A STUDY on FAILURE of FLOOD CONTROL EMBANKMENTS in BANGLADESH by AMANULLAH in Partial Fulfillment of the Requirements for the De

727.8 • 1989 ; AHA

A STUDY ON FAILURE OF FLOOD CONTROL EMBANKMENTS

IN BANGLADESH

by AMANULLAH

•

In partial fulfillment of the requirements for the Degree of Master of Engineering (Water Resources)

DEPARTMENT OF WATER RESOURCES ENGINEERING

BANGLADESH UNIVERSITY OF ENGINEERING AND TECHNOLOGY DHAKA ,.BANGLADESH

November, 1989

1111111111111111111111111111111111 #77002# , I

CERTIFICATE

This is to certify that this research work has been done by me and neither this research work nor any part thereof has been

submitted elsewhere for the award of any degree or diploma.

\I,~~ I ,

Countersigned Signature

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------Dr. Ainun Nishat Amanullah Supervisor Candidate . ,

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, ~ i ,'J . , , BANGLADESH UNIVERSITY OF ENGINEERING AND TECHNOLOGY DEPARTMENT OF WATER RESOURCES ENGINEERING

November" 13,1989

We hereby recommend that the project prepared by

AMANULLAH entitled A STUDY ON FAILURE OF FLOOD CONTROL EMBANKMENTS ------IN BANGLADESH

be accepted as fulfilling this part of the requirements for the degree of Master of Engineering (Water Resources).

Chairman of the Committee ------(Dr.Ainun Nishat)

Member ------(Dr.Abdul Hannan)

Member __~-:?~_0~~~~~ (Dr.Md.Abdul Halim)

Head of the Department ------(Dr.Md.Abdul Halim) iv

ABSTRACT ------

In Bangladesh, the main efforts in flood control has been~through

construction of embankments and polders. However frequent failure

~ of embankments have resulted in doubts as to usefulness of em- ~~) . ij as an effective technology in flood mitigation •I bankments , i projects. Embankments are often damaged during floods rendering j,, them ineffective in providing protection.This study investigated I.J . ' • on the nature, mode and extent of failure of embankments in

Bangladesh. Main modes of failure of embankments are breaching,

overtopping, public cut and river erosion. For indepth evalua-

tion eight major flood control projects were taken up. It was

found that breach of embankment section and erosion by river were

the major causes of failure of embankments prior to 1987 flood.

In major floods of 1987 and 1988 overtopping and public cut also.

constitute major causes of embankment failure. Use of unsuitable

construction materials, lack of proper maintenance, incomplete

repair of damaged embankments and deviation from the design were

found as other causes of failures.

In the severe floods of 1987 and 1988 , 137.36 km and 35.69 km

were damaged respectively out of a total of ,989.05 km of embank-

ment in the selected projects. On the otner hand 10.09 km and

93.4 km bf protection works were damaged by the 1987 and 1988

floods indicating that major damage to embankment had occurred in

1988 due to failure of protection works. It was found that in

1987 flood main causes of embankment failure were: overtopping v

62.22 km (45%), erosion 36.34 km (27%), public cut 25.11 km (18%) and breach 13.69 km (10%). Whereas in 1988 flood breach 21.51 km

(60%) and erosion 8.63 km (24%) were the main causes of embankment failure; and overtopping 3.28 km (9%) and public cut 2.27 km (7%) constituted the other important causes.

The study made detailed recommendation so that embankments can

provide effective protection against floods. vi

ACKNOWLEDGEMENTS ------

The author acknowledges his sincere gratitude and indebtedness to Dr. Ainun Nishat, Professor, Department of Water Resources Engi- neering for his supervision, guidance and encouragement throughout the course of this study . His active interest in this topic and valuable advice throughout the study were of immense help.The author also acknowledges his gratitude to Professor Abdul Hannan d and Professor Abdul Halim for their valuable comments, construc- } tive criticism and suggestions regarding the study.

Gratitude is also expressed to Dr. S.K. Choudhury, Mr. Reazuddin Ahmed, Mr. Kazi Hamidur Rahman, Mr. Bara Bhuiyan, for their co-operations and providing useful data, on failure of embankments, used in this study. Sincere appreciations are expressed to the field staffs of Gaibandha Div, Rajsahi' Div, Rangpur Div, Comilla Div,Jessore Div, Barisal Div and Dhaka Div. of Bangla- desh Water Development Board who are encrusted with O&M responsi- bilities of flood control and irrigation projects for their cooperation with the author during his field trips to the project areas to help the author during the field visits to project areas.

The author acknowledges the co-operations of the Engineers of Master Plan Organisation,NWP for providing with technical reports and using their computer facilities. , . ~' The Assistance of Mr.Shahadat Hossain for word processing and of Mr.Karim for drafting is gratefully aCknowledged.

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TABLE OF CONTENTS J' .11 Page

ABSTRACT iv ACKNOWLEDGEMENTS vi LIST OF TABLES x LIST OF FIGURES xii LIST OF ABBREVIATIONS xiv

Chapter 1 INTRODUCTION 1

1.1 General 1 '.1 1.2 Objective of Study 2

Chapter 2 LITERATURE REVIEW 3

2.1 Planning Aspects 3

2.2 Type of Embankments 3

2.3 Design Criteria of Embankments 4 2.3. 1 Design Crest Level 4 2.3.2 Side Slope 8 2.3.3 River Side Slope Protection 8 2.3.4 Country Side Slope Protection 10 2.3.5 Slope Stability 1 1 2.3.6 Seepage Line and Seepage Quantity 12 2.3.7 Design Crest Width 13 2.3.8 Freeboard 14 , 2.3.9 Berm and Borrow Pits 15 ) 2.3.10 Set Back Distance 16 2.3.11 Alignment 16 )~. 2.3.12 Compaction 1 7 2.3.13 f " Confinement Effect 17

2.4 Adverse Impacts of Embankments 1 7

2.5 Embankments in Bangladesh 18 2.5.1 Review of Major Studies on Flood Control 19 2.5.2 Types of Embankments in Bangladesh 21

2.6 Construction of Embankments 22 2.6.1 Methods of Construction 22 2.6.2 Construction Phases 23

2.7 Maintenance and Supervision 24 2.7.1 Preventive Maintenance 24 2.7.2 Emergency Maintenance 26 2.7.3 Inspection 29

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TABLE OF CONTENTS ( CONT'O ) ------Page

Chapter 3 CAUSES OF FAILURE OF EMBANKMENTS 30

3.1 Hydraulic and Hydrologic Failure 30 3.1.1 Washout From Overtopping 30 3.1.2 Wave Erosion of River Side Face 30 3.1.3 Erosion By Gully Formation 30 3.1.4 Piping Action Failure 31 3.1.5 Conduit Leakage 31 1 3.1.6 Sloughing 32 . , 3.2 Structural Failure 32 3.2.1 Foundation Slide 32 3.2.2 Slides in Embankments 32

3.3 Operation and Maintenance Failure 33 3.3.1 Public Cut 33 3.3.2 Animal Intervention 33 3.3.3 Improper O&M 33 Chapter 4 RESEARCH METHODOLOGY AND DATA COLLECTION 34

4.1 Methodological Approach 34 4.2 Details of Questionnaire 34 4.3 Data Collection Procedure 37 Chapter 5 DATA ANALYSIS AND DISCUSSION 39

5.1 Failure Modes in Different Projects 39

5.2 Causes of Failure by Different Modes 40 5.2.1 Failure Mode by Erosion 40 5.2.2 Failure Mechanism by Breach 41 5.2.3 Failure Mode by Overtopping 42 5.2.4 Failure Mode by Public Cut 42 5.2.5 Protection Work Failure 43 5.3 Operation and Management Problems 43

5.4 Impact on Agriculture Sector 43

5.5 Discussion on Design Practice 44 5.5.1 Improving Embankment Stability 44 5.5.2 Increasing Crest Height and Maintaining Crest Width 44 5.5.3 Extension in the Outer and Inner Slope 44 5.5.4 Measure to Control Erosion 45 5.5.5 Rehabilitation with Earth 46 ix

TABLE OF CONTENTS ( CONT'O ) ------

Page

.5.5.6 Retirement of Embankments 46 5.5.7 Non-Uniform Design Crteria and Inter Project Interference 47 5.5.8 Recommended Design Criteria 47

5.6 Discussion on Construction 48 5.6.1 Sliding due to use of Peat Soil 48 5.6.2 Sliding due to use of Sandy Soil 48 5.6.3 Construction of Dowels 48

5.7 Discussion on Maintenance and Supervision 49 5.7.1 Maintaining the Designed Section 49 5.7.2 Maintenance and Supervision of Leaks and Cuts 49 5.7.3 Fund Constraint for Maintenance 49

5.8 Remedies/Steps to Control the Failure Modes 50 5.8.1 Erosion 50 5.8.2 Breach 50 5.8.3 Overtopping 52 5.8.4 Public Cut 52 Chapter 6 CONCLUSION 54

REFERENCES 56 TABLES 59

FIGURES 82

APPENDICES 108

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LIST OF TABLES ------Table Page 1 • 1 Basin-wise flood vulnerable area, protected area and area under ongoing projects for flood protection 60 2. 1 BWDB recommended side slopes for major and medium rivers 61 2.2 Recommended embankment slopes by Terzaghi 61 2.3 Recommended riprap design criteria \ 62 I 2.4 Minimum thickness of single layer filters under riprap blankets 62 2.5 Design criteria of river side protection 62 2.6 Recommended values of~, and ~~ Fellinius construction 63 2.7 Relation among fetch , wind velocity and wave height 63 2.8 Recommended values of freeboards 64 2.9 Freeboard by river type 64 2.10 Set-back distance for the embankment 64 2. 11 Backwater effect of confinement of rivers 65 2. 12 Embankment (or Levee) construction methods 66 2.13 ,. Conditions threatening safety of embankments 67 4.1 List of projects selected with location and purpose 68 5.1 Comparison of differnt failure modes Project: TRE 69 5.2 Comparison of differnt failure modes, Project :BRE 70 5.3 .Comparison of differnt failure modes, Project :CBP 71 5.4 Comparison of differnt failure modes. Project :NNP 72 5.5 Comparison of differnt failure modes, Project :GESP 73 5.6 Comparison of differnt failure modes, Project :MDIP 74 5.7 Comparison of differnt failure modes. Project :SBP 75 5.8 Comparison of differnt failure modes. Project :CCB 76 xi

,1. ' \) LIST OF TABLES (CONT'D) ------

Table Page 5.9 Comparison of different . failure modes in FCDI/FCD projects, Mode . Erosion 77

5. 10 Comparison of different failure modes in FCDI/FCD projects,Mode Breach 78

:I 5. 11 Comparison of different failure modes in FCDI/FCD projects,Mode : Overtopping 79

\ 5.12 Comparison of different failure !.:-;:. modes in FCDI/FCD projects,Mode Public Cut 80

5. 13 Comparison of different failure modes in FCDI/FCD projects,Protection Works 81

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LIST OF FIGURES

Figure Page

2.1 a Purely homogeneous type earthen embankments 83

2.1 b MOdlfied homogenous type earthen embankments 83

2.2 Zoned type earthen embankments 83

2.3a Diaphragm type earthen embankments 83

2.3b Inclined diaphragm type earthen embankments 83

2.4 Relation between wind velocity , fetch and wave height 84

2.5 Wave run- up 84

2.6 Relationship of wave height to fetch, wind duration 85 2.7 Taylors stability numbers for various slopes and angles of internal friction ( ) 85

2.8 Fellenius method of locating line of centre for critical slip circle 86

2.9 Locating centre of the critical slip circle for o inclination of slope < 53 86 2.10 Vertical strips or slices between the critical slip circle and embankment slope line 86- .1 2. 11 Set back for river embankments 87

2. 12 Additional set back at sluices 87

2.13 Location of the phreatic line through an embankment 88

2.14a Cambering of an embankment 89

2.14b Crest raising of an embankment 89

2.14c Crest and side slope raising of an embankment 89

2. 15 Embankment after slip failure in the CIS 90

2.16 River side slip of an embankment 90

2.17 Construction methods for high water mud box 91

2. 18 Ghog repair of an embankment 92 ,I, xiii .

LIST OF FIGURES (CONT'D)

Figure Page

2.19 Construction methods for high water sand boil 93

2.20 Loading of Large boil 94

2.21 Methods for raising embankment height in emergencies 94

2.22 Section of a bleeder well 94

2.23 Embankment breach protection 95

2.24 Embankment breach closure 96

2.25 Closure arrangement of a breached Embankment 97

2.26 Slope protection through vegetative cover or turfing 97

2.27 Underseepage control measures for embankments 98

2.28 Types of drainage arrangements 98

3.1 Embankment showing proper berms at suitable height 99

3.2 Piping through embankment and foundations 99

3.3 Sliding due to soft or weak foundation 100 3~4 Cracking of embankment due to foundation settlement 100

3.5 RIS slope slide due to sudden draw down 100

3.6 CIS slope slide during steady seepage condition 100 4.1 Map showing location of the FCDI/FCD projects selected 101

5.1 Mode of repairs 102 , 5.2(a) Schematic layout of a spur 103

5.2(b) Schematic layout of a groyne 104

5.2(c) Schematic layout of a purcupine 105 5.3 Embankment rehabilitation with application of crest bund 106

5.4 Resectioning of the large breached portion of sliding embankment 107

5.5 Construction of dwarf embankment in the RIS ,107 xiv

LIST OF ABBREVIATIONS

ASCE American Society for Civil Engineers BCEL Bureau of Consulting Engineers Limited BETS Bangladesh Engineering and Technogical Services BRE Brahmaputra Right Embankment BWDB Bangladesh Water Development Board CBP Chalan Beel Project CCB Chen-Churi Beel Project I CIS Country Side DCS Development Consulting Services DDP Delta Development Project t FB Freeboard FC Flood Control FCD Flood Control and Drainage FCDI Flood Control Drainage and Irrigation GESP Gumti Embankment Strengthening Project GOB Government of Bangladesh HYV High Yeilding Veriety IDA International Development Agencies LGEB Local Government Engineering Bureau MPO Master Plan Organisation MIWDFC Ministry of Irrigation Water Development and Flood Control MDIP Meghna Dhonagoda Irrigation Project NNP Narayangonj-Norshingdi Project PMACS Project Management and Consulting Services RIS River Side SBP Satla Bagda Project , TRE Teesta Right Emabnkment , ' , . UNDP United National Development Programme USBR United States Bureau of Reclamation

I \ ;' fl- I I: ,I Chapter 1 ," INTRODUCTION

1.1 General

-'Embankments along river banks have been accepted as a major tool for flood control allover the world. Its wide use is manifested in the economics of embankment construction; it can be built cheaply with local material and labour, the level of construction technology required is not high and operation and maintenance is also cheap and easy .•

~The embankment projects are designed to provide protection from flood to the area behind it which then can be suitably developed for enhanced economic and agricultural production. Before the implementation of the project, the area used to be subjected to frequent flooding during the monsoon seasons when adjacent rivers attain high flood stage . In some projects, drainage may become serious problem. A properly designed and constructed embankment project prevents the flood water intrusion and drains off the excess water through the regulators and sluices.

In Bangladesh, flooding is a perennial problem. About "32,325 sq.km, ie. 59 percent of Bangladesh prone to flooding.(BWDB,1987). At present half of that area ( about 10,969 sq.km, 34 percent) is protected against floods (Table' 1.1). During the floods of 1987 and 1988, besides the unprotected areas, it is estimated that roughly one half of the protected areas were flooded due to failure of the flood protection or the drainage systems.

The damage and disorder set by the two consecutive floods for 1987 and 1988 have been ubiquitous in nature. Hardly had the nation completed the rehabilitation of and recovery from the damage caused by the flood of 1987 when it was hit the floods of 1988. It has wrecked havoc in almost all sectors, including water resources.

There are 416 completed and 40 ongoing small, medium and large Flood Control and Drainage (FCD) and Flood Control Drainage and Irrigation (FeDI) projects under the Bangladesh Water Development Board (BWDB). A list of completed and ongoing embankment projects is appended ( Appendices A & B). Total flood protection area ( 30.17 lakh ha) under the completed projects as planned is not ensured in 1987 and 1988 floods (BWDB,1989). Of the 416 completed and 40 ongoing projects, 256 have been affected by the flood of 1988.

-/ The failure of embankments are due to river bank erosion, public I " , cuts, overtopping, breaches, encroachment by dwellings, wave action, and faulty instalment of pipe sluices by local authori- ! ties. To a lesser extend , unsuitable construction materials, ~

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poor ring bunds while constructing structures, incomplete repair of previous breaches and deviation from the design may also be causes of failure. Poor compaction and faulty design are also reasons for embankment failure.

Failure of embankment breaks to confidence in embankment. We take up the study with the aim to through light on the nature, mode and extent of failure of embankments in Bangladesh.- This will lead to formulation of remedial measures for proper functioning of these embankments, safety of which are so vital for our economy.

1.2 Objective of Study

The purpose of the study is to investigate the performance of the flood control component (embankment) of the selected FCDI and FCD projects located at various parts over the country.

The objectives of the proposed study are:

1. To investigate the nature, extent and causes of failure of embankments/polders in the selected FCDI and FCD projects.

2. To recommend the appropriate maintenance and treatment procedure which should be applied to check the failure of embankments.

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Chapter 2 f,. LITERATURE REVIEW

2.1 Planning Considerations

In planning of embankment projects (USSR, 1974), the following points need serious attention: o That the project is responsive to an urgent present or anticipated social or economic need.

o That the project as planned will adequately serve the intended purpose

o That the services proposed to be performed through the project (i.e. FC & D) and the benefits (i.e. irrigation) it will produCe will justify the cost.

o That the project will cause minimal disturbance to the ecology and environment of the area i.e.

there should be adequate provision for the drainage while internal road communications are planned with the poldered area.

there should be no adverse effects of the FCD projects on the surrounding areas.

2.2 Type of Embankments

Embankments may be classified into three major types depending 'on the nature of protection they provide and their location:

o Full flood protection embankments o Submersible embankments o Tidal dykes

Submersible embankments are usually built to afford protection during the pre-monsoon flood; thereafter they are overtopped and remain submerged during the monsoon. Tidal dykes are usually built along the coastal belt to protect lands against flooding, surges and intrusion of saline water.

Embankments may again be classified into three types depending on construction techniques and material used :

1. Homogeneous type 2. Zoned type and 3. Diaphragm type

1. Homogeneous Type: This type of embankment (Fig. 2.la) are constructed of earthen materials of essentially the same quality 4

throughout. This type are convenient where the slopes are re- ,. quired to be flat. A modified homogeneous type (Fig. 2.1b) are in use which permit steeper slopes (Varshney, 1982).

2. Zoned Type: Zone type (Fig. 2.2) usually have a central zone of selected soil material to form a relatively impermeable core, and outer zones of more pervious material for stability. This type is selected whenever suitable material are available (Fran- zini, 1987).

3. Diaphragm Type: This type (Fig. 2.3a) have a thin central section of earth, concrete, steel of timber which serves as a water barrier, while the surrounding earth of rock fill provides stability. The position of the impervious diaphragm may be in between the river side face and central core and are termed as inclined diaphragm type as shown in Fig. 2.3b (Varshney, 1982) . • C The type of earthen embankment would be dictated essentially by the materials available at or near the site as also the founda~ tions. In the interest of economy, the design of earthen embankment should be adopted to the full utilisation of the available materials. Thus if only sandy material is available the design .should utilize material for the bulk of the embankment, limiting the imported material for providing impervious membrane to the minimum IVarsh~ey, 1982).

2.3 DESIGN CRITERIA OF EMBANKMENTS

The basic principle of design is to produce a satisfactory functional structure at a minimum total cost. Consideration must be given to maintenance requirements so that economics achieved in the initial cost of construction will not result in excessive maintenance costs.

The design of an embankment must fulfill the following two major criteria:

Ii) the embankment must not be overtopped during the passage of the design flood i.e it should have sufficient freeboard,

Iii) The body of the embankment must remain stable against exter- nal forces and foundation failure during normal and critical conditions of loading.

2.3.1 Design Crest Level

The height of an embankment is determined by:

the maximum water level that has to be retained: the" design flood level". - an additional height for setup of water due to wind. - an additional height for wave run-up. 5 Furthermore, allowance has to be provided for the shrinkage of the freshly built embankment bOdy and the settlement of the subsoil due to surcharge. However, this additional height is not considered part of the design crest height.

In addition an extra freeboard of 1.0 m is to be-applied to arrive at the design crest level.

The design crest level is thus composed of: H = H + H + H + 1 m DES FL W Z in which H = design crest level DES H = design flood level FL H = wind set-up W H = wave run-up Z 1m = safety margin According to Punmia (1982),

H = H + [(H + H ) or USBR recommended F.B.] DES FL W Z whichever is greater

= H + USBR recommended F.B, where H FL & H not known W Z H = H + 0.91 m DES(min) FL

Design Flood Level

The design flood level, which the embankment has to retain, is a major criteria for the design of the embankment. The recurrence interval of floods that needs to be selected for the design of a particular embankment depends on the acceptable extent of damage by inundation in the locality. Considering likely agricultural damage, high property values and loss of human lives, the following flood frequencies may be adopted (Thompson & Rippin, 1985):

- the 1:20 year flood where agricultural damage is predominant - the 1:100 years flood where significant socio-economic development as well as human lives are threatened.

Having selected the flood frequency the design flood level need to be assessed in two cases, as follows, depending upon whether embankments are to be provided in one bank or on both banks.

Where constructed on one bank only, H may be computed by FL frequency analysis of available annual maximum river level data for full flood protection embankments and maximum river level data before some specified time during the year ego 30 June, for submersibles method, and 6

Where constructed on both banks, H need to be computed from FL the design flood discharge under confined conditions. Wind Set-up

According to Saville, McClendon & Cochran (1962) wind setup may be estimated from 2 Z = (V) F/1400d S w

where, Z = the rise in feet above still-water level S V = the wind speed in mph w F = the fetch or length of water surface over which the wind blows in miles d = average depth of the river orbeel along the fetch in feet.

If wind is blowing long anough from one direction over a significant water surface, a rise of the water level will result at the down-wind side. The general formula for calculating the wind set-up is given by -6 2 4x10 * W * 1 * Cos~ H = ------_ w gh in which w = wind velocity in (m/s) at 6 m above water level 1 = length of water area over which the wind is blowing g = specific gravity h = average water depth along stretch 1 1 i' ~ = angle at which the wind is approaching the coast Wind setup develop during wind condition that last for atleast 24 hours. The effect of wind setup may be included in design calculation in case the water level data are from a temporary gauge (or gauge with < 10 years record). Wave Run-up

With respect to embankment design, two aspect of waves have to be considered:

the forces of breaking waves against the slope an embabnkment causes erosion if no protection is provided.

- the run-up of waves against a slope might cause overtopping of the embankment if the crest level is not high enough.

Waves, generated by wind blowing over water, are increasing in , height, if the fetch is increasing. A relation between fetch (F), I wind velocity (w). Wind duration (t), wave height (H) and wave "' period (T) is presented in Fig. 2.4 7

The general experession for the wave runup is (shown in Fig. 2.5) -~.'-- ., H = 8 f H tan (?( * Sin 1.3(l-B/L) , m z * * '" in which f = constant factor H = wave height (m) (?( = slope of embankment 1.3= direction of increment waves B = berm width (m) L = wave length (m) Note: Factor (l-B/L) may be omitted if no berm is applied.

The factor f = depends on the smooth ness of the slope surface (0.75-1.25)

= 0.75, for very rough rip-rap = 1.25, for very smooth asphalt-concrete slopes = 1.1, for turfed slopes.

Furthermore, it should be noted that the formula is only valid for slopes with 1/8 < tan (?( < 1/3.

Shrinkage and Settlement

A settlement of an impervious zone varies according to factors such as type of materials, degree of compaction and water control, and a settlement of a previous zone varies according to factors such as the type, gradation and grain shape of materials, compaction method, thickness of layers of dumping height and whether of not water jetting is employed.

It is to be estimated how much the design crest level should be raised to allow for shrinkage and settlements. Experience has learned that shrinkage of a fresh embankment average 10% of the maximum fill height. In case of organic subsoil layers, a shrinkage allowance of 50% has to be considered and should be added to the 10% alowance for fill-shrinkage.

According to Varshney (1987) the settlement allowance of 2% can be adequately taken both for the foundation and the embankment and for embankment more than 30 m in height, an extra 1% allowance is provided to account for the settlBment due to earthquake.

There exist some empirical formulas for predicting the settlement of the embankment. The Spudie formula (Hungspreug, 1987) gives S = 0.033 (H'- 13)

where S = settlement of the embankment H = embankment height

Whereas if H is less than 13 meters, the settlement is predicted to be 0.2-0.4% of the embankment height. This formula is, however, not often used. 8 2.3.2 Side Slopes

The criteria for selection of design side slopes shall be based on the following requirements:

- embankment slopes should be stable against adverse seepage flow the embankment should be stable against shear failure through its base.

Country side slopes should never be less than 1 in 2 (horizontal) even if the stability calculations might indicate steeper permis- sible gradient. Generally a CIS slope of 1 in 3 (horizontal) will be adequate but in case of sandy material this might have to be reduced. The slope at RIS is designed as steep as the stability of the earth bOdy allows, in order to reduce cost of revetment necessary. Under normal conditions a close turfing will provide sufficient protection and a slope of 1 in 2 (horizontal) is

,I adequate. The side slopes for major and medium rivers as recommended by BWDB are given in Table 2.1.

Side Slope for Homogeneous & Zoned Embankment:

As a general rule for homogeneous embankments of fine-grained soil, the higher the embankment, the flatter must be the slopes .. Internal zoning in a embankment permits the use of steeper slopes.

For any given safety factor against shear failure, and embankment with minimum volume is usually obtained when the side slopes are made steeper at the upper elevations and flatter near the bottom. Variable slopes should be considered for all earthen embankments higher than about 100 ft. The higher the embankments and the softer the foundation, the greater is the economic advantage to be gained from varying the slopes. .

For fixing tentative section of earthen embankment the RIS and CIS slopes may be taken from Table 2.2 given by Terzaghi (1975).

2.3.3 River Side Slope Protection

Surface protection of river side (RIS) slope is meant to prevent the destructive wave action. Usual type of surface protection for the RIS slope is stone rip-rap either dry dumped or hand placed. When a thin layer is used, hand placed rip-rap may be more economical than dumped rip-rap.

Size and gradation of rock and Thickness of Riprap Layer:

The minimum suitable size and gradation of rock and thickness of riprap layer depend on the intensity of the wave action expected and on the steepness of the embankment slope on which the riprap rests. Fig. 2.6 is a chart developed by the U.S. Navy Hydrographic Office modified by the U.S. Army Engineers for short reservoirs relating wind velocity, reservoir fetch, and maximum wave height, which is sufficiently accurate and reliable for riprap design. From all the experience available the riprap sizes given I I ~~':~ , ~ ,. :. , 9 i I in Table 2.3 are reasonable and conservative for earthen embankments with ordinary slopes. I.

Hand Placed Rip-rap: The hand placed rip-rap for upstream protection:.is very common in this country. The size of stones used for hand placed rip-rap may be determined with the following formula (Varsh~ey, 1982). 2 1/2 d ::2.23 c * h *d"w/(i- iw)* (1 + s) /s(s+2) m w where d :: diameter of stone brought to form a ball, in m meter, in the zone of maximum blow of the wave 3 J :: unit weight of stones in tim 3 ~ ?Jw :: unit weight of water in tim 1,\ s ::.slope of embankment

h :: height of wave in meter w

C :: factor depending on the type of protection ::0.54, for hand placed riprap

= 0.80, for rockfil1 or dumped riprap d ::average size of stone required d /0.85 av m (average shape) The average weight of the stone can be found out by the formula: 3 w ::~/6 * (d ) * ¥ av av Filters below Riprap Layers:

A layer of filter material consisting of gravel or crushed rock is always required under riprap to prevent waves from eroding the underlying embankment material.

Filters which are reasonably well graded between a maximum of 3 or 4 inch and coarse sand sizes are satisfactory for the great majority of embankments.

On the great majority of earthen embankment, one layer of material has been adequate. No definite rule can be given for the minimum necessary thickness of the filter layer. Most filters are constructed with thickness ranging from 20 cm to 75 cm. 10

The following are the factors which should be considered in the selection of filter thickness: wave action,gradation of the rip- " rap,p1asticity and gradation of embankment material and cost of 1(, filter.

The U.S. Army Engineers use the recommended filter thicknesses as a function of wave height as shown in Table 2.4.The values in Table 2.4 should be considered as absolute minimum thickness. Where the embankment material comprising the R/S slope directly under the riprap is composed of a very fine-grained soil, such as silt, it is often necessary to use two layers of progressively coarser material in order to meet the filter gradation requirements. These should not be less than 6 inch thickness and preferably thicker.

Filter Design

It is generally accepted as good practice to:require that the relative gradation of adjacent soil zones meet established "filter criteria" to prevent any possibility of appreciable migration of soil particles. •

The two principal requirements for a satisfactory filter are that it must be more pervious than the protected soil in order to act as a drain, and that it must be fine enough to prevent particles of the protected soil from washing into its voids.

Horizontal filter layers can safely be made thinner than steeply inclined or vertical filters. Minimum thickness of each horizontal layer is 15 cm for sand and 30 cm for gravel. If the filter excessive fines or coarse material such that

D of fi lter 15 ------> 4 but < 5 I I' D of base 15

D of filter 15 ------> 5 but < 6 D of base 85

the thickness of filter layer may be increased by 50 percent.

Table 2.5 shows the design criteria of R/S protection as adapted by Central Design Directorate of Irrigation Department, UP.

The entire R/S face should be pitched right upto the top of bund.

2.3.4 Country Side Slope Protection

The problem of erosion of country side slopes due to surface run- off may be effectively controlled by turfing. In areas too deficient in rainfall during parts of the year to maintain a proper cover, berms and other erosion control methods may be applied. 11

2.3.5 Stability of Slopes

Every soil mass which has slope at its end is subjected to shear stresses on internal surfaces in the soil mass. The stability of slopes of earth-structures depends on the shear resistance or strength of the soil. Various methods have been proposed for computing stability of slopes of earth fill embankments. Among those, two methods will be described here,

A. Taylor's method: Based on Swedish Slip Circle idea, to avoid tedious computations for stability analysis, Taylor generated a series of curves (Fig.2.7). These curves are i (slope angle) vs m (stability number). Knowing the slope angle i, the stability number m can be found out from the curve for respective angle of internal friction (0). Taylor "formulated the stability number m as c c m = F =

where, c = cohesion F = factor of safety ~m = mean unit weight of embkt. material H = height of embkt.

B. Swedish Slip Circle method (or slices meth6d) In this method, it is supposed that, the surface of rupture takes a cylindrical shape. Finding process of the critical (or dangerous) slip circle:

i) The point Q is found out as shown in the Figure 2.8. ii) Knowing the slope of the embankment, the directional angles "", and ""2 are found from Table 2.6. iii) Based on the directional angles 0<1 and 02the point P is located as shown in the Fig. 2.8. The line QP is the locus of the centre of the slip circle. o iv) Now if the inclination of the slope is less than 53 , the centre lies on the vertical line drawn through the mid point of the slope as shown in the Fig. 2.9. Thus, the crossing point is the centre of the critical slip circle. v) Except for very small values of ~ , the critical arc passes through toe of the slope. The earth mass between the critical slip circle arc and the embankment slope line is divided into a number of equal spaced vertical strips or slices as shown in the Fig. 2.10.

The weight W of each slice resolved in normal and tangential components as :

N = W Cos 0< T = W Si n oC where,o(= angle of the slope line with horizontal. 12

cL + tan fJ (IN-LU)

I Finally, factor of safety, F.S. = ------i, ~T where, c = cohesion L = length of slip arc LU = summation of uplift forces due to pore water pressure along the arc.

The area enclosed by the slip arc and the seepage line contains saturated earth. The water pressure (¥wh) at the bottom of the area for each slice (pore water pressure) is calculated.

2.3.6 Seepage line and Seepage Quantity

The phreatic, seepage or saturation line is defined. as the line within the embankment section below which there is postive ,. hydrostatic pressure. It is essential to determine the position of phreatic line because it:

o gives a divide line between the dry (or moist) 'and submerged soil and is important for computation of the shear strength of the soil.

o represents the top streamline and so assists in drawing the flow net.

o helps to ensure that it does not cut the dis face of the embankment.

For stability analysis of an embankment, determination of phreatic line i.e the seepage gradient, along the embankment x-section is the prime requirement. The preatic line is assumed to be a 2 2 base parabola and is given by x + y = x + s, where s is the distance of the point (x,y) from the directrix, called the focal distance.

At the exit the base parabola, will cut the CIS slope at J & extend beyond the limits of the embankment as shown by the broken line in Fig. 2.13 . The correction L>a, by which the parabola is to be shifted downwards, can be determined by using the equation

Ll.a= (a+ll.a)[(180-0<) 1400 ]

where a, L>a and 0< (in degrees) are as shown in Fig. 2.13 A general analytical method for computation of a is

d [d 2 h2 ] 1/2 o = Case>< - CosZ"c - Sin2o< .• When 0< <30. 2 2 = Yb + h -(b~h2COI2o(, When 30.~ '" ~60.

d= HCh+b+[ HC+~]f+B Vc. V VR H c . L = 0 h Vo All other parameters are as shown in Fig ..2.13

;" . From above it is seen that for the homogeneous earth fill embankment, the seepage line always emerges through the lower side of CIS slope. so, for safety factor, the exit gradient must be less than the critical gradient.

Exit gradient, i = -lim ~ .0.6-..0 As i = (S -1)/1+e cr 5

where, Ah = total head loss of the fluid over the distance As S = specific gravity of embkt. material. 5 e = void ratio.

Seepage Quantity:

The seepage quantity can be determined by drawing a flow net for the embankment under the design flood condition and taking values of n and n ,the number of flow channels and no. of potential f d drops respectively from the flow net. Seepage quantity (q) is given by

q = Kh n In f d 1/2 where K = (K IK) H v

h = total head loss 3 If q is greater then 1m IdaYllin m of embankment, a filter may be provided to protect the discharge face. j j

2.3.7 Design Crest Width

The crest width of an earthen embankment should be sufficient to keep the phreatic line, or upper surface of seepage, within the embankment when the river or bee1 is full. Crest width should also be sufficient to withstand earthquake shock and wave action. For most of existing embankments, the width is 8 to 12 m for high embankments and 4 to 7 for low embankments.

According to the Design Manual for Polders,\ Delta Development Project (1985), minimum crest width should be 2.5 m.

Smaller crest widths will make the embankment more vulnerable in case of overtopping which will cause erosion of inner slope and crest. , I For the determination of an appropriate minimum crest width of i embankments the following empirical rule can be used: H < = 2 m 8 = 2.50 m H > = 5 m B = 6.00 m 2 < H < 5 m 8 is chosen at a proportionate size in between 2.5 and 6.0 m, rounded of to the nearest 0.5 m in which

H = H minus existing ground level or, DES = H minus berm level (if avai lable). DES I (',. U.S Bureau of Reclamation (1974) suggested the formula for the determination of crest width for small earthen embankments:

W = Z/5 + 10 where W = width of crest in feet, and Z = height of embankment in feet above the streambed

For higher embankments the crest width (8) can be selected as per the following recommendations (Garg, 1983): 1/2 8 = 0.55 H + 0.2 H for embankments < 30 m 1/3 8 = 1.65 (H+ 1 .5) for embankments > 30 m where H = height of the embankment

According to Varshney & Varshney (19a7), it can be fixed as 1/2 8 = 5/3 * H where 8 = crest width in meters H = height of the embankment in meters In case inspection of the embankment is to be executed with a vehicle (four wheel driver"off road), the minimum crest width should be 4 m.

For a road at crest level a road berm has to be provided of minimum 1.5 m width at both sides of the road. If the embankment is rather high, then it might be more economic to reduce crest width and construct an extra c/s berm at 0.5 m above maximum spring tide level (H.W.S) thus reducing earthwork. 2.3.8 Freeboard

Sufficient freeboard must be provided so that there is no possibility whatever of the embankment being overtopped. The rational determination of freeboard would require a determination 15

of the height and action of waves. Various empirical formulae depending on wind velocity and fetch have been suggested for computing wave heights. The Molitor-Stevenson formulas (Hung- spreug, 1987) are normally used which are 1/2 1/4 h = 0.032 (FV) + 0.763-0.271 F ,where F<32km w 1/2 h = 0.032 (FV) where F>32km w

where h = wave height in meters measured between trough and w crest V = wind velocity in km per hour F = fetch in km On a sloping surface the wave rides along the slope upto a vertical height of 1.5 times the wave height above the water level (HFL), hence 1.5 h is provided as freeboard. A summary of w

empirical formulas proposed for determination of wave heights is shown in Table 2.7 (USBR, 1974).

According to USBR ,criteria distinction, is to be made between the normal and minimum freeboards. Normal freeboard is defined as the difference in elevation between the crest of the embankment and normal water surface. According to the fetch the freeboard may be provided as given in Table 2.8.

It is also be " recommended that freeboard shown in Table 2.8 increased by 50 percent if a smooth pavement is provided as protection on the R/S slope.

The BWDB has recommended freeboard for major and medium type rivers as shown in Table 2.9.

2.3.9 Berms and Borrow Pits

Under certain conditions the application of a berm in the embankment may be useful.

Berm might be effectively applied to reduce the wave run-up against an .embankment. In other cases, where artificial protection of the R/S slope have to be designed, a small berm is applied to facilitate the transition between two different types of slope revetments.

Borrowpits should be excavated in such a way that a berm is left between the toe of embankment and the edge of the excavation. The berm width varies from 3m to 6m, depending upon the depth of the borrow pit. But according to DDP the berm width should be 10m for river embankments. The depth of the borrowpits should not exceed 2.0m below ground level (Fig. 2.11). A berm of not less 16

,. than 6m should be left between edge of borrowpit and actual i, riverbank a berm of 6m has to be left. Cross berms, perpendicular to the embankment, have to be left in the excavation every 30m measured along the embankment. These berms have to have a width of 6m and are to prevent the development of flow concentration during flood conditions.

2.3.10 Set Back Distance

The criteria on which the set back distance for the embankment (i.e, space between actual riverbank and R/S toe of the embankment) in a river is to be designed can be formulated as follows:

if earth is borrowed from the riverside, provision of borrow pit and berm

- there should be sufficient space to increase the height of the embankment by putting additional material against outer slope

- an extra margin, equivalent to 10 years of the present erosion rate, should be added to the minimum setback to be applied.

- adequate floodway for the designed discharge: and

adjustment of set-back distance to keep the flow around critical velocity so that both erosion and siltation are minimum

if the above criteria cannot be maintained, a minimum setback equal to 6.0 m for the eroded bank may be kept but bank pro~ection work are to be provided.

The setback at a water control structure should be atleast be 2 times the minimum setback for the adjacent embankments (Fig. 2.12).

The setback distance for the embankment in proximity of different rivers are given in Table 2.10.

2.3.11 Alignment of Embankments

The determination of the alignment of an embankment is governed by technical, socio-economical and morphological considerations. An ideal alignment should satisfy the following criteria:

- it requires least land acquisition

- scouring of river banks has to be studied from maps and aerial photos in order to determine whether rivers tend to be moving towards the planned embankment.

- set-back criteria should be considered.

I 17

- Abrupt changes of the alignment have to be avoided.

Soil survey has to be executed to make an inventory of the available soils to be used to the embankment construction.

- Sub-soil and potential borrow materials with a fair portion of clay preferred and should not consist of peat or organic soils. This may be done by auger borings to a depth of 4 m and at 250 m interval along the proposed alignment.

- the orientation of an embankment respective to prevailing wind direction during flood conditions is important.

2.3.12 Compaction

No embankment should be constructed without campaction. But in Bangladesh it is very difficult to get the embankment compacted by the local contractors. However, the compaction is accepted as the most important component in the construction of embankment and in no case this item should be neglected or omitted. All embankments to be constructed whether new or rehabi1ated must be properly compacted (95 percent compaction) with mechanical equipment.

2.3.13 Confinement Effect

The confinement effect due to construction of embankments on both banks of the rivers should be determined. The general model of surface water simulation model of MPO is capable of computing this effect on all the three major rivers. The rise of water level due to confinement should be added to the 100 years frequency level for the purpose of design of embankments. Table 2.11 shows the backwater effect of confinement of rivers by FCD projects.

2.4 Adverse Impacts of Embankments

The flood control by embankment and polderisation which is the main thrust may have serious adverse consequences. Embankment on one side of a river increases discharge on the unprotected side of the river increasing intensity of flood there. Embankment on both sides of the river while confining the flow in channel, increases stage, forces sediment deposit on channel bed causing it to rise gradually and thus causing channel instability.

Furthermore many of the embankment schemes built in relative isolation and without any integrated approach may be blamed for localised flooding. 18

According to Volker (Volker, 1983) the effects of embanking can be divided into three groups:

- the hydraulic effects; - the morphological effects; - other environmental impacts;

Hydraulic Effects: These effects are caused by the elimination, by embanking, of the overland flow and overland storage of water on the land areas. The result is a rise of the flood levels, the downstream areas are exposed to higher floods and the rise propa- gates also in upstream direction. The strip between the channel and the embankment will be exposed to deeper flooding than be~ore which led to public cut of embankments. Morphological Effects: Embanking tends to increase the velocity of the flood flow and as such, enable the river to carry more silt load. Thus, after embanking, while some river show aggrading tendency (braided form) on account of progressive silt deposit, some remain stable (Srivastave, 1985). The bank erosion may introduce a failure of the embankments. In many cases, after embanking, a rise of the river bed has been observed leading to still higher flood levels. Embanking halts the natural process of building up of the land areas. Embanking also stops the deposi- tion of fertilizing silt. other Environmental Impacts: After embanking excess water from local rainfall will not flow to the receeding river. Not only drainage outfalls (sluices) in the embankments are necessary but also a system of drainage canals to convey the water to the outfalls. This leads to disadppearance of water conservation and to storage of water in the beginning of the dry season. Also the beneficial effects of flooding in the early stages of the growing season has been eliminated. In a number of cases, like in Polder 22, the farmers have made cuts in the embankments to admit the water. Embankments also eliminate the beneficial effects of the floods in removing dirt, wastes and salanity accumualted during the dry season, rinsing of the canals will be necessary.

The question is how the farmers will react to this drastic change in the environmental conditions. New possibilities have been created but the farmer may not be in a position to seize these opportunities unless facilities like crediting, extention and marketing are available. The problem of embanking in Bangladesh is not only a technical problem but even more so a socio-economic and a human problem.

2.5 Embankments in Bangladesh There are 249 completed and 34 ongoing embankment projects under the Bangladesh Water Development Board . A breif review of the major studies on flood control and various types of embankment in Bangladesh are described in the following sections. ]9

2.5.1 Review of Major Studies.on Flood Control

The first attempt to assess the magnitude of flooding or its consequence was made by Mohalnobish (Mohalnobish,1927) in 1927 when he analysed the flood that occurred between 1870 to 1922. Modern and scientific approach to flood control and water development as a whole was made in this country in the late 1950s. After two consequitive major floods of 1954 and 1955 a major study was launched by the United Nations to investigate into the causes of floods and find its solution. The report of this study now known as krug Mission Report (1957) considered various methods of protection against flood and suggested construction of embankments and channel improvement. The report also stated that only available method for reducing the flooded area was confinement of flood waters within the river channels. Other notable major studies was carried out by Hardin (1963) and

Thijsse (1964) whose findings paralleled those of the Krug Mis- sion in the analysis of flooding and possible means of reducing the damages.

Then in 1964, International Engineering Co. of USA (IECO), prepared a comprehensive Master Plan wherein about 55 flood control, drainage and irrigation (FCDI) schemes were identified for implementation over the period 1965-1985 (UNDP,1989). Typical projects comprised FCD components in the first stage followed in most cases by irrigation in the second stage. A total of about 3200 km of embankments along the major rivers and tributaries was to provide flood protection to about 3.24 million hectares (Mha). Embankments on both banks of the Ganges, the Brahmaputra and the Meghna were to be completed by 1985 (Siddiqui, 1985).

About 30 projects were to be taken up during the third Five Year Plan (1965-70) of Pakistan Although the plan was being implemented in stages it was not acceptable in full . Implementa- tion of' large flood protection projects was not taken up in full earnestness mainly due to lack of funding. Moreover, with the lapse of time and changed economic circumstances, need for fresh appraisal of the flood control plan was felt and modified plans were prepared in 1968. Among others, three factors appear to be dominant for the retarded implementation of major FCD projects (Siddiqi, 1987).

First, as indicated in the IBRD Review of 1966 that it was risky to embark on massive projects along such mighty rivers with inadequate data as was available. As there was no satisfactory answer to some serious technical issues international donors were reluctant to finance the plan and accept the approach or strategy embodied in the master plan. The second factor, was the growing recognition that there were alternative and cheaper ways to achieve substantial increase in crop production than through large FCD projects. Thirdly, the amount of land acquisition for building dykes and the cumberous procedure involved therein stood on the way to timely implementation of projects in an alarming degree. The Master Plan was never officially accepted by the East Pakistan government, although its projects served as the basis for the subsequent five year plans (Khan, 1985). In 1969 World Bank hired Acres International of Canada and ILACO of the Netherlands to review the Master Plan and in 1970 produced a "Hard Core Program" consisting of 26 projects from 1964 Master

Plan that were considered to be feasible and economic (Khan 1985). By the Early 1970's technical data on the land and water resources of Bangladesh matured to significant extent. The joint IBRD and IDA Sector Study "The Land and Water Resources Sector Study, 1972", called for a significant different program from that of the IECO Master Plan. Food production rather than flood protection was emphasized and in the water sector small quick yielding FCD projects in shallow flooded areas became the focal point of water development efforts. Such schemes would involve low embankments and gravity drainage requiring simple and less sophisticated technology. However, the study was never accepted officially by GOB. After two years launching the 1st plan it was found that the achievement was far short of expectation. No financial aid to implement large FCD project was forthcoming. Therefore, a more pragmatic three year Hardcore program was drawn. It was during this period when the low cost FCD projects in shallow flooded areas started receiving attention but in fact the investment programme consisted mainly of minor irrigation schemes and of some Dutch Early Implementation Projects (EIP). IDA financed DFC studies started from late 1976. It was not until 1979/80 the low cost FCD schemes received great emphasis in development planning (Siddiqui, 1985). The government has for sometime acknowledged the need for a new national water resources development plan. To carry out this objective Master Plan Organization (MPO) was established in 1983 to formulate a National Water Master plan for the period 1985 to 2005 (Khan, 1985). Harza Engineering Company International was selected as the consultant to MPO which submitted its final report on Dec' 1986. No action plan or project identification has been framed in this NWP-Phase I. It was not until the occurrence of the consecutive and catastrophic floods of 1987 and 1988 that there has been a renewed awakening nationally as well as internationally over floods in Bangladesh and their solution. In order to formulate a comprehensive flood policy and to mitigate the effects of such catastrophic events the Ministry of Planning of the GOB decided to initiate a study which would examine the cause, nature and effects of the floods, remedial meaures and establish a sound flood policy (UNDP, 1989). ( 21

In May 1989, United Nations Development Programme (UNDP) with j the 1 assistance of local and international experts presented the GOB the 'Bangladesh Flood Policy Study' report and recommended the various means of flood protection.

2.5.2 Types of Embankments in Bangladesh

Bangladesh more than Any country is vulnerable to frequent and disruptive flooding and therefore needs planned measure for flood mitigation. Properly planned and maintained embankments offer the country a permanent solution to its age-old problems of flooding. The Government now considers this structural approach combined with integrated development of the protected area, as its long- term national policy. However, non-structural measures can help people live with floods especially in the short-term until embankments are built. The most important of these measures include flood forecasting, early warnitlg and flood preparedness.

While accepting the construction of embankments as a means to protect against regular flooding, there remain various options that could be followed (UNDP, 1989).

i) Provide a high degree of safety against flooding to all areas atld accept overtopping of the embankment only in exceptional cases. The advantage of this option is that th~ risk of flooding minimal and optimum physical conditions are created for the socio-economic development of the country. The disadvantages are the high costs of investment and maintenance.

ii) Provide a high degree of safety to urban centres and a reasonable degree of protection to rural areas. Floods may still overtop the embatlkments, but with such frequency as is commensu- rate with socio-economic development in the protected areas. The advantage over the previous option is that investments will be lower and the construction period shorter, althoguh it may still take some decades before all rural areas are protected.

iii) Maintain a high degree of safety to urban centres, but proide relatively low degree of protection to rural areas, which may be upgraded later, possibly to the same level as indicated 0nder (2) above. The advantage is that all rural areas experience in a relatively short time the benefits of the flood protection programme. The disadvantages is that too low embankments will not be able to enlist the confidence and Cooperation of the popula- tion, while the costs of the two-staged construction will be higher than that of cO/lstruction to same level in the operation.

Provided option 2 can be framed into a programme of works that can be executed in a logical sequence over not too long a period, it appears to be the most appropriate course for Bangladesh under present conditions.

While planning embankments for Bangladesh there are again a 22 number of options as to the extent to which they are to be built (UNDP, 1989).

1) Embankments are constructed along the major rivers and their main distributaries. The advantage is that additional discharge capacity is maintained through the distributaries. However, discharge measurements confirm that the capacity of the distributaries is relatively small and that these channels do not give any substantial relief to the flow in the main rivers. Their discharge could be increased by dredging their off takes, but this is not considered a viable option,' as explained earlier. The disadvantage of embanking the distributaries is the extra length of embankments that has to be built and maintained, against no appreciable saving on the embankments along the major rivers.

2) Embankments are built along the major rivers, only, while the distributaries are left as they are if they already show a tendency to die, or are closed at their offtake in due COurse. The closure of the distributaries would add to the discharge in the main rivers, but not in an appreciable way. Moreover, this has to be viewed against the background of the prevention of overbank spill by the embankments~ which generally is more important than the flow through the distributary channels. The advantages are the shorter length of embankments, compared to the option described above, while moreover the distributaries are transformed to drainage channels, which will improve water control in the interior.

2.6 Construction fo Embankments

The necessity for quality control in Fonstruction of embankments has been recognized for many years.,~n 1932, Justin wrote: "An entirely safe and substantial design may be entirely ruined by careless and shoddy execution, and the failure of the structure may very possibly be the result. Careful attention to the details construction is, therefore, fully as important as the preliminary investigation and design".

. , ,. The consequences of ignoring contro.l are exemplified by the failure of large number of earthen embankments. Records show that most of these embankments were constructed without moistening the soil and without applying special compactive effort. 2.6.1 Methods of Construction

Embankments may be classified according to their method of construction: compacted, semi compacted , and uncompacted fill. The entire embankment cross section is not necessarily constructed by one method; the central core may be compacted or semi compacted with berms semi-compacted or uncompacted. However in our country the embankments (earthen) are of homogeneous type and are constructed as uncompacted. The various construction methods are described by the U.S. Army Corps of Engineers as listed in Table 2.12. 23

2.6.2 Construction Phases

" " The most important variables affecting construction of earthen embankments are distribution of soils, placement, water content and its uniformity throughout the spread material, water content of the borrow material, methods for correcting borrow material water content if too wet or too dry, roller characteristic, number of roller phases, thickness of layers, maximum size and quantity of gravel sizes in the material, condition of the surface of layers after rolling, and effectiveness of power tamping in places inaccessible or undesirable for roller operation.

Adequate inspection and laboratory testing are essential to maintain the control of earthfill construction. There is no satisfactory substitute for control testing to determine the degree of compactness for cohesive soils. The testing must include all critical areas where seepage or loss of strength may induce failure.

Areas to be excavated are selected, depths of cut are determined, and the zone of the embankment in which a particular material should be placed is predetermined. The amount of water to be added to the borrow pit or to be removed to attain proper water content of the materials prior to placing should be determined.

Either the rapid method of compaction control or the proctor needle value can be used to determine the status of natural moisture conditions in the borrow pit with respect to the optimum water content. Every effort should be made to have the excavated material as close as possible to the optimum water content prior to delivery on the embankment.

After the materials are placed in the proper location the embankment inspector determines wheth~r they contain the proper amount of moisture prior to compadtion. This is of utmost i\ importance. The rapid compaction control method or the proctor needle value should be used for this determination. Should the materials arrive on the embankment too dry, it will be necessary to condition them by sprinkling prior to, during, or after spreading.

Another important inspection task is the determination of the thickness of the compacted layer. A layer that is spread too thick will not give the desired density for given compaction conditions. Initial placing operations will determine the proper spread thickness of a layer that will compact to the specified thickness. This is usually 8 to 9 inches for a 6 inch compacted lift of earthfill. A method of determining average thickness of placed layers is to take and plot daily a cross section of the fill at a reference station.

The final check on the degree of compaction attained is done by the rapid method of compaction control. If the field dry density 24

of the material passing the No.4 screen is above the minimum ,! allowable density and if the water content is within the allowable limits, the emtiankment will be ready for the next layer after such scarifying and moistening as may be necessary to secure a good bond between the layers.

Mechanical tamping, when used around structures, along abutments and in areas inaccessible to the rolling equipment, should be carefully watched and checked by frequent density tests. The procedure to be followed for mechancial tamping will depend greatly on the type of tamper used.

When embankment operations are concentrated in a small area (i.e if many layers of material are being placed one over the other in a single day), tests should be made in this area in every third or fourth layer to assure that the desired density is being attained. If areas of doubtful compaction do not exist and no tests are required because of concentrated areas, at least one field density test should be made for each 2000.cubic yards of compacted embankment and it should be representative of the degree of compaction being obtained.

2.7 Maintenance and Supervision

Proper maintenance of an earthen embankment is very essential. They need repair, maintenance and rehabilitation due to subsiding of slopes, excessive settlements, erosion by waves/currents or damages due to overtopping and breaches.

There are two kinds of maintenance: preventive or Routine maintenance and Emergency or Corrective maintenance.

2.7.1 Preventive Maintenance

It is the action taken to prevent the embankment from damage. By .minor inexpensive work, we can stop damage before it really starts. This type of maintenance can be planned and scheduled so that a minimum work force and material expenditure can keep the dyke in good operating condition.

The preventive measures (Emaduddin, 1988) to be taken are described below:

i) Camber: For quick drainage of rain water, the embankment crest is provided with generally 6" cambering (Fig.2.14a). In absence of cambering part of rain water is accumulated over the embankment and sometime find its way through weak layers to meet with flood water. Embankment gets saturated and is easily washed out by waves, water pressure or self-weight.

ii) Rain Cut: In the absence of well grown close turfs, the rain water drains at the low and weak sections which erodes the soil in the slopes and form gullies. During heavy shower, these gullies increase in sections and <imate1y open the embankment. I 25 I iii) Turfing: Well grown closJ turf prevents the soil from ero-

I sion and stands against wave action. Before turfing, the slopes i of embankment are to be rebuilt to design section. Undulations if i any, are to be rectified. Tur~ing is done just before the rainy season.

iv) Plantation: Plantation in embankment slopes acts against erosion and wave action. These have been found to be very good means of slope protection. Babla, Epil etc. are presently pre- scribed for plantation in the slopes.

v) Maintenance of Design Crest Level: Subsiding of slopes, excessive settlements or e~osion lowers the crest level embankment and overtopping may occur during flood. To safe guard against overtopping, the low areas are upgraded to design section through periodic resectioning during dry season. Normally, at the end of flood season, the embankment is surveyed to know the status of section at all location. The plotting position reflects the repair if any needed to upgrade the cross-section up to design standard.

Fig. 2.14b shows how crest height can be increased if crest width is still sufficient. Seepage through the joint between old and new fill material is to be prevented by excavating and refill part A-B of the old embankment. In case, crest width has to be maintained, the fill should be placed as indicated in Fig. 2.14c.

vi) Maintenance of Side Slope: Graphical representation of dyke after detailed survey in lean period provides the status of slope. It is very much likely that the cross-sections at deep flooded zone, gets saturated. These areas are prone to wave wash, rain cut etc. Resectioning of embankment provides design slope.

It should be tried, as much as possible, to place any additional fill against the outer slope of an embankment. If placed against the inner slope, water pressure caused by seepage water, press of the new fill. Additional fill against the outer slope will be pressed against the old embankment. In case where extension works cannot be constructed against the outer slope and in case the outer slope is revetted, additional fill can be applied at the CIS with proper joint between old and new fill.

vii) Slips: Slips are caused by saturation of the soil in the embankment or its foundation and its subsequent failure. Slips on the CIS must be repaired by first filling khals/ponds, which will allow a stable flattened slope to be constructed .. The existing slope shall be stripped, flattened by layers from bottom, .starting from far end (Fig.2.15). Flattening is impossible if the river has undercut the R/S of the embankment (Fig. 2.16). Spurs are built to induce sedimentation and deflect the current. If positive result is not achieved, retirement is the only solution.

Sometimes, hard materials are dumped to stop attraction of river. However, this is also expensive. 26

viii) Scour Protection: Due to overtopping, scour holes can I ~ develop at the CIS of the embankments and if overtopping lasts l long enough, the erosion of the inner slope and the scour holes can completely disrupt the embankment. To stop advancement of scour hole, sand bags may be dumped and simultaneously the overtopping is to be stopped by raising the section with mud box (Fig. 2.17) or with brush wood box. Once the flow receeds, sand bag of earth may be dumped in the brush wood box.

However, in case of a breach, scour holes may develop to such a size that refilling more material then building a new embankment. A new embankment alignment has to be designed than to by-pass the scour holes.

ix) Cross Bar: The construction of X-bar diminish the river erosion. In absence of x-bar, parallel flow may develop along the toe and severe erosion to embankment may occur. Sometimes fisherman cut the bars.

x) Traffic Movement: the loaded wheel base of the plying bullock/buffalo carts penetrates into the embankment and forms cavity to store rain water. In addition to damage, this causes the top and sloping side of the embankment to become muddy and disrupts normal inspection. Traffic movement can be stopped with the co-operation of Local Govt. representatives.

xi) Retiring of Embankment: If the possibility of defending the existing embankment seems poor, a retired embankment may be constructed to contain the flood waters which would enter through a break in the main embankment (Hannan,1988). The 10cati6n of the retired embankment should be selected primarily on the basis of case and speed of construction, although as much land and property as possible should be protected without endangering the entire embanked area. Retiring of embankment can be predicted with some accuracy, studing the rate of advancement of the channel. This , should be compared with similar movement. of channel in other areas if possible.

2.7.2 Emergency Maintenance

Emergency maintenance procedures are needed when unexpected deterioration starts. These can arise from deficiencies in planning and construction, from insufficient routine maintenance or from a natural calamity. During flood to maintain the effectiveness of an embankment fast work considerable ingenuity are required and the necessary material and equipment should be available at all times.

The emergency measures to be taken are described below:

i) Ghogs: Ghogs are small holes in embankment caused due to the presence of treacherous character of soil (hard clay), faulty construction (clods not properly broken), rat, crab or snake holes, roots/vegetative matters not removed during construction 27

of dyke, to leak out water and fine particles of soil (Emaduddin, 1988) .

When a small leak or ghog is discovered, the RIS hole must be closed by stamping earth into it. If the flow on the CIS does not stop, the entrance should be plugged with a gunny bag of earth and mark the spot. Permanent repair of a ghog is done by digging up the full length of the channel or course through the embankment, stepping the sides and then refilling with the removed earth in 6" layers (Fig. 2.18).

ii) Sand Boils: The most effective method of controlling boils is to provide ring bund of sand bags. The diameter of the ring should be at least 10 times the diameter of boil (Varshney, 1988). The ring bund should be large enough to avoid blow ups in the adjacent areas and its height shall be sufficient to create a pool causing a back pressure sufficient to reduce the net head to the point where the flow velocity is too low to cause washing of the soil (Franzini, 1987; Fig. 2.19). When a still pond is formed inside the ring, filter material should be laid layer by layer in this pond. Fig.2.20 illustrates the laying of different layers of fil ter.

In case numerous small boils occur in large area, the entire area should be loaded with 1.0 to 1.5 meter thick filter blanket. The filter should fulfill the usual filter criteria. Parmanent measure to check boiling is to provide relief wells on the downstream side and upstream blanket on the upstream side.

iii) Overtopping: Overtopping occurs due to inadequate free board, subsiding of slopes, excessive settlement or unprecedented flood. To flight against such high water, the top of the embankment has to be raised. During emergency, if the earth in the CiS is not available, earth may be procured by cutting the CIS crest above saturation line. To raise the embankment a foot or two (0.3 to 0.6 m) gunny bags filled with earth may be placed in the U/S edge in alternate layers as shown in Fig. 2.21b (Franzini, 1987).If further raising is necessary, a timber wall supported by earth or sandbags or a mud box filled with earth is usually necessary (Fig. 2.21 c,d).

iv) Wave Wash: Placement of earth filled sacks over the area can withstand against wave wash nicely (Emaduddin,1988). Sufficient Quantity of sacks may be kept reserved in such area. The sites may be determined earlier. Wave wash is also effectively checked by encircling a close layer of floating water hyacinth in the area. Planting bab1a, hilly ka1my can solve the problem.

(v) Boggy Areas: The provision of good drainage system is essential if boggy conditions are observed on the downstream side of the embankment. The drainage system may consist of cross-drains, jointed to longitudinal drains. Bleeder wells at 15 meter clc at the base of cross drains are preferably provided since they are very effective (Varshney, 1982). A typical cross-section of the bleeder well is given in Fig. 2.22. 28

; vi) Breach: In case the levee has actually breached at a certain ,., place steps should be taken to repair the breach as early as possible so as to prevent the breach from widening as well as to shorten the period of inundation of the flooded areas. This can be done with piling, matting or dumping brush wood (Emaduddin, 1988). Fig. 2.23 and 2.24 demonstrate the way to close a breach. High velocity in the breach may be lowered by deflecting a large volume of discharge with placement of spur.

Another way of closing the breach is carried out in two stages (Ghosh, 1986). First of all a ring around the breached portion is made by sinking timber trestles filled with sand bags. This will prevent free flow of water. After that a second ring is placed at its back with earth filled mud box to make the structure water tight (Fig. 2.25). Once a breach closing starts, it must proceed non-stop until the closure is completed and. its permanence is assured.

vii) Protection against sliding of the land side level slope: Usually slope drains coupled with a horizontal channel at the toe of the embankment is provided to -tackle seepage water from an embankment. When it is excessive as may be during a high flood the situation may become very bad and in such a case there is inherent danger of failure of the embankment by sliding. In order to prevent this a wooden mattress is laid over the slope which i~ then loaded by gUnny bags filled with sand or gravel, the maximum load being placed near the berm. The above measure will permit easy drainage as well as prevent failure of the slope (Ghosh, 1986).

viii) Erosion Protection: If the embankment is threatened by erosion and undercutting on the RIS, attempts should be made to divert the full current of the river. This may be done by sinking trees and brush wood weighted with earth filled gunny bags at the point of scour and holding them in place by bullah and bamboo piling (Emaduddin, 1988). Matting may also be pinned to the embankment with bamboo pegs. In case of emergency fills, temporary protection against erosion and seepage can be done by placing plastic sheeting weighted with sand bags (Hannan, 1988).

Erosion to embankment may also occur from wave action. This can be temporarily prevented by protective works with double rows of bullah piling with braced and filled with brush wood. Placed at a certain angle can deflect the partial flow. Earth filled bags may also be placed over the damaged area. Mats of double tarja over lapped and pegged to the embankment will give some very temporary protection. However, retirement is the only solution (Emaduddin, 1988).

River Side Slope Protection of Embankments and Upper Banks:

River side slope of embankments and upper banks of rivers if not subject to strong current can be well protected from erosion by a 29

vegetative cover, either by turfing or by sodding or by other ~ ~. natural growth (Fig. 2.26). Low growth of shrubs and willows is j by far the most effective cover, but they require a longer period to grow. In such cases, a temporary cover with mattresses of woven willow brushes is often necessary for the initial period of one to two years. After the natural growth has taken place, it just needs cutting once every year to keep the brushwood from growing into tall trees.

ix) Seepage control Measures: Underseepage in pervious foundations beneath embankments may result in the build up of excessive hydrostatic pressure beneath an impervious top stratum on the land side, in sand boils, or in piping beneath the embankment itself unless seepage control measures are provided. Principal control measures, shown in Fig. 2.27, include riverside impervious blankets, landside seepage berms, pervious toe trenches, pressure relief wells, cutoff trenches, and sheet piling (Turnbull and Mansur, 1959).

If seepage through the embankment emerges on the landside embankment slope, it can soften fine-grained fill at the landside toe, cause sloughing of the landside slope, or result in piping of fine material from the embankment. If there are no landside berms, if landside slopes are step, or if flood stages are of long duration, special measures for drainage should be provided in the embankment section, such as horizontal or inclined drains or toe drains as shown in Fig. 2.28 (Petersen, 1986).

2.7:3 Inspection

Identification of the problem before taking up of maintenance is called inspection. Timely visiting site, searching of the trouble spots and to select the correct approach for maintaining design condition is the purpose of inspection. Once the repair work is ,• completed, it must be re-inspected and the routine is to be repeated. There is need for careful inspection and construction of all embankment work because construction deficiencies such as those listed in Table 2.13 can cause future problems or embankment failure (Petersen, 1986).

Embankments should undergo regular annual inspection with the aim of looking for evidence of bank caving, weak spots created by animals or vegetation, foundation settlement, bank sloughing, erosion around the outlets of sewers or other pipes passing through the embankment and other possible sources of danger. Any alarming condition should be corrected promptly. 30

Chapter 3

CAUSES OF FAILURES OF EMBANKMENTS

Failures of embankments may be grouped into the following broad catagories :

(1) Hydraulic and Hydrologic Failures

(2) Structural Failures and

(3) Operation and Maintenance Failures

3.1 Hydraulic and Hydrologic Failures

They account for about one third of the failure of embankments and are produced by surface erosion of the embankment by water (Garg,1983). The failure under this category may occur due to the following reasons:

3.1.1 Washout from overtopping

The water may overtop the embankment, if the design flood is under-estimated. Usually embankments for major projects are designed against 100 year flood and for other condition the return period is between 5 to 20 years (Thompson and Rippin,1985). In case of floods having higher return periods,the provision of freeboard help in safe guarding the embankment upto certain extent .

3.1.2 Wave erosion of river side face

The waves developed near the top water surface due to the winds , , try to notchout the soil from the river side face and may even, " ,:\ sometimes, cause the slip of the river side slope as the slope becomes steeper. Stone pitching or riprap should, therefore, be provided to avoid such failures.

3.1.3 Erosion by gully formation

Heavy rains falling directly over the country side face and the erosive action of the moving water, may lead to the formation of gullies on the country side face, ultimately leading to the embankment failure. This can be avoided by proper maintenance, filling the cuts from time to time especially during rainy season, by turfing ~he slopes and by providing proper berms at suitable heights (Fig 3.1). The proper drainage arrangements are made from the removal of the rain water collected on the horizon~ tal berms. Since the provision of berms ensures the collection and removal of water before it acquires high downward velocities, " i the consequent erosion caused by moving water (run off) is con- I siderably reduced. I I

,,' ", 31

3.1.4 Piping Action failure

Seepage of water through the foundation or embankment which subsequently results into piping action has been responsible for more than one third of embankment failures. Seepage is inevitable in all earth embankments.

Piping through embankment body and foundation

Piping is a major cause of earthen embankment failure and many of the modern techniques of embankment design and construction have been developed to prevent it. For example, the present stringent requirements for uniformly compacted embankments with emphasis on control of construction water content and density have been developed to provide dense and homogenous cores which reduce the incidence of concentrated leaks and resist piping when leaks do develop (Hungspreug,1987).

Mechanism of Piping: As water seeps through the compacted soil of an embankment or the natural soil of foundation, the pressure head is dissipated in overcoming the viscous drag forces which resist the flow through the small soil pores. Conversely, the seeping water generates erosive forces which tend to pull the soil particles with it in its travel through and under the embankment. If the forces resisting erosion are less than those which tend to cause it, the soil particles are washed aWay and piping commences. The resisting forces depend on the cohesion, the interlocking effect, and the weight of the soil particles, as well as on the action of the downstream filter, if any.

If the embankment and foundation w~re completely homogenous, the erosive forces would be evenly distributed; but actually the embankment and foundation are not uniform seepage media and the flow is not uniform. Concentration of seepage quantity and velocity inevitably develop even, though the total seepage may be small, and at the places where'these concentrations emerge on the \ country side of the embankment, the erosive forces on the soil particles are greatest. The removal of a small portion of the embankment or foundation by erosive action at any point accentu- ates the subsequent concentrations of seepage and erosive forces there.

Experience indicates that graded filters are very effective in controlling piping, and many abutment or foundation leaks strong enough to cause serious erosion have been made safe by the installation of drains or blankets of pervious material graded in such a manner that tne eroded soil cannot be washed away.

3.1.5 Conduit leakage

Conduits or hydraulic structures located across the embankments have been a major cause of failures (Varshney,1982). Failures are of two types (i) contact ~eepage along the outside of the conduit which develops into piping and (ii) seepage through leaks in the conduit which may also develop into piping.

'. '2 Conduit seepage along the conduit wall is caused either by a zone of .poorly compacted soil or small gap between the conduit and remainder of the embankment. Seepage through poorly compacted zones soon develops into piping. Conduit cracking may also be caused by differential settlement or by overloading from embankment.

3.1.6 Sloughing

Failure due to sloughing takes place where country side portion of the embankment becomes saturated either due to chocking of filter toe drain, or due to the presence of highly pervious layer in the body. The process begins when a small amount of material at the country side toe is eroded and produces a small slide. It leaves a relatively steep face which becomes saturated by seepage and slumps again, forming a higher and more unstable face. This process is continued until the remaining portion can no longer withstand the water pressure and complete failure occurs (Varsh- neY,1982).

3.2 Structural Failure

Structural failures of the embankment or its foundation account for about one fifth of the total number of failures. Structural failures may result in slides in foundation or embankment. Slides, which are one of the frequent causes of failure, occur in embankments in the same way that landslides develop in natural earth slopes when the average stress along any potential sliding surface becomes greater than the average strength. Because earth movements are spectacular phenomena, and because they lend them- selves to analytical treatment, the mechanics of this type of failure have received considerable attention by the profession. Present method of stability analysis have been developed largely as the result of studies of actual slides.

3.2.1 Foundation Failures

Faults and seams of weathered rocks, shales, soft clay strata are responsible for the foundation failure in which the top of the embankment cracks and subsides and the lower slope moves outward and large mud waves are formed beyond the toe ( Fig 3.3). Another form of foundation failure occurs because of excessive pore water pressure in confined seams of sand or silt or hydrostatic excess developed due to consolidation of clays interbedded with the sand or silt. It reduces the shear strength of the soil to the extent that it may not be able to resist the induced shear stresses, leading to the failure without warning. Excess settlement of foundation may also cause cracking of the embankment (Fig 3.4).

3.2.2 Slides in Embankment

An embankment is subjected to shear stresses imposed by pool fluctuations, seepage or earthquake forces. Embankment slides may occur when the slopes are too steep for the shear strength of the embankment material to resist the stresses imposed. 33 Usually the movement develops slowly and is preceded by cracks on the top or the slope near the top. Failure of this type are usually due to faulty design and construction. In high embankments slope failure may occur during dissipation of pore pressure just after construction. The river side slope failure may occur due to sudden drawdown as shown in Fig 3.5. The country side slope is critical during steady seepage condition (Fig 3.6).

According to Safiullah (1982) the reason for sliding failure of embankments (case study of DND) can be attributed to reduction in soil strength due to increase in pore water pressure set up by the seepage flow during high flood. The sliding failure can also be attributed to shrinkage cracks (due to high clay content and overconsolidation ratio) exposed on the surface of the slope.

3.3 Operation and Maintenance Failure

Operation and Maintenance (O&M) failure of embankment account for a number of failures. Lack of supervision and maintenance may lead to public cut, animal intervention, seepage and habitation problem.

3.3.1 Public Cut

Improper planning and misconception of the hydraulic behaviour by the local people are the prime reason of public cut of embankments/polders. Drainage congestion in the country side and abnormal heading up of flood water in the river side or unprotected areas neighbouring the flood control projects leads to public cut.

3.3.2 Animal Intervention

The presence of ghogs and habitation in the embankment/polders sometimes lead to failure. Ghogs caused by rat, crab or snake holes may lead to failure by setting up a free passage of water through the embankment. Failure may also occur due to the growing up habitation on or adjacent to the embankment/polders. The inhabitants directly or indirectly are responsible for weakening the embankment section leading to their failure.

3.3.3 Improper Operation and Maintenance

The operation and maintenance of embankments if not carried out properly and timely may lead to their failure. Lack of supervision may result in human settlement on the top and adjacent to the embankment. It obstruct partially or completely the O&M operation and may lead to their failure.lmproper O&M of the embankment expedite the occurrence of sand boils, boggy areas or settlement and may lead to seepage failure. 34

Chapter 4

RESEARCH METHODOLOGY AND DATA COLLECTION

For studying the factors leading to failure of embankments eight FCDI/FCD projects scattering allover the country shown in Fig 4.1 were taken up. The projects selected are shown in Table 4.1.

4.1 Methodological Approach

In order to investigate the nature, extent and causes of failure it is required to study the detail of the embankment performance in the FCDI/FCD projects. For the perspective study of the failure mode we must focus into the following points viz.

- whether the embankment was properly designed, - whether it was properly constructed and finally and - whether proper maintenance and supervision was exercised. Verification of the damaged embankment and to collect informatio- n of the selected projects required extensive site visits, checking the structures, conducting survey and study of the damages. The data of parameters such as of length, number , location , cross-section as well as year/date of failure of embankments are collected. The embankment damaged by the various modes of failure since completion of the project are collected from field officials, through field trip for additional data and verification and through consulting the local people. Further data recently been collected by the consultants of BWDB are also .utilized and verified during field visits. In addition various other research journals/reports have been consulted for further data and indepth study. The information regarding the causes of breaches, erosion, public cuts, overtopping, protection work failures are collected from the local people and BWDB field personnels .They are also consulted to adopt the remedial measures Moreover their opinion/suggestions regarding future programme for control of flood & flood damage to the embankments are taken.

Regarding the field investigation to be conducted for the verification of damages, appropriateness of proposals, indepth study of the damages and checking of estimates an embankment survey has been carried out. A check list/quesionnaire was prepared to facilitate the data collection

4.2. DETAILS OF QUESTIONNAIRE

The questionnaire was designed to get a overall picture of the embankment performance in the FCDI/FCD projects in different regions of the country. The questionnaire sample and the details of the projects surveyed are appended (Appendices C&D). 35

4.2.1 Selection of Projects

Type and Location : The eight projects selected for this study are scattered in all the five regions of Bangladesh. All the projects are of multipurpose type. Out of the eight projects selected five are of FCDI type and the rest three are of FCD type.

Selection Criteria: No definite criteria has been followed in the selection of the above projects. But the random selection has been done on two considerations. First point was that the projects must have suffered from colossal damage. of embankments Second consideration was that projects should be located covering all the five regions of the country.

4.2.2 Project Location & River Alignment • The geographical location of the project with the administrative units are clearly defined so as to know the hydro-geological as well as hydro-meteorological condition of the projects selected. In addition the alignment of the rivers, bee1s or haors in and around the embankment/polders and their hydraulic behaviour in extreme conditions are thoroughly studied.

4.2.3 Embankment Status

All the FCDI/FCD projects selected are completed excepting Chalan Bee1 Polder was partially completed. The state of embankment/polder constructed with their length and date of completion are collected to evaluate their effectiveness.

4.2.4 Details of Embankment Constructed (Design Consideration) . The construction of embankment must be based on standard design • criteria in fulfillment of the site condition. Again the criteria on which the design is to be based, depend on the requirement of the embankment. The question is to be answered is : How safe has the embankment to be, and what damages with respect to total Cost and recurrence period, are acceptable.

In the light of the above criteria the design parameters of an embankment: crest height, crest width, river side slope, country side slope, freeboard, recurrence interval etc are fixed. This designed section must be maintained during construction. Further- more, the construction material, turfing or facing material must be used as recommended. During the visit of the project sites any discrepancy found are noted and BWDB field engineers are consulted.

4.2.5 Details of Water Control Structures

For efficient drainage and flushing of irrigation water adequate number of regulator/sluice should be provided. The number of vent and size of these structures are selected as per hydrologic 36

design. Any deficiency in planning may result in drainage congestion or may stop functioning. The state of the water control structures in the different projects at present and during flood time are collected from project site visit and in consultation with the local people and BWDB personnels.

4.2.6 Area Protected by the Embankment

.The embankment projects are designed to provide flood protection, drainage and/irrigation to the area behind it or inside the polder. Catchment characteristic, socio-economic need or politi- cal affiliation govern the selection criteria (purpose). The area with their specific purposes it serve are collected from related project offices.

4.2.7 Irrigation in the Protected Area

All the FCDI/FCD projects designed has 'an ultimate objective that on completion of the projects overall agro-economic scenario of the area will undergo a radical change. To materialise this intensified irrigation programme has been set by the government in these projects to attain food autarky by the year 1992. In addition irrigation component are yet to be introduced in the completed FCD projects. The irrigation data was collected from the projectwise evaluation reports and from the project offices. 4.2.8 Crop Data

, ' . Crop grown during pre-project condition : The pre-project cropping as well as cropping intensity in the project areas has been taken into consideration to evaluate benefit after the completion of the embankment projects. The crop consisted mainly of low yielding traditional deep water Aman with Aus or Jute and usually followed by fallow or low yielding cash crops in the winter season. Mostli single crop used to grow during pre-project condition.

Crops Grown now : Improvement in the cropping pattern is among the most direct, tangible as well as immediate benefit from the FCDI/FCD projects. The post project cropping in most of the projects considered is a combination of HYV Aman with HYV Boro/early T.Aus replacing the existing Aman-Aus combination. Moreover the cropping intensity has also been increased in many fold. However complete data could not be collected due to time constraint .

4.2.9 Failure/Problems During Construction and Since Completion

Most of the FCDI/FCD projects completion has been delayed due to fund constraints, land acquisition and other problems. Since flooding is a recurrent phenomena in our country, during construction and si.nce completion these projects are encrusted with various problems and number of cases consequent failure took place. The mosi common troubles which lead to the failure of

~ . . 37

embankments are: erosion, breach, overtopping, public cut and failure of protection works.

Erosion of Embankments: The embankments are constructed providing necessary set back distance. Moreover slope mattressing and river protection works are long been practised to protect the embankment. Inspite of this embankments are threatened by erosion and undercutting on the R/S. It may also occur from wave action during flood. The data regarding the location and extent of erosion in any particular year of the selected projects are collected in the designed questionnaire. It has also been investigated whether the damaged embankment were reconstructed before the next flood season .

Breach of Embankments: Due to various reasons breach occurred in the embankments/polders of the FCDI/FCD projects. It may occur due to lack of attention to ghog,failure to timely repair' the .' raincut, embankment/foundation seepage, sand boiling etc. In each of the project the location, extent and the year of breach with their probable cause are investigated.

Overtopping of Embankments: Overtopping of embankments in the FCDI/FCD projects has previously occurred in some places of limited extent. But it has now become a major concern as most of the projects are effected by this mode of failure. Overtopping occurs due to inadequate freeboard, subsiding of slopes, excessive settlement or unprecedented flood. For each of the selected projects, the location, length/number and year of overtopping are collected.

Public Cut of Embankments: This is a unusual phenomena as has been observed in the last two consequitive years flood responsible for extensive failure of embankments. Improper planning and misconception of the hydraulic behaviour by the local people are the prime reason of public cut of " embankment/polders in the FCDI/FCD projects. The location,number, \ extent and year of public cut in the selected projects are collected .

Protection Works: Due to river erosion embankments and protection works of different BWDB projects have been damaged or threatened for damage. The term protection works use in this study means bank protection works like x-bars, groynes, spurs and slope protection works like brick mattressing, c.c. or brick block pitching. The data regarding the failure of protection works are collected on a set of questionnaire. Moreover to have preliminary study regarding repair and restoration work to be taken up and the protection measures to be adopted different water expert working within or outside BWDB are consulted and their expert opinion are endorsed.

4.3 Data Collection

The data regarding the nature, extent and causes of failure of embankment/polders in the eight FCDI/FCD projects are collected in three different approaches:

By consulting the flood damage assessment report of the four consultants (BETS, BCEL, PMACS & DCS) engaged by the BWDB and various other research journals/reports or project evaluation and performance to asses the damage caused to the infrastructure of various projects.

Through field visit of the respective project sites. For the field investigation to be conducted a questionnaire was made ready to be used for collecting necessary information, and

Through discussion with the local people and BWDB field personnels during field visit of the project sites. Their observation, opinion and suggestion regarding the failure of embankments/poiders and overall performance of the projects are consulted. :l' - ,,~.,

I,.., ., ~ 39

Chapter 5

DATA ANALYSIS AND DISCUSSION .. Data on performance of the selected project since their completion have been analysed which are presented in Table 5.1 to 5.8. The length and number of failure due to various modes at various locations were compiled and are presented in Table 5.9 to 5.13.

5.1 Failure Modes in the Different Projects

The comparison of the different failure modes for the individual FCDI/FCD projects as well as the comparison of single failure mode in the different FCDI/FCD projects were made and are described in the following sections.

5.1.1 Erosion

In all but one of the selected FCDI/FCD projects, failure of embankments by erosion was the significant mode. In Gumti Embank- ment Strengthening Project (GESP) it is a persistant problem since its inaugration. In BRFE prior to the 1987 flood. erosion caused more than 80 percent failure for two previous years. In 1987 flood it is observed that in the four out of eight selected projects erosion took place. In GESP (57 percent) and Chalan Beel Polder (91 percent) it constituted the major problem whereas in other projects it caused little or no problem. In 1988 flood two contrasting picture were observed, firstly, two new projects namely Chalan Beel Project (CBP) and Meghna Dhonagoda Irrigation Project (MDIP) were effected by erosion, secondly, two projects namely Teesta Right Embankment (TRE) and Satla Bagda Project (SBP) which were effected earlier in 1987 flood showed no such problem. In three projects GESP, MDIP and CBP on an average more than 60 percent damage of embankment was caused by erosion. 5.1.2 Breach

In all the selected projects this failure mode is seen to be a recurring phenomena. In majority of the FCD projects this is the principal cause, accounting for almost 100 percent of failure, before the 1987 flood. In this flood in the FCD projects adjacent to the major rivers more than 60 percent damage of the embankments were caused by this mode whereas in other FCD projects lying adjacent to the medium rivers the proportion of failure was nearly 18 percent. In 1988 flood almost all the FCD projects were effected by this failure mode. It is interesting to note that identical 38 percent damage in CBP and MDIP were caused by this mode. In an average 50 percent of failure of embankment are of this type.

5.1.3 Overtopping

In all the selected FCDI/FCD projects except two namely GESP and Chenchuri Beel Project (CCB) project, overtopping never took

<, 40

place prior to 1987 flood. In 1965 and 1968 in GESP and in 1984 in CCB overtopping was observed. In 1987 flood overtopping took place in five projects which caused more than 80 percent of the damage. In 1988 flood only those FCD projects lying in the North-West region was effected by overtopping. The most significant observation is that the BRFE which was never been overtopped since its inaugaration was overtopped and it constitutes 68 percent of the effected damage of the embankment. Minor damage was caused by this mode in CBP.

5.1.4 Public Cut

This type of failure mode was never been observed in any FCD projects before the 1987 flood in any report. The FCD projects located in the North-West(NW) and South-West(SW) region were effected by this mode in the 1987 flood. In an average 40 percent

J damage of embankments in the NW region was of this type but the damage of the SW region could not be ascertained due to incomplete or non-availability of data. In 1988 flood, this failure mode persisted in the NW region and in CBP this caused the major devastating effect. In an average 36 percent failure of embank- men~ in the FCD projects are of this type.

5.1.5 Protection Works

Prior to 1987 flood the failure of protection works was not so alarming in the FCD projects. Data related to the failure of protection works has not been found prior to 1987 flood. In 1987 flood, old FCD projects like BRFE (80%) and GESP (50%) whose performance were satisfactory so far were also affected. In 1988 flood major damage occurred in protection works. In an average 80 percent of the damage are of this type.

5.2 Study of Mechanism of Failure

Evaluatios have been made to understand the mode and mechanism of \ failure of the embankments studied. The causes of failure of embankments by the different modes are described below in the following sections.

5.2.1 Failure Mode by Erosion

The main causes of erosion in flood control embankments have been as follows:

i) Due to wave action and attack by current the embankment weaken in section and thus was gradually eroded. The embankments get exposed to large fetches of pond water in the beels in the CIS and flood water of the river in the RIS of the embankment. This resulted in wave action.

ii) Shifting characteristics of the river. At several places the rivers devoured the embankments, while in some other places the river came dangerously close to the embankments. 41

iii) Unplanned protective work obstructing or deflecting the river current, hit the unprotected places which in some places might not be effected without such work.

iv) Inadequate section of the embankment particularly in the retired section. The section of the embankment at those places were weak and could not stand the pressure of flood water. v) In many places the embankments were constructed with poor soil and raincut in these portion made the embankment section weak. These section of the embankments slided due to erosion.

5.2.2 Failure Mechanism by Breach

The main causes of breaches in FC embankments have been:

i) Exceedance of hydrologic design parameters ii) Lack of compaction of earth in construction of embankments. iii) Lack of systematic annual maintenance. iv) Inadequate design of the embankments in the retired portion. v) Incomplete or unfinished work where embankment could not be completed in full section due to field problems. vi) Existence of small pockets at several places as the local people put pipes in the embankment. Laying of these pipes were not proper. vii) Improper closing of the flowing channel at the closure points. viii) Due to presence of "ghogs" and rat holes seepage of flood water through or beneath the embankment causes the development of piping action which ultimately resulted into breaches. ix) Due to abnorma 1 flood the free.board of the embankment was decreased and the embankment sustained prolonged heavy flood pressure which it could not withstand. x) Due to presence of peat soil in the embankment materials. xi) Lack of supervision specially in the flood time. As sma 11 defects arising from the negligence caused breach which may lead to serious damage and devastation. xii) Cracks in moderate height of embankment generally occur in upper portion of embankment due to differential settlement. They may be localised or continuous and may run transversely or longitudinally. Transverse cracks are most dangerous because they can create concentrated seepage. 42

5.2.3 Failure Mode by Overtopping

The main causes of overtopping in FC embankment have been:

i) Exceedance of hydrologic design parameters. Return period of 1987 and 1988 flood in different places of the country was estimated to be between 50 to 100 years. But the height of the embankment constructed under the different projects had been prepared on the basis of 20 yrs/25 yrs return period of flood in most cases.

ii) Inadequate height of embankment.

iii) Lack of systematic annual maintenance of the embankments. Maintenance of embankments, the most vital component of FC projects, gets low priority and irregular and inadequate maintenance leads to overtopping of the embankments.

iv) Effect of confinement of rivers as a result of construction of flood embankment along the river banks and polderisation of project areas.

v) Interaction of adverse effects of contiguous flood control project in flood plain causing increased flood heights and drainage congestion. vi) Inadequate freeboard. vii) Subsidence of the embankment due to weak foundation soil (peat soil). viii) The height and section of the embankment have been reduced due to heavy rainfall during the flood period.

5.2.4 Failure Mode by Public Cut

The principal reasons of public cuts, which were really large in numbers, in FC embankments were: i) Increased flooding in the unprotected area neighbouring the FC projects. ii) False expectation of the flood affected people of the unprotected areas neighbouring the FC projects that cutting of embankment will relieve their sufferings. iii) To effect drainage of flood water from project area. It occurs during flood period and also in receeding period. iv) Abnormal heading up of water as a consequence of unplanned construction of roads having inadequate openings for drainage. v) To avoid drainage congestion caused by heavy rain falls people cut the embankment in some places. 43

vi) In some places people cut the embankment for taking irrigation water from the river.

5.2.5 Protection Work Failures

Causes of failure of protection works:

i) The direct attack of river flow.

ii) The construction of the protection work was not in accordance with proper designed section.

iii) The cross-embankments at different places sustained heavy flood pressure and their end protection done with hard materials was attacked by erosion and under cuts.

iv) The slope protection by brick mattressing o~ by brick block protection in CIS or R/S of the embankment were not properly anchored.

v) The construction of major protection works like x-bars, groynes or spurs were not been done properly by model study.

5.3 Operation and Management Problems of the Completed Projects.

Most of the projects studied suffer from various problems which result in their poor performance. The main reasons for such performance as revealed are:

- Lack of proper maintenance of infrastructure mainly because of inadequate funding.

- Improper operation of facilities.

- Lack of proper management and co-ordination among complementary agencies.

- Lack of trained personnel.

'Absence of standard operation and maintenance manual in most of the cases.

Lack of participation of the beneficiaries in operation and maintenance of the project.

5.4 Impact on Agriculture Sector

On completion of the projects, overall agro-economic scenario of the area undergo a radical change. According to the local farmers the yield/ acre of different types of paddy as well as other crops have gone up . Different paddies in the Kharif-I and Kha- rif-II seasons have been benefitted substantially which indicates the positive impact of flood protection component of the project. But the failure of embankments due to recurrent floods has generated considerable anguish and despair amongst the farmers, who 44

said they had been encouraged to believe that they would recieve flood protection and hence expended considerable resources in their crops which was completely destroyed.

The pre~project cropping in the project areas consisted low yielding B.Aman mixed with Aus or jute and usually followed by fallow or low yielding cash crops in the winter season. But in the post project condition the cropping pattern has been changed and the existing Aman-Aus combi~ation has been replaced by HYV Aman and HYV Borol early T.Aus.

The cropping intensity in the project areas has also shown dis- tinct trends before the 1987/88 great floods. It was due to the introduction of HYV Boro and Kharif-II crops that this increase in cropping intensity has bee!! .achieved.

5.5 Discussion on Design Practice

Subsiding of slopes, excessive settlements, erosion by waves and/or currents or damages due to overtopping, public cut and breaches, necessitate repair and/or rehabilitation works. Several possibilities can be considered to upgrade the cross-section upto design standard.

5.5.1 Improving Embankment Stability

In case crest level is still adequate, the stability of the embankment slopes can be improved by making the slopes less steep. This can be done by increasing the base width of the embankment. By reducing the outer slope gradient, automatically wave run-up will be reduced which in its term might decrease required crest height. In this respect outer slope gradient reduction has the same effect as crest height increment.

5.5.2 Increasing Crest Height and Maintaining Crest Width

Fig. 5.1 (left) demonstrates how crest height can be increased if crest width is still sufficient. Seepage through the joint between old and new fill material, is to be prevented by excavating and refill part A-B of the old embankment.

Incase crest width has to be maintained the fill should be placed as ind ica ted in Fig. 5. 1 (right ).

5.5.3 Extension in the outer and inner slope

It should be tried, as much as possible, to place any additional fill against the outer slope of an embankment. If placed against the inner slope, water pressure caused by seepage might press off the new fill. Additional fill against the outer slope will be pressed against the old embankment.

There will however be situations where the extension works cannot be constructed against the outer slope, or only with high costs, i i.e in case old borrow pits are located close to the toe and in I case the outer slope is revetted. In such cases the additional (1 ~., fill can b~ applied at the CIS but due attention ~hould be given' to the joint between old and new fill. 45 5.5.4 Measures to Control Erosion

Due to overtopping scour holes can develop at the CIS of the embankment, and if overtopping lasts long enough, the erosion of the inner slope and the scour holes can completely disrupt the embankment, and a breach will be formed. In case of such a breach, scour holes may develop to such a size that re-filling requires more material than building a new embankment. A new embankment alignment has to be designed then, to bypass the scour holes. Whether this alignment is enclosing or excluding the breach depends mainly on available land for construction and borrowpits and provisions for set-back. , To prevent that the continued erosion of a riverbank will reach the toe of an embankment, a number of remedial measures like x- bars, bank revetment, purcupines are opted. Fig. 5.2 shows a schematic layout of a spur, groyne and purcupine. .. Option Cross-Bars: As a remedial measure a series of x-bars have to be constructed. The x-bars, would be constructed of local earthfill and protection by hard materials e.g.c.c. block.

Option 2 Bank Revetment: As an alternative to construction of x-bars construction of bank revetment with stones or c.c blocks would provide a solution.

Option 3 Bank Protection By Purcupines: A temporary solution to the bank erosion problem could be provided at reasonable cost by the placement of large purcupines. Purcupines are bamboo crates filled with bricks which are lowered onto the river bed and banks to prevent." further erosion. While they are constructed for temporary solution they have proved successful in several locations in Bangladesh.

The option to be selected depends on the nature and extent of protection, need and importance and finally availability of fund.

At Fulchori ghat in the BRE river has been eroding its bank and has devoured a vast tract of land by the progressive advancement of the river bank. Upazila headquarter along with major installa- tions are threatened. The situation is a very serious one and the design engineers have made the above options ready to protect from further flood losses. The following recommendation was made by the comparative study of the available alternatives:

The cost of construction of x-bars at this stage is considered to be too high without further investigation of their design. Also, to construct the x-bars satisfactorily, it will be essential that a contractor using equipment for intensive construction methods be engaged because of the difficult work situation. Bank protection by dumping c.c. blocks to form a revetment could provide a final solution but at an obviously, prohibitive cost. In these circumstances, it is concluded that bank protection by purcupines and three x-bars (constructed on land only)should proceed as a 46

temporary measure in FY 1988/89. The estimated cost of all works involved is about Tk. 4 crore.

As part of the ongoing FOR project, and the BRE model studies which are due to commence early in the new year, it is recommended that the proposal for four x-bars be refined and implemented in FY 1989/90. The main additional work would be the extension of the three x-bars (proposed for construction in FY 1988/89 into the river and construction of one more x-bar.

5.5.5 Rehabilitation with Earth

For repair and/or rehabilitation work on existing embankments the availability of sufficient earth at the R/S might be a problem which only is to be solved by acquiring additional land at the C/S.In order to reduce earthwork an alternative design for the cross-section of the embankment as shown in Fig. 5.3 can be applied which might save upto 60 percent of earthwork .. Minimum dimensions to be maintained are mentioned in the figure. The reasoning is that the additional 1 m freeboard, applicable to embankments, is only water retaining in exceptional cases. There- fore the crest bund can be of dimensions as shown: "whether the application of split level crests on embankments will be introduced on a larger scale is a matter of evaluating construction costs and maintenance costs to keep the embankment at design dimension. The experiences in Polder 22 (OOP, 1985), where the crest band was introduced on an experimental basis, indicate that maintenance of this type of embankment is not likely to costs more than the maintenance of conventional embankments.

5.5.6 Retirement of Embankments

In 1987 and 1988 flood, frequent breaches occurred in the embank-. ments along the BRE which were constructed with reduced sections on peoples initiative. The devastation of flood attained acceler- ./ ation due to these breaches in the embankments. This proves that the original design was adequate in case of a river like Brahma- putra.

However,only possible protection against constant erosion and shifting behaviour of BRE is not retirement of the embankment but construction of series of groynes as cost of continuous revetment is high. Retirement of embankment is usually done on the basis of estimate of shifting and the feasibility of such measure was unsound, particularly in the Bangladesh context where man land ratio is 4:1, more than 56 percent of its economy is dependable on agriculture and 85 percent of its work force earn their sub- sistence through agriculture: .

Generally the banks are not protected against erosion and the normal practice has been to retire the embankment when threatened by the rive~. Socially ahd economically this practice is increas- ingly being questioned and attitudes towards river training are rapidly changing (IDA Mission 1988). 41

5.5.7 Non-uniform Design Criteria and Inter-project Interference

It is found from the water level in Atrai Basin during the 1987 and 1988 floods that the height of the embankment under different projects (CBP-A,B,C & D) in the basin is quite inadequate. Number of sluices provided in the project is found to be inadequate in many cases. It is also found that uniform design criteria has not been followed in the design of embankments and sluices under different projects in the basin. Besides, the projects in the basin suffer from inter project interference. According to the Appraisal report, the polder-A of the CBP must be completed before the completion of Pabna Project. But this has not been done and hence the problem. Had the said polder been completed, the Pabna Project area could have been totally free from flooding (BWDB, 1987). ,, , To overcome these problem uniform design criteria of these projects must be followed and accordingly the crest level is to be raised and number of sluices increased. And interproject interference should be eliminated through model study.

5.5.8 Recommended Design Criteria

The 1987 and 1988 flood has exceeded the past records in respect of magnitude, extent and duration. In this context the design criteria and specification should be reviewed and refined as per proper study. The following are some design standards and speci- fications refixed after the 1988 flood:

1. Return period for design of flood embankments should be as follows:

- At 100 yrs along major rivers (Brahmaputra, Padma, Meghna) and flashy rivers.

- At 50 yrs along major distributaries.

- At 10 to 20 yrs for projects following within the area behind embankments as mentioned above

2. Crest width of embankment:

Along the major rivers should be 24 ft (7.32 m) and they must have adequate set back distance area.

Along medium and minor rivers which will be used as road should be 18 ft (5.48 m) minimum and which should have brick soling for a width of 14 ft (4.27 mI.

3. Embankments along the major rivers and major' distributaries, tributaries must be mechanically compacted during construction. 48

5.6 Discussion on Construction

There is need for careful inspection and construction of all embankment work because construction deficiencies can cause future problems or embankment failure.

5.6.1 Embankment sliding due to use of peat soil

In CBP-D embankment sliding of CIS slope has been observed in the resectioning work of the post 1988 flood damage restoration work. It has been reported that after resectioning the reaches 5A, 5B and 6 of CBP-D with the earth carried from the CIS land the CIS slope settles down and slided towards toe which is clear by the swelling toe. In these reaches brick mattressing work also slided although proper anchorage was done to check sliding. While visit- ,, ing the site it is seen that peat soil was used in these reaches which is black in colour. Peat soil is non-cohesive and does not take any load. So in these circumstance the only alternative is to remove the peat soil of those reaches and fill it up with carried earth from elsewhere.

5.6.2 Embankment sliding due to use of sandy soil

In CBP-C near Lalua where public cut of the 1988 flood has to be repaired has the problem of sliding. Here the resectioning of the large breached portion started as per the design as shown in Fig. 5.4 . But the berm of the R/S could not be kept in position due to sliding. During the visit it is observed that in the R/S a depression exists along the side of the embankment althrough and due to continuous seepage of water from the river a ~tagnent water body exists. Moreover the material of embankment is found to be sandy soil. So in this circumstances tharja bera oven bamboo mat" supported by 8 to 10 feet height bamboo pins with 5 to 6 feet spacing can be suggested to check the. sliding of the R/S berm.

5.6.3 Construction of dowels in the retired road-cum embankment of BRE

In the retired embankment of BRE from Kukrahat to Bharatkhali there was 16 breaches occured during the 1988 flood. This portion of the retired embankment is in use as road and was not designed as per the original BRE. Its crest level is RL 69.5 in place of RL 72.2 of the original BRE and was overtopped inundating a vast tract of land and the damage was colossal. In the FOR 1988-89 this retired embankment was resectioned considering the 1988 design flood level (RL 73.6). Here the road pavement was required to be kept as it is with the breach portion to be repaired. So the only alternative is to built a dwarf embankment in the R/S with the crest level well above the 1988 HFL (Fig. 5.5) The dowels have the crest width of 6'-0" with slope 1:3 in the R/S and 1:2 in the CIS. The minimum shoulder length of two feet is kept in the both side of the road. 49

5.7 Discussion on Maintenance and Supervision

Foundation conditions and building materials for embankments are rarely fully satisfactory, and thus, even with the best construction techniques, there remains possibiliti of failure.

5.7.1 Maintaining the Designed Section

In SSP there was subsidence in the embankments which caused overtopping. The embankment subsided due to weak foundation soil. There are peat soil in the whole project area. It appears there are no other economical solution other than occasional re- resectioning to maintain the designed crest elevation. The embankment is therefore proposed to be brought to the designed section by closing the breaches and resectioning. , ~ 5.7.2 Maintenance and Supervision of Leaks and Cuts

In NNP the embankment is in a very poor state of repair and is less than 2 m wide in places at the crest. At the breach site there is a large hole on the outside of the previous embankment and the embankment material still in situ are spread out over nearby fields. Moreover the steepness of the embankment has resulted in numerous sets of steps being cut into the embankment, and many holes and rain or cattle eroded patches appear throughout its length.

In MDIP there were piping and sand boiling in the CIS of the embankment during the flood time at several places and the embankment gave away at Rishikandi.

For an effective measure constant supervision/patrolling of the embankment in the flood time must be ensured and leaks/cuts where noticed should be opened and refilled with good earth, rammed and watered. Moreover stock piling of some materials should be made at some vulnerable places and arrangement of other materials required during emergency should be arranged with probable suppliers in the area.

A note should be made in the register of leaks of the treatment given to each leak and holes/cavaties, during the summer season. On water touching the embankment, these points should be specially watched, in order to staunch them throughly in advance of the floods.

5.7.3 Fund Constraint for Maintenance

In Teesta Right Embankment, the yearly maintenance work done to the embankment is not satisfactory. Major repair works are needed to the embankment and to attain the objective cash provision of a & M fund is needed so that the embankment can be brought to original section. Annual a & M fund should be ensured in all embankment projects to prevent its failure.

\. ~ i . 50

5.8 Remedies/Steps to Control the Failure Modes

The perpetual threat and recurrence of floods has seriously damaged the flood protection effort by embankment and po1derisa- tion. In order to prevent such failur~ of embankments remedial measures for the different failure modes are recommended and are described below in the subsequent sections.

5.8.1 Erosion

i) Early turfing with good quality sorts may reduce the damage to wave action.

ii) In places where the river have come dangerously close to the embankment then an alternative is to retire the embankment without any alteration of the original embankment section. The retired embankments has to be completed before the monsoon sets in. The alternative on such condition would be to go for river training works, aimed at deflecting the flow, or bank protection works to prevent erosion. However such setps may only be taken up if it is cost effective.

iii) In places where the rivers have devoured the embankment, protective measures like brick revetment, x-bars, groynes or bamboo purcupines may be undertaken to prevent further encroachment by the rivers. The length, number, alignment as well as the selection of the protective measures should be based upon feasibility and model study.

iv) Recently BWDB has recommeded the use of Geo-textile, in erosion control. With the use of this new measure in embankment slopes and in bank and bed of the river erosion may be controlled to a great extent.

v) In places where the embankment have been built with sandy material and raincuts is present then proper care is to be taken to grow good turfing and the raincuts should be immediately repaired in order to stop sliding or washout. The embankment may also be saved from erosion of sandy bank by dumping brick or sand-cement block.

5.8.2 Breach

i) All embankments to be constructed whether new or rehabilated must be properly compacted (95% compaction) with mechanical equipment. This will reduce the failure by ghogs or rat holes to some extent. Where mechanical compaction is not possible due to various constraints care should be taken for manual compaction after proper clot breaking and ramming manually. ii) To withstand the abnormal flood pressure and to prevent the piping failure proper designed section of the embankment with adequate berm in the R/S and CIS must be provided. iii) The retired embankments in reduced section are found to be the major reason of breach. All retired embankments must be resectioned to their original design section. iv) The properties of embankment materials as well as the foundation soil must be determined before construction. Once the properties are known the embankments may be constructed with proper gradation and zoning. It will prevent seepage piping, sand boiling and ghogs type failure or will prevent such action to initiate. v) At the closure points, the selection of the type of embankment should be given proper importance and at the same time foundation treatment must be carried out if necessary.

vi) In case of horizontal piping through embankment the only remedy is to dump inverted filter material on the downstream seepage face where piping is occuring so that an improvised drain and filter be formed to stop piping.

vii) The most effective method of controlling boils is to provide ring bund of sand bags. In case numerous small boils occur in large area, the entire area should be loaded with 1.0. to 1.5 m thick filter blanket. Permanent measure to check boiling is to provide relief wells on the downstream side and upstream blanket on the upstream side. viii) The provision of good drainage system is essential if boggy conditions are observed on the country side of the embankment. The drainage system may consist of cross-drains, jointed to longitudinal drains. Bleeder wells at 15 m clc at the base of cross-drains are preferably provided since they are very effective. ix) In order to stop differential settlement which led to the formation of transverse cracks, through which concentrated seepage takes place, inspection pits are made to examine the depth and nature of crack. If the cracks are more than 1.5 m deep and are above the water level of the river it should be excavated in the form of trench upto the end of crack and trench should be filled with well compacted soil. Fine cracks, upto 12 mm width, should be grouted from top surface by clay grout of thin consist- ency from about 1:3 clay water ratio.

If the cracks is more than 1.5 m deep and travels below water level of the river, than a trench of 1.5 to 2.0 m depth be excavated along the crack. From the excavated level of trench, grouting with clay mix or clay cement of 1:8 to 1:1 (soil-water) ratio depending upon the width of crack may be done. After grouting, the excavated trench should be filled with well compacted clayey soil.

I ~ 52 5.8.3 Overtopping

i) In most of the FCDI/FCD projects the embankment are not designed to control such abnormal flood as experienced in 1987 and 1988. So embankment profile should be checked and provided with proper height and free-board in accordance with flood of selected return period.

ii) All weak foundation soil (peat soil) must be replaced by good quality clayey soil to check subsidence of the embankment. In cases where the whole project area is made of peat soil then there is no other economical solution other than occasional re- resectioning to maintain the designed crest level.

iii) The confinement effect of the rivers as a result of embankment construction and polderisation must be determined by proper model study.

iv) In order to overcome the interaction of adverse effects of contiguous flood control projects in flood plain all significant FCDI & FCD projects should be tested for its compatibility in its hydrologic zone by applying Flood Flow Simulation Models. Compre- hensive plan should be developed for each hydrologic region but implementation may be done in phases.

v) In the selection of hydrologic design parameters in FCDI & FCD projects there always remain some uncertainity as the actual one cannot be provided for economical reason, so in case of flood emergency when there is probability of overtopping, flood fighting measure should be taken immediately. An organised effort through Upazila Parishad should be made to effectively involve the local people in flood fighting.

vi) In places where the flood control embankment cum road was overtopped due to abnormal flood, a dwarf embankment if possible to execute in the shoulder of the road or construction of dowels in the riverside of the embankment with proper height and crest width will save the benefited area from abnormal flood.

5.8.4 Public Cut

i) Flood protection works should not be taken up in isolation. Flood protection plans for hydrologically contiguous basins should be studied as a whole and components of such total plan may be implemented in phases.

ii) People residing in the area between flood control embankment and ~iver bank should be brought under Flood Plain Zoning. People living in the area should be rehabilitated in the flood protected area behind the embankment and the flood way between the embankment should be available for unobstructed flood flow during flood time.

iii) Construction of roads, embankments and small water resources projects being undertaken by different Government agencies as

,.'. 53 well as NGOs should be co-ordinated atleast at the District level so that adverse effects - specially, drainage congestion created by these projects are eliminated. iv) Ventage should be checked against adequacy so that the drainage regulators/sluices can work efficiently and eliminate drainage problem. v) The people of the unprotected area in the neighbourhood of flood control project should be motivated and make their misconception about the hydraulic behaviour clear so that they donot commit the similar mistakes. vi) For irrigation needs, field study is to be conducted for providing irrigation structures at the places of necessity. Chapter 6

CONCLUSION

Based on the study carried out following are the major conclusion

1. It has been found that in almost all the FCDI/FCD projects selected breach and erosion are the major causes of failure of embankment prior to 1987 flood. In 1987 and 1988 floods overtopping and public cut constitutes the other two major causes of embankment failure. To a lesser extend also unsuitable construction materials, delayed normal annual maintenance, incomplete repair of flood damages, deviation from the design were found to be causes of failure.

2. In 1987 severe flood 137.36 km of embankment out of total 989.05 km and 10.09 km of protection work in the eight FCDI/FCD projects selected were damaged. On the other hand it was 35.69 km and 93.4 km respectively in the 1988 flood, indicating that major damage to embankment has been occured due to failure of protection works. It has been found that in 1987 flood main causes of embankment failure are: overtopping 62.22 km (45%), erosion 36.34 km (27%) and public cut 25.11 km (18%). Other important cause is breach 13.69 km (10%). Whereas in 1988 great flood breach 21.51 km (60%) and erosion 8.63 km (24%) are the main causes of embankment failure and overtopping 3.28 km (9%) and public cut 2.27 km (7%) constitutes the other important causes.

3. Design criteria and construction standards of flood embankments have not been uniform even in neighbouring projects. These have sometimes been the reason for ineffectiveness and inadequate performance of FCDI/FCD projects.

4. Embankments along the major rivers having a design crest corresponding to a return period of 100 years and a freeboard of 150 cm were not overtopped during the 1988 flood.

5. The failure of embankments greatly aggravated as major works such as protection at groynes, large retirements of embankments, and long stretches of breaches were on1y'partia11y completed because of several constraints.

6. FCDI/FCD projects must be made fully effective in protecting crops and properties of the projects area. Incomplete or partially complete projects and completed projects that could not prove fully effective have made people to suffer more and to loose confidence in the projects in one hand and on the other, there has been a general tendency of some people to cut the embankments for triff1ing reasons or due to misconception about the hydraulic behaviour. 55

7. Maintenance of embankments, the most vital component of FC projects, gets less priority and irregular and inadequate maintenance leads to breaches or overtopping of the embankments.

8. Flood embankments have been proposed to be used as roads in suitable places where their maintenance should be better than at present and their importance would increase.

Further Research on Project Performance

Operational research on FCDI projects under a functional research set-up is necessary to form a strong base for technological know- how appropriate for the conditions of the country to improve the appropriateness of the various planning and design parameters of the FeDI projects.

, ' Reasons of unsatisfactory performance of the projects are to be studied, and the technical, agricultural, socio-economic, environmental, operational and management problems of the projects are to be identified through such study. The identified reasons are to be translated into action research in designing an improved management system which should be tested through field experiment for identifying viable approaches to planning and management of projects.

The planning of a system of embankments and channel improvements as flood protection measures in Bangladesh should be based on a master plan. The master plan should be based on a mathematical model, simulating the present conditions of flood flows in the channels and flooding and overland flow of the land areas. In addition to the available data special data will have to be collected on the depths of flooding of the land areas and the overland flow. With this model it will be possible to predict the hydraulic effects of a number of options ranging from a complete embanking to partial embanking of different areas.

\ Planning of on-going projects should be reviewed and revised if necessary through regional model study for overall development planning in the respective basin.

In almost all the FCDI/FCD projects people cut the embankment due to drainage problem or misconception of the hydraulic behaviour. So further research is necessary to check whether it is due to improper planning or merely due to misconception of the people.

A study related to the involvement of the beneficiaries in the O&M of embankments specially for flood fighting should be undertaken. 56

REFERENCES

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BCEl and Sir William Halcrow & Partners ltd. (1988), "Flood Preparedness Study, Project Studies", Vol . II, BWDB, Dhaka. . I

" , BCEl and Sir William Halcro~' & Partners ltd. (1988), "Flood , , , Preparedness Study, Proposals for Strengthening Flood Preparedness System", Vol. I., , i BCEl (1988), "Flood Preparednes~1 Study, Review Report, Flood Control Projects, Flood Monitoring and Govt. Agency Roles.

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BWDB (1987), "Flood in Bangladesh - 1987", Investigation, Review and Recommendation for Flood control. " BWDB (1988) , "National Flood ~rdtection Programme", Vol. I, MIWDFC. II

BWDB (1988), "National Flood Protection Programme", Vol. II, MIWDFC.

BWDB (1979), "Inception Reportlfor Meghna Dhonaghoda Irrigation Project", Consortium of Chou Kaihatsu Co. & Prokaushali Sangsad ltd.

BWDB (1988), "Flood Damage Rehabilitation Project - Brahmaputra River at Fulchori Ghat, Bank Protection"

DCS (1989), "Final Report on Assessment of Flood Damages 1988", Flood Damage Restoration Project, SE Zone jCTG) and SW Zone (IDA) Projects.

Delta Development Project (1)>85), "Desi~n Manual for Polders in South-West Bangladesh", Part 1, VoJ. I-IV, Bangladesh-Natherland Joint Programme under BWDB. 57

EPC Ltd.(1987), "Design Manual of 3rd FCD Project", Dhaka.

Garg, S.K. (1983), "Irrigation Engineering & Hydraulic Structures", Khanna Publishers, Delhi, India.

Ghosh, S.N. (1986), "Flood Control and Drainage Engineering", Oxford and IBH Publishing Co. Pvt. Ltd, Calcutta, India.

Hossain, A.N.H.A. & Shahjahan, M. {1987), "Impact of Large, Medium and Small Scale Flood Control & Drainage Projects" , Seminar on Flood and Bangladesh, IEB, Dhaka.

Hannan, A. (1987), "Failure of Flood Control Embankments", Training Course on Operation and Maintenance of Small Scale Water Resources Projects, lGEB .

Hungspreug, S. (1987), "Training Course on: Small Scale Water Control Structures", Continuing Education Center, AIT, Thailand.

Khan, H.R. (1985), "Water Resources Development in Bangladesh Problems and Prospects", Regional Symposium on Water Resources Policy in Agro-Socio-Economic Development, North-West Hydraulic Consultant ltd. Dhaka,

linsley, R.K and Franzini, J.B. (1987), "Water Resources Engineering", Third Edition, McGraw Hill Inter'l Edition.

PMACS (1988), "Inception and Final Assessment Report For Flood Rehabilitation Project (FC & Irrig.) , FDR'87.

PMACS (1988), "Inception and Final Assessment Report For Flood Rehabilitation Project (FC & Irrjg.)a, FDR'88.

Petersen, M.S. (1986), "River Engineering", Prentice-Hall, Englewood Cliffs, N.J. 07632. ,i Punmia,B.C.(1982), "Soil Mechariics,and Foundat ions" , 7th ed. , Standard Book House, New Delhi. I '

Rahman, S.F. (1989), "Flooding and the Highway System of Bangladesh", Published in the Bangladesh Observer, Mar' 16 .

Safiullah, A.M.M.(1982), "Failure of Embankment Slopes - A case Study", Journal of IEB; Vol.l0, NO.1, Dhaka.

Siddiqui, M.H. (1987), "Flood Control in Bangladesh-an Appraisal of Past Efforts", Seminar on Flood and Bangladesh, IEB, Dhaka. " Srivastave,P.L.(1985), "Adverse ~ffects of Embankments and Mea- suresto Avoid Them ",2nd Inter'l 'conference on the Hydraulics of Floods and Flood Control, Cambridge,England.

Taylor, D.W. (1937), "Stabi 1ity of Earth Slopes", J .Boston Soc. Civil Engineers. Terzaghi,K. and Peck;R.(1967), "Soil Mechanics in Engineering Practice", 2nd ed., Jhon Wiley and Sons, New York.

Turnbull, W.J., and Mansur, C.I. (1959), "Design of Underseepage Control Measures for Dams and Levees", ASCE Journal of the Soil Mechanics and Foundation DiviSion. (Original not seen, Cited in Petersen, 1986).

UNDP (1989), "Bangladesh Flood Policy Study", Final Report,Dhaka.

U.S. Army, Corps of Engineers (1978), "Design and Construction of Levees", Engineer Manual 1110-2-1913. (Original not seen, cited in Petersen, 1986).

USBR (1974), "Design of Small Dams", U.S. Department of Interior, Danver Colorado.

Varshney, R.S. ,Gupta, S.C., Gupta, R.L. (1982), "Theory and Design of Irrigation Structures", Vol. II, Canal and Storage Works, Nem Chand & Bros. Roorkee, India.

Voorthuizen, H.V, Schokman, G.S.M. etc. (1988), "BWDB Flood Rehabilitation Review", Aid Memoire, IDA.

VOlker,A.(1983),"Floods and Flood Control (with special refrence to Bangladesh)", Training course on Bangladesh Water Sector Master Plan Project.

I. 59 ,!.

~'\I';i" . , !

" .

!,.

. I , I u., .,I ~,

TABLES /

III i: '~ . ~

I I 60

Tabl,e 1 .1' BASIN-WISE FLOOD VULNERABLE AREA. FLOOD PROTECTED AREA AND AREA UNDER ONGOING PROJECTS FOR FLOOD PROTECTION ------51. : Basin Basin :Flood IArea already IResidual lAres IResldual area No. : name ares. :Vulnerable:protected in lares in lunder lafter completion ,I sq. : sq. miles: sq. miles' lsq.miles , :ongoinglongoing projects : miles ,I :project: sq.ml1es J I lsq.milel ------~------2 3 4 6 7 8 ------I. Brahmaputra 1$,849 10,247 I,B2 8,715 4,916 3,799 2. Ganges 20,745 8,944 2,816 6,128 1,022 5, 106 3. Meghna 8,519 6,830 2,609 4,221 1,160 3,061 4. South-Eastern IIi 11 Basin 9,953 2,535 314 2,221 241 1,980 5. Coastal Region 3,769 3,698 71 71 0 ------Total : 55,126 32,325 10,969 21,356 7,410 13.946 (5n) (34%) (667.) (237.) (437.) ------Note. : 1. Flood vulnerable al'"eas are taken from the "\.Iorking Paper on Question of Formulating A Flood Cotltrol Programme for Batlgladesll" wittl slight modi- ", fications. 2. 59% of the country is flood vulnerable J. Percentage shown in column ~.6t7 and 8 are the percenttages of flood vulneruhle lU"CRM Mhown 1n column 4. SOURCE BWDB:

i \ " 61

Table 2.1 Recommended Side Slopes ------Selection Criteria CIS slope R/S slope ------River type: Major and Medium river

Design based on: Slip circle analysis 1 : 3 1 : 3 and seepage gradient

Performance Perfactly satisfactory

Recommended for: Fresh and remodelled embankment ------Source: BWDB

Table 2.2 Recommended Embankment Slopes - Terzaghi , , ------Type of material R/S slope CIS slope H:V H:V ------Homogeneous well graded material 2.5: 1 2: 1 \~ 'I; Homogeneous course si 1t 2.5: 1 2: 1

Homogeneous si It clay or clay 3: 1 2.5:1

Height ~ 15 m 2.5: 1 2: 1

Height ~ 15 m 3: 1 2.5: 1

Sand or sand and gravel with clay core 3: 1 2.5: 1

With R.C. core wall 2.5: 1 2: 1 ------62

Table 2.3 Recommended Riprap Design criteria ------Maximum wave Minimum average Layer thickness height, ft Rock size (D50). in in ------0-2 10 12 2-4 12 18 4-6 15 24 6-8 18 30 8-10 21 36 ------

I.., ••

Table 2.4 Minimum Thickness of Single Layer Filters Under Riprap Blankets ------Computed wave height Minimum filter thickness (ft) ( in) ------0-4 6 4-8 9 8-10 10 ------

Table 2.5 Design Criteria of Upstream Protection ,, ------Height of Thickness of stone patching Thickness of graded bound. m over graded single or or spal1s, m spalls, m ------Upto 5 No pitching

5-10 0.25 O. 15 10-15 0.30 0.15 15-25 0.50 0.25 25-50 0.50 0.30 50-75 0.75 0.50 >75 1.00 0.75 ------~------Source: Varshney ( Central Design Directorate of Irrigation Dept. UP) 63

Table 2.6 Recommended values of 0(, andq(, Fell inius construction

Slope 0<"I 0<"2

1 : 1 27.5 37 2: 1 25 32 3: 1 25 35 4: 1 25 36 5: 1 25 37

Source: Varshney

Table 2.7 Relation among fetch, wind velocity and wave height

Fetch, .mi1es Wind velocity Wave height miles per hour feet

1 50 2.7 1 75 3.0 2.5 50 3.2 ;\ 2.5 75 3.2 2.5 1'00 3.6 5 50 3.9 5 75 3.7 5 100 4.3 10 50 4.8 10 75 5.4 10 100 6. 1

Source: ASCE

r, 64

Table 2.8 Recommended Values of Freeboards ------Fetch in km Normal Freeboard Minimum Freeboard in meter in meter ------< 1.5 1.25 1.00 1.5 1.50 1.25 4.0 1.80 .(~ 1.50 8.0 2.50 1.80 15.0 3.00 2.20 ;~~~~~~-~~~~~~~~------1------

j.;: . ,,; Table 2.9 Freeboard by River Type ------~------Type of River Freeboard, m ------Major River (Brahmaputra, Ganges and Meghna) 1. 52

Medium Rivers (!eesta and Similar size of 0.91 rivers) ------\~------Source: BWDB ,.,d ....'C

Table 2.10 Set-back Distance for the Embankment ------Proximity of river $~t-back distance, mile ------(~t------Left bank of Brahmaputra j~ 1/2 to 3/4 J,:2, .. Ganges on both banks 1/4 to 1/2 Padma on both banks

Meghna 1/4 Lower Meghna on both bank ------Source: BWDB 65

---'------~.----_. Table 2.11 'BACKWATER EFFECT OF CONFINEMENT OF RIVERS BY FCD PROJECTS ------d/------__ Discharge- Projects: Length : Rise of water level (m): Flood Name of the ) :Confine-: U/s endlMaximuml D/s endlFrequency River m lu :me"l(km): : I : 1 : xyr. ------A. MA./OR CIIANNELS

L. Brahmaputra ID9,OOO!!1 BRE 217 0.00 0.27 0.06 100 1,8

~.;,. BRE+BLE 217 0.00 0.67 0.85 lOO 1,8

Full confinement 0.46 1.89 o 100 B. MEDIUM CHANNELS

1. Dhaleswary 1,700 DSW 1,9 0.30 0.61 0.15 lOO

2. Kal1gonga 4, ))0 DSW 63 0.61~1 0.61 O.l, lOO

3. Buriganga DSW O.l, :}, 0.1, O.I, 100

4. Alrsi-Cur-Gumsni 1.190 CBP+BP 157 2.61 0.90 0.90 100

,. Barna! 790 CBP 87 3.7) 4.12 3.415.1 100 6. Barna! 490 . CBP+BP 2.30 N.A. 1 , ,' 2.305. 20 7. Nandokuja 25, CBP+BP ), 2.,6 2.74 2.685.1 100 ------_.

Source : S1. 1 to 4 - Draft F.S.Report, DSW Project,Hydrology Annex. ECI/BWDB,I968 S1. 5,6 & 8 - Draft F.S.Report. Chalan Beel Project. ECI/8WDB. 1970 51. 7 - F.S. Report, Barnai Project. NEDECO/BWDB. 1984

~/ Embankment on each side ~I At the off-take of Dhaleswary E/ High because of the effect of the confinement of Atral in C8P ~/ Discharge for the design flood frequency

BRE - Brahmaputra Right Embankment BLE - Brahmaputra Left Embankment osw - Dhaka South Weat Project CBP • Chalan Beel Project SP • Bogra Project

SOURCE Ml'O ~, 66

Table 2.12 lmIbankment construction methods :,- Description

Compacted Specify: 'Vater content range with Emhankmenr section respect to standard occupies minimum effort optimum water space and is of low content. compressibility (as Loose lift thickness. needed a

"Arter V.S. Army. Corps of Ellgillee.r~.. 1978. SOURCE PETERSEN '67

Table 2.13 Con

POJ.\"ibie oUl...,equt:lIas Organic material not stripped Differential settlemcrH from foundation Shear bilure ! Internal erosiu~ caused by through seepage High'}' organic or excessi\'e1y wet Excessi\'c ~eltlemenl or t!l'y fill Inadequate strength Placement of penitius layers Allows through seepage which may lead 10 extending completely through internal erosion and failure the embankment

Inadequate compat.:tion of Excessive sculemcllt embankment (lifts too "thick; Inadequate strength . incomplete coverage by Through seepage compacting equipment, etc.)

Inadequarc compaction of bat.:kfill Excessive setllelll.enl around structures in Inade(~lIate .~trcngth embankment Provides seepage palh herween 'itruc[ure and fill lIIalc,.ial which lI1a~.learl to illlernal erosion and failure hy piping- "After U.S. Army. Corps of Enlo{incers. J!J78.

SOURCE : PETERSEN 68

Table 4.1 List of projects selected with location and purpose ------Sl. Region Name of the project Location Purpose No. ------1 NW Teesta Right Flood Embankment Rangpur FCD

2 Brahmaputra Right Flood Rangpur, FCD Embankment Bogra & Pabna

3 Chalan Beel Project Rajshahi FCDI

4 NE Narayanganj-Narshingdi (N-N) Dhaka FCDI Project

5 SE Gumti Embankment Strengthening Comilla FCI Project

6 Meghna Dhonagoda Irrigation Comilla FCDI Project

7 SC Satla-Bagda Project Barisal & FCDI Faridpur

8 SW Chenchuri and Other Beel Jessore FCDI Project ------

\. J 69

'j' I' ~. 5.1 .. , TABLE COMPARI SON OF DIFFERENT FILURE MODES

PROJECT NAME : TE:I'JSTARIGHT FLOOD EMBANKMENT

S1 Year Since Completion CAUSES OF FAILURES lUnit No 82 I 83 84 85 86 87 88 No. 1 1• EROSION 1--"------.' I - - I. -- - * 0.2T km * v, ,,', I BREACH No. , 2. * 2 2 2 1 r-----I. ..'-_.._- _ .._------.__._*..... * km 0.14 1.09 0.87 0.76 8.0 19.0 ~ * , \! . OVERTOPPING No. 4 3. -_._,---~.. --- _ .. ", --._- .. ...•. .. - - km * - No. 3 ~--_._._-- . . . -.•._- .. - .. .. 4. PUBLIC CUT _ - "- .. - .. km, f 21 .ffi .. , No. 1 5. FAILURE OF PROTECTION !

WORKS km ! ,, 0.3 .', ...... , [-BAR \'. 6 / iJ . :~ i 1 No. I 4 RESECTIONING OF ------, - - .. -_.- -_.' ...... EMBANKMENT km . 18.59 No.

------.-. ._~---- .. __ ... RETIRED EMBANKMENT - . _. --- . _ .... -- II km STRUCTURE DAMAGED No •

. PERCENTAGE OF FAILURE ,.... MODES ~ 'I< 0 ~ ~ ~ 0 ~ , 0 0 0 0 r:~ ~ ~ ~ ~ NI:- J\ I , ~ '\ II II 1 II II II II i "-- ~ ~. ~ ~ *~ ~ P< I~#. Note: 1. The data related to the failure of embankment by erosion and overtopping in the year 1987 are incomplete or not available. 2. The '*' sign indicates data missing or not available •

• 7..;~"- - - -.------. ri#:_ -)~- ~ ------

TABL1l 5.2 COMPARISON OF DIFFER1!NT FAILUR1l MODES

PROUECT NA..'IE : BRAHMAPUTRA RIGHT FLOOD EMBANKMENT

Y~ar Since -Completion ~'ICAUSES OF FAILUR3 Unit roo 68 69 70 ,72 7' 73 1 74 75 76 I 77 78 I 79 80 1 8, 82 183 84 85 86 I 87 88 No. I I I I 7 1 !.IERomON i I T t I i 25.7~ , 3.22 ~ I 1 I I' I 2 2 1 • I 3 2. IBREACH I k1:l I 13.22 ~ __22J4.83 1.61 17.7116.44 I '0.'9[0-:1:;' I No. I I j 21-' 3. I OVERTOPPING I km j I --I ~+--f--- i +I , Iii 3.13 No. I i i ; Ii*, .,-- 4. IPUBLIC CUT • I-1--'1I I I _,__ '--- km ! I t No. ,I I 1- ! i t-~ _!I_~~~+~":8" 5. IFAILURS OF PROTECTION -j : i : I ~--j-----:-,,~i,~,L'--,. "'ORKS km ! J i 'I I, I, I I ! : __ L_--l",-l7 .1,:j~~,75 r'-3AR , I I " i , 1 I I' Ii: ,! i 11 i 20 I ., I; I RSS6CTIONING OF No. '--'-1---1 --~ I i i ~J:-*" -;------'12--! -24--- ,r H-I I ! iii . ! I &~BA.UMlIiT : j. ! km , ' ' I I' " , , ,' I I I iii : , 144. , 4175 F8 '1"-- I I I _---L~ . !,. ~_~....__~. .~ _ No. I I , ' I 2 RETI R3D 3;'offiA~,;'n!:1JT ~I~: IiI i' 1 I ' I : i '0 I 3 :'3 : 5 km , 1 18.45 : 3.22 j' 4.83 2.41 '6.60 ' I ; 29.541'3.683857 ["i4.o i ! I I !: I STRUCTUR1l DANAGllD No. H I 'I I t' I I I 2 : 16 :----'I ' i I I ! ,';

PERClmTAGB OF FAILURE 1 ! I I I I i ~ '';'~ MODES I I ! it iI . i'I' I I ; ~'" ~-!,<-'" ! ~ ~ ' ~ I '~I '~~,\; dI."'. l 0 I ~ I ~ I ~ ~ ;0;0 I ;0 I ;0' ~'" ';'';~" I I o 0 0 0 I ,~~ 1I.!d.;d\Oll'\ .- .- I - I .- J1 II 11 i I ~ ,co (\J tl I II .n"o n - , I !I I, ~ ,I d\ d\ i d\ 'd\ '" '" ~d\ ., J ",U, ••2dl

<5 71 -. TABLE 5.3 COMPARISONOF])];FFERENT FAIWR"l MODES PROJECT NAME : CHALAN BEEL POLDER PROJECT

Year Since Completion 31, CAUSES OF FAILURES Unit "0. 82 83 84 85 86 ,i 87 88 No. I- I 3 1• EROSICE I km , 0.12 : [ i I No. I , , i , * * 42 3 2. BREACH , ,I I km i i * * 3.51 1.15 No. ! 6 2 ,I I i I 3. OVERTOPPING , I I km i 1 24'°1°.15 I 1 I i i No. I 69 I 29 4. PUBLIC CUT ! - I, I i km i ! 2.33+ 1.57 i I i No. I 7 I 25 I 5. FAILURE OF PROTECTION i~ km I I 11.28~4.5B WORKS I I I X-BAR I i , I I . I No. ,I I 77 RESECTIONING OF I ~ I I i I EMBANKMENT km I 153.53 I ! ! No. I RETIRED EMBANKMENT I I km I I i STRUCTURE DAMAGED No. t-- 15 I

PERCENTAGE OF FAILURE '~ i MODES ~..-N~*"v! '~*nco J\ II ~II b> ~i5':~ie D~. ,-....:--~,o •.~ (l) ~ ~~r<'I ~,II _ i 1llI\lI\ I 2J\ ~~ ~' Note:- 1. '+' sign means the figure is still higher, which can not be exactly quantified due to inadequate data. 2. The '*' sign indicates data missing or not available 72

TABLE 5.4 COMPARISON OF DIFFERENT FAILURE MODES

PROJRCT NAME : NARAYANGANJ NARSINGDI FCDI PROJECT

Year Since Completion ~,o.~. CAUSES OF FAILURE Unit 84 85 86 87 88 No. 1. EROSION * km *

No. . 2 2. BREACH * * kIn I 0.08 0.03 No. 4 3. OVERTOPPING km 0.50 No. * 4 • PUBLI C CUT km 0.02 No. 5. FAILURE OF PROTECTION WORKS I km

X-BAR U , i! I ! No. ! . . RESECTIONING OF EMBANKMENT I I km I I iO.4511.36 No. I RETIRED EMBANKMENT i i kIn '----- I STRUCTURE DAMAGED No. PERCENTAGE OF FAILURE MODES I I ~~~~ 1 Ill" ~ 0 0 ro __ 1.0 v

I I II II II II , 0 P'l P'lPi Note: The sign '*' indicates data missing or not available.

I, L 1 .-"'- ....••.. ."J:.~ ~ ----" ------~-

TABL8 5.5 COMPARISON OF DIFFERENT FAILUR~ MODES

PROJECT NAME : GUMTI EMBANKMENT STRENGTHENING PROJECT

------Year Since Completion ra:1 CAUSBS OF FAILUR8 Unit 63 T64TT5'T66T67 68 69 r~7i -V2-73, 74-75176-77 ,78-79 801 81 I 82 I 83 I 84 !' 85 86 ! 87 88 r- No. I I T- II-yn I 1 8 3 1.1 EROSION km 1 ' j ---r-n U I I " ! 0.991 0.35 No. • • T ! 2 I 66 2.1 BR~CH 1'1 i ~X-J' n km I 'I r-~-l i J~- n r--.+. I I ~--:II . , 1 No. I ~ t--r--""'" i "' I i I I I 3.1 OVERTOPPING _J' Ii km I .: I I • l I : H! R I n I i f 1 ! I No. i , I----r, i-r-r-----t-, , , I 4.1 PUBLIC CUT I J I km LI I 1----1 ! --'~i ; I! 1 --+--+--! No. r----I " I" I 14 33 I, I I I I i t-H ;1 ,i, I - :' 1 1.7 __3. 1 ,I 'I L '; 86 "--- I, 1 '-(---, 41 31 I r~r---!-I----+-~ --r-~' -I -: II i -1---1'-- 6----1 ! I I I .. 1 I ! 1 I I-L?I I CU''"! i i i__ I 1s ctiona-; reti, I '~ I '! : ! I --1--[1-S,v"", L.,I I I FR, ,I I' ,1 ' I I I 'I ------, --r-'. I 'I ~-f--- ,---I 1 r--r I !I.~_I !

,~U"\ ! +,I I 'to- jl, I I II,,:, I I I I I !~I ! I I I hi' Note:- 1. *~ indicates data on specific location not available 2. + indicates data missing or not available.

,..:J VI 74

TABLE 5.6 COMPARI SON OF DIFFERENT FAILURE MODES . - '. - ...- - --- ..... PROJECT NAMB MEGHNA DHONAGODA IRRIGATION PROJECT _._------._. ,.- " .. _-- ..- . , .., -

31. Year Since Completion

No. 1 1 BREACH '. km 0.14 I 0.56 No. 3. OVERTOPPING km

No. 4. PUBLIC FUT -- km No. 2 5. FAILURE OF PROTECTION ,r WORKS km ! i 2.46 'I -, ~' .1 [-BAR I 19 No. t RESECTIONING OF 21 EMBANKMENT km c-- 45.2 No. RETIRED EMBANKMENT I km i ,I STRUCTURE DAMAGED , No. ,i 17

PERCRNTAGE OF FAILURE ~ t<'\ MODES J\ ~ 0 ~~~ ~ f;:;~\D \D II III &l~"db~ 75

TABLE 5.7 COMPARISON OF DIFFERENT FAILURE MODES

PROJECT NAME : SATLA BAGDA PROJECT

Year Since Completion ~: CAUSES OF FAILURE Unit 0-81 82-83 84-85 86 87 88 No. 2 1. EROSION km _. No. 8 100 2. BREACH km 0.31 * No. I 29 3. OVERTOPPING km I 54.72 No. . 39 4. FUELI C CUT I km * , 2 No. i Ii 5 5. FAILURE OF PROTECTION i km WORKS i 1.45 X-BAR I I No. I 47 RESECTIONING OF EMBANKMENT. km i 7.0 44.64 No. I I I I 14 RETIRED EMBANKMENT I~ . km I I i 5.53 I I STRUCTURE DAMAGED No. I 20 I 29 ~ , ! PERCENTAGE OF FAILURE I~ I I : O"l ,I MODES , II 10 I ~ '\t-. itr\'~i~ ! II II II II!'l P'l !P'l l Note: In percent damage calculation of 1987 the public cut is not included due to non-availability of data. * indicates data not available 76

TABLE 5.8 COMPARISONOF DIFFERENT FAILURE MODES

PROJECT NAME : CHENCHURI AND OTHER BEEL PROJECT

ro. Year Since Completion No. CAUSES OF FAILURE Unit 84 85 86 87 88 No. * 10 1 • EROSION * km ,. - * 7.25 !,/. ' No. 2. BREACH * * ~ km 1---- - * * No. * ,~ 3. OVERTOPPING kin * 3

No. 4. PUBLIC CUT I 8 kin I j * I No. I I 5. -FAILURE OF PROTECTION WORKS , kin I I i I I ~-BAR I I - I I I No. ! I I RESECTIONING I I I OF EMBANKMENT ; I km I i I I ,I i 16.95 i , I I I I i No. I i RETIRED EMBANKMENT ,I I i I I I , I I kin I I I I I I i I STRUCTUREDAMAGED , I I No. ,I I I 1 1 I I I , I , i ! ! PFBCENTAGEOF FAILURE MODES j ,I I I i ~ I 0 , ~ I~*i '" I ,! II " , I ; I'tI0 " I : I'tI \."

" Note: In percent damage calculation of 1987 flood damage by breach and public cut is not included due to non-availability of data. Y"ry- *~ ,~ '-".~ - ~~---._------~----- ~ TABLE 5.9 COMPARISONOF FAILURE MODESIN FCDI/FCD PROJECTS . MOD.R: EROST(W

Year Since Completion fc;: I NAMEOF THE PROJECT IUnit 63 64 65 ! 66 I 67 i 68 169-831 84 I 85 I 86 I 87 I 88 I . i I 1 • I Teesta Right Flood I kin i . ii, I I i j i : ' til * I Embankment I 1 I ' I ! ! I , i --~1--1 ! ;- I i % I i ii' : : i 2.1 Brahmaputra Right kin ] 25 76 Flood Embankment f-- -_1= 1 . 3~!t) : u_ I I Ii I 80 /100 _ _ "kin 3. I Chalan Bael Polder 1 I I ---1- J~_.~~__. " I I ~_4_ 4/ I Narayanganj Narsingdi kin • FCDI Project -._-- 1 ..-1-. -- - =*.=l= I . " --r-- IGumti lbbankment II kin I , --f i • 0.99' 0.35 5. strengthening Project :1 " --I 57--1;- . r-' --,------.--L... .._ 6. I Meghna Dhonagoda kin Irrigation Project ---+----~--I----'------r-62I L p.91 r- -ic------" I km 7. Isatla Bagcla Project -----"----j--- % -1~E_-b-~iJ-- 8. IChenchuri and Other km * 34.2917.25 :Beel Project f9~100 -:l " -:l ~:tI[~------=------:;::C::"'."'.-.------::t!""------.~'4_ ..'r------

"'"a1 :--=-::,,..- - - - ~~k-;. ~k_ r.~~ -

TABLE5.11 COMPARISONOF FAILUREMODESIN FCDI/FCD PROJECTS MODE: OVERTOPPING

81. NAMEOF THE PROJECT Year Since Completion No. Unit 63 64 65 66 67 68 69-83 84 ! 85 , 86 87 i 88 km , i, i 1• Teesta Right Flood I I * I --- lbbankment ! I, , I I ,I i I I : I -- " I I j I km I ,I I 2. Brahmaputra Right , I - I I ! I ! 1--.1 13.13 Flood lbbankment -- I , I ! I I .: 1-----68 I I, I ! I I I - "km I i 24 0.15 3. Chalan Beel~Bolder J I , . I I I 80 05 - -- " / i 1 4. Narayanganj Narsingdi km 10.50 I FCDI Project I ,I -- _._ .. : 1" I I - I -- . I , I 86 I I ,I I I - " I . - r . - ! 5•• Gumti lbbankment km * I , Strengthening Project I I * I I J I J , J% -_._.- .. ~ I I - , I I - - 6. :Meghna Dhonagoda km I - Irrigation Project I I ! I I I I I I I I ~ "km ?4.72 3:ltla Bagda Project I • I I I I I -".--- I 96 ,I I iI I I " I km I 3.00 ~.Chenchuri and other I I I I I * I Beel Project I I I 09 I I I I I I T I 1 , -'l " I.C ------~-JO!'-:~.~------.------~~====--=~=~=.,.,--=~~",'~c.,'=-=-.,.,.,.,-----..,.,-.,.,.,.,-.,.,•.•------~~'t~-~:-.,.,------"":',~~I~~~;------

TABLE 5 .12 COMPARISONOF FAILURE MODESIN FCDI/FCD PROJECTS MODE: PUBLIC CUT

Year Since Completion ~:iNAMEOF THE PROJECT Unit ; I ! 63 64 65 66 67 68 69-83 84 . 85 86 I , , I ! 87 i 88 I I] . I !1. ! Teesta Right Flood km I I i ! I 21.881_J : I I Bnbankment 1 I i I ! I I , 1% I i I ! , 73 I I , I I ! I /, I , [km i ! . i 6 I 12• Brahmaputra Right I ! [0.9010•8, I J J I ! . ! r i I Flood »nbankment i i% - , ,I 50 115- ; I ikm i I I , I I ! 2 .33 11• 57 I I'.i CbaJan.,.1 Fold.r I I I I i i ! I I 1 :% I I e ! : I ! i ---, I I 1 , 53 1 i4. ! Narayanganj Narsin'gdi ! km . I , I r ! I ! ! / I ! J , FCD! Project I I I i 0.02 , I ! : % I , , I f 40 : I I i I I I 15. I Gumti Embankment i km I I I [Strengthening Project: ! ! I I. Ii i i I' % I ; , ,I I I I , I I I I , I Meghna Dhonagoda----r km i I r:-I i I I I I I I I I I ! ! Irrigation Pro j ect i I I i j I ; I :" I I i . I I ,! I ', I . - I I . , i . i 1m I I i :7. : S;ltla Bagda Project I i . 1 1 I ,I I .* I I , ----._- iii"I : I I- , I I . , I ! TI i I , ; 1 , - '8. I Chenchuri and other I km 1 I i , ,Beal Project I I I I I * I I I I ! iii % I I I ! I I I I & .$------, 1•••••••••••••••••••• -~,- ..::------._~ - "':'+:.:..

TABLE5 .13 COMPARISONOF FAILURE MODESIN FCDI!FCD PROJECTS MODE: PROTECTIONWORKS

, Year Since Completion Ill. NAMEOF THE PROJECT jUnit No I 63 64 65 I 66 67 I 68 169-83 84 85 : 86 87 I 88 , I I , I , I i I i 1 Teesta Right Flood Ikm I j ,I 0.30 i 1 • i ! I ,I , I 1 Bnbankment I , I 1------~;-i ,!% I I I I : I I I 1 I I I , I ' I I , I i I I '"I km. I~I I I 2 Brahmaputra Right I ; . : ! , I ! ' I , : , I 1 • , I I r------.,----, , ' Flood Bnbankment , ' , , , , : , I I I ! % i: i 80 I 93 r-- I i I 13. Chalan Beel Polder Ii km I ! 1.28 ~4.58 , I I: i % I ! 04 I 89 I ' i----- 1 ! --,. i 4. I Narayangan j Narsingdi km FCDI Project ....----~------~------_._------

I " I ------1--- 5. i Gumti lmlbankment km : : j 1.7 3.86 i strengthening Project I ,:; I ttl I ' ,I I 50 I I 7" ' 'i I * ! t-i .------. I ,i--'-_' --'------'- 2.46 i 16• I Meghna Dhonagoda i km : : iii i i Irrigation Project' i ' i f I ,,! ! I 63 i I

I -km--,'--l ! :! i i 45 7. satla J:Bgda Project I I Ii! ! * jl_1_. __._

i !: 'I ~______: % ! I 1 i f-----*

8. Chenchuri and other i km i! i I I I .! Beel Project I I' I I , ttl , I 7" I I ------~--- CD I-' 82

,i .".,

d II , ," FIGURES I

" il 'J. 1I .! !I "

.1 83

-----~_.._------,------,_. -r .", ..,.... ,',', . ','.....~m::. • \ 0(\ 1.') Silty , 9 ~/JI_,J clay J ~ ! . 1.1'lAli\, 'lOM'ft •••O..,.

~ai Simple lOned embankment •...."'" , "WIrf"nc UH1 TfanSlhon lone

ROCk fill tr>e ~ -----'------'-, ~ ::::,. Per'''i~)lJ<' strala

'~.OI)l'IU ,1oIOtlI'UNt.;)1JJ .

Fig. 2. r Humogeneous type earthen. EmbfJnkment. .--._- ._---.._.--- 01\ 1.\ ~ClaJ' blanket \ ~~

Pervious mattrial .r Concrete cutoff wall

Ie} Earth dam on pervious material

Fig. 2.2 Zoned type earthen embankment

,{"'If I •• L , > IMP[R.I/'Ou~ CLAyCOQ, i" O~'GINAI. GIlOUNO • jUA'A(J

•• J( •

Fig.2.30 l.li;ll'hrAIII IYJlI' 1~"I(lJen Embankment.

':"':~IVlhjj~i "".MU:'f.

fllH'IIM Illll'FIIIIlnus,-, I' "'Ff~~VIIIlI'~• M. u.tr t nv.ot.lS _ t:M:: SEt",- IMPERVIOVS 5". ,"H"t-II Pf,H~.o US

Fig. 2.3 b IJlrliJH~d diaphragm type e:uthen Embllnkment.

I ~' ( 84

~t.i 14 25 10 E ~ 20!!! I1.SE

1°.f 75. 2~ Jf; ,= - - - 5 , '. :"',

2 3 6 9 12 11 24 36 J.8 72 96 I wind duration In hrs

Fig. 2.4 Relation between wind velocity, fetch and wave height.

" ~.-~--..

)

Fig. 2.5 --Wave run-up 85

.clfl

Fig. 2.6 Rclationthfp 01 W

r--.. ' .... ' ..•••. , r...... I

.06 , ~ "" "~,",, ---f-- .D4 , " --!-- .02 COu"ient.... ~ '" r-... "- i 1.0 IS- 2.0- ~_O 51l JXJ ~ "r 60' SO' 40. 300 20' 10. Slope Ant'e. "," Flo. 2.7 Ta)'lor's llability Dumbtrs for YJl.riouslJ1opn Aod anaJe, o! internAl friction (,p) 86

0' C('HJ!. 0' CRITICAL SlTJt CIRCLf

H \ L ""5 H

2.8 Fellenius method of locating line of centre for c~itical slip circle.

ro I

2.9 Locating centre of the critical slip circle for inclination of slope < 530

0",_ I •••.•.••.•- n , " ,I , 0 p I ~~ I : I : I , Q I $'1 I ,,I ,I I ,• , :""'1s...•• f Go!

) ( /I )

METlinf' rfiN C-fD

o __ ~.~ _

2.10 Vertical strips or slices between the critical slip circle and embankment slope line 87

r=~6m T---~ 10 m r-----~ ••In. 50m II I I i ------max, Z '"

Fig' '2.11 Set back for embankments

.------. ------.- .0. "__. _

, G

(

Fig. ? 12 Additional set back at sluices. "-~"~- ""'~--1. . v ~.' ...•~ '.'...... "~-

RIS CIS'

J b I

8=.o,3L ~~S!(~~f .•. HFL c e ~

, -'= phr~ctic lin. J OGL ~ A //~Y""-:'.' ~ ''--t;. d -I ~

Fig .2.13 Location of the phreatic line through an embankment

CD (ll 89

.'-'\)

.b H Camherin:l.

Rts

Fig ••2 14a cambering of an embankment

._---. __._------

" .~ cis /' os:~'_ __ ~------

Fig.2.14b Crest raising of an embankment

Fig.2.14c Crest and side slope raising of an embankment -~-T"~ :~ --~ -$..

R/S CIS

"'- Embankment

...... ••' .••••.---.:::.;:\------Wuler ISYeI ..• -SI" ---- ....•._ IIJ -- -\..\ ------r" Khal i F1g.2.15 Emabankment after slip failure

----_ ..~---'"._-----~------~------(.~!~ f " •• \ .• CIS

H iSh water level

.•- "VV\. ••••Jr ""- __ .. Embankment ~-~------

'-.'" . lJtlder cut - "".

Fig.2.16 River side slip of an embankment , i.:'~... '8 91

3' Minimum

BurntlGO Polos spaced opproxi- ", .•.motely 3' aport Bamboo Mot, '. .. ..' .,' and drived 2 to 3 feat into ~round

" . . Bamboo'l LAND SI/)E RIVER SIDE , Poles "

,. / .~./ •.. / '/ , EXIsting Emb kt.

. / SECTION

Fig.2.17 Construction methods for high water mud box -f- . ¥ -- K. _.J:.

steps. H '1:': :,. Section A-A AI ':".~'::~ HWL R/S ...,. -_.,- ~------~- ._-~ cis

A~ GH OGo REPAIR I The entire charr/1e~ of tke ghog mu.st be dug up I q.nd then {ilied vp with compacted. edrlh (shd

Fig.2.18 Ghog repair of an embankment

\0 '" 93

'-. ,',,',.'." ..~;.,.; " - .. , '. I 1 Ql U t t Spillway

PLAN OF EMBANKMENT

CiS R/5 This Irnc re present upward pTes6ur~ of watEtT under embonknumt . ~. -.. -- --- ...... ~. .~'~ ~~iM~n~,,;~~~t/.;;:....;..: ,.(;.\!I( ..•.".~.. .i'(._,,;- ..:.~-.:l,""/'" ,"j. ," .••.•...::,••;.;-.(;"l.'!"' : ..I,:".,./f.' •..• I". " ; ./(, •.,.:, ••••••_ .•• , .' " •• "I, ••••• .': '.' ••.. .. .,~ ,J •. ' .'r'.' _ •.• 11-.... ,.' .••••.•• " .'~ S-,u. 'tJyY." •. ---~.' .• ,t,.,.. . .- . ," .•." ...... '.' '.• Pat he of S6'Cp~g. water ,SECTION OF EMBANKMENT --~_..-...... •.__ .•.,-...,...-.....~-

Note: Do t k b" L' L I -no f,CC 01 Willen run. C ear. hei9htof sack r.'.IQ!, or rln9 ,nould b. only :5ufficicmt to slowdoliln flow through boll IlO .-that 1'lO moremotsriol ($ di5chorg8d . .1)Ollot stop flow of wahrr.

Fig.2.19 Construction methods for high water sand boil 94

, ~ " - [mt,genq emb.!lnkment ~;;;~;;;( .•~

'a!, Earth embankment

~- r' Sand bags

__ eo•• lb) Sand bilgs __ UItO

... "'[Il'II"\I~ - SHII"U ;:i:~oe~.

"1 • Irl Earth WithlImblH rel~I"lng "'ilil

C,osshe '" •....PJank f""'g _•.AN

Fig. 2,20 Loading of large boil

(dl Mud bo~

Fig.2.21 Methods for ra1 s1nl!; . _ embankment height in emergencies

In ••••••1,""e. "0"'( iI"TC"""'~ 'so •••", c ••.•.,fu OR (10" •••• 0 STONe r'OO~'" co.:.",!. '''''0 ., (TR.~'.~C"S(0""''''

, 10':0 m rr --.-.oo:l

(OAIU lAlCl SHACVOING ('''. 0' l'lt.". Tb II •.••HD 0'"' fil". CIlITll'l~ 'OR •.••U ••.••U1U ••, I

S[.eTION ON AA ,jgEDER WEb\,t F1g.2.22 section of a bleeder well 95

I , l'\ ' , Fig.2.23 , i

EMBANKMENT BREACH PROTECTIO!:l

tWl \,._1 1

Now Breach, El,vatio.o

Mot.

E~~'~~'_ ---- -

protecttd Breach. ElevatlRn

:,., CIS

I " i ,I i . ., ,us ~~.I ( 96

, . ;~ \ -_: Fig. 2.24 ..~gM8ANf(M~T,(EU3!AG~i.!!!g ( I!tWi.2ll'

t.\ClX HWL :.. J\:;::::f5?:':::~:::' '-='.~ e~H

Mall HWL . •

" MOll H Avg HWL.

,CJ 91 /

closure ring levee

Breached embankment

Platform Trestles made of timber or bo",boo Ties Eorth fill Bogs filled with send Loteral suppOrt

River be

Section (0--0) Fig. 2.25 Closure arrangement of n breached embank-ment

---~------~._-----

i,_, (a) PROl Eel ION BV ~ e! NA.TURAL GROWTH "" ~ TREE REVETMENT

HEAVY WOVEN WlRC FENCING

STREAMBED

WEIGHT CONSISTING OF' BLOCKS OF CONCRETE

CROSS- SECTION

STREAMBED'

,(b),COVERING BY BRASHWOOO AND WEIGHTED DOWN BV STONES -'.-" Fig. 2.26 Slope protection, throueh ,'egclable cover or lurfing 98

levee Impervious top strale

• Pervious Cutoff trench or sheet pile

Impervious top strata ReliefweU

II Pervious /I Ii

Impervious top strata k..Drainage trench

Pervious

Landside seepage berm

Pervious

Riverside imperviousblanket;';') 2 ;.- ~7'. Pervious

Fig' 2.27 Underseepage control measures for embkt. (After U.S. Arm). Corps of Engineers. 1978.) !

••••• _ ..-,;,"--l •.. ••

(0) HORIlON1AL DRAINAGE BL:ANk£l WITIi nOC.K TO(

...... •.

Fig.2.28 Type. of drainage arrangemenll 99

..': :::.' ".,' .:- ..:...

"------Berms at suHable heights

sorL GRAIN:! AND WATER . COMINS OUT -,'~:::',:::\,{: :'':.~:',"-:'::':':;,<.>.~:;:,'

Piping through embankmentbody

- . "--- -._---- Fig.3.2b Piping through foundations

, . 100

Fill.. 3.3. Sliding due to ~ort or weak foun.dation.

-'"' ------Cracking of embankment due to foundation '; settlement ..

- ~ S~fOE"~=,;;:/-,,- OAOWOoWU __ .// ._" lOW I I :_- - -' . w,~=- -:-/~ ',:_.", --r~£ ~_-.c-... ,~ . _-";' SURFACE ..:.... :.:;"~,::..;...".

Fig.' 3.5,. R /S slope slide due to su:t(!en draw.down. ";, '. '~rAllURE " ,SURFACE ,, , .•• .: ,~.~.' -..' ..-

Fig. 3.6 .CiS slope slide during steady seepage condition

".. ~ 'I

1 N 01 A "[$1 SUlGAL

BAY o r B ("GAL ...,..-

, ~ • • • __I , ! f . ~.- ': -- - Ed-- ....-.,~.,- ..,. Fig 4.1 Map showing location of the FCDI/FCD projects 'selected 102

III ...•••• ••0- •••••

••••0

.-., ----.,...,....",''R'''' ...••....•.-- .••.- .•.••.••...".-"'--"'." .•.•••••.-- •••.•.,;p'l'!,----- •••.- •••.----- •••-- •••.JI'!'.. ,::,!. ,------~-L~.~ -----

.":'c._ .• -I •.• t."." •.•..••..•• _,.'

I .•••. , ~".'.'" _ •• 0 •••••

"1_1 '_I •..•... _ ••.• , ••• , .• ., ••.•. _. ,oO' • ," (J11 , ",0'" ..~"".-. '-"" ~~~~ ..,-,,- . .

"._, r .••1•••••• _ •• ., •. ~11'''I ••••.•

, i " \',! " " "O •._I._l~ .• ",, " II •.. 11.- •.•.• _.~ " " I' "I, I'" " v" " " "v ".;

SECTION A.A

4 f- I -0_ , I IIO_CI, J l.'~~ ;;" -l ...... ,4 .. t " U " " ~1 U j'" /1 " rH. I' :! . " " " ~ .." i' " ~'-:r-r; " " " (':1=;-- V ,. " " I' 't II ., i' •• ,t '1 ;. " " " l' I' " " I' , " ~ V "" " ., ,.. ' ,. , .: oJ " V ~V\JlJ V "

HEvAT,aN

Saure 'Harking papa r No. 12. Fen III. BI'/SB. / Col ••• .• ; ,.'')O--I& ....J •.•

LL A >/. fit::.5,2a A Typical ~erm('ableSp~r. :",6 104 .J1. \

.J' •• '"

0 \I, « ,)~ , I U • •• « 0 E '" 0 ~ 0 " u r- l- l- • v v ••V> •• = •• i •• ! •• 0 , [ . :. 0 • • • " L; ~ ~ :1: 0 ,',, . ... r, • f.-,; '-' .:1, ."., ." :1 • tl ..c:•• I • f-4 ...• d ...•v

f-o'"••• .. .( • "1 ., .D ., N : •• -•..- - - - "- '" .1..0' ---- '----- " is • ...•"" • k. ----.0 ~_.--_. ~. ;;. • ~ l•

'0'.•.., l'

I: 105 . NO TE 8 AMB00 F<)RCUPINE DE T~I L ~, . , , , , -- (inner dimensioo I l. Q gno. I) l2.no~ 'QrllCT' k'~i 6'.ffl/ll banwoo2.1f ' 2;6). 2:6'x 2~6' 'ou.ter ;1imen5ion) 2. b Qtld. b 12 no$",ro~ Ilia \IQn(lI~ S-\)' t\lll bO;" bc.o'~~ I ,I 6,6x 6'.t/x ~~6M,. 3. 30nCli.~O'lon9 f~ubomboopit'~IlLo l'2florinner . . . , ,a~e~ it. In sidt tile porcujline fjut ~Io~ brick~pt~ , equivlllrntlg IHogs. fuH bric;.,~, ' II ~.llU bomboo ,lli'CH.mlJst nov, lie'cia drill hoi,,,> In lilt. ,nllr, leogth {OM betl"~~(} lWo~no~) I h ~. lor riling filing botns country nQil~ j;.'\(J 120WG Q , (i.I •.•••.lr' ,will be iS~\lra. , 2.2i'dio bomooo ' , ~' ~ VQ'dia !>flw.en two kno IS In tn 1I~ Q .or.,"'" .. ~ PLAN section \ ,)wing 'It' drill hole. TYPICAL BAMBOJTO Bf; uSe. in porc\lJplne

P1.g. 5. 2c: Typical b••.••boo _ Porcupilll' • ~t!URIC VIEWOFR)R(UPINE NOT TO SCALE ~.- .'k... -~=(i-- ~~~~------.;.. _~k

~ -- I 1--,;. i- - , - I i. + l I 1.-.',.

':i "T" -;'4.

Fig.5.3 Embankmentrehabilitation with application of crest bund. .J-, .,

oH '" 107

--i.,

CIS 201_011 RIS ,r ------~, " .'1-, " "'- " " ," " " ..-v "

',,1

Fig. 5.4 Resectionlng of the large breached portion of sliding embankment

CIS 6'_011 RIS r- - - - -..... ,~I "... -¥:H.F.L. 72..20 _..../ . " I. ,.t...

Fig. 5.5 Construction of dwarf embankment in the RIS

.. 108 ~ i

"'i '1

. ,

~~I "

I APPENDICES

, . I' ~ .,•.~-- -~- _ •.•...... I

List of completed embankment projects under BWDB Appendix-A

I 31. Benefi ted l"bin l.Oca Uori---" 'Year or No. Name of the 'Type components Comp~e- I Project area in haj District 1Upazila completion cost, tion (in lac~: 2 , i 3 4 j 5 6 7 8' 9 1 Improvement, of old!I I&:D Irg=2024 F}nbkt=4.8 km I Comilla Chowddagram LRkatia &: L:l.ttle ; Drg=65263 1967-68 318.59 Dr~.Channel=29 km Feni Sonagazi Feni river I Struc = 5 Nos. 2 D-N-D Irrigation ,I FCD! Irg=41'19 Irg cana1=55.62kmINarayanganj I Narayanganj 11967-68 276.88 I Project Drg= 8340 Drg canal=28.12mi , I sadar 'FC =5870 Structure=259 no. I Dhaka Dhaka sadar I I Demra 3 iG-K-Project I FCDI Irg=74972 Embkt=38.85 km I Kushtia i( Phase-I &:II)' Drg=13806 Kushtia 11982-83 18280 I Irg canal=1507 km Bheramara I I FC =19028 i Drg canal=964 km Mirpur i Eyd.Str.=2177 No. I Khoksha , Kamarkhali i Jhenaidha Jhenaidha i Karinakunda 8ailakupa Chuadanl!:li i I -- Chuadanll:a ! Alanrlan~ , Mall:ura Maa-ura.- ,I I " Sreepur 4 'Chandpur Irriga- I FCD! Irg=24103 F}nbkt=100.8 km Chandpur : tion Project I Chandpur ( Part )11979-80 5419.34 , FC =53846 Irg canal=22.8 kml Haim Char Drg=53846 Drg canal=556.8 Bn Faridganj Eyd.Str.=7 No. I Iakshmipur llamganj ( Part) Raipur 1 Iakshmipur (Part) 5 Karnafuli Irrgn. I FCDI Project Irg=12046IEmbkt=12.21 km I Chittall:ong uzan ( Part Ir,g canal=132 km I Ita 1983-84 4805.17 Hatha"ari ~d. Str.",26 No. Ran=ia

oI-' \!l -;if' ,_..uu,~ ----.- _""" ";l:..

List of completed embankment projects under BWDB Appendix-A

! Benefited 31. location Year or compre- f No. ~ame of the -Type area in he I'Jain components Project District Upazila completion cQJt ! tion (in lac ,' 1 2 , 4 , , v 'r l:l 9 6 Manu River FCDI Irg=670 Embkt=58.85 km Moulvi B:lzar Moulvi B:lzar 1982-83 Project' FC =22672 iIrg canal=1 09. 34km Drg=22672 ~g canal=148 km /HY'.str.= 18 Nos. 7 Pratappur Irgn Irgn. Irg =5234 Embkt=10.83 km Bogra Kahalu 1977-78 Project Hyd. str.=7 Nos. a Mari Char Dhandra II ". Irg=4923 E)nbkt=3.79 km Nawabganj Nawabganj 1976-77 Irgn.Project Drg ,canal=5 .12 km Shibganj Hyd.3tr.=2 Nos. 9 Narayanganj-Nars- II Irg=1506 E)nbkt=6.56 km Narayanganj Narayanganj 1983-84 ingdi Irg.Project Irg canal=7. 68 km I Narsingdi Narsingdi Drg canal = 8.48 km 10 FC &: I of Paruli jl. II Irg=81 0 lE)nb~t=3.2 km G-opalganj Kashi ani 1982-83 Char Bhat Para ISlUJ.ce=2 Nos.

11 E)nbkt. along FC F0=2085 E)nbkt=11.2 km Habiganj Baniachang Hangor bhanga 1954-55 beel to Iattapur 12 Drg.scheme of FCD F0=6073 Embkt=2.4 km Thulna Terekhoda 1957-58 Bhutiar beel Drg=3239 str.= 20 Nos. 13 Embkt.along SUkti FC FC=12146 Embkt=35.2 km Habiganj Baniachang. 1958-59 River , 14 Constr. of Regula- Drg Drg=1620 Embkt=2.1 6 km Rl.bna Chatmohar 1959-60 :bor on Kinoo Drg canal=2.91 km Slrker Jola Str. = 1 No. I I :::; o '*~~------_.-;~~f -~ _L

List of compleVed embankment project under BWDB Appendix-A

81. Name of the Benefited .LOcation Year or Comple- No. Project Type area in halM3.in componentS District I UIRzila completion cost tion (in lac 1 2 , -6 4 5 7 8' 9 15 IKumarnai Dnbkt. FCD Embkt=7 •2 km Gaiband ha S9.dar' 1960-61 12.56 Project str.=l No.

16 IReclamation of I Drg Drg =3240 I Embkt=0.8 km I Pabna Chatmohar 1961-62 15.75 Nimaichara & othe Drg canal=34.61 km Rajshahi Baraigram beels

17 ITown Protection FC IFC=9717 Dnbkt=6.03 km Gaibandha I sadar of Gaibandh3. • 1962-63 13.36

18 I~~ti »nbkt. I FC IFC=46640 »nbkt=72.0 km IComilla: sadar 1962-63 I 17 •63 strengthening Pr~' Burichang 19 IRe-excavatiO~ of I Irgn IDrg=810 »nbkt=0.608.km Il'abna Chatmohar '1'962\-63I 2.56 Drg channel of Drg canal=6.34 km Dikshi beel proj. str.= 1 No.

20 IConstr.of Bhatia- lZbkt=14.4 km GOIR1ganj Kashini 11968-6910.09 para regulator & embkt.from Bhatia para to Char -Bhatpara

21 I Brahmaputra Right FCD IFC=225911 I lZbkt=215.84 km Bogra Bogra Shibganj11969-70 1789.54 I Flood »nbkt. Drg=225911 str.= 23 Nos. _.Sherpur ,GabtaJi Shariakandi sonatola I Gaibandha Gaibandha Sundarganj Falashbari sadulla pur Fulchor!, f-' Shal2:hatta f-' 1"1 ....,1 -{..~ ~J._

List of completed embankment project under BWDB Appendix-A

81- I Benefited location, rrear 01' j Comple- No. Name,of the completion cost Project I Type area in hal Main components District ~zila tion (in lac ,. ~ f 5 4 5 6 7 A Q Pir.gacha. Kaunia Gobindaganj Serajganj Serajganj Kazipur Tarafh Sha.iad pur , I Belkuchi Raiganj 221',FC embkt.along (FC =6883 IFC Embkt=20.93 km I Dinajpur Birol 1976-77 10.40 the west bank of i Hyd. str.=3 Nos. "':-Punarbhaba river I ,I i 23 I S3.ti Nadi Scheme FCD IFC=14170 »nbkt=26.56 km I Rangpur Kaliganj 198' -82 252.66 lDrg=1619 Drg canab24. 15 kin Ialmonirhat str.= 10 Nos. 24 Teesta Right »nbldl FC FC=38866 Embkt=42 •50 km Rangpur Dimla 1981-82 I 261.44 Str.=1 No. Ganga Chara Jaldhaka I 25 Dev.of Karnahar FCD IFC =6073 IEmbkt=30.38 km Rajshahi Iaba Barabeela other 11976-77 I 62. 16 & Drg.=6073 str.=8 Nos. Tanore adjoining beels 26 Improvement of Fe JiEbkt=2 km 'Nawabganj Gomastapur 979-80 170.60 'Bhitabari Domah r""4049 Drg. canal=14 km & other ad joinin 1 , beels str,= No. I 27 Constr.of regula- FCD 'FC=972 Embkt=0.92 km ~aogaon Atrai 1967-77 I 5.90 tor at Bisha IDrg=1943 str. 2 Nos. Union I •..• f" N >I, -- ,'*-'~, ::L

List of completed embankment project under BWDB Appendix-A

I Benefited Year of Comple- I 31. ~.m, of th, Type larea in ha Main components Location No. Project District Upazila completion cast. I tion 1 . 2 Ji!g-lac / 4 ~ b "( 8 I _ • 28 iRatkadaha Lohach-I FCD FC=810 Embkt=32.20 km Naogaon Atrai 1979-80 198.70 iura beel drg. Drg=11417 Drg cana1=22 km Raninagar ischeme ! str. 4 Nos. I 29 Iconstr.of flood FCD IFC=4858 l'inbkt=6.44 km Naogaon ~nda 1 CJ76-77 4.58 i embnkt. and IDrg=5960 Drg canal=3.22 km iregulator at str. 1 No. i Jotibazar -~ ! "",-=I~" ._~,.•) :'l ,-.:~~,----..

30 !Re-excavation of It Drg Drg=2348 l'inbkt=0.92 km Fabna Fabna 1977-78 42 iDrg canal from . Drg canal=15.29 km Atghoria

iSomeshpur beel I str.= 1 'No.c _ • , ;to Chicknai river ,I 31 Chicknai-Ghechua I Drg Drg=4049 Embkt=O.1 5 km I Fabna Faridpur 1979-80 85.94 bundh Drg canal= 13. 18 kll I I Str.= 1 No. 32 soamukhi Banman- I FCD I FC=9069 Embkt=2.41 km Jessore 3aroa 1977-78 54.72 dar &: Other beel I Drg=7385 Drg canal=43.20 km Jhekorgacha Drg scheme str.= 5 Nos. I I I Polder-26 Embkt=12.07 km Khulna Dumuria 1979-80 38.S7 33 FCD . 'I' FC=1215 Drg=1215 str.= 2 Nos. I 34 Barnal-S3.limpur FC. FC=23156 Embkt=72.85 km IKhulna Terokhada 1982-83 901.44 Kolabasu khali , Drg=17004 Drg.canaL_= 30.59kI Daulatpur Project str.= 13 Nos.. IJessore Rupganj I Kalia. ! I

ip [~'I-' 'H 4i '.1 "it.- _. - _"".~ .c." _X--

List of completed embankment project under BWDB Appendix-A

Name of the 'Benefited location Year of Comple- 31.1 Type comple- No. Project larea in ha Main components District I Upazila ,tion cost I tion (in lac 1 2 6 7_ 8 35 Kapotakhi-Sitikha IDrg=2389 Embkt=14.49 km Sitkhira Tala 1980-81 I 96.97 Scheme Drg.canal=3.22 km I I tr. = 9 Nos. 36 I Constr.of FC FCD I IIFC=14170 Embkt=53.13 km Faridpur ~fadanga 1977-78 120.88 embnkt.in Alfadan- ,Drg=14170 : Str.= 7 Nos. I Boalmari ga & Boalmari . I jDrg.canal =11.27 37 I Madaripur beel FCD ~rg=26721 IEmbkt=35.42 km Gopalganj route Kotalipara !FC=26721 iDrg canal=112.7km Go 'alganj i I Str.= 12 Nos. MOksudpur I Ml.daripur Rajoir I 38 ! Tarail :Fanchuria Drg iDrg=3198 IEmbkt=69.23 km GOIRlganj Gopalganj ~979-80 12243.23 Project(Polder I iDrg.canal=17.71 J KotaliIRra , No.3 completed) Str.=7 Nos. I Tongipara ! 39 !Reparing of Hizla: FCD tFC=5263 IEmbkt=41.86 km Barisal Hizla 978-79 I 92.29 emb ' ~g=5263 Str.= 3 Nos. ,i I 40 !Polder 58/3,Char FCD FC=1336 Embkt=16.93 km I Bhola Monpura 1982-831253.86 Faizuddin i Str.=2 Nos. I Drg.cana1=9.66 km i 41 :Construction of ; FC FC=2429 Embkt=38.80 km Bhola Bhola ~:l..ar 11982-831 62.70 embkt.from Itaha I to Bazipur I

42 Re-excavation of I FCD FC=6219 Rnbkt=17.71 km Dhaka KaIRsia. 1978-79 !20.00 Dardar khal Drg=4251 Drg.canal=22.54km IStr= 3 Nos.

~ "" :,~ "-- .--. '"';4:' ~ ~~

L1,rt xl c.!l:£..!.!.teJ ProjllJct uDl~r the l")B Mff'1l1L: A

. Sl. ------\ No. If."," er PrOJ. at •.•.l'rF.-I1:Bi:.irrt •• :r "iitli .COC;pOIO:;Dr.-. area ill he - - - :-reo;: or I ~o::pT.=------Q I Coopltt- tioD. Coat • .... ------1- _ tloD.. (1c loe - - - -1- _ ------_T~~): _ 4.3, "roteetten or aero crop.lr.:, I'.C .• 1619 ------Elbkt •• 20.44 DO. IlD - " - t O':lV'lkr.1a Ii.t.or. j::-.:..i.:.;.ufl'. Or~..lJa, •• ,619 S 02q .•- Dare.pua t977-78 ".5";' S t r1,lCture. 1 lio. oj. 44, I Protoetioc of Bar. 6721 1£00H.-:06.)5 roVe ot H.lla l:!aJ)I'. T.:. ,. Ir.c .• t". SllnaCf;&.- :UI&.J4u.j. =':,d.o~c:.~.Drain., •• 6C'?, 1977-7~ .&..tD.~OlJt 41).~ oj. 45, ProtectSon 801'o ot T.C. , T.~•• 2$72 crop. ot P.lon~':r !:SaoI'. ~.bkt •• ~.~ T.Y.. • • DT~:-..:.ce. Dra.in1Gh 607' 1977.71 ~"~e. n,.t '7.?" 46, Proteetior: of noro ero;" r.c. l Ir.: .• "5) . [chill. t tarcbrr 1:'01'. r7.J7 ~. • SG.D..ac.c &DJ Dr1.1n:\€e. Oru...,'C_ 4lt~j} S trlolctu,.... • 2 li04l. t977-?8 ?c. ";7 47. rl'otocUon er Boro crop t 6721 of SCl.1r HeoI'. r.C. .Ir.c.• i:obkt •• 61.1~ tJ:. • Ora.i."::~•• nra1n", •• f:.CJ7' .:~ l.ta.nj '9n_o~ ?~.7~ Struct~ •• " ~oa. T a.h c I'JI ur 48~ ll-rohcUon a! Bora f.C. Co 6c7J IT.C .. J;a:btt. ,s.6'" 1:;;. :'ahu-pl.U" ero~& .of XatiD H.or Dr Un"",. llrUn.... 5}06 • 'm8-7'! 'o.l'? 49, rroteat1oD of Poro t 1~17 ~.11. r.c. IT.c.• i:oblr.t. 8.('\~ u. r • ~.ber;tu' crop. of Bao,. ~~.!J:laCt'. ;"-&i.n•••• 198'-'12 'J ''''17 . Jaaa1&az:.J. , Prot.CUOD of Bora 50. t )2..."9 T.C. IT.C••. I..IIbtt. ZIt.,.5 DI. tJl~e •• cro;e of c.'l&odr. '\ID.&r t'ralz:..Ase.Or~ •• 28}1o • ,,?e 1-2.,:: ,8.a, ALl. 51, Prot4cUoc of Dof"O r.c.' IT.c.• ,.:'} E.~tt•• '1.f6 tr.. • crop. of Cbap:1r Baal'. ~rC-:l.:.ce. DrLi.:oa,e. 28-" t'1ra1 me..7'! :'.99 52 Frotectioo ot Bol'o crope IT.:.or. ~9 l:I.t.kt••. ~.!O D:. • at I:.l,u.r D.r&1.nsce.r.c. ~ Ir.cDreJ.D.,.• •• 31Z:S !iu.c.u.c aJl ~ 197e..7'! ~~.s~ 53 Sazloo7an Schaae. .c. r, .C•• F T ,,e,5 tc:t-k T7.~ lJ:. I S: 11:.t .Dr:s.i.~~.trai.:ac" 2~' t._ J01JJll1pClr 1979~~ , ::r. Chall..::" 1. 9. -'~ lJ.:. :ae.5C !trueture. 2 J;o_.

.; Ct'tr:td •• •...".. \.l1 --- . _. - -","~"-- ~~ _. . '.\ ;'fK 4'- "",~ (

Itl" ot 'complete' 'ryJ.ct unJer tbe ~B App-n4ts.-A

tIt~.:J- conou------:--roor or m:,- II •••• ,t ProJect ~~.ll-ai•.• iiA c06po•••"r.- t:Ot;rr.=.- 8e.ll:.rka No. are. 'in be : . .' .tnc~ OpuIlIa , CODpl••. tlof& coat Uon. (111loc • ....- - .• - - - "'1- _T!!2h _

54. I Pro\eot101l1 ot iOt'o T.e. r. . F.e •• 12" ~kt ••'9.U 1.::. I • I tl..••rnQ •••. 11981~2 ~l'Orso'! J074oct. :&Cr. D~~. DralD.ac.. 121~ I S5., I~pro ••• 'Dt of to•. L11A T.e. :. T .C•• 8~21 ~1r:t •• "0;,,, r.;.; •. 11~lh.t I aer.,n1 B.c. •.••• ' 11'180-31 I }4.2" are•• be"H!! lu~11ar. DrAin,,!:_ nrd:a:.It'. 8"21 !:lI'.0Ia.::.:..1.10.'6 D.o. Bc..rul !lAd 38,aDl ba...-r . IC,a"'mU."" !~.16 56. 0;'~~~'P:-.~:-.--r~~~-~;;'_.F~.;.~-;~~"(r.. !ahoPat - I rio I::-~'~ ra~: 'Dbankae.;J~ r _ _',

57. 11'atbakhaU tOka! a•• l r.a• 1m ~" ~~ IT_aJl ,I Hi•.•." •••. 11918-n I ;,9.66 .cb."•• r.c" la.v ...•• 1 )to.

I sa... /Ezt.DalOD of PaUla.th.l1 r.C. t •• 5.~2 VI. - • • 81.26 !.ODai bu 1 ache.. . I r'c. ~22 .I:.C. Pip. out.1t't. f98W' f?9 r.•••

5~. c•••••.•• ot lIOSUla-f:" 711 . t ••• 1.20 Cl. J7.~7 . tor OYerUJanuipllr.. khal &1A:2Ge..rC.'aJ.za.C" -j .-.-- m .CbaADe1.0.80'D:. t"ctll". 1 ..~1_. no. , . , f I~~'Co'o d •••• :::: 0'\ . ~~ •.c.. _ ~---,~,:-~",.:..=-"",,,,,,,,,,,---,,,,,,,,"."".."""'-"".""...,....----...,.- ••••-~,tz:•.---- •...•...•...------<~~r..-.-----

List of completed embankment project under BWDB Appendix-A , I 1; ,I 31. Name of the jtlE!neIJ. eu I No. Project Type area in hs ~in components location Year of rComp.le, District Upazila completion I tion cost 1 2 3 4 , b 7 I::l 9 60 Constr. of Bridge FCD F0=2227 Fmbkt=7.24 km .nJ.malpur cum regulator Drg=2227 SElrisabari 1982-83 95.13 over Katakhali Drg.canab6.92 km khal Str.= 8 Nos.

61 Improvement of FC F0=4146 Fmbkt=25.76 kIn Comilla marginal dyke Chowddagram 1976-77 '42.32 along both bank of Kankri river 62 Comprehensive Drg Drg=98462 Drg. scheme for »nbakt=14.63 km Noakhal1 _ .. a Begamganj 1977-78 533.20 Noakhal1 8adar Drg.c nal=40.48 km ' Iakshmi pur Iakshmipur Str.=l No. Sub-division Ii ! 53 Construction of FC IFC=12437 Fmbkt=44.67 km Noakhali road cum embkt. SUdharam 1981-82 151. 16 at 8ahoborhat &: I Iakshmipur Iakshmipur Bhabaniganj 54 Constr. of X-dam IFC . F0=5182 Bnbkt=O.72 km Noakhal1 cum embkt.at SUdharam 1981-82 20.57 Kakashipur ;5 Constr.of embkt. FC i FO=1377 Bnbkt=9.66 km Feni on both bank of l'arsuran 1981-$2 9.76 Solonia river ,6 Constr.of embkt. FC F0=7692 Bnbkt=53.13 kIn I . on both bank of Feni l'arsuran 1981-82 51.40 Mahua &: Muhuri river !

•...••• -J ------""'lji'le!"O.- ••--- •••••-.•..~.•.-- •••••.~.~.~..••-- ••---- ••••--~"":.l~,~;_------.•.•------,l<;c-~,------~..~~;;,\:_------

~lst Vt ,complete' ProJoct' v.lor the lI!)B Appl::"l.Jb ••A

'ii "'-17Pe-j1-B.".tftre! 'i1D cOC;PO•.iDf,- - r"'e .trIce; OPUl o Coc.ple- tloD co.t t1on. (111 loe - - wT!!!!g) < _ - . -7;.82 - 67. ta;'f'oncent ot I..xalb!u,~~a.1D~. IDralD..t.~ 121' !.tltt.r-5e'1 .tK. 11'&0£&11 lal1k.haU -'9s':e4 •• ':har-" b•• l. B•• l r ••• ~o••• tloa- ".27 Dt• • traUvr •• 2 Jio',

.--,.'

'~H~ 68. 5aacba.1r "eor ach_=- r.c. ~ Ir.c.• ~~ tabkt •• 71.11 II:' 9'.'- D2".~ft&l" Or.1na, •• \,,,, fiV' .1alc•• 20 ~04. ,}e~~ -'99.S, 6):1. Shal. f;ortb t ••t •• bIlt.lr.c. r.c •• ~700 tcblct. '2." 1K. (tlutehd~.d). .lu1e •• 9 flo"'. j'-'--~, ;e •.tl!J B•.•.I - 'ge~.~ 1Y.'" 70. E~t.n.iO'~: pol~~r66/ .C. I- F.e, &. 1"""11%," LobU. '~.2& D!.. (I.D.ol, ) In 1£11. • 2186 6lruet~r .••• 2 :.0'. ,sr. 9 •••• 1I 71. , fIoldu' 6~/A-~ I,.c. ~ T.e ••. 11'1'1,::.._ t-tllct. 9. KM. 'ge~~ trT1r.an. "<'5 Stt'\lct\lra • 2 fIlOA. 72. I Lcbasara r}..,04 Co.ctro~ Ir.:. L F.e ••• Dr&1nat., tllbllt._ 17.71111. I"&rail IlDh-eua 'ge}-~" '7Z.~'. &a'~a ••nt tn':::.!!la,::a. ('295S rlue.~) St.,. .••CWtf.) Ito •• :Of'tl! ..

•••••... Ql J . ----y,1 . - - . .-

List of completed embankment projects under BWDB Appendix-A

~r ~ ~'-i~i~irrtr.!- QUi cotpO'WDrS- - I:ocono~------:-roo;:or ~r-,,:";-r;OJ';'- are. 1Ji h•. co£r:r.= ------rmrlClI Opoulla , CoCtple- tloll c::...t aeC':ak J tiOD. (111 lao .., .... - - - -1- _ ------1- ~ _ ------1- ~ _ _2'!!9h _ - - - .•. - 73 SlalU.~.bu:.tl b~.l F,C." F.e. " ll'ZOlGA •• '/ tbbll:t. D.Y? 12:. "eo" 1Ahq...,.. 196~~~- :rJG.'!7 ir.~D.~'ach.oe. !tT1$a. (Pl&f1n.d 6"78) Str'\lct\ll' •••• 11'0•• : 1.1 ! ;:;:r1.~ti~- 1611'1------t.c1l1tlla. -1------f 74-154 ~i&d.rCOoiu_l kob-.JJl=:~-T7c; r - f.E.: ~,;;-;~ ..- £Db~t=.-"'51 15.; -- ;:i~;.-:-. ._------1-----1--- __ - rrojl:ct 8, No•• PoU.r. ~a1na.8'. ~ra.1J:•..;••....•e6.'1 StTU"'hr-'.122) )(0 •• .t ..hIre, Pl. •••••• A;.-a4..1K. . "I." ~.r~.t, •• -.0" • •:-l.al, 1981- •• Z ~.,,.,.,8.'l at' '. tuak.1ll al.,. •.•u .t •... co.t • arl!\Cl., 01_, :oakh.U • • ro1;\U" • •:.1, hi t t e.4ODII, 01:&. 8_ • 155 I Fr3.ridpurTown j Prote-j FC=1}60 . ;Flnbkt=11.27~..." rid,:,"~Faridpur 1976 26.71 Protection ction Spur=3 No. ./ pur c.cba Ba.adar prouo ••.. cet arh. .155' II!L...•. oh.- ~ •• "T.~lrt.c:oftJltr1llct1..,a.t.atlC'ur I X.WT.h tllZ. !;loc. 198Z-8, 1~4.~~ ".04 n:. 2) ~c1r. r••..t •• 1.2' D: ~) r.t""J'ora.r;r rohe- t 1(1n.~.'12 JQ:, 1571BRFE [FCD IFCD:7287 4 I Str.=1 6 Nos IRang- Mi.tha plikur1 I'-. pur Pri/!'B.nj; 1984- Teesta Reeee Bogra Kahalu embkt=44 kin BoI!T8. Brahmaputra Gabtali Resec embkt Pabna Bera = 128.80 km :Brahmaputra seraj- Kamarkandtta onj Kazipur alter. embkt= Shajadpur I 106.26 km I I •...•••• '" . 111 !JPI~ ------: .. . 1]12------/ ...,- ---z-.------1..- . .------

Lilt oC oomphtel project uoJer the i!lB Apttenol;c. .• A

oil! - - - :-reoi' or ----- 1;]1------bPeil1liuiCrtfel .co£po,:ior.- eocrr.= - Beo~rk. JIIo •. II•••• tC. PI'O~~ ••.•• in he o r Coc.l'le- tJOI. 'c:: c, (lit ,,100. (1~ Inc _r~~). 1r~.?"...- 1)t-bt~ )r;},. r.b~r:urJat•• 15-&0 ADcvr .11 aeor 1'.C.' IDT.l~ r.e •• ,8.51 &D~~~'~~':~~ Drc.1.a •••• , r.c. 2' Dr.C~~,.l-1."r:: :t'll.r. ~)!tructur.- 9 Noa. .T.rl6;Nr 11:0\.slS/)l~ark LD~. n.! '--85 ,21.1~ 159. Ia:ro •• oeftt ot S&k\lAh T. C. l I" c. &. tr &1J'ter-- "Cr.Cba.r.Dt'1a16.10 I b•• l tor IDill lrr1C> Dr' :llk"'_, • 2)StnlCtW"h , ko •• tion, !r.s.1A~ ud flood. "Flood .~bI<•• a.O~ cODtrol. ~2:;;:"~-I. 2l~;7~. 160. IBarolr.r.,.-~lC~.lla r.c. Ir , .C •• 1ZO'15 J;f\. ')t"•••• 1'1.72 lM ::I'11ft".' Dr.u. ••••• 't'>I06~ 2)~.""1.UUt1OCI ot Ki!. •. ob~ael.. 8.05 10:, ~) Structur •• ~ ~o•• '. II) ClGaur'h It 1=0_, ~8 __~~ 1)Eoblr:t. .!~.~ 01. ....".rb., Ja.« ertl " tlila,apal ".:'."7 1.61. J5/)/B ••• rb,t) !.C••. r.c •• 1"ld" ".u.D":_ • • 1n.a...;a. 2)Dr.'1~lr.-~~oc• }) Clo-""'- 22 Ilor, I

l-' ~ >tr- __m_ ------,J.- ; _

List pC eccplete1 Projltct u=.Jer the lela Appendix.. A

',- - - -In - - - .. - - ~ ~'Pd-[;-Bil.J;'trt£e! c,J!io":.- - No NnC4 ct Proj.~' i1Z coipo~illra- - ~i.r or ~oEpro=- Jhl.t::'lrko aNa 1ll b., !tcrlcU: "UfQZo • Ccoplo- tloll Ccat tiOD. (1 D loc .. .. _T~i!) , ------1- - -. - .-

T1c'~,1 Control LcUrt. 16't .• r•.c. T.C._ 150'2 :t=~kt•• l~ rJ;. j;ouh1'" }:ou hi B. r..r }o~~f 1:,,11;)1,'.L"tt Sa'llo. of Spur. 6 J.')e" B&&:u" }:au'.l .ir1.o1'.

163-. s-..nI1.'r "abkt.Projectl I::-rl,;=.t1- • r.C. t. rr1,;_ 7287 '. toblt t.~.~&.ir-,.e.~t.:~1tt .C"c. Sa.:Id.lp ,~&;-31 elt',.C'9 ;r~n:.oe ".C._ 22,672 ;,;... 'raint4'h 22, 672 z.::,.. EII1:kt •• ".6 D: Tr":.'lt:..frojoet ).Dra1l:.~ •• lute •• _~h! '9Bs-86) a 1;0". -,."_.~""""If"'"... i64. he;u. V•.ll.l Project r. c. : ".C. , ;)raina.e;. .eB'Ul:.ter ••• J.o.. 1506r& Aliaa:Jl&hll '$~6-t7 !::1.'.(' =r&..1:1a~. ;.:'-'1..:ltor i!lIecoat,."o ;."r:~asar , t:'o.c. 2 :;0 •• Atl'&.1 .• W1bkt._ 5'9.,z tr. n.-C1c."1.UCa 1:&:1.1- 2'.,52 t:::.

~-----

••• •••'" ~ .•_.-C. __On . n.. ~* .. u;: ;J,:.

( •

( }'OGt r,lboral;lon i-eriC'd ) -... t.lot ot C"Qp18te1 Project unleT th~ ~~ A?;>cnd 1x-A

, - a. _ ~d. .~~cer( fr~jQo' . " fJ'Po-,:-si"',rrtrol - r~:ii1iicocpo.iof.- art.o in he.' . - - - - - ~'-.r c ~o:pro:::- u ( Co[;plo- t10n CDt;!. R~eJ,rlo:fl - 1 __ tiaD. (l r. lac 1 __ ... .. To' 0). • 2: : - -5- _1 a __ "" '-5------'- - r.------: : 2 - _I=:~: - .• - - - ~0-- 165" L:~~b:1CDt.or.:lr,01a Irr1~,t! Irgo.-14, ~67:I rgo. COlool. 218 E. froJect. o ti.. ax:t1. Drg.- 17.5 :Jrb.Chan- 125.57 J.latl Bb 1967-88 14302.~3 & l:Jr8:lu(.e F.;.- 17.5 ••• 1; J..:ain J."UDp } House. 2 };o •• I , :r.LH •• 50.56 1.11 -T .Jr. Str._ 62 !loa. 166 '. So.asl1 .abaaDl!at F .C. F.C •• 460:) .-- ...••. Eobkt.~19.4 l.~. Gai bau1do Fulobar1 1987-88 2:)8 (Dutch :a) Bo~'Uloto~ ~ No•• ripe out :..t.e. 1 110 Irgn.lt:.l.et .• dtli:o&

1$7 rethailJol1 Ion&!- It.C.' F.: •• 1822 El>blct •• 91: •••• Tl'lDe;ail Ulrz8j)ur 11987~ 22<:~7~ I . bod (1'01') ~rg. & :Jr •• £e~lator. 1 ~o. (Dutch E:P) Unl ro- .xceTno'5.5-[.W.

168 • S~hair !lour F.C. & I F.C. , Ao-S.e. or I sun •• g"4j Sun.mgonj 1987-a8 1 ~O.58 Prg. Dro:.. 42CZ ••b~. 25.4 l.~. So~dl~ dOlI • 0 ••40 E.••. :~.-s.cor 00 •• boll<1J> • 10 K.Io:. I~~. 10 lot- ~ONo Jr. Slu1eo/boot tra.n.rer • 2 lio ••

\ I

\\; N .., ... _--_._. ~ .;;.~~~--~~ :~H l' .,:1-

List of ongoing embankment project under BWDB Appendix-A

81. Name of the ~nefi ted I LocatIon Year of .,p.p.cost ' Type rea in ha [Main components Remark! No. I Project I in lac I . District Upazila 1 I 2 Taka 3 4 , i b '7 8 9 10 ! 1 ~bna Irrigation FCDI 184534 Bnbkt=160.90 km ! Pabna 1970-71 27290.00 !PrOject . Irg.cana1=268.43kmi to Drg.canal=128.72kml 1989-90 HYd.str.=6 Nos. ! ! 2 I Teesta Barrage FCDI 612146 Embkt=80.5 km i Rangpur 1960-61 149836.9

"" \>l'" ~ :1 w ~

List of ongoing embankment project under BWDB APpendix-A

Sl. Name of the Benefited location Year of p.p.cos No. Project Type area in ha \'fain components District Upazila i~~(j Remarks 1 2 3 4 5 6 7 8 9 10

Naogaon Project FeD 46100 Embkt= 6 km Noagaon Sldar 1984-85 5238.17 Polder-1 Hyd.Str.=198 Nos. MOhadebpur to Irg.canal=230 km Atrai 1990-91 Baninagar »l.nda North Rupganj FCD 2270 "8nbkt=18 km Narayanganj R\l.pganj 1984-85 2565.39 Irg.canal=38.5 km to , Drg.canal=15.5km \ 1989-90 Hyd.str.=22 Nos. ~ -c- I ADBAided KIP FCDI 101215 ]<)nbkt,&Drg.canal All over i - 1982-83' '17070~01 Type = 1350 kin Bangladesh i to Hyd. str.=14 Nos. 1990-91 ' 2 1 Dutch Aided KIP FCDI 19860 Embkt=97.90 kin - : - 1985-86 \99 .42 Phase-II Hyd. str.22 Nos. ! to i 1989-90 1 DutchAici.ed EIP FCDI 28866 Embankt=140.80kln - - 1983-841592.35 Phase-I Hyd.str.=22 Nos. to \ 1988-89

I 1 Dutch Aided EIP _ I 53929 . Embkt=135.30 km - - 1986-87 2831.95 I Phase-III i 'Hyd. str.=34 Nos. i to

(Group-I) \ 'r Closure=15 Nos. '\ i 1988-89 1 Barnai Project ' FCDI I 48300 Embkt=135.30 kin I Natore i - 1986-87 9057.89 : EJ;cav.& Re-excava.1 ! to , ! of canal=485 kin \ \ 1993-94 1 I ,Hyd.str.=21 Nos. i I r \ I " : 'I I i' ! I " t' ••• ""'------~* (1. l

List of ongoing embankment project under BWDB Appendix-A

3I• Nameof the Benefi ted ------.~-.------Location Yea:r-of--p:p.~oijt------N • Project Type . area in hi Main components District Upazila _ i~~ c Remarks

I I '" 3 4 I. 5 .6. -'L 8; 9 10 I 14 Khulna Coastal FCD! 31900 Embkt=23.02 km Khulna - 1987-88 6418.19 Enbankment Eircavation &: Re- to rehabilitation excavation of 1991-92 I ' project . canal/river=96.4kn , ! i Sluice=5 Nos. I I 15 :Dutch Aided EIP FCD 21350 15mbkt=102.40km Sunamganj - ~987-88 11934.62 ~Phase-III Re-sectioning Gaibandha I to I ;Group-2 = 14.9 km Bogra i 1989-90 I ' ~. Drg.canal=58.8 km Nator - i I ! -! Byd.3tr.=21 Nos. Patuakhali i I c I B:l.risal, I Faridpur , .... I 16 'Rehabilitation arl - Retired Enbkt=48kmRangpur - [1987-88 . 1273.83 .Brahmaputra embk1l Closure &: X-embkt Bogra ! to : .\ = 100 Nos. S rajganj i 1988-89 . By .3tr.=15 Nos. I . I I I. I_ 1 7 SIRDP i FeD! : 47368 E:nbkt=57.27 km serajganj - IJUl.l977 3573.05 I I Embkt.re-modelling , to 1= 19.03 km Jun.1989 Dr~.canal=upgradin& i = 43.47 km I ! ~bkt. re-sec'ion1n~ j : = 34.30 kin i IByd.3tr.= 15 Nos. I

I I i i

~ 1,11'" -iOIi ' ,,;- - --'l ., "'.:.. .-p-.

(

List of ongoing embankment project under BWDB Appendix-A .--_._- - ._------_ .._------_._._------_._.

• . I ,c : 'i T I Jl., rlu. ot J"roje-:t , Tl~ , uea,tittld I ';':.1a :;"'a"ODt'nCI I Location Je.r of .:ict..Jl.le ,J. .1'. co~t ri~r:lr.k. Ho., I Irla 14 ha f >, JIlt. I C):&&!.ll" eou.~c. tor .(111 LbU rnc'l '

t I I I , •• ot, .co.pleot- I I tit I I ,lOA • 1 1 2 i, i 4 : , i 0 i 2 I 8 ,u--r_q '-,,,~ L-UI_ _18, ':%1a180 i:'!~i Jroha.sa }e,5d} h4 ' 1.~b.kt.- 1,~.2& ~. n~j~aQi 1~1_"~ 1~,~'..-5'.! ( follor -~) ~ '100.1 2.Jt,&vlator- l' ::o.J. :" ~576.b5 Coatrol. ,. ;)ru~. ";':1,);..;.~1 ••.I0l')aolil - 19;.2' D. ~. arlj~t/;uly.rt -101'0 •• 5. 1Io0'J 1I.l.A - 76.09 Ir•• Y1l1aga-25.e5 Ir•. - 6. 'lu.ll1~';:'clceo c"".,. ...;,-_.~... • 0 1:"5.

19. Sotla-',ag1. ProJ.ct '1. Eobkt. 121.5 Ca. Orai •• g. Drg ••• r.c aorlo01 1972 jun.' 69 x-55.0;' ••r .C. -21,457 II. (I••• ) PoroJ~ur - 2. i,381 h4 2. aotd. l)Ibkt. do•• r. -2.6'> k.B. 3. i

""'I\) 0'1 ~.- :*-~_. -... '~ ,;-

List of ongoing embankment project underBWDB Appendix-A

.;N" I Iii _ i , • • "I.:) •• ,iye or Project I rn~ I Oeul!Il"ltted I J(al~ :a_a;oueat. .,. Locatlou , tear ot ~Jcl.e1ul~ I r.r.~otJt I .,-:'lnrit•• • • I I, IreQ in .b.3I JoIt.t. i 0;..:111. I comGu'!uc:. I r"r . (10 LuLU I .' ,.eDt. cOllpletlQ,ll 'rs.,,; l' 2. . 3 . ..: 2 i 6 :? i 8 :.---9 I 10-: 21 N-N ilel1.b.Irrl,,;otloA flood - 1.Dobi

22 1l00JJ •• oge ae- _.Jo- 1. Dobkt. A.polr 411 o••r 19t14-85 1Q67-tod Ge14.OC •• t.bl11Jle1 iroJ.c~ - 818 •.••• b&Jl6lldloh (CreJlt foo.-15d78J) 2. l&~£t. Frot~ctloa. - 6a U. ,. SI,*,Vao~ulotor r.palr- ~6 j;" •• 4. Other' ,3tructurft - 17 :t05. 23 J'JT~:1UJ.j :IP, 1100.1 <:OAt- 21350 1. Eabkt .• 169 ka. 1987-88 1<;91-92 -2(.•9. ~~, pn•• e- 3. G~up-' MI & 2, Drg.C.aal-14 Le. Jral"4e;8 ,. arljge - 8 :;01.

,"24 • I:-H Irri,.("tl~n Fleal (AD- .'500 11. 1. Dobkt. 6 :u.. Nor01Dll60aj 1')68-89 1991-92 ,. ,~..o'.GO rroj.ct r.IOC<-4/1)trol " • (1/ •• ) t. Orel D8S~ , "••~ctlo~lQ~-1~k2.N4r.~cJl Irrlgatloa. 2.Pu.~ 3:.:)- 1 l.O. ,. Jr

I-' ~

~.'~,...... -"* •. '":..1.:""':.:.. _ • ~- -- -- u -- -:~: i~ ~.;.,

List of ongoing embankment project under BWDB Appendix-A

p.p.coso Sl ., Name of the Benefited. Location Year N, Type area in ha Main components District Upazila in lac /RemarkIs • Project Taka. 1- 1 2 3 4 i, 5 6 7 I. Fl 9 25 Nagor Velly FeD - I Ibbkt=60 .•00 km Na oga on Ranirxagar - - Project I Atrai I ,I I , Bogra Adamdighi I , - I 26 Hurasagar, FCD! I FCD! - i Jbbkt=l 6.00 km Sera jgan j Shahzadpur - , sub-project I I I - i I : ' 27 SonaU Bundh I FCD I I Jbbkt=19.30 km I Gaibandha I - I , Gaibandha - I - Project I I I . i I Fulchori 28 iP.aisarhat-RamshiliFCD~~ I - I Embkt=1;.60 km I Earisal Agailjhara I - i - I sub-project I' Gournadi I , I i i , i I Madaripur Kalkini , ,i I , i ! i Gopalganj __KotaUpara I ! i ! 29 .Faridpur area-I :FCD - I Embkt=78.50 km Iang-sha • - - I - : Khoksha I Kumarkhali i 30 i Dhuldi scheme ,FCD! , , - Embkt=29.00 km Faridpur sadar - I - 31 Tarail-Ianchuria FCD - Embkt=51.00 km Gopalganj Gopalganj - I - i i , , Project, Bolder-2 Kotalipara i i I Tongipara I : I I 32 south Kalkini I i . I FCD! - Embkt=35.00 km Madaripur Kalkini - I - FCD! SUb-project I 33 :North Kalkini FCD! - Embkt=30.60 km I Madaripur Kalkini - I - I .FCD! SUb-project. I 34 Ma.daripur beel FCD - Jbbkt=35.50 km Gopalganj Gopalganj I - I - Route project Muksudpur ! I , I i I i KotaUpara ! I , I M3.daripur Rajoir , i i ; I I i ••• CD'" ,.., .~'J. ¥. ",~

,. '..~.:..;, .. ,>,- '.

l,111't of cOIDplete1 Pl"oJect uoJer tbe IDB C04~"I'AL Ubo;'l:l:U:r H.1rl ~. I PoUor _ •• l.e. & F.C.-10.;Z4 IEabtt.- 10 I.M. Ububun1 • 1964-651 141l"9 Drs. Drg.- 7,287 structur •••• 22 Noo XtllguJ 9 •• I 1'01' or - 24 , F,C•• '.:. -'26.,.,ao ilDbtt.-23.81 1.1:. I.".oro l4bbo;naoser 1m-78 96.-6 Drg. 'Drg.-22,6?2 St,Ncture •.• 11 Uo. .&A1raapur •. II:olblbpur. 10. I Po1'or _ 1 l.e. &. F.C.-26,"29 Eabtt.- 100.8,1.l'/Sltltb1r.l ~ob.tbu.J. 1964-6~ 542.90 Drs. Drg.-21.142 structuft •••27 Noo. III.bbatl •••• 2

~ N 1.0 "'!: .-.. . -, - -. ~- ."-l ~ 2'..

~1&t ~t r.ocpletelProj~ct uDJe~ ~be lOB W!~~~~IL. -1- ",.-i"""''''' -["'••''''''''.•,-l;J:"mo ------"..., r - ---.- . Mo."r -,;.;;,-';:';,;' arta in b. J • rIa JIll. Q Cotlple-'j,.,.,.~tloll Coot-R•••:uta . . t10D. (10 IDe 1..r- -...- - .2------1-- -'- - - - __-- 'L- - - _- _- _- _-i _-_-_-_-l-_ _ _6_-_-t _-")-- _----G' .:. - _1'~i').: - r -- 1<1"- - 11. 10U.r- 15 "C." 1.C.- "20 ;;atkt.- 152.7 1.1I. S.tkh1r Stq'; ;'0'; - 1;6;'~ - -65-.';;'------Drg. Drtl.- 2656 "tnlcturea - 5 1.0. 12•. PoUer- 5 1 1"0- '.~.- 55,425 "*bkt.-152.7 I.lI. Io.l1c;uJ •• I1981-a2 I b/lO.71 Dro.- 4It.340 . .;tl'Jcture.- 34 Z..OI Sh.;raa liaoar 13. I PoUer - , 18,70" . bkt:- .&0.0 1.11. I-lo- l,.c.- Dobhoto " 11~66-6? I ~'.75 Drp;.- 1",9!l4 it:nJcturol- ,0 .hoa .hl1,"'J 14. J 10U.r 17/1 I-co- I '.~.- 5,020 Duaurl. " 1971-72 12O.}" Drs.- ',267 f.ik,.ab. 1 15.' Pol•••. 17/2 1-40.- I l'.C.- ',441 DUllUrla 118.06 lI•.S.- ',2'9 1977-78/ 16.1 PoU ••. 27/1 1-'0- I I'.C.- 3765 lwla. J:N8ur1. 1965-661 10'.60 Drs.- W~8 17./ FoUer 27/2 I-co- l,.c.- '765 I D•••••• 1o 11cn~7? I 8'.25 Drcl.- '298 18.1 PoU ••. 28/1 1-'0- l,.c.- 5628 ~bkt~ - ~'.~041.1I~ lbul... I Dunr10 ) 19?Q-71I 44.19 D•.,.- 4781

;9./ 1'014••. 28/2 /, .C.- 2591 ~bkt~- 2? ~.1I. ~la. I Du8U'1. 11975-76 I 115"0 I-'o~ DrS.- 2202 20. POU••. - 29 -'0- . 1.C.- 8219 ~blct:- ~6.75 1.1/. PWla. I Du.•u•.1o ) 197G-?1J 160.4' DrS.- 6575 21,1 Pol •••. - 25 1-'0- I 1.C.- 16,275 I:bkt. - '5.7 I.Il. f"'l" , IN.uri •• 17'.70 Drs.Q 1',8" Stnlct. l' Ho•• naula'tpur rt6?-68/

( Co;U ••• ' )

'"" '"o -~ -" u, --,' n" - ":4' , -- '"A #-'

.It:lst r.t cor:phte1 Project uo!er the EB .l;';,&~.l.x -_-8

.bl:l.- -}f-c.; ~"(-P;oJ.;t"": - T7Pe-i~iui[rtr.J -stii c~t:pr;Jr•• r.occE'lou- - - - - .- - ['-riior c:r Jfo.1 n . area 1n h. Dr'-l- l:,-::rT.= ------.. Dl.trlcG Opotliia Cor.ople- t10rl co.t Rec-:Jrk.1 . :) .... _--- tiOD • 0" loc '- ----_2 __ _ .i -,------'" - _- - - - 5.------1- .fi_- - _- t _- _- '2.- - - - -1- -6 -__ - -Tokn)--, -• - - - .•.. - - :1( : 22. PoUer - }Gl1 F. :;& 1.:.- "5.}44 ~bkt.-9Il •• t.M. D&.iJerb~tl l!ollarblio.t. 19'70-71 }76. ;'() Drs. 'rs.~ }9.676 StnJct.- 2' No•• Fulr~lilt, iup •• aD. em t&1.llar1 PoU •••.- }4/1 2'. •••0- T.:.- 2"29 !:abkt.- 8.54 t.lI.llkgitrtuat B••••rtuat 1960-65 45.18 ;):s.- 194} StNct.- , NOl.

2". Pol"r '5/1 ';'40- T.:. - 18'161 EIIbkt.- 60 t.M. B.g-.re.t lhrrelS&:1j It 1966-67 5}7.'9 :lrs. - 15}85 StnJct.-5} ~o•• i Saran i~l. 25. PoUer - " -.0- T.C.-10.}6'" !:abkt._ 72.6 t.lI. lKl:uJl•• h1t~tuat. 17'" Drs.- 9<>"6 Btroc.- 1'1lie •. 1''f7,-n ..,,-'It 26. PoUe.-. 2} -'0- 1.C.- 492', EIIbkt. - }6.6 t.lIl~ul~. P&1kgach. 1964-65 :lrg.- 4162 St:uc.- 1C ~p" 56.'9

Z7. Polier - 21 -'0- 1. :.- }Z79 :::'bkt. '5.76 [.14. tKllul•• P&ll~.ch. 1971-72 };; 61 Jrg. 1619 Iitruct.- 2 ho'. 28. Po14er - 9 -110- !.:.- 109' Eabkt. - 8.,0 t.IIIKhula. Pa1i:t;acb. 1971-72 <'J. e7 'r•. - 9'5 6tI\Jc. 3 Ho •• ?j3: IoHor - ~ -40- 1.:. - 66'05 El

f-' VI f-' 'f'~~~"~"~''~'.~-~~--:-~~'14(~'----~---___=-:---;r------.,.".."...--- , ~' (' 4 " .,' eo,,,, "~::

l.1st er eocrletelProSoct uol.r tbe WB APpe". a In. .' ------'"nl:l' DC ProJect '" 'rrlle-I ~B.~irrtr.l- 'iilii coEpr".nr.- tocnflou. -- - ";"- - or Ilo. areo in h. "'1- tro0r .t'ocpr.= ------. biljErtcq Opaullo Coopl.- tiOD co.t R.m~rtb tiOD. (In 10. :1. ....------_T!!a)~_ -}. ::::~::: - "'leT ------~-- :::~:::::I:l::f::}::::tl:: - ~------FoH.r - 20 F.C. " IF.c. - ,,219 Eabl

36. I PoUe.,.,. 55/1 -40- 7.('.-8'704 E:tlbkt. 45.26 I.W. I P.tuakh~l1 Qal•• hip. 197&-77 218.80, Dr•• - 8704 $tl'\lc.- 'l7 lio •• DrlS.C;'lIWIel-'.2A. 37.1 Pol'.r - 54 = -00- r .C.- 'n52 ,EIobkt.- 58.68 I.K'fetUall1.~1 Ibepupare 1971-78 191.59 Dr,;.- 9352 BtrJc.- 31 !lo•. - -.) Drc:. .:ba....uel-2.8 1. '. ." 38.1 Fol'.r - 47/1 -.0- F.e.- 20&5 ~~~~.- 21.38 1.11.• tuakh.~1 I:h•••••p.r. 196~66 62.00 Jr,;.-2065 5truc.- .3 1;0', Dr;. Cb~D.l - 0.8 I.~. 39.' Folter - 41/2 I.C.- 850 3=bkt.- 11." 1,I:.r.tUakh.tl U•••••par. 196~66 3C.~6 -'0- Drg.- 850 Struc.- 1 ~o. Dr~.Cba=el.0.4 I •. , 40.1 PolC.r - 47/3 -!o- 1'.C.-1.660 ]labkt.- 19.61.11. lFetuakhatl &h.pupere 196~ 41.83 o~ruC.- 5 MOl. DrlS.Cb•••••1-1.2 I

( j;oaU ••• p/S/)

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h" \.>l \.>l .,. -"J,' ---'iI(' ,~_ "::!-. ,-,( ~ 't (

1&1at t't cOw-rhto' Project uc.1er tb. fOB ~~. - B

- bP,-,h!.".trtl"eJ' - 'iiUi coEpolloinr.- - toea!'l1;L ------:--reoi' ot l:cEpre= - ~3--ll~::':;I-?;~Je;s- aNa 1J>Ila etricG U,pD&lllo f C"cple. tioD. cGet t1oc. (1r. lac .... ------.1. _ ------.1- ~ 1__ - - _ri!~)._ - - - - -1- _ - - _,_ - ~ ------.1- - - - ~ ------~-----~-----13•••6 "9. I ialhr - "117 r.c.' 1141 Eabltt. 18." It... 111•.•.11"•• IllorguAa 196;-66 Drs. 1"C'-Dro'- 17••1 5t.l"'YC. 11 )'0•• Brs.C~el-1.6 1. 5'i. Ifal •• r - ,,1/;. Jo- 1.C.- 2105 ~bkt. "9.86 t.~. -40- ' 33.9'+ Ors. -2105 Qtrua. 1~.0 •. -40- "I Or6.~~2." 1. .' . 51. IroHer - "2, 0- 1.C.- V9'+ Eallloto 81.77 Drg.- 2105 ,otrw:.. 8 Noo. -- , Ors.~:.nel-1.6 l . 1.1:. 53.1rolier - "0/2 r .C.- 28'" ~blr.t. 35.2 I.1:. -40- -40- 96;-66 11•••97 28'" Strue. 15 Soa. " r,. Jr6.Che~el-2.96 , 1.11

54.lrolJor - ~S/1 0- 1.C.- 2'+,291 Eablr.t" 9~.22 It.L. -40- -40- 1978-79' '28.1" Oro' 2'+,291 IStruc. 13 I;oe. ' 01'6'C~""el- 6.4t I •.k. 55.11-oHer - "3/1 40- 1.C.- 28,"21 EDblr.t.- 78.9 t .•• otualr.l1al1.&atall 979-80 169.07 Dr6.- 28,"21 Struc. 10 1100., 01';;.Chawlel- 3.2 1:.1:. 2'+3.21 5c.1 Pohu - 4"+ 0- 7.=.- 17,530 I~.lr.t. 80 I:.~. -40- -~o- 9??-78 Drol.- 17,530 Struc. 8 ~o•• OrO'Cha.oJ>el- 1.92 1.1i. ••.7

••• '"-1>0 'H' SJ~- -

l.t1:it of co;:r,ldt.dProject undor tb_ WOD I.pp.- B . .. ~ ~ b~o-I~Bi•••HtroJ - 'aiii co£po:'inra-l- tocn£1olo------~'iDt ot CoC:pIo= ------tic. l'tou. c.! ProJ"C\' ••••• 1 n ll.a . Dlstrlcq Opol1110 Coc.pl.- tlor. ccut B'.crk. .tioe. (1L 1•• _l'!!!ah _ :1. :::~:::::: ::~::::::j::':f::i:- _]I: : -~------10- - - ,:;3.86 57. l-oU.r - 58/~ ;1~04--I-,.~C.~~;3:- ~b~'.-16.b3 I.Y bbolo .~puro 1982-83 ';l.dt' 1.1zu441. COQtrol Struc. - 2 ho•• Dro.Ch.-.w.-7 1135.~ StnlC.- 21 150•• Dr~.- 1>0,259 Daulut lb,1Jl Dr~. Ch&:.J.ol - CQ&r , ••• 10A 1b.1& 1.1t. 1";.76 59.1 fo •• e: - 59/1.1. -00- t.C.- 11.053 l.&b~'. 36 1:.... h.~lSu.hor ••• ~ 1970-71 Dr~.- 11.053 6eru •• - 2" lioo. Cv.fo.:>J'g~

6:,j.} .i ,J.i.""'otr - ;(j/1.e 1.:.-15,385 ""bke. 3<;.2 •• 11. ~oollal ""ohuoa 1970-71 8~.51 -.0- Dri.-15.3aj ~truc. 1; ~O•• 61.1 Pol••: - 59/2 -10- 1.:.- 15'>t>6 i.IoDk1:.77.6 t.lIl. Ilolr..loIIljur lok.ulfur 119'"10-71 Dr,;. - 15'>60 Struc. }O Noa. 1 .n. Bug.tl. 60<.1 foHer - bO -40- 1.C.-7409 E&bkt. 30."3 lell. I roal ~.a.ae.z.1 1970-71 1;'5. )B Dr•• - 7"09 Struc. S i.05. 1970-71 60,."2 ~~. ?ol~er- 7~/1. l.~.- _9 o.b"'. 6';:7c ~.I:~ );o •••••.• l~ lIoUl0 •••• 7Y1b -"0- ~rg. 4009 Str'\.lC. 2'+ :10'- • .ot

f"" \,11'" ..-:r...... _~ n_ ••• - (~:.J- _

App.- B - 11 st of complato!d t'roJ&ct \J~.dt!r UII,: If)D

'T -,-,;;,-,;';';.-!--l"i"'" t.,-!",••''''',i.t,-T ,.<,n" ------iTO" 110. n an. 1r. h. ~~trlctt ORo&111n Coc.plo-'1,,,,,.~tiOL co.t-r.-'C1;rka---- tlo~. (1~ loc •••••• ------~ ------) - ______%~~)L_ ~ ____ ~ ~ -----~---- -~------_ .--~--_. __ ~_. ______b_ ~ j~ b,J i'al~.r - 63/1.. t.c;" 1. C.- 32'+ D;,~ct.- 49.6 lI:.~.1CtUtt.:L ;.r.oa.ra R9 ••••..6~ - 2fiJ~2~- - • - Jrg. DrD.- ~C4 :;it1"\,lC.- 1~ llio'. ~7.ll'alJu - ,,"/1 .• I-oa- t.C.- 4{)(, J:):lbkt.- 67.21.1:. I -00- I .Buat.k.Aall 11~<»-67 I ~5.'I3 01'6.- 4<;6 .'itruc.- 15 1'I~•• ~rc:.C".DJl.l - 1.611:.11. ab. I FoHtr - &<+/1•• I-co- Il.C.- 610 I<;t.bC1;.-11~" 1.0:.1 -40- I -la- 119<»-6'1 I 'l::>~.n 01'0'- 010 St1'\lo.- 2'l WOI. Oro' Ch&=bn. 22.4 1.1:. I -do- I -.0- /19<»-67 I 111.60 ;lr ••. Drg.- 1~9 .;tnu:. 7 .HOI. Dr.;_ Ch#.DL.l • 3.2 I.J.:. '10. I Pal.er - n 1-.0- 11. C.- 16,194 El:>bkt.- 1>2.41(.1:. -do- a•.••.••lp . 1196'1-66I 450.59 DrcS.- 16,194 8t1'\l0.- 13 NOl. , .. 71. I l'aUer - fl>/2.i. 1-&0- 11.C.~ 931' Z.b~.- }4•• t.l:. Con Cl>lltorla. 11960-6'1I 100.00 01'0;.- 931 8t1'\lC.- 15 AOI. BklU' Ors.CAu.<:el - • '.2 1.11. ~~.Ifol.er - &<+/2iJ 1--40- 1,.c.- 21C~ I ~bkt.- ~.6 t ••.•I -40- I --40- 11965-66 I 159.88 Drs•• 2105 ,stI'\,lC.- lie'. Or•••Ch""".l • 6.4 1.11. I I I I (Coctd. .~/9)

•••• '"'" ~'f( ------~. ~ - ,. . - ( ~" (

~r cOQpleta1 Project unler tbe woa APp.-.8 • .. " '1'lP'- ~i"'.!r~f.l - 'alii. ,COf'po..illf.- lrocpI.= - r:- - - - - ~------••••• 1Jl;ha Cl011e,.c a••orE. K~ :!_r~o~.:,_ (ill 100 :oJ .. ' fair,) 1...; _____ 2. ____ • ____ 'Ill ___ ::,::::{::::: ------Ji:: - ~- L - t - - -,- - I - - ~-- - - 7}. PoU.r - 65 I.C, ••• I.C.-',4'+1 Eabkt.- ~6.4 I.». x'. CI>aE•.•.lo ' 19€6-,66 77.}4 .or,. ~r'.-'."'+1 Str.Jct;\l,r •.• 18 noa Bas&r Drol.~ol • - 4.6 1.11.

7~., Pol •• r - C611 1-40- J l.e.- 1lO~' EobAt•• 19,2 1.~J-~o- I a•• u 11967-661 47.75 Dr,.- 1lO~ SONt. 6 :Jo••

75. IoU.r - 66/2 1-40- ll.e.- }f.A" <;AbU.- 19.2 I.~.I -~o- I '(o-!ol. Sal&%, 11967-66 I 27.85 Dr,.- ~" SeNe.- ? /;0•• . 71'>. PoHer - 66/' 1-40- I,.e.~ f:/J?> Eab~e.- 19.52 1.~J-40- I •..•0- 11%6-69 I '08.55 Dr;;.- f:/J? SeNe.- 5 tiOI. 7?~ FoUer' - '67 /-40- l'.c.- 6'08" Dlb".-12.6' 1.1l.1 -40- I hboat 11966-69 I 42.59 Dr•• - 6'08 SON".- 9 50•• '76~ FoUer - 66 I•.•••..~.;. 810 2A a I 'j -!-&o- L ...-. 11966-691 69.62 Ilr, •• 610 <' JtnJ( •• 10 :Jo •• o " , 79. Pol •• r - 69 I I 0040- I,'.C.-f:/J?:. DlbkC.-12.6'1.~.I-.o- r bhulll

80, Poller .'70 4 ~ 1.C.-405 ' i:olb:

81; rolJ.r - 71 140- I '.~.• 810 I Do~e. - 49.6 1.»1 -'0- I luCub.1& 11965-66 I 104.2' Dr,.-ll10 .' atruo. - 10 UOI.

o 0- o 'C "

p '"-:l 1.38

Appendix-C

SURVEY OF EMBANKMENTS

S1. No. Completed by Date I, 1. Name of Embankment/Project:

2. Districts(s) Location in: 3. River(s) Protects from 4. Date of Construction with Length of Completed Embankment:

5. Date of Completion with Completed total Length 6 ..Sinc. that date has the embankment been retired at any place? If yes, give details with year location and length

7. Details of embankment constructed a) Crest Hiehgt b) Crest width c) Slope ins ide d) Slope outside

e) Construction material used, is it from nearby location? f) Turfing g) Any unusual features e.g. facing material etc.

h) Design standard of embankment e.g. 1 in year flood, or flood of 19: additional free board ft.

8. Brief details of water control structures in embankment e.g. number of sluices and regulators with sizes and locations.

9. Area reproted to be protected by the embankment. 10. Is the irrigation in the area protected: give details

11. Crops grown during pre-project condition

II ! 139

12. Crops grown now. Is there any change in cropping pattern and cropping intensity.If possible give crop yield and cropping intensity during pre- project and post-project condition.

13. Give details for each year during construction and since completion of all of the following possible problems. In each year specify the number of events/locations affected with approximate date (e.g. late July. mid Aug). a. Erosion of embankment: Give length eroded in each case, was it reconstructed for next flood season? If not. when reconstructed. Details Year Date Locations Length

b. Overtropping of embankment: Give length overtropped in each case. Details Year Date Locations Length

c. Breach of embankment: Give number of locations and. 1ength in each case, was it reconstructed for next flood season. With comment on reason for failure in each case:

Year Date Location Length Detai 1

d. Public Cut of embankment: Give number of locations and length in each case, was it reconstructed for next flood season.With comment on reason for failure in each case

Year Date Location Length Deta i1

14. Any other details that you think might be relevant. 140

Appendix-D PROJECT DETAILS

TEESTA RIGHT EMBANKMENT

------~------1. Location Kaunia and Gangachara UZ. of RANGPUR dist. and Kishoregang and Jaldhaka UZ. of NILPHAMAIU dist.

2. River Protect From Teesta

3. Critical Flood Type Flash Flooding

4. Region NW

5. Purpose FeD

6. Status Completed Project Starting Date 1975-1976 Project Completion Date 1982

7. Main Feature Benefitted Area 75,300 ha Embankment 81 km Drainage Regulator 5 No. Groyne 1 No.

8. Embankment Section Crest Height 2.1 to 4.9 m Detials Crest Width 4.3 m CIS Slope 1:3 RIS Slope 1:3 Freeboard 1.0 to 1.5 m Berm Design Flood R. I 1 : 25 yrs

9. Embankment Failure Modes Erosion 1982,1987 Since Completion Breach 1982-]988 Overtopping 1987 Public Cut ]987 Protection Works 1988 Resectioning of Embkt. 1988 Retired Embkt.

10. FF&W Stations Dalia and Kaunia

ll. Patrolling No such arrangement

------~------

, '- 141

Appendix-D PROJECT DETAILS

BRAHMAPIJTHA HIGHT noon EMIlANKMllNT

------1. Location Along the right bank of Brahmaputra river from KAUNIA in RANGPUR dist. to BEllA in PAIlNA dist. ~ 2. River Protect From Bralunaputra & Teesta

3. Critical Flood Type : Monsoon Flooding & Local rainfall drainage iT 4. Region NW

5. Purpose FCD

6. Status Completed Project Starting Date Pr-ojeet Completion Date 1968

7. Main Feature FCD Area 72,875 ha Emt\ankment 217 km Dniinage Regulator 16 No. Cross Bundh 115 No. Groyne 1 No.

8. Embankment Section Crest Height 3.7 to 5.5 m Detials Crest Width 4.3 to 7.3 m CIS Slope 1 : 3 RIS Slope 1 : 3 Fr~eboard -Brahmaputra 1.5 m \. -Teesta 0.9 m Berin Des~gn Flood R. I 1 : 100 yrs

9. Embankment Failure Modes Erosion Cont. problem Since Completion Breach 69,70,74-78,80-81, 84-85,87-88 Overtopping 88 Public Cut 87,88 P,"otection Works 87,88 Hesectioning of Embkt. 87,88 Retired Embkt. 68-69,74,78-81, 85-88 10. FF&W Stations Dalia,Kaunia,Chilmari, Bahadurabad, Serajganj

11. Patrolling Very limited ------H2

Appendix-D PROJECT DETAILS

CIIAl.ANBEEL PROJECT (POWER A, B, C & D)

------_._------1. Location Bagmara,Mohonpur & Paba UZ of Ra.;shahi, Singra,. Gurdaspur & Natore UZ of Natore district and Manda and Atrai of Naogaon district.

2. River Protect From Atrai, Sib-Fakirni, Barnai & Baral

" 3. Critical Flood Type Monsoon Flooding & Local flainfall

4. Region NW

5. Purpose FCDI

6. Status Ongoing (Polder A,B & C-lst phase completed) Project Starting Date Project Completion Date

7..Main Feature FCD Area :106,753(52,860) ha Embankment 203(134) km Drainage flegulator 19(14) No Drainage Channel 167(193) km Smaller Structure 164(107) No

8. Embankment.Section Crest Height 3.7 m Detials Crest Width 4.3 m CIS Slope 1: 2 RIS Slope 1:3 Freeboard 0.9 m I Berm ); Design Flood R. I :No definite criteria

9. Embankment Failure Modes Erosion 1988 Since Completion Breach 1985-1988 Overtopping 1987,1988 Public Cut 1987,1988 Protection Works 1987,1988 flesectioning of Embkt. 1988 Retired Embkt.

10. FF&W Stations No such station

11. Patrolling No organised system ------~------Note: The figure in parenthesis are applicable for Polder-D

o 343

Appendi~:-D PROJECT DETAUS , NARAYANGANJ-NARSlIINGDI FeDI PROJECT

------1. Location Narayanganj and Narshingdi district

2. River Protect From Lakhya and Meghna

3. Critical Flood Type Monsoon Flooding and Local Rainfall

4. Region NE

5. Purpose FCDI , 6. Status Completed Project Starting Date Pt'oject Completion Date 1984

7. Main Feature Benefitted Area (gross) 1400 ha Embankment 8.3 km Drainage Regulator 1 No Drainage Sluice 3 No Drainage Channel 9 krn

8. Embankment Section Crest, Height 4.0 rn Detinls Crest Width . 2.5 rn CIS Slope 1.5 : 1 RIS Slope 1.5 : 1 Freeboard 0.2 rn Berm Design Flood R.I 1:20 yr

9. Embankment Failure Modes Erosion 1987 Since Completion Breach 1985,1987,1988 Overtopping 1987 Public Cut 1988 Protection Works Resectioning of Embkt. 1987,1988 Reti red Ernbkt.

10. FF&W Stations Narayanganj and Myrnensingh

11. Patrolling

------

\ I 144 Appendix-D PROJECT DETAILS

GUMTI EMBANKMENT STRENGTHENING PHOJECT

------~------1. Location Kotwali,Burichong and Debidwar UZ of Comilla district I ) 2. River Protect From Gumti 3. Critical Flood Type Flash Flooding and Local Rainfall

4. Region SE

5. Purpose FCI

6. Status Completed Project Starting Date 1956 Project Completion Date 1963

7. Main Feature Benefitted Area 47,000 ha Embankment 68 km Drainage Regulator 1 No

8. Embankment Section Crest Height 5.0 m DetiaIs Crest Width 4.3 m CIS Slope 1: 2 RIS Slope 1:3 Freeboard 0.9 m Berm 3 m below crest Design, Flood R. I 1:50 yr

.9. Embankment Failure Modes Erosion Continuous Problem Since Completion Breach 1964,1968,1982 1983,1987,1988 Overtopping 1965,1968 ~I Public Cut Protection Works 1987,1988 Resect ion ing of EmbkL 1988 Retired Embkt. Sever'al Section Retired

10. FF&W Stations Comilla

ll. Patroll ing 1 or 2 man I mile during floods, depending on flood level and whether day or night

\ \ 145

,. ~? Appendix-D ~~ PROJECT DETAILS

MEGIlNA DIIONAGOIlA IRllIllGATlON PIlO.lECT

------J Motlal. lJZ of Chundpur district 1- Locution' Meghna and Dhonagoda 2. Iliver Protect From Monsoon Flooding Hnd l,oeal Ilainfall 3. Critical Flood Type

Region SE =; 4. FCIlI >l 5. Purpose r 6. Status

7. Main Feature

8. Embankment Section L Detials

9. Embankment Failure Modes Since Completion

10. FF&W Stations

11. Patrolling o \ 146

Appendix-D PROJEq DETAILS " i

SATLA BAGDA PROJECT, I ( POLDER 1,2 & 3 ) ------f----I'~------, 1. Location Ga:"ranadi,Agail,jhara and Uzirpur UZ of Badsal dil"t. B~naripara & Nazirpur UZ of Pirojpur dist. and Tongipara, & Kotalipara UZ of Gopalganj dist.

2. River Protect From SatIa, .Jhan,jhania,Harta & Uzirpur

3. Critical Flood Type Tidal ,Monsoon

4. Region SC

5. Purpose FCDI

6. Status Completed Project Starting Date 1983-84 (1977) Project Completion Date 1986-87 (1980)

7. Main Feature Gross Project Area 29,218.62 ha Net Project Area 21,448.57 ha Embankment 120.75 km Drainage Regulator 12 No Drainage Channel 217.35 km Closure . 29 No Irrig.lnlet Structure 450 No

8. Embankment Section Crest Height (3.4) m Detials Crest Width 4.88(:1.6) m CIS Slope 1:2 RIS Slope 1:3 Freeboard 0.9 m Berm Design Flood R. I 1:20 yr

9. Embankment Failure Modes Erosion 1987 Since Completion Breach 1987,1988 Overtopping 1987 Public Cut 1987 Protection Works 1987,1988 Resectioning of Embkt. 1987,1988 Reti red Embkt. 1988

10. FF&W Stations

11. Patrolling No organised patrolling

------Note: The figure in parenthesis are applicable for Polder No.3

c , , :, 't' 141

Appendix-D

PROJECT DETAILS

CHENCHURI AND OTHER BEEL PROJECT

1. Location Narail and Jessore district.

2. River Protect From Chitra, Nabaganga,O. Nabaganga

3. Critical Flood Type Coastal Flooding,Monsoon Flooding &Local Rainfall

4. Region SW

t: 5. Purpose FCDI

6. Status Completed Project Starting Date Prc',jeclCompletion.; Date 1987 7. Main Feature Gross Project Area 26,900 ha Cult ivab Ie Area 19,000 ha Embankment 93 km Drainage Regulator 5 No Drainage Channel 14 km

8. Embankment Section Crest Height 2.0 m Detials Crest Width 4.3 m CIS Slope 1:2 RIS Slope 1:3 Freeboard 0.9 m Berm Design Flood H.I .:.., '''~ 9. Embankment Failure Modes Erosion 1985,1987,1988 Since Completion Breach 1985-1987 Overtopping 1984,1987 Public Cut 1988 Protection Works Resectioning of Embkt. 1988 Retired Embkt.

10. FF&W Stations Gorai Railway Bridge, Hardinge Bridge

11. Patrolling No regular patrolling system