 162,634,850 263,741,350 218,042,700

. CONTRACT COSTS 197,269,850 346,513,350 270,066,700

PRE-CONTRACT COSTS 7,830,000 13,708,800 10,710,000

CONTINGENCIES 30% 61,529,950 108,066,640 84,233,000

X PERFORMANCE BOND (2,700,000) - (2,700,000)

/ INSURANCE (6,400,000) - (6,400,000)

ENGINEERING & ADMINISTRATION 17,500,000 55,692,000 29,200,000

LAND & RESETTLEMENT - 349,860,000 73,500,000

TOTAL CONSTRUCTION COST (Ist Stage) $214,129i,800 Rs873,840,790 $67,F709,700

jJ Performance Bond and Insurance Costs are included in unit prices. Total amounts shown separately for information.

NOTE: Total cost here excludes Pakistan taxes, duties, etc., and interest during constniction.

MARCH 1967 IBRD-1988

STUDY OF THE WATER AND POWER RESOURCES VOLUME III OF WEST PAKISTAN COMPREHENSIVE REPORT ANNEX 3-FIGURE 7 ESTIMATED CONSTRUCTION COSTS GARI ALA P AM TWO STAGE CONSTRIICTION SECOND STAGE - 4.6 MAF TO 0.0 NAF LIVE STORAGE UNIT UNIT TOTAL TOTAL TOTAL UNIT QUANTITY PRICE PRICE COST $ COST Rs EQUIVALENT $ Rs COST$ DIVERSION & CARE OF THE RIVER I N C L U D E D I N S T A G E I INTAKES, CONWUITS & STILLING BASIN

Intake Bridge Extension L.S. Item - - 29,000 282,000 88,000

SUB TOTAL 29,000 282,000 88,250

MAIN MBANi(ENT - EAM & ROCKFILL

Remove Roadway 6 Prepare Crest L.S. Item - - 50,000 25,000 Strip & Grade for Dam & Blanket c.y. 761,000 0.65 0.95 495,000 723,000 Impervious Core Material c.y. 10.934,000 1.30 2.20 14,214,000 24,055,000 Impervious Blanket c.y. 1,073,000 1.60 2.70 1,717,000 2,897,000 Grouting at Fault Zones c.f. 25,000 5.00 40.00 125,000 1,000,000 Transition Filters c.y. 3,368,000 1.55 2.60 5,220,000 8,757,000 Pervious Fill c.y. 910,000 1.00 1.30 910,000 1,183,000 Free Draining Material - Upstream Slope c.y. 5,961,000 0.90 1.10 5,365,000 6,557,000 Rock 6 Gravel Fill - Downstream Slope c.y. 6,381,000 1.35 2.75 8,614,000 17.548,000 Riprap Slope Protection c.y. 1,115,000 1.15 3.00 1,282,000 3,345,000 SUB TOTAL 37,992,000 66,090,000 51,876,450

!J CONTRACT COSTS 38,021,000 66,372,000 51,964,700 PRE-CONTRACT COSTS 870,000 1,523,200 1,190,000 CONTINGENCIES (30%) 11,667,300 20,368.560 15,946,200 .1 PERFORMANCE BOND (384,000) - (384,000) INSURANCE (1,358,000) - (1,358,000) ENGINEERING & ADMINISTRATION 3,318,000 10,520,080 5,528,100 LAND & RESETTLEMENT - 42,364,000 8,900,000

TOTAL CONSTRUCTION COST (2nd STAGE) $53,876,300 Rs 141,147,840 $83,529,000

Performance Bond & Insurance Costs are included in unit prices. Total amounts are shown separately for information.

NOTE: Total cost here excludes Pakistan taxes, duties, etc., and interest during construction.

MARCH 1967 I BRD-1989

STUDY OF THE WATER AND POWER RESOURCES VOLUME III OF WEST PAKISTAN ANX3FGR COMPREHENSIVE REPORT ANNEX 3-FIGURE 8 ESTIMATED CODNSTRUCTION COSTS

TARBELA - HARO CANAL

UNIT UNIT TOTAL TOTAL TOTAL I T EM UNIT QUANTITY PRICE PRICE COTR EQUIVALENT $ $ ~~~OT OT sCOST$

DIVERSION AND CONTROL OF WATER Diversion Conduits 36" 0 Rein. Conc. Pipe l.f. 24,000 4.80 45.25 115,000 1,086,000 Concrete in Headwalls and Discharge Pads c.y. 16,000 45.00 115.00 720,000 1,840,000 Sluice Gates & Operators 36" ¢t - 24 Required Item L.S. - - 143.000 291,000 Earth and Rock Cofferdams and Removal Item L.S. - - 1,155.000 1,925,000 $2,133,000 Rs 5,142,000 $ 3,213,000

CHECKDAMS AND CONTROL WORKS Concrete in Spillways and Stilling Basins c.y. 256,000 45.00 115.00 11,520,000 29,440,000 Reinforcing Steel lb. 32,000,000 0.14 0.25 4,480,000 8,000,000 Impervious Core in Earth Dikes c.y. 415,000 1.55 2.75 643,000 1,141,000 Transition Filters c.y. 720,000 1.75 3.00 1,260,000 2,160,000 Pervious Fill in Dikes c.y. I, 100,000 1.10 1.35 1,210,000 1,485,000 Riprap Slope Protection c.y. 320,000 1.15 2.00 368,000 640,000 Impervious Banket c.y. 1,120,000 1.40 2.50 1,568,000 2,800,000 Cast-in-place Concrete Piles 114" t l.f. 200,000 5.25 17.50 1,050.000 3,500,000 Taintor Gates, Guides, Sills& Fixed Hoists 30 ' x 18' lb. 500,000 0.60 0.50 300,000 250,000 Excavation for Link Canal & Channel Improvement c.y. 7,500.000 0.90 1.05 6,750,2 00 7,875,000 $29,149,000 Rs 57.291,000 $141,185.000

CONTRACT COSTS - 38,000 CFS CAPACITY $31,282,000 Rs 62,433,000 $44.398,000

ESTIMATED CONSTRUCTION COST 76,000 CFS CAPACITY

LI 1. CONTRACT COSTS $62,564,000 Rs 124,864,000 $88,796,000 2. PRECONTRACT COSTS 2.400,000 5,236,000 3,500,000 3. CONTINGENCIES 18.800,000 37,128,000 26,600,000 4. ENGINEERING AND ADMINISTRATION (8% ON I AND 3) 6,500,000 12,852,000 9,200,000 LI 5. INSURANCE ANDMISCELLANEOUS (1,900,000) - (1,900,000) LI 6. PERFORMANCE BONDS ( 900,000) - 900,000) 7. LAND AND RESETTLEMENT 1,904,000 400,000 $90,264,000 Rs 181,984,000 $128,496,000

L Performance Bond and Insurance Costs are included In unit prices. Total amounts are shown separately for information.

NOTE: Total cost here excludes Pakistan taxes, duties, etc., and interest during construction.

MARCH 1967 IBRD-1990

STUDY OF THE WATER AND POWER RESOURCES VOLUME III OF WEST PAKISTAN COMPREHENSIVE REPORT ANNEX 3-FIGURE 9 SUMMARY Estimated Cost of the Gariala Project (U. S. $ million equivalent)

Conveyance System Gdriala Dam Gariala Project Foreign Foreign Foreign Total Exchange Total Exchanqe Total Exchange

Precontract Costs 3.5 2.4 11.9 8.7 15.4 11.1

Net Coritract Costs 86.0 59.7 295.5 212.9 381.5 272.6

Contingencies (30%) 26.6 18.8 91.5 66.8 118.1 85.6

Engineering and Administration 9.2 6.5 31.7 23.1 40.9 29.6

Insurance and Miscellaneous 1.9 1.9 6.6 6.6 8.5 8.5

Performance Bond 0.9 0.9 3.0 3.0 3.9 3.9

Land Acquisition and Resettlement 0.4 - 82.4 - 82.8

Total 128.5 90.2 522.6 321.1 651.1 411.3

Say 128 90 523 321 651 411

NOTE: Total cost here is for 8.0 maf project and excludes Pakistan taxes, duties, etc., estimated to be U.S. $102.4 million, equivalent, and interest during construction estimated at 6% to be U.S.$170.1 million equivalent, with foreign exchange component of U.S. $111.7 million, equivalent.

MARCH 1967 IBRD-1991

ANNE 4

SKARDU PROJECT

ANNEX 4

LIST OF FIGURES

1. Skardu Dam Project: Reservoir Map

2. Skardu Dam Project: Plan

3. Skardu Dam Project: Sections

4. Estimated Construction Costs: Skardu Dam: 5.2 MAF Capacity

5. Estimated Construction Costs: Skardu Dam: 8.0 MAF Capacity

ANNEX 4 Page 1

SKARDU

Introduction

The Skardu Valley appears to offer the most promising reservoir basin on the Upper Indus. (See Map III.3) It possibly could be developed to store more than the mean annual flow of the Indus at that point, estimated to-be approximately 35 MAF. A large reservoir would, however, require the relocation of most; of the 30,000 people living in the valley at present and completely-disrupt the farm and trading economy of the region.

Skardu lies at a general elevation of 7000 feet and is extremely difficult to-reach, being separated from the rest of West Pakistan by high mountain ranges. Two one-way jeep routes lead into the area but are usable on a seasonable basis only.

WAPDA/Harza teams visited the region in 1960. 1962 and 1964, and identified several possible storage sites in the immediate vicinity of Skardu. It appeared to Chas. T. Main that superior dam sites existed further downstream, but the steep slope of the river in this section would necessitate extremely high dams to impound a large reservoir.

Thus, for their desk study, Chas. T. Main chose the Kandore site at the downstream end of Skardu Valley, two miles upstream from Ayub Bridge and about 315 miles upstream from Tarbela. It was considered to be representative only, selection of the most desirable site being dependent on more extensive investigations.

For the purpose of this study, although the data available are severely limited, Chas. T. Main has outlined a possible development at Skardu. Such a project would consist of an earth and rockfill dam, abutting a concreti gravity spillway and reservoir outlet structure on the right bank. Two heights of dam were considered, one with a height of 260 feet to impound 5.2 M4AF of usable storage and the other 310 feet high to impound 8.0 MAF. The spillway in either case would be provided with 13 radial control gates to permit the discharge of flood waters. Eight sluiceways at river level would be used for diversion during construction and subsequently for releasing water from storage.

Chas. T. Main estimated that depending on foundation conditions the cost of the low dam might lie between $427 million and $510 million, and that of the high dam between $498 million and $588 million. Foreign exchange costs would be about 45 percent of the totals. In view of the great uncertainties involved, and to nake these estimates more comparable to those of projects where more data are available, the Bank Group believes that cost ranges of $550 million to $825 million for the low dam and $600 million to $900 million for the high dam should be assumed.

Geology

The several sites identified by the WAPDA/Harza teams have common geologic features consisting of a rock abutment on one or the other side ANNEX 4 Page 2 of the river and extensive glacial deposits on the opposite side. The glacial deposits extend more than 100 feet in height above the river and to unknown depths below the valley floor. The bedrock is exposed in the sides of the gorge above the elevations of the tops of the glacial deposits.

The valley wall on the right side of the Kandore site is composed of alluvial and detrital material resting against a nearly vertical rock face. The left bank is alluvium bordered by a terrace covered with granitic rock fragments up to 50 feet in diameter. A small valley on the left side of the terrace contains several ponds. The depth of the alluvium below the level of the streambed is unknown.

Hydrology

A station was established at Skardu to gauge water levels, but no data on river discharge have been published. The record for a single year, 1964, was available for the Indus at Partab Bridge, downstream of its confluence with the Gilgit. Rough estimates of the flow at Skardu were made on the basis of this record and are shown in Table 1 below.

Table 1

Estimate of the 1964 Monthly Runoff of the Indus River at Skardu (Drainage Area 52,800 Square Miles) (MAr)

Indus River Indus River Estimated At Partab Gilgit River above Mouth Discharge Month Bridge a/ at Gilgit a/ of Gilgit b/ at Skardu c/

January o.8 0.2 o.6 0.5 February 0.7 0.1 o.6 0.5 March 0.7 0.1 o.6 0.5 April 0.8 0.1 0.7 o.6 May 1.7 0.3 1.4 1.2 June 4.8 1.2 3.6 3.1 July 13.3 2.1 11.2 9.8 August 13.4 1.7 11.7 10.2 September 6.o o.8 5.2 4.5 October 2.1 0.3 1.8 1.6 November 1.3 0.2 1.1 1.0 December 1.0 0.2 o.8 0.7

Total 46.6 7.3 39.3 34.2

Say 35

a/ Published records. b/ Computed by subtracting published flows of Gilgit River from published flows of Indus River at Partab Bridge. c/ Estimated by direct prorating of tributary drainage areas at the two localities. ANNEX 4 Page 3

It can be seen from the table that the discharge during the months of July and August is of the order of 20 MAF.

The tentative nature of these estimates must be borne in mind, of course. One year is quite inadequate to establish any reliable record, and the actual measurements may contain a substantial error because the cross- sectional areas for different gauge heights are not known. In addition, examination by Chas. T. Main indicated that many of the daily flows at Partab were estimated by correlation with the flows at Darband. This pro- cedure is not reliable during the monsoon season since the monsoons do not reach Partab. Even if the mean discherge were only half the amounts estimated, however, it would still be sufficient to fill an 8 MAF reservoir.

The runoff at Skardu during the flood season results almost entirely from snow andl glacial melt since, as mentioned above, the monsoons do not penetrate to the area. While this makes seasonal variations of river discharge easier to predict, there is still the hazard of sudden releases that may result from the breeching of natural dams formed by glacial drift or landslides across the channel of the main river or its tributaries. With such contingencies in mind a figure of 1,100,000 cusecs was assumed for the design flood. Since no discharge records of consequence are available, it has been impossible to establish any relationships between the flows at Skardu and those further downstream as a basis for filling and release pattern.

As in the case of river discharge, no records of the sediment transport at Skardu were obtainable, but the results of sediment sampling at Partab Bridge in 1963 and 1964, and the sediment transport record at Darband for the period 1960-64 were available. The figures from Partab are subject to the same reservations as the flow record.

The sediment transport for the Indus at Partab in 1964 was estimated by IACA at 177 million tons. Prorating on the basis of drainage areas, Chas. T. Main estimated the sediment transport at Skardu to be 140 million tons.

Taking the record at Darband and using the same technique of prorating according to drainage areas, Chas. T. Main calculated the sediment transport at Skardu to be 270 million tons per year.

Therefore, Chas. T. Main estimated that the average sediment transport at Skardu would lie between 140 million and 270 million tons per year or, on the basis of 85 pounds per cubic foot, between 76,000 and 1467000 acre feet per year.

Access to the Project Site

Existing roads to the region are single lane and are impassable to anything except jeeps and pack animals. They are closed seven to eight months of the year by winter snow and sustain heavy damage as a result of snowmelt runoff. ANNEX 4 Page 4

There are two routes. The first runs 240 miles from Balakot 9 at the end of the Kunhar Valley, across the Babu-Sar Pass at an elevation of 13000 feet 9 through Bunji to Skardu. The total distance from Rawalpindi along this route is about 325 miles.

The second begins at Khavwza-Khel in the Swat Valley and follows the Indus to connect with the above route near Chilas. This road was scheduled for completion in 1966. The distance from Rawalpindi to Skardu along this route is about 400 miles.

No maps suitable for highway location studies were available, but the route along the Indus River from Tarbela was chosen as the most likely. It is longer than the Kunhar Valley route, but it should be easier to keep open during winter since its highest elevation is about 7000 feet as compared to that of the Babu-Sar Pass on the Kunhar Valley route of 13000 feet.

A gravel surfaced road, 40 feet wide and 340 miles long was assumed. A typical mile of road was estimated to involve the following:

Item Quantity

Excavation 130,000 cubic yards Fill 4,000 cubic yards Culverts (7 feet in diameter, 70 feet long) 5 Bridges (20 feet by 60 feet) 1 to every 9 miles

Proposed Design as Basis for Estimates

Data available to Chas. T. Main for their study included reports of the reconnaissance trips made by the W4APDA/Harza teams, aerial photographs of the Indus from Tarbela to the Shyok Dam site upstream of the Skardu Valley at a scale of about 1:30,000, and topographic maps with a scale of 1:15,000 and a 20-foot contour interval of the Skardu area of the Indus and the lower portion of the Shigar River. These data were adequate for a general appraisal only, and therefore the proposed structure must be considered as merely a possible development of the site.

Dams of two different heights were considered by Chas. T. Main (see plan and sections for the higher project in Figures 2 and 3). One would impound live storage of 8.0 MAF and the other, 5.2 MAF. The idea was to explore the relationship between cost and storage volume at the site. The major features of the two dams considered are outlined in Table 2 below: ANNEX 4 Page 5

Table 2

Skardu Project Statistics

Reservoir

Gross Capacity 5.2 8.o MAF Dead Storage 0 0 High Water Elevation 7360 7410 feet Low Operating Level 7150+ 7150+ feet Total Area 48,000 61,000 acres Farmlands Involved 5,500 8,000 acres Riverbed (waste land) 19,500 22,000 acres

Dam

Crest Elevation 7380 7430 feet Height above Streambed 260 310 feet

Outlet Works

8 Sluiceways 45 feet high x 13.5 feet wide (no power facilities considered)

Spillway

Overflow with 13 Radial Gates 58 feet high x 50 feet wide each, length 830 feet

Design Flood Flow (snowmelt plus flood from failure of natural dam) 1,100,000 1,100,000 cusecs

Hydrology

Estimated Average Annual Runoff 35 MAF

Estimated Average Ainual Sediment Discharge 140 - 270 million tons per year ANNEX 4 Page 6

The designs are based on the assumption that the site conditions are less favorable for the construction and operation of diversion tunnels through the abutments than for river diversion through a combination sluiceway/spillway structure of concrete gravity design constructed in a channel excavated on the right side of the river. As bases for the alternative designs, assumptions were made that bedrock would be found at depths of 50 feet and 200 feet respectively. These assumptions provide a basis for assessing the technical feasibility of a project at the site, but field investigations will be required to establish cost estimates with any certainty.

The proposed dan would be of eartb and rockfill. Flows through the diversion channel on the right side would be controlled by the spillway and outlet structure, constructed in stages as necessary to handle the flood flows. A concrete bulkhead section on the right side of the spillway would extend to the bedrock abutment. At the other end a concrete section would tie into the earth and rockfill darn on the left. A loW earth dam would be constructed in a saddle about 0.7 mile beyond the left end of the main dam to close the reservoir.

The sluices at river level would be used for normal water releases. The spillway would be utilized only in cases of high floods and would discharge the design flood of 1,100,000 cusecs at the normal reservoir storage level.

Materials for construction probably would be available from required excavations and from detrital deposits and bedrock near the site. The reservoir would displace a considerable number of people and inundate large areas of cultivated land. The 5.2-MAF reservoir would flood approximately 5,000 acres of land now under cultivation and the 8.0--MAF reservoir about 8,000 acres. Either would require the resettlement of a large proportion of the 30,000 people who presently inhabit the valley.

Although a power plant could be installed, Skardu was at this stage of the analysis considered only as a storage project. The local market would in any case absorb a very small amount of power, and the long transmission lines over mountainous terrain to the major markets would be extremely expensive to construct and maintain.

Operation

The operational characteristics of the reservoir can only be sketched roughly at this time. The amount of water available for storage, the period of its availability, and the required release pattern will depend on the ability to predict the flows at canal heads based on correlations with the flows at Skardu.

If the annual flows do not vary greatly from the figures listed in Table 1, the reservoir could be allowed to remain empty until about July. In this case, much of the early season sediment would be transported through the reservoir without detention. Also, some of the sediment deposited in previous years would be scoured out. Chas. T. Main estimated that, on the AmINEX 4 Page 7 basis of these considerations, a depletion rate of 0.1 MAF per year would be the probable maximum.

The trapping effect of Skardu is not expected to be significant for Tarbela because it appears that the Indus below Skardu has available to it all the sediment it can carry. The attenuation of peaks caused by Skardu would have some effect, however, since it would reduce the sediment carrying capacity of the river.

Cost Estimates

The cost estimates prepared for the project are highly speculative because data were almost completely lacking and many assumptions had to be made. No subsurface explorations were carried out and no detailed survey of surface geology was available. The foundation, materials for construction, and other important site conditions may be vastly different from those assumed. Costs were based on world market prices and labor and materials prices existing in West Pakistan in July 1964.

Access to the site is a point of serious question. The costs of the road chargeable to the project, based on quantities indicated above, were estimated to be in the neighbourhood of $235,000 per mile. More detailed studies might reveal the cost to be considerably higher. The total allocable cost according to Chas. T. Main, including contingencies (30 percent) and engineering and administration (8 percent) was estimated to be $112 million of which $37 million would be in foreign exchange.

Land and resettlement costs were estimated by WAPDA in January 1966 to be $1,700 or more per acre.

Chas. T. Main's detailed cost estimates for the two projects considered are shown in Figures 4 and 5 based on the assumption that bedrock would be found 200 feet below river level. Another set of estimates was prepared on the basis of bedrock being located 50 feet below river level. The cost ranges as estimated by Chas. T. Main are $427 million to $510 million for the 'Low dam and $498 million to $588 million for the high dam. Foreign exchange costs comprise about 45 percent of the totals. Ex- cluded are provision for.inflation, financial contingencies,,Pakistann taxes and duties, and interest during construction.

Because of the very preliminary nature of the investigations and the almost total lack of data, the Bank Group has adopted the following cost ranges: $550 million to $825 million for the low dam and $600 million to $900 million for the high dam.

Additional Investigations Required

Extensive investigations of the site and the compilation and evaluation of many data are required before meaningful designs and cost estimates can be prepared. ANNEX 4 Page 8

The present network of hydrometeorological stations should be extended by installing the proposed stations on the Gilgit, Shigar and Hunza Rivers. Sediment measurements in addition to discharge measurements should be taken at these and the newly established station at Skardu and correlated with measurements downstream. The input and output of glacial debris in the Shigar, Shyok and Indus Rivers should be studied over a long period to ascertain the mechanics of sediment movement. Snow courses should be established for correlating snow pack with runoff.

Understanding of the hydrometeorological processes of the Upper Indus Basin is necessary for the proper operation of the Skardu Project, but it is also invaluable to the operation of the entire storage system, especially when conditions of full development are approached.

Other sites should be investigated to identify those deserving further exploration. The depth and character of the overburden at all sites selected for further study should be determined. Test pits and borings of potential sources of materials for construction should be sufficient to identify sources and approximate the quantities of materials available.

Studies should be made of the inhabited land affected by the project, of areas that could be developed for relocating the people affected, and of the effects of the project on the economy of the region.

The problem of access to the area requires close examination. In particular, the feasibility of constructing and maintaining passable throughout the year a road strong enough to support heavy construction equipment needs to be established. Also, the basis for allocating the costs of the road to the project and to other national benefits should be developed. VOLUME III SHIGARTHANG DtKE

AF ' 4 ; , /4 P L A N _

CAPACITY CURVE CAAC T CEBCTV 0 SLUICEWAY ^"X->iL~ ~~~~~

_ w b,__o ht iX hf

z X 4 ''tu\ & 2 \I) 1 n d , , p'-/ f / , e ._ [ ' -// \ ]

\ NJ? \\ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~COFFERDA ______OF WE ST P AK I ST A N , , . . -4 \ 'I~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~ . x t ' / 4~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

-OR-~ ~ ~ ~~~~~~R

A ~~~~~~~~~~ -~P 0 400 8000 / _ AREA~~~~~~~~~~~~~~~~~0 CMRHIVRPORO DU'FHw:E~ ::M:PROJBCT i 6 j K 00 CLL TSKRu K6 UA t / O~~OLOiE&*[AIN TR0USANDIft TRBUSAND ACREACRES FEET VOLUNEff' AND DEVELOPMENT INTERNATIONAL BANK FOR RECONSTRUCTION RESERVOIR - AREA CAPACITY CURVES CHAS. T. MAIN INTERNATIONAL, INC. August 1966 Boston, Mass. U.S.A.

IBRD 1993R JUNE 1967

ANNEX 4M-FI GURE 3

EARTH EMBANTMENT 1690' SOUTHOULTEAE 470- SPILLW-T SECTION 15 GATES 50' 59,14 PIEASpII. ao860' 50CR ULRLEAO 590

TOPOF EARTH FILL EL 7430 O' EL 7 O420

,~~~~~EEL-2 TOO XwSt .0 L72 1.S SLOIOSEWAr.R720 F UPSTREAM SECTION

i~~~~RU R _IVE 40O RO'SE11.~ O~ ~ ~ ~ ~ ~ ~ ~ ~~-OTNSfl, u fl fL u 8u fi 09-fl. .-5-0 FOECKI

E~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~T 75OP5E72O,.... \ <00

{L./ItOO'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~W \-, IO;7,0, --.

A- E. *SECTIONl. USRA SETO ,' oSU"10 _ - t _ << oh 1 1 XJ SECTION ~~~~~~~~~~~~~~~~THRU DAM

ASSUMED ROCK SO'BELOW RIVER BEDi ''' CL, .7 ES40MAD ROCKO200 'OBELOW RIVEL BCD OCRES CRET i STR OF E TR'SE ELOROOS . \TTTSU"AOOX STAN

SPILLWAYROCK 200 ASSUMEDBELOW ELILLWAY70 RIVER EED BULKHEAD C~~~~~~~~~~~~OMPEHENSIYEREPORT EL73540. N S SECTON SKARDU DAM PROIST VIFVWb___ BANKIINTERNATIONAL FOR RECONSTRUCTION AND DEVELOPMENT AS.A T. MAIN INTERNATIONAL, INC.

0osto0. M... U. S.jA. AugSst 1966

MARCH 1967 IBRD-1994

VOLUME III ANNEX 5-FIGURE 1

; * 389R AR E A 1000 ACRES ERILLWENT CRIET SPILLWAYSECTION- 50 AD G 2S IX 0

GATES3 F5' 2300

-i ~~~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ _

SECTION .,00 + - ' 2-34, DIVERSION IRRIGATION DOWNSTREAM SCALE IN FEET S ETIOTNN - --TUNNEL

P ROCK RIVERSTUDYOFTHSWAT RED- - - REEVI -vARE CAAIYCRE /7~ ~ I t- I

1 CREST) _ _EL 1955 1 1- -

2F0ILOL'~~~~~~~~~190 EL 193391 a NIN NORN SPILLWPIiiIAY GATE SHAFIT P 300 ,ENOTECAI - & SEC SPILAY l'.000 0 lOGS 0GG PLAN FRO)MUNNUMBERED GWG GATES SEPT.2R. 1984 BAPOA.

K~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ABUL-SWAT-CRITRALBASIN , LASRER0880AXRGE PROJECTS NOTE SCALE 1. FEET A.RA.AR RIVER JGING SWAT RISER MAR NERBAL EL 2010' R300OFT UPSTREAM OF AXIS OF BAR AS EL22000 -_ J_ ERESERV6IR AREA B CAPACITY CURVES

CRESTELI05 - EL 933 MAX NORMALWS.EL O p, (CREST EL. 2010' EL -.933 -1020~~~~~~~~~~INNOMAROCK FILL

GROUTING -4 r --DRAINAGE ROCK FILL .1 SA RIVER BED t-CREST AXIS 1 300± SECTION GROUTING -- JH IPRIU OEIITR I 700'! TO SPILL.WAY IETRTE.O PLANING N INVETERNATIONALC 20O o 1oD400~~~~~~~~~~~CRS CAXS. MASS. U...AGUT 6 NOE SCALE FEET IN CRESTN ORIGINAL GROUND SURFACE AT t. OF CHANNEL 5 08 0 00 IO SECTION A- A ASW& ------MAR NORMAL _ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~I - a -4 -. - - - SCALE IN FEET4000

r .~~~~~~~. ,5~~~~S00000 SCALE IS FEET

ROCS STEDT OF TRE WATER 0N00 POWER RESOURCES~ OF REST PAR STAN COMPREHENSIVE REPORT

SPILLWAY PROFILE RXIVERAM HR DM POJC SCALE It- 200' PLAN & SECTIONS 200 V 200 400 INC. ______~~~~~~~~~CHAS.T. MAIN INTERNATIONAL, SCALE IS FEET BOSTON, MASS. U.S.A. AUGUST, 1966 IBRD-1997R JUNE 1967

STUDYOf THE WATERAND POWERRESOURCES VOLUME III OF REST PAKISTAM COMPREHENSIVEREPORT ANNEX 4-FIGURE 4

ESTIMATED CONSTRUCTION COSTS

SKARDU DAM - 5. 2 MAF Capacity (ASSUMED 200 FOOT DEPTH TO BEDROCK)

UNIT UNIT TOTAL TOTAL TOTAL I T E M QUANTITY UNIT PRICE PRICE Rs EQUIVALENT

STRIJCflRESAND0 IMPOEIVD4EJI ConstructionAccess Road 303 mi. - - 26,000,000 2511,000,000 79,361,000 Constructionl C-lp- - - j,00$,000 .3,0L0S00 20,030,000 SOB TOTAL. 37,000,000 297,000,000 00,300,000

DIVERSIONMID CCOITROLOF WATER Earth Fill 1,000,000 U.p. 0.95 16.10 1,330,000 5,7O0,000 2,536.000 R,prap 66,000 ED.y 2.20 5.60 1169,000 3,000 229.000 E.UR-t0 -, E-rth-DinRr.iRR CIt-flI 3.671,000 c.p. 0.916 0.10 3,057.000 IS.OSI,0OO0 6.609,000 P.ap,.g Syst.., I.stRIIREtRIIAnd OprIatIoS L S. .. 95.000 5,650.000 1.282.000 SUB TOTAL 5,061,000 26,822,000 10.696.000 DAM4MID WATERWYS SPILLWAYDAM4 EcOU-taiO.. E.rth 9.076,000 C.Y. 0.90 0. 10 0,622.000 37.212,000 16,000,000 B at 8tl.36.000 c.0. 0.25 0.60 200,000 41616000 297,000 Foan.dAtio:nCot-'off Drilling and GroAting 0.600 1.1. 5.50 03.00 07,000 370,000 125,000 Foandat,on Prop... t.ofl 07.800 .. Y. I 15 1.75 50.000 60,000 73,000 CORrcrAt, WeRir and Bucket 2.580,000 opY. 7.00 30.00 18,086.000 77,520.000 30,370,000 Concrete, PiRra 60,000 C Y. 9.00 tO 00 500.000 2,4000.000 1,040,000 CO...rRt..Bridge 2.600 c.o. 20.00 60.00 52,005 200,000 90,000 Fo.- 2.073,000 RIf. 0.00 1.90 029.000 ,0.02.000 1,670,000 ORintoOrUIng,StoaIl 6,6800.000 l-b. 0.11 0 la 966.000 1,060,00 1,301,000 JoI A SRAl. Onr.... I,S: - 65,000 60,~000 78,000 MlcIUIIr:OROAStRRI 106,000 l b. 0,25 0,05 25,000 05,000 30.000 SpillARy O.tRa and Hoists 10 Each - - 3.700,000 2.005,000 0,256,000 SIu UR Teat And Hoiats 6 E-1, 8 ,052,000 7,113,000 10.306.000 ORI, Sop Poop L.S. - 00,000 100,000 121.000 En,RrgenUyStoptLO:o LS.$.- 300,000 250.000 353.000 Po rY and Lightin LO.S - - 150,000 300,00$0 213.000 SOB TOTAL 02,602,000 130,351,000 70,629,000

SPIL.LWAYTRAINING WALLS "Eacoal. Earth 2,907.000, C-y 0,95 0.10 2.762,000 11,919,000 0. 266,000 ack tnI;,Eart 650,00 U..Y. 0.25 0,80 213.000 662,000 356.000 FoAnda.ioR Propralo 990 a , 15 1.75 11,000 17,000 15,000 Concrete, MOss 510,000O U.n. 9.00 40000 4.626,000 20,560.000 8,900,000 For... 096,000 aUf. 0,40 I 95 199,000 971,000 003.000 Jolta SRsIs and OralosL,, - 35,000 25.000 00,000

SU8 TOTAL 7.806,000 30. 170,000 15,025,000

NOR1THBULKHEAD E.coRvtl, Earth 5,0630,000 n.Y. 0,90 0,10 5,309,000 23,063,000 10.196.000 Bath,oill 12,2.000 coY. 0,25 0.80 256.000 820,000 428,000 FoundAtOo. CUt-Uff. Drilling end Grouting 5.0100 1,f, 5.50 03.00 30,000 232,000 79,000 FoondRtioo FraporAtinon15~~,, 800 a.Y. 1.15 1,75 1000 28,000 20.000 Cocrote ,09,000 op .00 0.00 9,001,000 t3,560.0000 18,952,000 CFo- 669,000 af 0 t0 1.95 276.000 1,340.000 558.000 Jont,R lsad. Drama LO. - - - 00,000 30.000 52,000 MiRUIC oR atStI L.S. - - - 200,000 170,00 236,00 S08 TOTAL 15.975.000 09,272,000 30.528,000 SOVJIHBUJLKHEAD E$Uaoat 'On' Earth 2,370,000 op,. 0,95 0.810 2,256.000 9,730,000 0.302,000 BaUhfili 1.069.000 co. 0.25 0.80 272,000 671,000 055.000 Found:tion Cut-off. Drilling and Grouting 3,600 1.f. 5.50 03.00 20.000 155,000 03,000 Foonrdaton P-ap-rtion 11,700 a n I Is 1.75 13,000 20.000 17,000 Con.r.tR 901.000 C Y. 9,00 000 R,O,00 00,000,000165, 0001 ,60000 Fornin 603.000 U.n 0.00 1,95 277,000 ,351.000 561,000) Jont., SealR and OraloiL0 - - 00,000 35,000 02.000 MIac.lla-ous Steel L.S - - - 200.000 170Z,000 236,000

SU8 TOTAL 11,192.000 00,380,000 21.356,000 EARTHBIBANIO4ENT Eocaoation. St,opping 321,000 c,n. I 25 0.00 400000 128,000 07.000 RolleddFIll, lerv,oA- 5,150,000 CoY. 1,20 2.00 d.700,000 10,308,000 8.606.000 OoldFils,pIenrOiou. 817.000 c.p. 1.65 2.75 1,308,000 2,207,000 1,820,000 Random Fu, 707.000 U..n. 0,25 0,80 187,000 598.000 313,000 FiIURF Matarlal 307000 ..Y. 2 00 0,00 8600,000 1,388,000 1,160.000 Rlprap 236,000 U.n. 2.20 5.60~~~7 519.000 1,322.000 797,000 DooOR'treaa,Slope Protectio. 76,0000 sn. 0,35 3.75 27.000 285.000 87,000 Draloag,. ,,,LO.S - - 190.000 280.000 209,000 OroUt. otI 315,000 o f. 5 50 03.00 1,733.000 13,500.000 4.579.000 SUBTOTAL 11,612,000 30,101.000 17,938,000 SPILLWAYCIWINEL Eoca-at-o, Earth 23,093,000 C.Y. 1.00 3,00 33.169,000 80.553.000 50,092,000 R,prap 00.000 .pY. 2.20 5,60 1412,000 35B.000 216,000 008 TOTAL 33.310.000 B0,911.000 50,30B.000 CGI8CT OOSTS 160.598.000 721.01000 316,:075,000 PRECGIrRCTCOSTS 5,000,000 29,003'6,000 11100.000 COIRTIRGENICIES 01,6000.000 269,010,000 98.200,000 ENGINEERINGMID AIO41NISTRATIGN 10,100,000 10,720,000 30,000,000 INSURANCEMIDPERFOIN4MCE WIND0 10,700.ODO 10,700,000 LMIDAND RESErrLEIENT -_ Ij7A500.O0 39~,000,000 TOTALCGISTRUCTI COdST 236.000,000 1,201,731,800 509,000,000

NOTE: The total cost here excludes Pakistan taXes, duties, etc. , estimated to be U.S. $85. 0 million, equivalent , and interest during construction estimated at 6%. to be $176.8 million, equivalent. with foreign exChange component of U.S. $81.4 million, equivalent. MARCH 1967 IBRD-1995

STUDYOr THE WATERMD POWERRESOURCES VOLUME IlI OF WESTPAKIST O CONPRERENSIE REPORT ANNEX 4-FIGURE 5 ESTIMATIED CONSTRUCTION COSTS

SKCARDU DAM - 8. 0 MAF Capacxty

(ASSUMED 200 FOOT DEPTH TO BEDROCK) T ~~~~~~~~~~~~~TOTAL UNIT UNRIT TOTAL TOTAL EQUIRALENT ITEM QUANTITY UNIT PRICE PRICE Rs $

STRUJCTURESANDIHPROVB'2fS 7,6,0 Constroctien Acce.. WRad 3i43 Wi, - 26.000.000 2514,000.0000 0 7,0,0 ConstructIoCaap L S. L.0S. - - 11.000.000 AL$-QL9 O 20.034.000 SU8 TOTAL 07,000,000 297,000.000 99,395,000

DIVERSIERNAND COllOL OFWATER Earth Fill i,5aR,DOO ..R. 0.95 4.10 1,560,000 6,010,000 2,929,000 Riprap 77,000 C.Y. 2.20 0.60 173,000 1431,000 2614,000 E-ac-tlon, Earth, Dlverlon- Channe 3,671,000 Eq.- 2.95 4.10 0,407,000 15,001,000 6,649,000 Pueplog System, Installationand Operatian L S. L.S. - - 95...00AO 6.1500000 1.387,000 SUBTOTAL 0,315,000 20,147,000 11,229,000

DAMAND WATERWAYS SPILLWAYDAM ExEc-ation, Earth 0,400,000 c.o. 0.05 4.10 6,959,000 38,603,000 17,081,000 Reckfill, Earth 830,000 ..Y. 0.25 0.00 209,000 018,000 297,000 Foudation Cut-aft, Drilling and Orau.ting 96,000 1.f 5 50 43.00 47,000 370,000 125,000 FoundatiRn Preparation 04,000 eqY. 1.15 1.75 59.000 89,000 78,000 CUncreta Weir and Bucket 3,145,000 ..Y. 7,00 30 00 22,015,000 94,350,000 44,836,000 Concre.te,Piara 64,500 cey. 9.00 40.00 554,000 2,464,000 1,072,000 Cancrete, Bridge 2,600 c.y. 20,00 80.00 52,000 208,000 96,000 For- 2,307,000 s.f. 0.40 4.95 923,000 0,099,000 1,8600,000 Reinforcing StacI 9,800,000 Ib. 0,11 0.18 900,000 1,064,000 1,001,000 Joints, Deals and DraIns 1.S. - - - 70,000 65,000 04,000 Miscellaneous Steel 100,000 lb 0 25 0,45 25,000 45,000 34,000 Opllos.y Gate And Rolats 14 Each - - 3,700,000 2,005,000 4,250,000 Slulcenay Gates and Haista 0 Each - - 8,652,000 7,113,000 40,340.000 ia11ery Dump. Niscallaneou. Equipmen.t LUS. L.S .- '- 00,000 100,000 121,000 Emergency StRp Logs L.S. L.3 - - 300,000 250,000 353,000 Po..rand Lighting L S. L.S. I10.000 300,,000JfQ 213,000 DAB TOTAL 46,963,000 153,163,000 79,101,000

SPILLWAY TRAINING WALLS E.ccaatlRn, Earth 2,907,000 cfy. 0.95 4.10 2,702,000 11,919,000 5,206,000 BacfIl 853.0D0 c.y. 0.25 0,80 213,000 682,000 356,000 Fou.nda.tIonPreparatlRn 9,900 s.Y. 1.15 1,75 44,000 17,000 15,000 Concrte 514.000 c.Y. 9 00 40.00 4,626,000 20,560,000 8,905,000 Forma, 400,000 s.f. 0 00 1.05 199,000 971,000 403,000 J.alnts,Seals end Drains LO.S - - 40,000 30.000 4,990QQ DUB TOTAL 7,851,000 34,179,000 15,031,000

NORTHBIULKHEAD Eaca-atIan, Earth 5,900,000 cfy. 0.95 4,10 5,610,000 26,190,000 10,692,000 BackfIll 1,255,000 c.Y. 0.25 0 80 344,000 1,004,000 525,000 raundatnt Cut-olf, DrIlling and GUrouting 0,000 1,f. 5.50 43 00 35,000 274,000 92.000 Feundotien Praparation 10,600 s.p, I is 1.70 22,000 33,000 29,000 Concrete 1,442,000 c.y. 9.00 40.00 12,970,000 57,000,000 25,090,000 Fares 090.000 g... 0 40 1.95 350.000 1,730,000 721,000 Joints, Deals and Drains L 0. - - - 50,000 40,000 58,000 Nlacellon-eaa Steel 1.0. - - 200.000 170,,,l090 230,000 SUB TOTAL 19,505,000 85,424,000 37,449,000

SOIT BULKHEAD occtc,Earth 4.107,000 u... 0 93 6.10 3,002,000 10,830,000 7,440,000 aeckOllI ~~~~~~~~~1,862,00c .y. 0,25 0.00 474,000 1,506,000 787.000 Feudatlen Cu-.f, Drilling and Oretieg 4,700 I.f. 50 43.00 20,000 202,000 00,000 Foundatlen, Prepra,tien 40, 700 mY. I It 1.75 19,000 29,000 25.000 Concrete 1,441,000 upy. 9.00 40.00 12,909,000 57,600,000 25,078,000 Forms 940,000 a.f. 0.40 1.95 378,000 4,045,000 766,000 Joits, Seal. and Drains 1.23 50,000 40.000 58,000 Nlscollane..us Steel L.3. - - -200,000 170,000 236.000 S0B TOTAL 18,015,000 78,271,000 34,450,000

EARTHS4OAN4EfS (INCLUDEDSADDLE DAO) Eo...c-tlon, Stripping 509,000 c.y. 4.25 4.00 711,000 2,270,0001,000 RolledFill, Per-ieu 7,910,000 c.y. I 30 2.00 10,283.000 15,820,000 13,007,000 RolledFill, lmpervleua 4,089,000c.y. 4.65 2.75 1,797,000 2,995,000 2,426,000 RandomFIll 543,000 c.y. 0.25 0 s0 420,000 410,000 214,000 FilterNAtrIal 466,000 c.y. 2,50 4.00 4,405,000 4,864,000 1,557,000 Rlpr.p 329.000 c.p. 2 20 U to 724,000 1.842,000 1,411,000 Deonstremi Slope Pret-ctien 102,000 s.y. 0.35 3.75 36.000 283,000 116,000 Drainage 1.S. - - - 200.000 300,000 203,000 GroutCurtain 300,000 a.f. 0.50 102.00 4.980.000 58,320.000 14,232,000 SU8 TOTAL 17,024,000 04,210,000 34,715,000 SPILLWAYCHANNEL E-acatloe, Earth 23,330,000 c y. 1.40 3.40 32,673,000 79,249,000 49.343,000 Riprap 64,000 cfy. 2.20 5.00 161.000 ,58,000 21,Aj000 SUB TOTAL 32,014,000 79,707,000 49,559,000

CONTRACT COSTS $484,567,000 Rs 839,801,000 $360,994,000 PRECOONTRACT COSTS 5,500,003 12,300,GO0 CONTINGENCIES 47,000,000 108,300,000 ENIGINEERINGA11D ADHII8ISTRATION 40,700,000 37,500,000 INSURANCEA140 PERFOWIASNCL 80N0 10,900,000 40,800,000 LAND AND RESETTLEMENT _____ 58.100.000 TOTAL CONSTRUCTION COST $204,700,000 $588,094,000 NOTE: The total cost bore excludes Pakistan taxes, duties, etc. , estimated to be U.S. $95. 0 million, equivalent, and interest during construction estimated at 6%, to be $200.06 million, equivalent, witb foreign excbange componenit of U.S. $00.0 million, equivalent. MARCH 1967 IB8RD-1996

ANNEX 5

AM'AHAR PROJECT

ANNEX 5

LIST OF FIGURES

1. Ambahar Dam Project: Plan and Sections

ANNEX 5 Page 1

AMBAHAR

Introduction

Review of the limited information available on the Swat Valley indicated that the most economical site for a dam is probably at Ambahar. In this location some 2 MAF could probably be stored and possibly a higher dam could be built to store an additional 4 MAF diverted from the Kabul or Chitral Rivers. Other sites may be equally attractive, however, and the entire gorge should be examined in greater detail during the feasibility stage of study.

Ambahar Dam site is in the Lower Swat Gorge, approximately 13 miles upstream of the Munda headworks and about one and one-half miles downstream of the mouth of the Ambahar River.

A rockfill dam, 710 feet high, has been proposed to store water to elevation 2000 feet (see Figure 1). The crest of the dam would be 10 feet above reservoir level. Gross capacity of the reservoir would be 2.84 MAF with a live capacity of about 2.00 MAF and the reservoir would cover 18,000 acres of land at full pool level. Cost of the project for storage features only has been estimated at $145 million, but the Bank Group believes that, in view of the uncertainties involved, a cost range of $145 to $215 million should be assumed. The project has been estimated to require six years to design and construct after all preliminary studies, access to the site and financing arrangements have been completed.

At present, the site is inaccessible by road, and neither WAPDA nor Chas. T. Main International, Inc. have carried out any investigations. Only generalized data on the area were available. Thus the problem of access must be overcome before on-site investigations can be performed, and no detailed analysis can be made until this point is reached.

The dam, to retain 2 MAF live storage with a crest elevation of 2010 feet and a conservation pool level of 2000 feet could be filled by the Swat flows alone and would affect little valuable farmland. The high dam, however, with a crest elevation of 2186 feet, would receive two-thirds of its water by diversion from either the Kabul or Chitral Rivers and would submerge some of the most productive farmland in the valley, according to WAPDA.

Status of Pro.ject

Reports published by WAPDA in 1964 and 1965 on possible dam sites in the basin and the geology of the region provided most of the information available on the site. Also at hand were Survey of Pakistan G.T. Sheets at a scale of 1 inch to 1 mile with 50-foot contour interval and aerial photographs at 1:40,000 scale. Geological information at the site was confined to what was derived from interpretation of topographic ANNEX 5 Page 2 maps and airphotos, from aerial reconnaissance, and from ground reconnaissance in adjacent areas. Whereas aerial reconnaissance was undertaken, it was not possible to visit the site on the ground.

Geology

The rock formations in the Lower Swat Gorge were described in the WAPDA report as being composed predominantly of calcareous schists, with subordinate members consisting of phyllites, granitic schists and granitic gneisses. The rock formations are thinly bedded in general with micaceous partings and weathered bedding planes. Steep slopes have prevented heavy overburdens. Major faulting at the site is not apparent. The foundation appears, therefore, suitable for constructing a high rockfill dam. Topographic features are favorable for an arch dam, but considerable investigation of the bedrock and design study would be required to determine structural feasibility. Materials for a rockfill dam would be obtained by quarrying rock in the adjacent hills. Impervious materials for the core would be imported, either from the Swat Valley or from the Vale of Peshawar.

Hydrology

Runoff from the Swat River in the summer flood season is almost entirely from snowmelt and is seldom affected by the monsoon rains which rarely fall on the Swat watershed. The river stage begins to rise at the end of February and reaches maximum seasonal discharge toward the end of June, whereas the Indus at Tarbela does not peak until late July or August.

Water presently is diverted from the Swat to irrigate lands of the Vale of Peshawar. In the future, these diversions will increase as will the requirements for Swat water in the lower reaches of the Indus system as the development of agriculture proceeds. It was estimated that, under mean-year conditions at full development, all flows would be required to fill downstream demands until June, when impounding could begin. About a three-month period would be available to fill the reservoir.

It was estimated in the WAPDA report that the Swat River has a nine-year mean annual discharge at Munda headworks of 6.118 MAF. Future additional withdrawals in the Panjkora Valley and at the Amandara headworks are expected to reduce the average discharge to about 4.758 MAF. Of this amount IACA estimates 2.0 MAF will be available for storage in mean-year flows. The sediment carried by the Swat River was estimated to be about 0.001 MAF per year.

Site

Ambahar Dam site is in the Lower Swat Gorge about 13 miles upstream of Munda headworks and about one and one-half miles downstream of the mouth of Ambahar River. It is representative of sites in the Lower Swat Gorge and was selected for study because the reservoir would flood a minimum of settled and farmed lands and at the same ANNEX 5 Page 3

time provide adequate volume of storage apparently at about the same costs as alternative project sites at Munda, Baragai and Kalangai. These other sites may be as good or better than Ambahar and should be studied before final selection is made.

The terrain is extremely rough and mountainous, and the site is presently inaccessible by road. An access road would have to be constructed before site explorations could be made. Apparently the best route would follow the course of the river from Munda headworks.

Proposed Design

The major characteristics of the Ambahar Project are outlined below.

Table 1

Ambahar Project Statistics

Reservoir

Gross Volume at Elevation 2000 feet 2.84 NAF Dead Storage Volume at Elevation 1760 feet 0.72 MAF Reservoir Area at Full Pool 18,000 acres Drainage Area 5,365 square miles Average Annual Rbunoff at Site 6.1 MAF

Dam

Rockfill with Impervious Earth Core Height above Streambed, approximately 710 feet Crest Length 850 feet Crest Elevation 2010 feet Riverbed Elevation 1300 feet

Spillway

Abutment Overflow Number gates 12 each 40 feet high x 40 feet wide 310,000 cusecs Outlet Works Two 34-foot diameter concrete-lined Tunnels for diversion. Each later equipped with Penstocks and 96-inch Howell-Bunger Valves for Outlets Discharge Capacity at Reservoir Elevation 1790 feet 14,000 cusecs Table 1 continued on next page. ANNEX 5 Page 4

Table 1 (cont' d)

Power Plant

Six Turbine-Generator Units:

Turbines - 100,000 hp Francis-type @ 600-foot head

Generators - 75 mw @ unity power factor with capability for 15 percent ccntinuous overload

The 2.84 NAF gross storage reservoir would inundate very little inhabited and farmed land. However, an 8 MAF reservoir, studied briefly in connection with storing imported water, would flood a considerable area of good farmlands and a large village. Protective works would be required at the Amandara headworks.

The gorge at the Ambahar site is very narrow, measuring only 100 feet wide at the bottom and 850 feet wide at the crest. The dam would be of rockfill construction containing an impervious earth core with suitable filters. The bedrock formations would be grouted as necessary to ensure safety of the structure. Since the site is in a region subject to earthquakes, seismic forces would be considered in the stability analyses of the structures when final designs were made.

On the basis of present sketchy information regarding the site, a much higher dam than proposed here apparently could be constructed should it be decided that a scheme for the diversion of water from the Kabul and Chitral Rivers were feasible.

The spillway proposed for the project would be an overflow structure on the left abutment. The topography of the site is such that excavation for the spillway would provide a source of part of the rock for the dam.

The spillway would consist of a gate structure, a concrete chute and a stilling basin. It would have a capacity of 350,000 cusecs, the maximum probable inflow flood as estimated by WAPDA.

The two concrete-lined tunnels, each about 4,000 feet long, would be required to handle flows while work on the dam was in progress. They would have a diversion capacity of 35,000 cusecs. Later, they would be converted to outlets for normal operation through the installation of steel penstocks and outlet valves.

A power plant for Ambahar was not designed because the project probably would not be constructed until later in the program for the development of surface water storage and because further studies must be made before optimum utilization of the site can be determined. However, ANNEX 5 Page 5 the power and energy potential for one set of assumed operating conditions was evaluated and will be presented in the following section.

Although the storage scheme would undoubtedly affect some of the temporary headworks located downstream, the necessary improvement of these facilities was not studied.

Operation

Water would be released from storage in a pattern that would best suit system storage releases for generation of power, subject to downstream irrigation requirements on the Swat. The remaining flows would be integrated with the Indus requirements. At full development, the operation of Ambahar is expected to approximate the pattern indicated in the following table for years of average flow.

Table 2

Operating Regime for the Ambahar Project at Full Development (MAF)

PRESENT FULL DEVELOPMENT Outflows Month Inflows Inflows River Stcrage a/ Total

Oct. 0.149 - - 0.030 0.030 Nov. 0.100 0.011 0.011 0.160 0.171 Dec. 0.091 0.043 0.043 0.220 0.263 Jan. 0.067 o.o58 0.o58 0.420 o.478 Feb. o.084 0.055 0.055 o.49o 0-545 Mar. 0.284 0.242 0.242 0.380 0.622 Ppr. 0.615 0.5o4 0.504 0.200 O.704 May 0.902 o.734 0.73h 0.100 0.83h June 1.095 0.897 0.897 (+)0.779 0.118 July 1.437 1.284 1.284 (+)1.191 0.093 Aug. o.868 0.717 0.717 (+)0.150 0.567 Sept. 0.426 0.213 0.213 0 0.213

Total 6.118 4.758 Evaporation (-0.120) 4.638 a/ Based on a release pattern similar to that for Tarbela.

Since the sediment carried by the Swat River is estimated to be about 0.001 MAF per year, the usable storage capacity of the reservoir would have an extremely long life.

The greatest value of the Ambahar power plant would probably be for peaking purposes, but a reregulating reservoir at Munda would be required. A power plant at Munda reregulating reservoir operated to provide uniform daily discharges might be feasible. ANNEX 5 Page 6

Since the Ambahar Project most likely would be constructed later in the development program at a time when the needs of the power system will be different from those which can be foreseen at present, no calculations were made of the power potential. However, in order to indicate the potential of Ambahar for power a study was made based on a 2.84 NAF gross capacity reservoir with releases of water from storage in accordance with the pattern adopted by the power consultant in the study of power generation at Tarbela. The size of plant was determined by judgment without benefit of economic study and without studying the merits of operating the plant for peaking power. The figures thus derived provide an indication of the power capability at the site. It can be seen from the table below that the monthly power capability would range from about 20 mw to more than 400 mw and that the potential annual energy output would be nearly 2 million mwh.

Table 3

Ambahar Project Power Potential

Based on assumptions:

a. gross reservoir volume 2.84 MAF (2.72 after evaporation) at elevation 2000 feet;

b. dead storage 0.72 NAF at elevation 1760 feet;

c. effective tailwater elevation (including allowance for friction loss) 1305 feet;

d. six Francis-type turbines, each rated 100,000 hp at 600 feet head;

e. six generators, 75 mw rating at unity power factor with capability for 15 percent continuous overload.

Table 3 continued on next page. ANNEX 5 Page 7

Table 3 (cont' d)

Plant Estimated Capa- Future Gross Dis- bility Thous. River Releases Con- charge mw mwhr Inflow Storage Total tent Level Head cusscs 100% Thous. spil- Month (MAF) (7.)a/ (MAF) (MAF) (MAF) Feet Feet xlO lf mwhr led

2.72 2000 Oct. 0 1+ 0.03 0.030 690 o.49 20 16 2.69 1990 Nov. 0.011 8 0.16 0.171 680 2.87 149 95 2.53 1980 Dec. 0.043 11 0.22 0.263 668 4.27 234 138 2.31 1965 Jan. 0.058 21 0.42 0.478 642 7.80 434 245 1.89 1930 Feb. 0.055 25+ 0.49 0.545 598 9.83 425 287 ~~ 1~~.40 1877 c/ c/ Mar. 0.242 19 0.38 0.622 544 10.13 400oc 242- 25

Apr. 0.504 10 0.20 0.704 1.02 1820 495 11.83 306-197 75 0.82 1780 May 0.734 5 0.10 0.834 465 '13.60 2682/19 / 118 0.72 1760 June 0.897 0 (+)O.78 0.118 520 1.98 79 50 1.50 1889 July 1.284 0 (+)1.19 0.093 634 1.51 75 47 b/ 2.69 1989 Aug. 0.717 0 (+)0.15- o.567 689 9.23 477 310 2.72 2000 Sept. 0.213 0 0.213 2.72 2000 695 3.58 185 121

Total 4.758 4.638 1938 218

a/ Similar to Tarbela release pattern. b/ For evaporation losses. c/ Generation limited by water capacity of turbines.

Program for Construction

Following completion of site investigations to the definite plan stage, completion of an access road and staff quarters, and after financing of the project had been arranged, a minimum of six years would be required to design and construct the Ambahar Project. ANNEX 5 Page 8

Cost Estimates

The cost estimates for Ambahar Project were based on tentative designs and, since neither the quantities nor the site conditions affecting costs were known accurately, are only approximate.

On the basis of information supplied by WAPDA, land and resettlement costs for the reservoir with water surface at 2010 feet with little good farmlands being inundated, was judged to be about $1000 per acre.

World market conditions and prices of labor and materials in West Pakistan as they existed in July 1964 were used as a basis for the cost estimates.

The cost estimated by Chas. T. Main of the Ambahar Project for a 710-foot high rockfill dam to provide 2 MAF net storage yield is $145 million, exclusive of provision for inflation, financial contingencies, Pakistan duties and taxes and interest during construction. The makeup of this cost is shown in Table 4 below.

As in the case of other potential dam projects, the Bank Group assigned a cost range to suggest the degree of uncertainty involved in the evaluation of the project at this time. The cost range for Ambahar, predicated on the fact that the site had not been visited on the ground and that only generalized information about the area exists, was fixed at $145 to $215 million.

It must also be borne in mind that a dam at the Ambahar site would probably require the improvement of downstream diversion works, and the costs of such improvements should be included in the cost of the project. In addition, protective works would be required at the upstream Amandara headworks if the larger dam of 7 MAF gross storage to accommodate diversion water were constructed. ANNEX 5 Page 9 Table 4 Ambahar Dam Estimated Costs Crest Elevation 2010 Feet US$ Equivalent Unit Item Unit Quantity Price Total

Diversion and Care of the River - L.S. 5.oo00,ooo Diversion Tunnels and Gate Shafts Excavation Rock cubic yards 420,000 19.00 8,000,000 ooncrete in Lining and Intake cubic yards 78,000 40.o0 3,120,000 Steel, :ieinforcing tons 1,700 450.00 765,000 Grouting cubic feet 48,000 7.00 336,000 Gates, Hoists, Rails, etc. tons 1,025 2,200.00 2,255,000 Steel, Lining tons 1,000 1,000.00 1 000 000 Subtotal T-75oo

Dam Foundation Preparation square feet 12,500,000 0.50 6,250,000 Grouting, Foundation Rock cubic feet 375,000 7.00 2,625,000 Impervious and Filter iMaterial cubic yards 4,000,000 3.15 12,600,000 Rockfill (select) cubic yards 825,000 3.50 2,880,000 Rockfill (largely from req'd exc.) cubic yards 7,200,000 3.00 21,600,000 Subtotal 45,955,000 Outlet Works Rock Excavation cubic yards 1.40,000 4.00 560,000 Concrete cubic yards 5,500 45.00 248,000 Steel, Reinforcing tons 75 450.00 34,000 Valves,(2-96") and ApPurtenances - L.S. - 220,000 Crane _ L.S. - 15,000 Steel, Tunnel Lining tons 1,000 1,000.00 1,000,000 SuUtotal 2,077,000 Spillway Crest Structure (incl. gates & hoists) - L.S. - 4,862,000 Rock Excavation cubic yards 7,000,000 1.50 10,500,000 Concrete, Channel Lining cubic yards 60,000 35.00 2,100,000 Steel, Reinforcing tons 350 450-00 158,000 Subtotal 17 620,000 Total Contract Costs 66128,000 Investigation 4,600,000 Contingencies 27,072,000 Eigineering and Administration 9,200,000 Land and Resettlement 18,000,000 Total Investment Cost a,/ $145,00,000 a/ Excluding Pakistan duties and taxes and interest during construction. ANNEX 5 Page 10

Additional Investigations Required

The existing data available for studying the Ambahar Project were completely inadequate for preparing designs, determining the economic size of structure and preparing accurate cost estimates.

Hydrographic work started in the river basin should be continued and expanded. The flows of the Swat River at Amandara headworks and the diversions to the Upper Swat Canal need to be known more accurately. Discharge measurements of the Panjkora River should be continued. Discharge measurements at Munda headworks should be accurately and systematically measured as should be discharges of the Swat River at Kabul. Sediment sampling should be systematic and complete at all sites.

Accurate measurements of all canal diversions from the river from Amandara headworks downstream to the mouth of the Swat River are required. Systematic studies of the areas being served by the several canal commands should be made periodically to update estimated future needs for surface water when the lands are brought to full development.

Investigations should be carried out to the extent necessary to select the optimum site for storage in the Lower Swat Gorge and then that site should be investigated sufficiently to determine its feasibility. Studies should cover the complete range of reservoir sizes likely to be needed, including study of storage space for imported water. The preliminary investigations should include study of surface geology of the site supplemented by subsurface explorations as needed to define fully the problems of design. Sources of materials should be located. Studies should include consideration of the site selected for various types of dam structures.

The site is in extremely rough, mountainous terrain and is presently inaccessible by road. This problem of access should be studied in considerable detail as should the location for an operator's colony.

The power aspects should be studied from the standpoint of load forecasts, etc., at the time.

Since access to the site is such a problem and since many investigations must be undertaken, the program should be initiated well in advance of the time when the project is expected to be needed.

Diversion Schemes

Chas. T. Main reviewed two schemes proposed by WAPDA for diverting water from other rivers for storage on the Swat. The first would involve diversion of about 4 MAF each year from the Kabul River at Warsak Reservoir and the second, transmountain diversion of the same amount from the Chitral River at the proposed Mirkhani Dam site. ANNEX 5 Page 11

The total storable volume of water in the future on the Kabul River at Warsak probably will be on the order of 5 to 6 MAF per year and 3 to 4 MAF per year on the Chitral at the proposed Mirkhani Dam site. The timing of diversions and the amounts of water that could be diverted would be governed by flow conditions existing on the Indus River at Attock and irrigation requirements downstream therefrom as well as the demands of the lands commanded exclusively by the Kabul and Chitral. Thus, water would be available for storage from the Kabul or Chitral for not more than about 60 days in years of mean-year flow. Diversion structures, including pumping plant, necessarily must be designed for these conditions.

Warsak Diversion Scheme

Diversion of 4 MAF in a 60-day period would require facilities to handle a flow of at least 34,000 cusecs. Studies of the pumping operations undoubtedly will require a larger diversion capacity. Ambahar Dam would be increased in height to crest elevation 2186 feet from elevation 2010 feet to provide a gross storage volume of 7 MAF.

Under the diversion plan proposed by WAPDA, water would be diverted from Warsak Dam through a 2.5-mile long tunnel and a 16-mile long canal to Swat River. From the end of the canal, water would be pumped about 100 feet in elevation into a reservoir formed by a dam at the Munda site. Minimum operating water surface in Munda Reservoir would be elevation 1324 feet. The reservoir would extend to the foot of Ambahar Dam where reversible pump/turbine units driven by reversible motor/generators would lift the water into Ambahar Reservoir. Maximum total pump lift at Ambahar Plant would be about 860 feet. Power would be generated by the reversible units as water were released from the reservoir.

When flows in the Indus River at Attock exceeded irrigation requirements downstream of Attock, the diversion-storage system would be operated by stopping flows in the Swat River at Ambahar Dam and replacing the flows needed to supply canals on the Swat River below Ambahar by water released from the Warsak Diversion Canal. The remaining water in the canal would be pumped into Ambahar Reservoir. This type of operation would minimize the power needed for lifting water into Ambahar.

Average flows of the Swat at Munda headworks, expected future irrigation withdrawals at and below Munda headworks under the sole command of the Swat and the water to be pumped into storage at Ambahar are shown in the following table. An allowance of 25 percent above. estimated irrigation canal withdrawals is included in the flows released from the Warsak Diversion Canal. ANNEX 5 Page 12

Table 5

Water Pumped to Storage in Ambahar Reservoir (MAF)

Future Demands Approx- Average of Swat Releases imate Flow Canals from Storable Diverted at Munda Below Warsak Flows Water Month Headworks a/ Ambahar b/ Diversion at Swat Pumped

May 0.734 o.432 - - June 0.897 o.498 0.624 0.897 1.80 c/ July 1.284 0.386 0.482 1.284 1.60 August 0.717 0.389 o.485 0.717 1.60 September 0.213 0.536 - - _

Average Swat Yield 2.90 4.00

Firm Swat Yield 2.0

a/ Based on WAPDA figures for a nine-year average flow at M.nda minus future uses upstream estimated by IACA in January 1965. b/ IACA estimates of January 1965. c/ Assumed to be all the storable water available in June.

On the above basis the pumping facilities would need to be capable of handling a continuous flow of about 27,000 cusecs during the reservoir filling season.

A pumping plant at Ambahar of approximately 3,200 mw capacity and one at Munda of approximately 450 mw capacity would be required to pump the 27,000 cusecs of water at maximum head. The maximum load on the power system for pumping would be about 3,600 mw.

Obviously the power system of West Pakistan will not have, in the foreseeable future, capacity to handle such a short-season load. The cost of providing special power facilities for the pumping would be very high. The project, therefore, appears to be infeasible for the foreseeable future at least and its cost, therefore, was not estimated.

Although not studied, a more probable alternative Warsak Diversion Scheme would be to supply all the requirements for water from the Swat River downstream of Ambahar Reservoir by gravity diversions from Warsak during the storage period when the flows of the Swat River would be stopped at Ambahar. Between 0.7 MAF and 0.9 MAF additional water could thus be stored in Ambahar without pumping. The power plant would be shut down during the entire filling period, but at that season excess hydro power would be available elsewhere for system use. ANNEX 5 Page 13

Chitral Diversion Scheme

A transmountain diversion project was proposed by WAPDA and FA0 for transferring water from the Chitral River to the Swat drainage basin for storage. A dam 400 feet high at the Mirkhani site on Chitral River 12 mtiles upstream from the border with Afghanistan would impound a reservoir having a capacity of about 0.58 MAF at water surface elevation 4200 feet. A 23-mile long tunnel under Lowari Pass would convey the water to the Panjkora River at Chutiatan. The Panjkora is a tributary of Swat River entering the Swat at the head of proposed Ambahar Reservoir. Assuming all the water stored in the MErkhani Reservoir were available for diversion, a tunnel capacity of at least 30,000 cusecs would be needed to divert 4 MAF per year. The tunnel would be about 42 feet in diameter. If the water in Mirkhani Reservoir were not available for diversion through the tunnel, the tunnel would need to carry 34,000 cusecs or more. The same size tunnel as above with a steeper gradient would carry the water.

A head of more than 1,250 feet is available between the outlet of the tunnel and the water level in Ambahar Reservoir. Dumping 30,000 cusecs into the steep Panjkora riverbed at a season of year when it already is carrying flood flows might require construction of extensive protective works.

Generating power with the water diverted from Chitral River for storage at Ambahar utilizing the 1,250 feet of head available above Ambahar is not practicable because of the short season, but if water could be diverted from Chitral on a year-round basis, a power plant to utilize the1,250 feet of head then might be feasible. The diversion project for adding stored water supply' to Ambahar would require Ambahar Dam to be raised to the same height as described for the Warsak Diversion Project. Any diversion of water from Chitral, particularly during the low flow season, probably would require prior concurrence of Afghanistan.

No cost estimates were made of the Chitral Diversion Project, but judgment indicates the project does not provide stored water as economically as in storage sites available elsewhere in the Indus Basin. The project may have value in the future for replacement storage and water for power generation, however, and further study should be given at the time feasibility studies for Ambahar (or its alternatives) are underway.

VOLUME III ANNEX 6-FIGURE 1

EN:.,DE RO TADS SALOAQTO -40

D TYPICAL ROAD SECTION SLS-'s ..BOE004O. WAR.~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~NWOENADP0

PLAN LEGENP

j______PROACOSECA.STRACTlIl 00*0 5 M1.341 SCIALE SILAS

DISTANCE IN MILES

0- - - - - _ _ - - PRR -F ILIE A …-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~c #-hGENLRAL - ie-A--PLAN

R!PoTuED R;CAIG1 UPLi- PROJECT SITE

STUDY OF THE WATER AND POWERRESOURCES RECT, UNAl., E RO!T S^ ^L KUNHAIRRIVER PROJIECT OF WEST PAKISTAN I ,. T... .ITER"M DE- T "OW..t!l .i COMPREHENSIVE REPORT COAST AIAN ING BO1O 1R55

MARCH 1967 1IBRD-1998

ANNEX 6

KUNMAR PRCJECT

ANNEX 6

LIST OF FIGURES

1. Kunhar River Project: General Plan: Project Site

2. Kunhar River Project: Suki-Kinyari Dam: Plans and Details

3. Kunhar River Project: Capacity Curve: Suki-Kinyari Reservoir

4. Kunhar River Project: Paras Power Plant: Transverse Section

5. Kunhar River Project: Naran Dam and Intake: Plans and Details

6. Kunhar River Project: Suki-Kinyari Power Plant: Sections

ANNEX 6 Page 1

KUNHAR

Introduction Located in the Kaghan Valley some 40 miles north of Muzaffar- garh, the Kunhar River Project for hydroelectric power development was studied in 1959 and 1960 by Chas. T. Main for WAPDA. The full project proposed would develop 500 mw of power at a 58 percent annual load factor from more than 4,000 feet of fall in a 35-mile reach of the river. The studies showed that the first stage of the development for a firm capability of 198 mw could be completed in five years. A program extending over a nine-year period was suggested for bringing the project to full development, but the schedule could be compressed if necessary'.

The completed project would consist of two reservoirs and two power plants with power tunnels for conveying waters from the reservoirs to the power plants (see Figure 1). Naran Reservoir would be the upper storage structure on the Kunhar River. Water would be conveyed from Naran Reservoir through the Naran-Suki-Kinyari Power Tunnel to steel penstocks supplying water to three units in the Suki- Kinyari Power Plant located at the headwaters of the downstream Suki- Kinyari Reservoir also located on the Kunhar River. Water would be conveyed from the Suki-Kinyari Reservoir through the Suki-Kinyari- Paras Power Tunnel to steel penstocks supplying four generating units in the Paras Power Plant.

Suki-Kinyari Reservoir, the Paras Power Tunnel and Paras Power Plant with two units would be the first-stage development.

Status of Project The two reports by Chas. T. Main of 1960 and 1961 are the only known reports on the Kunhar River Project. During the course of these investigations, the foundations for the Suki-Kinyari Dam site and the Paras Power Plant site were explored by subsurface drilling and by the study of surface outcrops of bedrock for purposes of estimating depths and character of suitable foundation. Sub- surface conditions were not explored at the other structure sites.

The investigations were sufficiently complete to develop the project plan and to select sites for the structures. Additional explorations and investigations would be required during the design stage. Sketchy meteorological data were available for 1958-60 from the stations at Lohargali and Garhi-Habibullah.

Staff gauges were installed at Potandes and Naran in 1959. In 1960 the program for current meter measurements at Naran and Kunian, as well as river stage measurements at Naran, Kaghan, Kunian, ANNEX 6 Page 2

and Paras was instituted. In addition, snow courses were laid out at Lake Saifal Mulak, Naran, and above Kawai.

Measurements of the sediment content of the water were made at Garhi-Habibullah for the period January 1955 through December 1957.

Geology

The Kunhar River is entrenched in a v-shaped valley with steep side slopes. The topography of the entire basin is steep and mountainous. Soil cover is generally shallow, and a large portion of the basin is exposed rock.

The bedrock formations of the region are predominantly gneisses and schists underlying varying depths of boulders, gravel and fine grain soils of glacial origin and talus from weathering of the adjacent mountains.

The Suki-Kinyari Dam site has steep slopes, few outcrops, and a deep overburden containing gravel and fine grain soils of glacial origin, talus from the adjacent mountains and many large boulders. The overburden is relatively impermeable, and the bedrock is largely crumpled and fractured but strong. Subsurface explorations suggested the presence of weak zones which might require considerable treatment for reduction of water seepage.

The dam site is in a "very active" seismic region. Therefore, a factor of 0.1 g was added to the active forces on the dam in the design for stability.

The site for the Paras Power Plant should present no unusual construction or design problems. The overburden is deep; bedrock is about at river elevation under part of the terrace. Overburden material should be impermeable enough to permit cofferdamming by leaving a rem- nant of the terrace between the excavation and the river. Bedrock is highly fractured argillite which probably can be decomposed by long exposure to water. Bearing strength is adequate to support reasonable foundation loads if the rock is blanket-grouted.

Little information is available on the sites for the Naran Dam and the Suki-Kinyari Power Plant. Conditions at the former suggest a relatively deep overburden, on the order of 200 feet, composed of permeable sands and gravel. Bedrock is a relatively hard micaceous, garnetiferous schist and is considered to be competent to support the dam. Considerable foundation exploration will be required for final design and treatment of the foundations by grouting will be necessary to provide a suitable foundation and to control seepage.

At the Suki-Kinyari Power Plant site, the rock exposed in the penstock line is strong and hard.

Little is known about the geology of the zones through which the tunnels would pass but no unusual problems in tunneling are expected, although supports might be required in many cases. ANNEX 6 Page 3

Several locations of construction materials, including sand and aggregate deposits, crushing material and riprap, and impermeable material, were identified and evaluated.

Meteorology

The normal annual precipitation as rainfall ranges from 40 inches near the Sulci-Kinyari Dam site to about 20 inches at the Babu- Sar divide. Precipitation as snowfall has not been measured, but it was estimated by observers that the average snowfall is about 30 feet with a snowpack depth of approximately 12 feet.

The drainage area above Suki-Kinyari normally receives a large snowfall each winter. Indirect evidence of the extent and effect of snow cover on the Kunhar Drainage Basin is found in the large diurnal variation of runoff at the project area throughout the summer months and in the relationship of river sediment and discharge at Garhi- Habibullah. Although the maximum water discharge as measured at Garhi-Habibullah occurs in late June or early July, the maximum sediment transport at that station occurs in August. The increase in sediment transport in August results from monsoon rainfall on the Kunhar Basin downstream of the project area. The monsoons do not penetrate the basin above the project area to a significant extent.

Hydrology

The Kunhar River has its source in the high mountains of the Himalayas; its main branch drains the southerly slopes of Nanga Parbat, one of the higher peaks of the Himalayan Ranges. The drainage area is roughly rectangular in shape with a length of approximately 65 miles and an average width of 15 miles. The total area above the only gauging station on the river at Garhi-Habibullah is 938 square miles. The drainage areas tributary to the two proposed reservoirs are 413 square miles for Naran and 162 square miles for Suki-Kinyari, or 44 percent and 17 percent, respectively, of the total gauge area.

The staff gauge at Garhi-Habibullah was established in 1944. Although data from the newer stations were insufficient to verify the validity of the assumption stated below, they did indicate that the assumptions were indeed of a conservative nature.

Although the large snowfall in the upper basin probably results in a large runoff relative to the size of the drainage area involved, it was decided to take the runoff into the Naran Reservoir as 44 percent of the Garhi-Habibullah flow and the intermediate inflow between Naran and Suki-Kinyari as 17 percent of the Garhi-Habibullah flow. IACA give the mean annual runoff at Naran as 1.2 MAF.

The variation of flow from day to day is usually very small, exhibiting the characteristics of a snowmelt watershed. Calculations indicated a maximum flood in almost 14 years of record of 30,000 cusecs, or only 1.63 times the average discharge for the month of July 1959. In general the maximum flow for the month is substantially less than ANNEX 6 Page4

1.2 times the average discharge for the month. The variation of discharge during the year follows a predictable pattern, starting with a minimum or near minimum flow in January and continuing through February, increasing slightly in March and markedly in April and continuing to increase in May. June or July is normally the maximum flow month with an average of about 9,500 cusecs tributary to Garhi-Habibullah. The flow in August reduces to about 60 percent of the maximum month and in September reduces to about 25 percent of the maximum month. The flow continues to decrease gradually in October, November and December, again reaching a minimum in January, which averages only 600 cusecs at Garhi- Habibullah, with a minimum monthly average record of only 180 cusecs. This regularity promises that the operation of the proposed project could be based on runoff predictions derived from snow survey analysis.

The sediment load of the Kunhar, as measured at Garhi- Habibullah for the period 1955 through 1957 and including an element for bed load of 20 percent, is shown in Table 1 below. Since the higher watershed is snow-covered for a longer period of time each year, it was expected that the sediment yield would decrease with elevation. However, it was assumed that the sediment load was proportioned to the drainage area in order to be on the conservative side.

Table 1

Annual Sediment Load of the Kunhar River a/ (MAF)

Naran to Year Garhi-Habibullah Naran Suki-Kinyari

1955 2900 1270 490 1956 3200 1410 545 1957 3350 1470 570 Average 3150 1380 535 a/ Including bed load at 20 percent and assuming deposited densities of 87 pounds per cubic foot for sand, 75 pounds per cubic foot for silt, and 60 pounds per cubic foot for clay.

The distribution of the sediment in the reservoirs is indeter- minant because of its composition of sand, silt and clay. The coarse material would form a delta at the upper end of the reservoirs, part of which would be above the normal reservoir level. Some of the clay would probably pass through the reservoirs during the flood season. Assuming that 50 percent of the total sediment remained in the reservoir, the dead storage allowance for both Euki-Kinyari and Naran would be adequate for at least 40 years. Continued sedimentation at the same rate would reduce the useful capacities of the reservoirs by 50 percent in about 200 years. ANNEX 6 Page 5

Proposed Design

The following are the principal features of the Kunhar River Project. The stages of development shown are those proposed in 1960. The project could be developed in one compressed schedule if required.

Table 2

Kunhar River Project Statistics

Stage I

Suki-Kinyari Reservoir

Maximum Storage Level Elevation 7245 feet Dead Storage Level Elevation 6880 feet Usable Storage Volume 0.128 MAF

Suki-Kinyari Dam

Type: Concrete Gravity Crest Elevation 7255 feet Height above Streambed 530 feet Crest Length 1,800 feet + Spillway: Crest Overflow Gates, seven radial 40 feet wide x 33 feet high Discharge capacity at normal water level at elevation 7245 190,000 cusecs Outlet Works - to river: Two conduits through dam at elevation 6850 each controlled by 72-inch Howell-Bunger valve

Paras Power Tunnel

Intake in Suki-Kinyari Reservoir at elevation 6880 with control ga-tes in the dam Tunnel, concrete lined 16 feet diameter Tunnel Length 48,300 feet Surge Chamber at Downstream End

Paras Power Plant

Number of Units - initial 2 a/ Number of Units - final 4 Turbines, vertical impulse 150,000 hp at 3,000 feet net head, 333 rpm. Generators, 122 mva at 0.90 PF 50 cycle, 333 rpm. a/ Units 3 and 4 at Paras of the same size as Nos. 1 and 2 would be added when additional stored water became available at Naran, Stage II. ANNEX 6 Page

Table 2 (Cont'd)

Stage II

Naran Reservoir

Gross Storage Volume at Elevation 8400 0.28 MAF Dead Storage Volume at Elevation 8100 0.03 MAF Usable Storage Volume 0.25 MAF

Naran Dam

Type: Concrete Gravity Crest Elevation 8410 feet Height above Streamnbed 410 feet + Spillway: Crest Overflow Crest Length 1,360 feet Gates, six radial 40 feet wide x 30 feet high Discharge capacity at normal reservoir level, elevation 8400 162,000 cusecs Outlet Works - to river: Two conduits through dam at elevation 8050 each controlled by a 72-inch Howell-Bunger valve

Stage III

Suki-Kinyari Power Tunnel

Intake and Trashrack in Naran Reservoir at Elevation 8100 feet Control Gates in Naran Dam Tunnel, concrete-lined 14 feet in diameter Tunnel Length 30,000 feet + Surge Chamber at Downstream End

Suki-Kinyari Power Plant

Three vertical impulse turbines - 50,000 hp at 1,100 feet net head at 333 rpm. Generators, 40 mw at 0.90 PF

The first-stage development of the project would consist of the Suki-Kinyari Dam, the Paras Power Tunnel, and two units of the Paras Plant. Suki-Kinyari Dam would be located about one mile upstream from Kaghan Rest House. The Paras Power Plant would be located about one-half mile downstream from the village of Paras.

The concrete gravity dam proposed for Suki-Kinyari would have an overflow spillway' in the center designed to discharge 190,000 cusecs at normal storage level. Releases from the reservoir to the river normally would be made through two conduits extending through the dam at about elevation 6850. ANNEX 6 Page 7

Five sluiceway's, 12 feet by 15 feet, would be installed near the bottom of the dam to handle diversion during construction. The river would be carried through two temporary pipelines laid along the foundation at present river level while the dam was being completed from lowest points in the foundation in the river up to the levels of the sluiceways.

The Paras Power Tunnel, a 16-foot diameter concrete-lined pressure tunnel would extend from the Suki-Kinyari Reservoir at elevation 6880 feet,a distance of 48,300 feet through the mountains across a loop in the Kunhar River. It would fork into four separate tunnels at the outlet end for connections with steel penstocks to the Paras Power Plant. A surge chamber would be constructed near the downstream end of the tunnel to absorb fluctuations in flow to the power plant.

The initial phase of the proposed Paras Power Plant would include two generating units to utilize the more than 3,000 feet of head available between the high water level of Suki-Kinyari Reservoir and the river level at Paras Power Plant. The power plant later would be increased in size by the addition of two units after Naran Reservoir were completed.

Each of the Paras units would be supplied with water by separate steel penstocks 8 feet in diameter extending about 4,000 feet from the outlet end of the tunnel.

Power generated at the proposed project would be transmitted over a two-circuit 220 kv transmission line from the Paras Power Plant to Wah, a distance of 80 miles. A single circuit would be constructed initially' and a second circuit would be added when the power project were enlarged. Stage II development would include Naran Reservoir for additional water storage and the addition of two units to the Paras Power Plant. Naran Dam would be located on the Kunhar River near the village of Naran. The concrete gravity structure wculd have an overflow spillway located near the middle which would be capable of discharging 162,000 cusecs without permitting the reservoir level to encroach on the 10 feet of freeboard. The five sluiceways would be provided on the left side of the river flows during construction of the dam. They would be plugged with concrete upon completion of construction.

Normal releases from the reservoir to the river would be made through two low-level conduits located at elevation 8050 feet. Releases to the Suki-Kinyari Power Tunnel would be made through a headworks structure on the right abutment at elevation 8100 feet.

Stage III would consist of the Fuki-Kinyari Power Tunnel and Power Plant. The tunnel, 14 feet in diameter inside the concrete lining and about 30,000 feet in length, would roughly parallel the ANNEX 6 Page 6 course of the river. The intake of the tunnel would be 300 feet below the high water level in Naran Reservoir. A closed surge chamber near the downstream end of the tunnel would absorb fluctuations in flows to reduce overpressure and to provide fast hydraulic response to changing loads on the turbines.

Three steel penstocks each 8 feet in diameter and more than 800 feet long would carry water from the power tunnel to three vertical impulse-type turbines located in the Suki-Kinyari Power Plant. Each turbine unit would be directly' connected to a generator having an output rating of 44.5 mva continuous. The maximum static head on the units would be about 1,100 feet.

Operation

The flows of the river would be regulated by the two proposed project reservoirs, having a combined usable storage volume of 0.37 NAF for generating electric power. The release of water from storage would provide water for irrigation incidental to its use for generating power.

At the completion of Stage I, the Suki-Kinyari Reservoir would regulate the seasonal flows of the Kunhar River and in addition would develop part of the head for the power plant at Paras. The Paras Power Tunnel would convey water from Suki-Kinyari Reservoir to the penstocks for the Paras Power Plant where the added fall of the river would result in a3,000-foot power drop. The 0.128 NAF usable capacity in Suki-Kinyari Reservoir would provide water to augment the low seasonal flows for a firm generating capability of 198 mw at 0.58 load factor from the two units at Paras.

Stage II development would add Naran Reservoir with a live storage capacity of 0.25 MAF. The storage capacity then available would permit the two Paras units to be operated continuously at full overload capacity for an output of 248 mw. The firm generating capacity could be increased to 372 mw by the addition of a third unit at Paras and increased to 405 mw by addition of the fourth unit, both outputs at 0.58 load factor.

Stage III development would be completed by the addition of the Naran-Suki-Kinyari Power Tunnel and the three-unit Suki- Kinyari Power Plant operating under aboutl,100 feet of head. The output capability' of the project would then increase to 500 mw at 0.58 load factor.

Power would be transmitted to Wah for delivery into the power system of West Pakistan.

The firm capability of the entire power project at partial and full development is shown in the following table. Firm capability is based on 58 percent load factor. ANNEX 6 Page 9

Table 3

Kunhar River Project Power Capabilities

Cumulative Annual Average Annual Stage Construction Firm Capacity Firm Energy Secondary Energy (million mwh) (million mwh) I Suki-Kinyari Dam Paras Power Tunnel Paras Power Plant with 2 Units 198 l.o14 0.198

II Naran Pool Filled 248 a/ No Data No Data Paras Power Plant Unit 3 added 372 Paras Power Plant Unit 4 added 405

III Suki-Kinyari Power Plant 500 2.545 1.095 a/ Water supply permits operating two units at Paras continuously at full overload.

The cost of power at the plants was estimated (1961) to be $0.00314 per kwh.

Water would be released from storage in the reservoir(s) to generate power in accordance with requirements of the power system. Inasmuch as reservoir releases would be made during the low runoff season, the additional benefits made available by the flow of the stored water through the Mangla Power Plant plus the value of the stored water for irrigation must be considered.

Program for Construction

Although a construction program covering nine years was proposed, the schedule could be compressed if necessary. Outlined below is the original schedule.

Stage I would require about five full years to complete after final design studies were commenced. Construction for Stage II, including the Naran Dam and Paras units 3 and 4, would begin in the fourth year and extend through the seventh. Stage III construction would begin in the sixth year and terminate in the ninth when all three units of the Suki-Kinyari Power Plant came on the line.

Cost Estimates

Included in -the cost estimates prepared by Chas. T. Main is an item of 15 percent of total direct project costs for contifigencies for unforeseeable developments in the design requirements or in unknown additional features that might be desired. Also included is the cost of the double circuit transmission line to Wah. ANNEX 6 Page 10

The prices of labor, supplies, materials and equipment used for estimating project costs were based on market conditions as they existed in late 1960 in the United States and prices of labor and materials in West Pakistan.

Provision for inflation, financial contingencies, Pakistan taxes and duties, and interest during construction were not included.

The following are estimates for Stage I and for the entire project.

Table 4

Kunhar River Project Preliminary Project Estimate

Stage I

Project Feature Estimated Cost U.S. Pakistan PRODUCTION PLANT Dollars Rupees

Land and Land Rights - 3,570,000 Powerhouse Structure 1,078,500 2,970,100 Dam and Intake 25,470,965 98,707,550 Tunnel, Surge Tank and Penstocks 13,837,300 44,235,500 Turbines and Generators 5,806,900 1,071,700 Accessory Electrical Equipment 579,900 135,600 Miscellaneous Equipment 322,000 156,500 Roads, Railroads and Bridges 1,o44,o000 9,645,700 Switchyard Structures 240,000 979,100 Switchyard Equipment 2,483,400 1,896,200

TRANSMISSION PLANT

Land and Land Rights - 1,013,800

Land Clearing - 1,731,000 Towers and Fixtures 1,578,900 2,668,800 Overhead Conductors and Devices 1,084,400 2,023,700 Roads and Trails 396,000 1,885,000

GENERAL PLANT

Structures and Improvements 40o,500 3,294,900

TOTAL CONSTRUCTION COST 54,322,765 175,985,150

Contingency - 15% 8,148,415 26,397,775 Engineering and Administration 4,800,000 500,000

TOTAL COST STAGE I 67,271,180 202,882,925

TOTAL COST EXPRESSED IN DOLLARS $109,894,000 ANNEX 6 Page 11

Table 5

Kunlhar River Project Preliminary Project Estimate

Stnaes I + II + III

Project Feature Estimated Cost U.S. Pakistan PRODUCTION PLANT Dollars Rupees

Land and Land Rights - 7,1 4 0,000 Powerhouse Structures 1,872,370 5,946,180 Dams and Intakes 4],335,680 168,546,490 Tunnels, Surge Tanks and Penstocks 26,062,960 73,657,420 Turbines and Generators 17,559,840 3,208,990 Accessory Electrical Equipment 1,620,780 363,940 Miscellaneous Equipment 584,500 277,500 Roads, Railroads and Bridges 1,210,000 11,465,660 Switchyard Structures 299,600 1,221,700 Switchyard Equipment; 5,188,620 3,937,025

TRANSMISSION PLANT

Land and Land Rights - 1,013,800 Land Clearing - 1,892,800 Towers and Fixtures 1,930,700 3,391,200 Overhead Conductors and Devices 2,818,600 4,339,000 Roads and Trails 396,000 1,885,000

GENERAL PLANT

Structures and Improvements 400,500 3,294,900 TOTAL CONSTRUCTION COST 101,280,150 291,581,605

Contingency - 15% 15,192,020 43,737,240 Ingineering and Administration 8,000,000 1,500,000

TOTAL PROJECT COST 124,472,170 336,818,845

TOTAL COST EXPRESSED IN DOLLARS $195,128,000

Additional Investigations Required

The explorations performed were sufficiently detailed for a feasibility study. However, they need to be supplemented by further subsurface exploration and testing during the final design stages. Foundation investigations, including additional drilling and tunneling into the bedrock, are needed at the dam sites. Grouting tests should also be done. The geology of the tunnel routes should be mapped and studied. ANNEX 6 Page 12

Investigations should include accurate large-scale topographic maps of the reservoir areas and detailed mapping of the various structure sites and route maps for the location of access highways. Aerial photographic coverage (where not already available) is needed for locating transmission lines. VOLUME III ANNEX 6-FIGURE 2

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ANNEX 7

MANGLA/RAISED MANGLA PROJECTS

ANNEX 7

LIST OF FIGURES

1. Mangla High Dam: Typical Sections of Dams

ANNEX 7 Page 1

MANGLA

Introduction

Mangla Dam is located on the Jhelum River at the southern edge of the Himalayan foothills and 20 miles upstream of the city of Jhelum. It occupies the only feasible site for larger storage known on the Jhelum River within West Pakistan. Binnie & Partners, consultants to WAPDA, designed the project.

Scheduled for initial storage during the flood season of 1967, the project will have a gross capacity of 5.88 M4AF and a live capacity at elevation 1040 feet of 5.22 MAF. An additional 0.12 MAF will be trapped behind the Mlirpur saddle but in certain circumstances may be released to the Upper Jhelum Canal via the Jari outlet. The reservoir will inundate an area of 65,100 acres and cause the dislocation of approximately 81,000 people. The estimated cost of the project is $534 million.

Design

The project consists of three earthfill embankments, with impervious cores carried down to impervious foundation material, which will contain the reservoir. The Mangla Dam on the Jhelum River, the largest of the three, which g:ives the project its name, has been built to a maximum height of 380 feet, and has a crest length of 11,000 feet, and a volume of 78 million cubic yards. Su]-ian Dyke, which closes gaps in the reservoir rim east of Mangla Dam, will have a maximum height of 80 feet, a crest length of 17,000 feet, and a volume of 7.2 million cubic yards. Jari Dam will be located on the Jari Nallah, about 12 miles east of Mangla Dam. This structure will have an embankment of 37 million cubic yards, a maximum height of 234 feet, and a crest length of 5,700 feet.

The dams ancd other structures have been built to a crest elevation of 1234 feet for storing water to elevation 1202 feet. They are designed, however, for later raising to elevation 1274 feet for impounding to elevation 1250 feet.

The project is designed to handle an inflow flood of 2,600,000 cusecs occurring when the reservoir is at maximum conservation pool level, elevation 1202 feet. The flood will be handled by superstorage of nearly 2 MAF in the reservoir to elevation 1228 feet while the main and emergency spillways are discharging at their maximum capacities. The combined capacity of the two spillways at maximum flood level is 1,300,000 cusecs. The highest flood of record was 1,100,000 cusecs and occurred in August of 1929.

The main spillway is of the submerged orifice type with nine openings each controlled by a radial gate 36 feet wide by 40 feet high. The crest elevation is 1086 feet. According to Sir Alexander Gibb & Partners, the model experiments carried out by WAPDA's consultants shou that the capacity of the spillway is 860,000 cusecs at the normal maximum reservoir elevation of 1202 feet and 1,070,000 cusecs at the maximum flood level of 1228 feet. ANNEX 7 Page 2

The emergency spillway is located about one-half mile beyond the right end of the dam. It discharges into Bara Kas, a small tributary of the Jhelum. Although its uncontrolled concrete crest is at normal maximum reservoir elevation 1202 feet, the inlet channel is blocked by an erodible "fuse plug" embankment with top at elevation 1206 feet. Thus, the emergency spillway will operate only during rare floods that exceed the capacity of the main spillway. At reservoir elevation 1228 feet the capacity of the emergency spillway will be 230,000 cusecs.

Five diversion tunnels, each 1,940 feet long, were excavated through the ridge at the left of Mangla Dam. Four tunnels have been lined with steel penstocks of 26-foot inside diameter to serve for irrigation releases and power generation. The fifth tunnel is closed with a steel bulkhead but could be commissioned later if required for irrigation or power.

Because Jari Dam had to be constructed downstream from the Mirpur saddle for technical reasons, it was necessary to provide a 7-foot diameter concrete lined tunnel on its right abutment to carry the trapped water (0.40 MAF down to level 1040 feet) to the Upper Jhelum Canal. It has been decided to excavate a cut 60 feet in maximum depth through the saddle to enable 0.28 MAF of this water to be released through the power plant and main outlet works.

A powerhouse at the discharge end of the main outlet tunnels is initially provided with three generating units, each with a rated capability of 100 mw, and a fourth unit has been ordered. Two generating units can be connected to each penstock, thus permitting an ultimate installation of up to ten units, although recent studies suggest that eight units may be the optimum number. Bypass valves will maintain uniform water releases regardless of the load on the turbines.

Operation

The Mangla Dam Project is being constructed as part of the system of works constituting the Indus Basin Settlement Plan. It will provide rabi irrigation supplies to the Jhelum and Chenab Commands as well as the Ravi and Sutlej Commands. Thus its function will become especially important after India exercises its rights under the Indus Waters Treaty of 1960 to divert the full flows of the Ravi and Sutlej Rivers.

With a minimum drawndown level of 1040 feet and the cut through the Mirpur saddle, 5.22 MAF useful storage will be available to meet irrigational demands. An additional 0.12 MAF from behind the Mirpur saddle could be released through the Jari outlet but, according to Sir Alexander Gibb & Partners, there is some question as to whether under anticipated operating conditions the outlet capacity is sufficient to permit its use during the very limited time when the reservoir will be down below the bottom of the cut. ANNEX 7 Page 3

The full peaking capability of the hydroelectric plant can be utilized without the necessity for any downstream reregulating structure. Specified total daily releases for irrigation will limit the daily generation of energy but will have no adverse effect on daily peaking operations. The need to maintain a uniform flow in the Upper Jhelum Canal (with an ultimate capacity of 12,850 cusecs) will restrict the flexibility of the power plant operation to some extent, but the effect should be slight. Stone & Webster estimated that, under 1985 conditions with eight units installed, the plant will have a firm power capability in a critical water year of about 380 mw and generate approximately 5,400 kwh of energy in a mean water year.

As indicated by Irrigation & Agriculture Consultants Association, the possible average annual sediment load of the Jhelum River at Mangla is 72 million tons. Chas. T. Main estimated that sedimentation in the live storage zone of Mangla Reservoir would take place at the rate of 0.02 MAF per year for the first 27 years of its life and thereafter at the rate of 0.04 M4AF until the usable volume is reduced to about 1 MAF. This residual capacity will thus be reached in about 120 years. It was reported by IACA that a recent study concluded that improved land management on the catchment could reduce silt movement into the reservoir by 30 percent and thereby extend considerably the useful life of the reservoir.

Estimated Cost

The estimated cost of Mangla, as compiled by Gibb, in January 1967, is given in the table following. Of the $534 million total, $18 million is for the first three generating units and $12 million is for provision for future raising.

Table 1

Estimated Cost of Mangla Dam (uS$ million equivalent)

Total Foreign Exchange

Preliminary Works 10.5 2.5 Construction Cost 433.3 297.0 Contingencies 16.8 10.9 Engineering and Administration 22.1 -11.3 Land Acquisition and Resettlement 51.8 - 534.5 321 .7

Estimated Cost of Units 4, 5 and 6 13.6 11.6 Estimated Cost of Units 7 and 8 11.6 9.7 ANNEX 7 Page 4

RAISED MPLNGLA

All the impounding structures of Mangla Dam Project have been built with provisions for raising them 40 feet to elevation 1274 feet. This would permit raising the full reservoir level 48 feet to elevation 1250 feet. The height of the main dam would then go to 420 feet and the capacity of its reservoirs would increase 3.55 MAF to a gross volume of 9.43 MAF. The live storage volume above elevation 1040 feet after raising would be 8.89 MAF less depletion by sedimentation. Of the 8.89 MAF volume, 8.77 MAF would be controlled through the main outlets. The 8-foot reduction in normal freeboard after raising is due to the fact that with the greater reservoir areas at higher elevations, equivalent superstorage volume for the design flood is attained with a lesser rise in reservoir elevation than at the lower level.

The Mangla and Jari Dams can be raised to final design height at any time without interference to or from the reservoir level, since all additional embankment would go on the tpps and the downstream slopes. Sukian Dyke raising would require the placing of fill on the reservoir slope down to a berm at elevation 1140 feet (see Figure 1).

The spillway crest would be raised from elevation 1086 feet to 1093 feet in order to provide proper discharge characteristics of the spillway orifices at full gate under the higher head. Work on the spillway crest, of course, can only be done when the reservoir is below elevation 1086 feet or by the use of caisson bulkheads.

A concrete ogee overflow dam 50 feet high with stilling basin would be required at the intake of the emergency spillway.

The impellers of the turbines installed under the initial contract are suitable for the higher head and would not require changing.

The time estimated to complete on-site construction work is three years.

The estimated cost of raising Mangla, derived by Gibb from WAPDA Report IBP 211 of September 1966, is indicated in the table below. ANNEX 7 Page 5

Table 2

Estimated Cost of Raising Mangla Dam (US$ million equivalent)

Total Foreign Exchange

Construction Cost 152.5 99.2 Contingencies 15.2 9.9 Escalation a! 16.8 10.9 Engineering and Administration b/ 18.3 9.8 Land c/ 13.7 216.5 129.8 a/ The estimate is based, where appropriate, on present Mangla contract rates with an allowance of 10 percent for rise in prices from the date of the original tender which was November 1961. b/ Based on information from WAPDA's consultant, Binnie & Partners. c/ The estimate is probably too low as it is based on PRs 1,850 per acre whereas good land awards have been PRs 12,000 per acre.

The unit cost of Raised Mangla is thus about $61 per acre-foot of live storage which compares favorably with other projects such as Tarbela and Kalabagh.

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ANNEX 8

CHASNA PROJECT

ANNEX 8

LIST OF FIGURES

1. Chasma Barrage: General Plan of Works

2. Chasma Barrage: Floor of Barrage: Cross Sections

ANNEX 8 Page 1

CHASMA

Introduction

Chasma Barrage, to be located on the Indus about 35 miles downstream from the Jinnah Barrage, is a part of the Indus Settlement Plan works which implement the Indus Waters Treaty with India. It constitutes the control structure for diverting water from the Indus to the Jhelum through the Chasma-Jhelum Link Canal, also a part of the Indus Settlement Plan works. The existing Paharpur Canal will also be supplied with water from the new headworks.

The design of the project by WAPDA's consultants, Coode & Part- ners, as originally approved, was based on a normal operating level of the headpond at elevation 640 feet to command the Chasma-Jhelum Link Canal. The design allowed for a 3-foot rise above normal operating level during passage of the project design flood. The super-storage volume to elevation 643 feet was also to provide short-term storage of water for release after the flood season passed.

WAPDA subsequently arranged for a study of the relative saving and cost of fixing the invert of the Chasma-Jhelum Link Canal 2 feet higher than planned and of raising the corresponding operating level in the headpond a like amount to elevation 642 feet. Three feet of height above normal operating level in the headpond still would be needed for handling the river in flood stage and would be usable in the postflood season for storage. This alternative arrangement was found more expensive than the accepted layout.

The Government of Pakistan then requested the Bank Group to consider the feasibility and benefits of raising the barrage by 6 feet to provide additional storage. This proposal was examined by Chas. T. Main, IACA and Sir Alexander Gibb & Partners, who found it feasible and confirmed that the water could be used. The Government of Pakistan decided to construct the barrage to the greater height and at the same time take advantage of the increased head to raise the invert of the link canal by 2 feet.

The necessary changes in design have been effected by WAPDA's consultants and the contract for construction of the barrage was awqarded in February 1967. Completion is scheduled for March 1971.

The additional storage capacity provided between 645 feet and 649 feet will be 0.33 MAF and the gross storage between the revised normal operating level of 642 feet and 649 feet will be 0.51 MAF. In assessing usable storage both figures must be reduced by about 14 percent on account of seepage and evaporation losses.

The cost allocated to storage totals $31.6 million, of which $9.0 million is in foreign exchange. ANNEX 8 Page 2

Proposed Design

The location of Chasma Barrage was determined in conjunction with the siting of the Chasma-Jhelum Link Canal on the left bank. The barrage will create a headpond to elevation 642 feet to supply the Chasma-Jhelum Canal, and also will supply water to the existing and planned future enlargement of Paharpur Canal on the right bank.

The Chasma-Jhelum Canal is designed to carry 21,700 cusecs. The Paharpur Canal head regulator in the barrage will have a capacity of 5,000 cusecs to provide for future expansion of the irrigation system. The headworks of the existing Paharpur Canal and part of the canal (1,100 cusec capacity) will be submerged in the headpond of Chasma Barrage.

The barrage, with 41 normal sluiceways and 11 sediment sluiceways will have a discharge capacity of 950,000 cusecs. Each opening will be 60 feet wide. The sediment sluicevays will be adjacent to each of the two canal head regulators. Closure bunds 17,000 feet long on the left side of the barrage and 16,000 feet long on the right side will extend to high ground at the banks of the flood plain. The canals will be carried across the flood plain of the Indus on embankment sections on the downstream side of these bunds. The project works are shown in general detail in Figures 1 and 2 which are copies of drawings prepared by Coode & Partners for the project.

Operation

The operation of Chasma must take into consideration the requirements of the Chasma-Jhelum and Paharpur Canals and the efficient utilization of its storage capacity.

According to Tipton and Kalmbach, hydraulic considerations make it desirable to maintain flow continuously in the Chasma-Jhelum Link pre- ferably in the range of 50 percent or more of the design capacity. The pool levels required are 642 feet for full flow and 637 feet for half capacity.

IACA's water distribution analysis for the year 1975 indicates that the link will probably need to run between September and March. During the months of April to August the link irrigation requirement will normally be low and this would probably afford an opportunity of drawing the reservoir down to the pool level necessary to command the Paharpur intake only, or 635 feet.

The Indus River flows entering Chasma Pond will be the flows at Kalabagh less diversions to the Thal Canal at Jinnah Barrage of up to about 10,000 cusecs when Thal Canal is developed to full capacity. For all practical purposes the flows at Chasma Barrage can be assumed to be equal to those at Attock.

During the months June to August river flows at Chasma are likely to be greatly in excess of irrigation requirements, and virtually the whole ANNEX 8 Page 3

flow can be allowed to pass through the barrage (the Chasma-Jhelum Link and Paharpur requirements being relatively small). The level at the beginning of September must be at least pond level of 642 feet in order to command the link. Filling therefore will probably commence in late August and be completed by early September.

The main irrigation deficiency is likely to occur in February, and the reservoir would be kept at its top water level until this month, when the whole stored volume would be released at a uniform rate, down to pool level.

During March, April and May there will be opportunities during some years to use the reservoir to store minor surplus flows, releases being made shortly afterwards to make up short-term deficiencies. The reservoir level can therefore be expected to fluctuate between top water level and pool level during these months.

The Indus River is expected to continue flowing in the present channels through the pond after the barrage is completed, but water velocities during high stages and during concurrent high sediment transport period of June to August will be reduced below those in the unrestricted channel. Sediment then will be deposited both in the present channels and on the present flood plain as a result of the backwater from the barrage. Thus, in time, channels and a flood plain will exist similar to the present ones, but higher in elevation. After the pond is filled to maximum storage level in September, additional sediment will settle mostly in the principal channels. Most of the sediment deposition when the pond is being filled probably will be scoured out during subsequent flood seasons. Sediment permanently deposited in the pond above the June-August operating level is expected to be of minor amount, causing no significant reduction in the live storage capacity of the pond.

After a period perhaps as short as five years, the pond capacity below normal canal operating level in the pond, elevation 642 feet, may be reduced from 0.27 MAF to about 0.04 DIAF, the latter figure representing volume in the channel that the river would maintain permanently. Sediment trapping at Tarbela, even if affecting sediment movement at Chasma Barrage, will occur too late to prolong significantly the life of usable storage volume below the normal canal operating level in the pond. With or without Tarbela, however, the storage capacity above the normal pond level is expected to be essentially permanent at about the following values.

Table 1

Storage Volume of Chasma Barrage Elevation Range Permanent Storage (feet) (MAF) 645-642 0.18 649-642 0.51 649-645 0.33 ANNEX 8 Page 4

Seepage and evaporation losses are expected to amount to approximately 14 percent of the live capacity, giving an effective capacity at the barrage of 0.44 MAF between 649 feet and 642 feet.

Cost Estimate

Following the decision to heighten the barrage for storage, hydraulic model tests and new stability analyses were made. The hydraulic model tests by the Irrigation Research Institute resulted in changes in the estimated downstream water levels, necessitating redesign which will require additional concrete quantities. Slopes of the guide banks and spurs and closure bunds have been flattened as a result of further stability analyses. The added fetch of wind over the larger pond coupled with the flattened slopes necessitated more freeboard than for the previous design.

These changes resulted in increased costs allocable to storage of $31.6 million as outlined in the following table. The figures do not include provision for Pakistan taxes or duties, or interest during construction.

Table 2

Estimated Cost of Incremental Storage at Chasma Barrage (us$ million equivalent)

Total Foreign Exchange

Incremental cost of raising from 643 feet to 649 feet less cost of raising canal invert 2 feet 18.3 9.0

Land and resettlement costs 13.3 -

Total 31.6 9.0 C AOMA A=RA nZ o- FLOOR OF B.

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ANNEX 9

SEHWAN-MANCHAR AND CHOTIARI PROJECTS

ANNEX 9 Page 1

SEHWAN-MANCHAR AND CHOTIARI

Introduction 1/

The Lower Indus region does not offer large potential storage sites as are found in the North, but several small sites could be developed to provide a significant addition to the rabi irrigation supplies. The most important of these are Sehwan, its associated reservoir Manchar Lake and Chotiari.

As proposed by the Lower Indus Project consultants (LIP), Hunt- ing Technical Services Limited, and S,r M. MacDonald & Partners, a barrage 3,500 feet long would be constructed on the Indus near Sehwan to impound water to a maximum level of 125 feet SPD. The present river level is 93 feet. Between the level necessary to command the feeder, 110 feet, and the normal retention level of 124.5 feet 9 1.0 MAF storage would be impounded. Of this amount, 0.8 MAF would be available at the canal head for irrigation. The total cost of the barrage was estimated to be $114 million, of which about $68 million would be in foreign exchange.

The containing bund at Manchar, 29 miles long, would be raised 7 feet to about 129 feet in order to contain a normal retention level of 124.5 feet. A new inlet channel of 202000 cusec capacity would be provided over the course of the present Aral-Lakhi Channel and the Manchar Outfall would be enlarged to 30,000 cusec capacity. The storage available between 110 feet and 124.5 feet would be 1.1 MAF. An additional 0.2 M4AF would be available between 105 feet and 110 feet, but it could be released only to the Ghulam Mohammed Command. Of the total of 1.3 MAF, about 1.0 MAF would be available at the canal head. Cost of the Manchar scheme was estimated to be $14 million.

Since full use of Manchar could not be made without the existence of the Sehwan Barrage, because the operation of the two would be closely linked and because the water stored could not be utilized in the Sehwan Command without the Sehwan Feeder, the entire complex may be treated as a unit. The total cost for the barrage, feeder, and Manchar works was estimated at $177 million. However, LIP indicated that the construction of the barrage would save extensive remodeling of much of the Rohri and Nara Canals and therefore the $150 million estimated cost of remodeling should be deducted to determine the true cost of storage. The resultant cost is $27 million which produces a unit cost of about $12 per acre foot and represents very low-cost storage in West Pakistan.

On the other hand, Sir Alexander Gibb & Partners examined the project during the preparation of their Tarbela Report and concluded that a more conservative approach might be warranted. In particular, they felt

1/ Most of the information for this annex was taken from the Lower Indus Report by Hunting Technical Services Limited and Sir M. MacDonald & Partners, 1965 and 1966. ANNEX 9 Page 2 that remodeling of the Rohri and Nara Canals might not be a practical alternative and therefore charged the entire amount of $177 million against storage. They also added a contingency of 25 percent, or $44 million, to provide for technical uncertainties. The total cost thus becomes $221 million and the unit cost $96 per acre foot of storage.

Chotiari Reservoir would be a development of Chotiari Lake located on the eastern fringe of the present Sukkur Left Bank Command near the junction of the Khipro and Mithrao Canals. A bund 14 miles long would be constructed to an elevation of 89 feet to permit impounding to a level of 85 feet. Live capacity would be 1.1 MAF and the storage available at canal head would be about 0.9 MAF. The reservoir would be filled by water from the existing Nara Canal, which would discharge up to its present capacity. A new outlet would be provided to the Khipro Canal. Approximately 8,500 acres of additional waterlogged, abandoned land would be inundated by the reservoir. Cost of the project was estimated to be $12 million or about $11 per acre foot. If a contingency of 25 percent for technical uncertainties were added, the cost would be $15 million or about $14 per acre foot.

The construction period envisaged by LIP for Sehwan Barrage extends from 1969 to 1976, for Sehwan Feeder from 1970 to 1985, for Manchar from 1979 to 1982, and for Chotiari from 1986 to 1990. Thus storage of 1.0 MAF would be available from Sehwan in 1976, 1.3 MAF from Manchar in 1982, and 1.1 MAF from Chotiari in 1990. The Bank Group envisages completion of Sehwan-Manchar in 1982 and Chotiari in 1990.

Two major problems confronting storage projects in the Lower Indus region are evaporation losses and seepage losses. The reservoirs are located in shallow basins which give rise to large surface areas relative to the volumes of water stored. This factor, together with the high temperature and low humidity of the region, leads to large evaporation losses. In addition, the reservoirs are all underlain to varying depths by sandy aquifer which results in high seepage losses. It was estimated by LIP that losses due to evaporation and seepage during the three to four month operating season would be on the order of 20 percent to 30 percent of the storage capacity involved. Considering these conditions and the additional problem of sedimentation, LIP suggested that it would be imperative for the reservoirs to be filled as late as possible in the flood season and drawn down rapidly at the beginning of the rabi growing season.

Investigations

Ground surveys were taken above the existing water levels. Where the greater part of the storage area lay under water, hydrographic surveys were also carried out. In addition, aerial photographs were utilized where they were available.

A study of sedimentation was carried out at Kalri Lake. The lake presented a good opportunity to measure the effects of sedimentation because it had been in use as a reservoir only a short time, and, since the volume of water passing through it is several times its capacity, it experiences an accelerated rate of sedimentation. ANNEX 9 Page 3

Probings and soundings were first taken in the beginning of hydrological year 1964 to establish the then existing and previous bed levels. In the two successive years, soundings were taken and the differences in bed level used to determine the volume of sediment deposits.

Water samples were taken from the Indus and from the Kalri-Baghar Feeder and analyzed for sediment load in order to determine the relationship between the sediment load in the river and in the canal and to establish a density for the sediment deposits.

Observations were made at several climatological stations to establish evaporation rates. Seepage was studied in connection with canal development.

It was suggested that the study started at Kalri Lake on sedimentation be continued and that a similar program be undertaken at Manchar Lake. It was also suggested that investigations on reservoir evaporation should continue.

Geology

The reservoirs of the Lower Indus region are generally underlain by a sandy aquifer ranging in depth from 100 feet at Manchar to over 500 feet on the Indus left bank at Sehwan. These conditions lead to heavy seepage losses.

Borings in the vicinity of the proposed Sehwan headpond indicated that on the right bank of the Indus, the aquifer varies in depth from about 100 feet at the barrage to some 400 feet near the town of Dadu. The average depth on the left bank is about 500 feet. Soils in the active flood plain are mostly sandy.

At Manchar, most of the upper soil is of piedmont origin although in the northern part of the lake it is probably Indus alluvium. Borings in the area produced mixed clays and sands. The nearest boring to the lake, at Bubak, showed 100 feet of sand at the top. Rock outcrops to the south and east of the lake indicate that the available depth of aquifer is restricted.

The aquifer at Chotiari is composed mainly of fine to medium sand and extends to a depth of about 250 feet.

Hydrology

In order to reduce sedimentation to a minimum and to ensure the maximum scouring of the headpond at Sehwan, it is advisable to fill the reservoirs as late in the flood season as possible. Consequently, LIP examined the recession curve of the Indus upstream of Sukkar Barrage and found that some 50 days elapse between a 10--day average discharge of 10.0 MAF and a 10-day average discharge of 1.0 MAF. Thus, the period might extend from the end of August to the third week in October and would be a propitious time for filling the reservoirs. A total flow of about 13 MAF occurs during the period, of which approximately 7 MAF is available for storage at the present time. ANNEX 9 Page 4

Studies also indicate that the sediment load of the Indus is at a minimum during this part of the flood season. The mean sediment load for the period June through September is about 2,500 ppm. It reaches a peak of over 3,000 ppm in August, then falls rapidly to less than 1,000 ppm at the end of September.

However, as development of the use of surface water proceeds elsewhere in the system, the filling of reservoirs will have to begin earlier, and the rate of sedimentation will increase.

Proposed Desigps

Sehwan Barrage, 3,500 feet in length, would be constructed to impound water to a maximum level of 125 feet. The present river level is 93 feet. It would be designed to pass a flood discharge of 1 million cusecs. A marginal bund would be provided on the right and left flanks to protect the right bank outfall drain and the Sehwan Feeder. The bunds would be continued northwards to join the existing river bunds which would be raised along both sides of the river to a point just north of Dadu, or a distance of about 55 miles. The present bund level at the barrage site is 124 feet, and it would be raised to 130 feet. Head regulators would be provided on the left bank for the Sehwan Feeder and on the right bank for the Aral- Manchar inlet channel.

Between the normal retention level of 124.5 feet and 93 feet,, the headpond would store 1.1 MAF of water. The amount available to the Sehwan Command would be the 1.0 MAF stored between 124.5 feet and 110 feet, the level necessary to command the Sehwan Feeder. The volume below 110 feet could actually be considered dead storage. It might be released to Ghulam Mohammed, but the headpond would have to be filled to 110 feet again before it could supply the feeder, and at a time when the river supplies are short. The volume release thus would represent a net loss to the Sehwan Command. Of the 1.0 MAF available to Sehwan at the headpond, about 0.8 MAF would be delivered at the canal head.

The Sehwran Feeder would have a maximum discharge capacity of 35,800 cusecs and would run about 75 miles from the barrage to the Mithrao and Khipro canal heads.

The containing bund at Manchar is presently at a level of 122 feet to impound water to 117 feet and would be raised to about 129 feet to permit a normal retention level of 124.5 feet. A new inlet channel with capacity of 20,000 cusecs and a head regulator of the same capacity would be provided over the same course as the present Aral-Lakhi Channel. It would also act as an outlet for Manchar when the lake is drawn down in connection with Sehwan headpond for supplying the Sehwan Command. A regulator of 30,000 cusec capacity would be installed to discharge water to the Indus downstream of Sehwan Barrage through the Manchar Outfall which would be enlarged to equal capacity. Such a large capacity would be necessary to handle flash floods from the hill torrents. ANNEX 9 Page 5

The Main Nara Valley Drain, which will become the Right Bank Out- fall Drain, would be realigned to bypass the lake. It would pass under the inlet channel in a syphon and join the Manchar Outfall to discharge into the river. This diversion is necessary because the high water levels envisaged would cause serious backing in the drain and the cost of works to prevent the consequent flooding would be prohibitive.

The storage capacity of Manchar between the normal retention level of 124.5 feet and 110 feet would be 1.1 M4AF, all of which could be used in the Sehwan Command. An additional 0.2 MAF would be contained between 110 feet and the minimum drawdown level of 105 feet, but it would be available only to the Ghulam Mohammed Command since the Sehwan Feeder could not be commanded below 110 feet. Of the total 1.3 M-AF storage, LIP estimated that 1.0 MAF would be available at the canal head.

Chotiari Reservoir would cover a total area of more than 50,000 acres, of which 8,500 acres is additional land which would be inundated as a result of the higher retention level. However, this land is at present waterlogged and abandoned and would not represent any significant loss. A bund 14 miles long would be constructed to a level of 89 feet to impound water to a level of 85 feet giving a live capacity of 1.1 MAF and an effective capacity at the canal head of 0.9 MAF.

The reservoir would be filled by the existing Nara Canal which would be realigned to feed directly into the lake. Inlet and outlet regulators would be provided, the latter for controlling discharge to the Khipro Canal system.

Operation

LIP submitted two basic principles which should be observed in order to make the most effective use of water stored in reservoirs in the Lower Indus region. The first is that filling should be accomplished on the falling hydrograph as late in the flood season as possible to reduce sedimentation. This stipulation has the further advantage of shortening the time between impounding and depletion. The second is that depletion should be started as soon as possible and should be accomplished rapidly. Adherence to these guidelines would not only serve to minimize permanent loss of storage capacity due to sedimentation, but would also minimize evaporation and seepage losses.

Evaporation losses vary directly with the surface area of the reservoir and the temperature, and inversely with the humidity. Unfor- tunately9 the conditions in the region are all adverse in that the potential reservoirs are shallow with large surface areas in comparison to the capacity, the temperature is high, and the humidity is low. Eight to nine feet of water could be lost in a full year. Although almost two-thirds of the losses occur during the summer months between April and November, they are still significant during the winter months when the reservoirs would be drawn down. ANNEX 9 Page 6

Since the reservoirs are underlain by sandy aquifer of varying depths, high seepage losses would result. These were estimated for each location on the basis of a study of canal seepage. However, the calculation thus derived produced overestimates because the hydraulic head would diminish as the reservoir level decreased and the rapid drawdown of the reservoir would not be accompanied by an equally rapid drawdown of the adjacent water table. Taking all factors into consideration, LIP estimated that the losses due to evaporation and seepage over the three to four month operating season of the reservoirs would amount to 20 to 30 percent of the live capacity.

Sedimentation rates were determined on the basis of the sediment load/discharge relationship of the Indus and the study conducted at Kalri Lake. It was found that the sediment load in the river and that in the Kalri-Baghar Feeder Canal were approximately the same and therefore the quantities obtaining for the Indus could be used for off-river storage as well. By comparing the volume of sediment deposits as determined by measurements in Kalri Lake with the discharge into the lake, LIP found that the in situ density of the sediment was about 75 pounds per cubic foot. This figure was then used in estimating the useful life of the proposed reservoirs.

Sehwan and Manchar would be operated as an integrated system. Filling would begin after the flood peak in August and would be completed by the end of October. Aside from the problem of sedimentation, late filling would have an added advantage in the case of Manchar because it is not until September that the danger of hill floods is past. Approximately 0.5 MAF of Manchar's storage capacity would be filled by drainage from the Main Nara Valley Drain. Sehwan would be filled until it reached the same level, then the two would be filled simultaneously. Fortunately, the greater part of Sehwan storage would be contained between the bunds in the area over the flood plain. Since both the Sehwan Feeder and the Aral-Manchar Channel could be commanded at a level of 110 feet, at which point the Indus is still within its own channel, it would not be necessary to fill the headpond before supply of the feeder or the filling of Manchar in years of low drainage could commence.

Storage would be used as soon after impoundment as possible in order to minimize evaporation and seepage losses. To this end, the integration of groundwater and surface water would be of great advantage because surface water would be used early in rabi and groundwater later. It was estimated by LIP that evaporation and seepage losses would amount to about 0.2 MAF in the case of Sehwan, which would benefit to some extent from regeneration in the Sukkur-Sehwan reach, and approximately 0.3 MAF in the case of Manchar. Thus, of the 1.0 MAF impounded above 110 feet at Sehwan, 0.8 MAF would be available at the canal head, and of the 1.3 M4AF above 105 feet at Manchar, 1.0 MAF would be available at the canal head.

Since it would be preferable to use the stored water in the Sehwan Command, the headpond would have to be drawn down before the lake or simultaneously with it. When the level in Manchar decreased to 110 feet, no ANNEX 9 Page 7

additional water could be supplied to the Sehwan Command, and the remainder of about 0.2 MAF down to level 105 feet would have to be discharged through the outfall to Ghulam Mohammed. A minimum level of 105 feet should be maintained at Manchar to ensure fish survival.

During the major part of the flood season, it would be possible to command the Sehwan Feeder with the gates of the barrage fully open, thus enabling the surplus flows to scour the headpond. Filling would be accomplished late in the flood season when the sediments load of the Indus had diminished. Under these conditions, and on the basis of the studies at Kalri Lake, LIP estimated that the headpond would be reduced to half its live storage capacity, or 0.5 MAF, in approximately 30 years. On the other hand, Manchar, which would be filled only once each year and would not have the great quantities of excess water passing through it, was estimated to reduce to half its live storage in some 300 years.

Since Manchar would receive a portion of its storage from the Main Nara Valley Drain, the problem of salinity must be considered. If the lake received drainage water during July and August and were then filled with river water, the salinity at the beginning of the release period in November is expected to be in the neighborhood of 550 ppm which would have no detrimental effect on crops. The storage would, in any case, be passed through Sehwan headpond before reaching the fields. However, the situation must be kept under review since the river water will probably become more saline as drainage schemes are established in the North.

Chotiari would be operated on a basis similar to the Sehwan complex, being filled from the existing Nara Canal late in the flood season and drawn down as rapidly as needed to meet the demands of the Khipro Canal system during the first part of the rabi growing season. Evaporation and seepage losses are expected to amount to about 0.2 MAF, giving an effective storage available at the canal head of 0.9 MAF. Again, being an off-river reservoir and experiencing only one filling each year, Chotiari is expected to reduce to half its live storage in about 300 years.

Program for Construction

Construction of Sehwan-Manchar as proposed by LIP would take place in two stages. During Stage 1, to be started in 1969 and completed by 1976, the barrage and headpond would be constructed to accommodate the maximum water level of 125 feet. The Sehwan Feeder would be taken as far as the Rohri Canal. During Stage 2, to be completed by 1982, the Manchar bunds would be raised to permit the normal retention level of 124.5 feet and the inlet and outlet works would be completed. The feeder would be extended to the Nara Command. Construction of Manchar actually would be started in 1979, while the program for the feeder would be continuous from 1970 with final completion by 1985. The Bank Group envisages an integrated program with completion of all Sehwan-Manchar works by 1982. Chotiari would be constructed during the period from 1986 to 1990. ANNEX 9 Page 8

Cost Estimates

The cost of the Sehwan complex was estimated by LIP to be $114 million for the barrage, of which Mt68 million would be in foreign exchange, $14 million for Manchar, and $49 million for the feeder, giving a total of $177 million. The staging of the costs would be as follows (US$ million equivalent):

Stage 1 Stage 2 Total

Sehwan 114 114 Sehwan Feeder 32 17 49 Manchar 14 14

146 31 177

Deducting $150 million for the extensive remodeling of the Rohri and Nara Canals which would be made unnecessary by the project, LIP estimated the net cost of storage to be $27 million. The resultant unit cost of storage of about $12 per acre foot would be quite low compared to other storage schemes in West Pakistan.

Gibb felt that the remodeling of the Rohri and Nara Canals was not necessarily a viable alternative to the Sehwan Barrage and Feeder. While recognizing that additional benefits would result from the increased delivery capacity to the southern part of the present Sukkur Command, they allocated the total $177 million to storage. A contingency of 25 percent, or $44 million, was also added to provide for technical uncertainties. The total estimated by Gibb was therefore $221 million, giving a unit cost of $96 per acre foot of storage.

Cost of the Chotiari Project was estimated by LIP to be $12 million or about $11 per acre foot. If a contingency of 25 percent for technical uncertainties were added, the cost would be $15 million or approximately $14 per acre foot.