HYDROGEOLOGY OF PART OF

SOUTH-EASTERN BANGLADESH

A Thesis

submitted for the Degree

of

Doctor of Philosophy

by

S. M. MAHABUB-UL-ALAM

DEPARTMENT OF GEOLOGICAL SCIENCES

UNIVERSITY COLLEGE LONDON

1990. ProQuest Number: 10797677

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ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106- 1346 TO MY MOTHER

AND

TO THE MEMORY OF MY FATHER ABSTRACT

The present study covers 10,223 km2 of the Ganges, Jamuna and Meghna river’s delta, at the head of the Bay of Bengal, which was deposited in a geosynclinal environment. The morphometry of the delta was controlled by three geomorphological units, recognised as geological formations. The main aquifer comprises primarily the sandy Dupitila Formation, of Pliocene age, which is composed of unconsolidated sands showing a gradation of grain size. Finer sands are at the top with the sequence coarsening downwards; the coarse sand at the bottom is usually associated with gravels and pebbles. The thickness of the aquifer ranges from 30 m to 120 m. The aquifer is almost entirely covered by a clay/silt aquiclude of thickness ranging from <3 m to >300 m. The loss of ground water storage during the dry season is restored rapidly and regularly by the rising water table reflecting monsoon conditions. The complicated flow behaviour suggests that all the perennial rivers maintain direct hydraulic continuity with the ground water. The flow-net analysis also reveals uniform distribution of water resource potential. Borehole pumping tests indicate a true confined condition for the smaller eastern part while leaky confined conditions prevail elsewhere. The maximum and minimum transmissivity range from >1400 m2/d to <400 m2/d while the storativity ranges from 4.1 x 10'3 to 3.7 x 10-4 and the maximum leakage (BL = 368 m) is recorded around Burichong. The values of well loss factor (C,) and aquifer loss factor (Bt) suggest highly efficient well conditions as deduced from the calculation of well efficiency and the analysis of yield-drawdown curves. The ground water towards the outcrop appears to have been an essentially NaHC03 type in nature but, as it moves, hydrochemical evolution modifies the ground water into a mixed NaHCOj/Cl type. Three major and two minor ion exchange fields were identified. The expanded Durov plot was most successful in identifying the existence of two different types of water, the dominant type being the ion-exchanged water and the less dominant but equally well defined type being old brackish water accompanied by some reverse ion exchange water. The existence of reverse ion exchange water is further suggested by the changing chemistry along flow (flow line 2 and 3). The brackish waters are segregated in few locations and are not linked to one another. Other than the brackish water, the ground water is found to be suitable both as potable as well as irrigation sources. The saturation indices calculated by means of the PHREEQE hydro-chemical model for Calcite and Dolomite establishes a unique linear relationship emphasising that the older and deeper waters are mainly super-saturated and the young waters are under-saturated with respect to these minerals, with few exceptions. The water balance computation and the present rate of withdrawal indicates a huge recharge surplus so that the aquifer may be regarded as in a youthful state of development. The perennial yield is estimated to be about 5.7 x 109 m3/year and the present rate of ground water withdrawal is about 37 percent of the perennial yield, suggesting a huge ground water potential yet to be exploited. CONTENTS

Page

CONTENTS...... i

LIST OF FIGURES...... vii

LIST OF TABLES......

LIST OF APPENDICES...... xix

CHAPTER 1 INTRODUCTION

1.1 Purpose and Scope...... 2

1.2 Acknowledgements...... 3

1.3 Size and Location of the Study Area...... 4

1.4 Physiography and Topography...... 4

1.5 Soil Type and Characteristics...... 7

1.5.1 Flood Plain Soils...... 8

1.5.2 Piedmont Soils...... 8

1.5.3 Hill Soils...... 9

1.6 Climatic Conditions...... 10

1.7 Vegetation and Land Use...... 13

-1 . 8-River -System.-— v-;-.-. . r-i-r-r--.--; ...... ^ ; ...... 14

1.9 Well Numbering System...... 16

1.10 Previous Studies...... 18 CHAPTER 2 GE0M0RPH0L06Y AND GEOLOGY

Page 2.1 Introduction...... 21

2.2 Major Geomorphic Units...... 22

2.2.1 Lalmai Deltaic Plain...... 28

2.2.2 Chandina Deltaic Plain...... 30

2.2.3 Meghna Flood Plain...... 31

2.3 Regional Geology...... 31

2.4 Surface Geology and Stratigraphy...... 32

2.4.1 Dupitila Formation...... 33

2.4.2 Madhupur Clay Formation...... 35

2.4.3 Chandina Formation...... 35

2.4.4 Flood Plain Deposits...... 36

2 . 5 Geologic Cross-Sections...... 36

2.6 Major Structural Trends...... 48

CHAPTER 3 HYDROGEOLOGY

3.1 Historical Development of Wells...... 52

3.2 Aquifer System and Classification...... 54

3.3 Main-Aquifer: . . . .-...... 59

3.3.1 Upper Semi-Confining Layer...... 59

3.3.2 Physical Characteristics and Extent...... 61

3.3.3 Aquifer Thickness...... 62

3.3.4 Aquifer Nature...... 65

3 . 4 Deep Aquifers...... 64

ii I

CHAPTER 4 GROUND WATER FLOW

Page 4.1 Water Level Monitoring System...... 69

4.2 Water Level Data Used...... 70

4.3 Ground Water Level Fluctuation...... 71

4.4 Water Table Contour Maps...... 75

4.4.1 Introduction...... 75

4.4.2 Minimum Elevation Contour Map...... 7 6

4.4.3 Maximum Elevation Contour Map...... 82

4.4.4 Annual Fluctuation Map...... 8 6

4 .5 Replenishment Calculation...... 88

4.6 Comments on Ground Water Movement

and Flow Pattern...... 91

CHAPTER 5 AQUIFER TEST ANALYSIS

5.1 Introduction...... 94

5.1.1 General Information...... 94

5.1.2 Well Structure...... 96

-•-5. Ir3 Hydraulic Properties...... 98

5 .2 Analytical Solution...... 100

5.2.1 Validity of Measurement...... 100

5.2.2 Selection of Methods...... 102

5.2.3 Presentation and

Discussion of Analysis...... 108

iii Page 5.3 Numerical Solution...... 182

5.3.1 Radial Flow Model...... 182

5.3.2 Presentation of Analysis...... 188

5.3.3 Discussion in Results...... 198

5.4 Comparison of the Results...... 202

5.4.1 Comparison of Individual Sites...... 202

5.4.2 Overall Comparison...... 202

CHAPTER 6 WELL PERFORMANCE

6.1 Step-Drawdown Tests...... 218

6.1.1 General...... 218

6.1.2 Standard Procedures...... 219

6.1.3 Test Procedures Used...... 220

6.2 Analysis of Step-Drawdown Tests...... 223

6.2.1 Method Used...... 224

6.2.2 Presentation of Analyses...... 226

6.2.3 Comments on the Results...... 254

6.3 Well Efficiency...... 257

6.4 Specific Capacity...... 262

CHAPTER 7 HYDROCHEMISTRY

7.1 Collation of Existing Chemical Analytical Data 267

7.2 Field Collection of Ground Water Samples...... 268

7.3 Chemical Analysis of Ground Water Samples...... 270

iv Page 7.4 Quality of Analytical Data...... 271

7.5 Graphical Interpretation...... 27 9

7.5.1 Distribution Maps...... 27 9

a) Introduction...... 27 9

b) TDS Distribution Map...... 280

c) Sodium/ Cation Ratios...... 282

7.5.2 Stiff Pattern Diagram...... 285

7.5.3 Trilinear Diagram...... 287

7.5.4 Chemistry Along Flow Lines...... 287

7.5.5 Expanded Durov Classification...... 292

7.6 Application of PHREEQE Hydrochemical Model...... 294

7.6.1 Introduction...... 294

7.6.2 PHREEQE Model...... 296

7.7 Groundwater Quality...... 302

7.7.1 Drinking Water Quality...... 302

7.7.2 Irrigation Water Quality...... 306

CHAPTER 8 GROUND WATER RESOURCES

8.1 Introduction . . . . . ; . t . 312

8.2 Assessment of Resources...... 312

8.2.1 Introduction...... 312

8.2.2 Ground Water Replenishment (Inputs)...... 312

a) Infiltration from Precipitation...... 314

b) Irrigation Return Flow...... 315

v Page c) Influent Seepage of Surface Flow...... 317

d) Influent Seepage of Sewage Water...... 32 9

e) Leakage from Contiguous Strata...... 323

f) Subsurface Inflow through

Aquifer Boundaries...... 324

8.2.3 Ground Water Discharge (Outputs)...... 326

a) Evapotranspiration...... 314

b) Effluent Flow to Rivers,

Canals and other Water Bodies...... 337

c) Leakage into Contiguous Strata...... 341

d) Subsurface Outflow through

Aquifer Boundaries...... 342

e) Artificial Withdrawal by Pumping...... 342

8.2.4 Ground Water Budget...... 345

8.3 Ground Water Management...... 34 9

8.3.1 Introduction...... 349

8.3.2 Development Status of Resources...... 350

8.3.3 Perennial Yield...... 350

8.3.4 Ground Water in Storage...... 352

- CHAPTER 9 CONCLUSIONS AND RECOMMENDATIONS

9.1 Conclusions...... 354

9.2 Recommendations...... 359

REFERENCES...... 364

APPENDICES...... 369

vi LIST OF FIGURES.

Fig. Page

1.1 Location of study area in Bangladesh...... 5

1.2 Map showing the distribution of major physiographic sub-division (After: Pitman, 1985).... 6

1.3 Isohyetal map on the basis of long-term annual rainfall (1951-1985)...... 12

1.4 Distribution of major primary and secondary rivers in the study area...... 15

2.1 Location of study area in tectonic map of Bangladesh...... 22

2.2 Estimated thickness contours of sediments in the Bengal Basin (Source: Mirkhamidov and Mannan, 1986)...... 23

2.3 Geological cross-section along selected lines across the Bengal Basin (After: Pitman, 1985)..... 24

2.4 Generalized geology of Bangladesh and adjoining areas (Sources: Holtrop and Keizer, 1970; Alam, 1985; Jones, 1985)...... 26

2.5 Depth to Basement in Bangladesh (Source: Aeromagnetic survey, O.D.A., 1980; Jones, 1985).... 27

2.6 Geology of the study area (After: Bakr, 1976)..... 29

2.7 Distribution of the identifiable lithological well logs...... 34

2.8 Correlation of lithological units along the line 'A-B'...... 39

2.9 Correlation of lithological units along the line 'B-C'...... 40

2.10 Correlation of lithological units along the line 'C-D'...... 42

2.11 Correlation of lithological units along the line 'E-B'...... 44

vii Fig. Page

2.12 Correlation of lithological units along the line 'F-G'...... 46

2.13 Distribution of major structural trends (Compiled from Bakr, 197 6 and Mcdonald and Partners, 1986)...... 49

3.1 Geological cross-section along 'A-B' line showing the distribution of both the main aquifer and the deeper aquifers of Bangladesh (After: Jones, 1985).. 55

3.2 Geological cross-section along 'C-D' line showing the distribution of both the main aquifer and the deeper aquifers of Bangladesh (After: Jones, 1985).. 56

3.3 Idealized W-E cross-sectional view of the main aquifer across the Lalmai Hills showing the recharge pattern...... 58

3.4 Thickness distribution of the surfacial clay/silt (aquiclude) layers...... 60

3.5 Thickness distribution map of the main aquifer..... 63

4.1 Groundwater level fluctuation...... 72

4.2 Water table contour map of minimum elevation (dry period) March 1985...... 77

4.3 Major flow direction based on minimum elevation contour map 7 9

4.4 Water table contour map of maximum elevation (wet period) August 1985...... 83

4.5 Major flow direction based on maximum elevation contour map...... 84

4.6 Contour map showing annual fluctuation for 1985.... 87

5.1 Map showing the location of aquifer testing wells... 95

5.2 Generalised structure of the constructed wells.... 97

5.3.A Aquifer test analysis for OW1 at Feni; (a) Type Curve and (b) Straight Line...... Ill

viii Fig. Page

5.3.B Aquifer test analysis for 0W2 at Feni; (a) Type Curve and (b) Straight Line...... 113

5.3.C Aquifer test analysis for 0W3 at Feni; (a) Type Curve and (b) Straight Line...... 115

5.3.D Aquifer test analysis for Feni; (a) Type Curve and (b) Straight Line...... 117

5.4.A Aquifer test analysis for 0W1 at Nabinagar; (a) Type Curve and (b) Straight Line...... 121

5.4.B Aquifer test analysis for 0W2 at Nabinagar; (a) Type Curve and (b) Straight Line...... 123

5.4.C Aquifer test analysis for 0W3 at Nabinagar; (a) Type Curve and (b) Straight Line...... 125

5.4.D Aquifer test analysis for Nabinagar; (a) Type Curve and (b) Straight Line...... 128

5.5.A Aquifer test analysis for 0W1 at B'Baria; (a) Type Curve and (b) Straight Line...... 132

5.5.B Aquifer test analysis for 0W2 at B'Baria; (a) Type Curve and (b) Straight Line...... 133

5.5.C Aquifer test analysis for 0W3 at B'Baria; (a) Type Curve and (b) Straight Line...... 134

5.6.A Aquifer test analysis for 0W1 at Daudkandi; (a) Type Curve and (b) Straight Line...... 138

5.6.B Aquifer test analysis for 0W2 at Daudkandi; (a) Type Curve and (b) Straight Line...... 139

5.6.C Aquifer test analysis for 0W3 at Daudkandi; (a) Type Curve and (b) Straight Line...... 140

5.7.A Aquifer test analysis for OW1 at Burichong; (a) Type Curve and (b) Straight Line...... 144

5.7.B Aquifer test analysis for OW2 at Burichong; (a) Type Curve and (b) Straight Line...... 145

5.7.C Aquifer test analysis for OW3 at Burichong; (a) Type Curve and (b) Straight Line...... 14 6

ix Fig. Page

5.8.A Aquifer test analysis for 0W1 at Chandina; (a) Type Curve and (b) Straight Line...... 14 9

5.8.B Aquifer test analysis for 0W2 at Chandina; (a) Type Curve and (b) Straight Line...... 150

5.8.Cl Aquifer test analysis for OW3 at Chandina; (a) Type Curve and (b) Straight Line...... 151

5.8.C2 Aquifer test analysis for OW3 at Chandina; (a) Type Curve and (b) Straight Line...... 152

5.9.A Aquifer test analysis for OW1 at Kotwali; (a) Type Curve and (b) Straight Line...... 156

5.9.B Aquifer test analysis for OW2 at Kotwali; (a) Type Curve and (b) Straight Line...... 157

5.9.C Aquifer test analysis for OW3 at Kotwali; (a) Type Curve and (b) Straight Line...... 158

5.10.A Aquifer test analysis for OW1 at Barura; (a) Type Curve and (b) Straight Line...... 161

5.10.B Aquifer test analysis for OW2 at Barura; (a) Type Curve and (b) Straight Line...... 162

5.10.C Aquifer test analysis for OW3 at Barura; (a) Type Curve and (b) Straight Line...... 163

5.11.A Aquifer test analysis for OW1 at Hazigang; (a) Type Curve and (b) Straight Line...... 167

5.11.B Aquifer test analysis for OW2 at Hazigang; (a) Type Curve and (b) Straight Line...... 168

5.11.C Aquifer test analysis for OW3 at Hazigang; (a) Type Curve and (b) Straight Line...... 169

5.12.A Aquifer test analysis for OW1 at Chauddagram; (a) Type Curve and (b) Straight Line...... 173

5.12.B Aquifer test analysis for OW2 at Chauddagram; (a) Type Curve and (b) Straight Line...... 174

5.12.C Aquifer test analysis for OW3 at Chauddagram; (a) Type Curve and (b) Straight Line...... 175

x Fig. Page

5.13.A Aquifer test analysis for 0W1 at Senbagh; (a) Type Curve and (b) Straight Line...... 178

5.13.B Aquifer test analysis for 0W2 at Senbagh; (a) Type Curve and (b) Straight Line...... 17 9

5.13.C Aquifer test analysis for 0W3 at Senbagh; (a) Type Curve and (b) Straight Line...... 180

5.14 Inflow due to leakage in a Confined aquifer...... 184

5.15(a) Basis of Numerical technique for radial flow model (Confined aquifer)...... 184

5.15(b) Discrete space - discrete time grid with radial distance increasing logarithmically (After: Rushton 1979)...... 184

5.16(a) Pictorial definition of drawdown Sf and Sb 187

5.16(b) Problems involving variable saturated depth. .. . 187

5.17.A Comparison of (a) Manual and (b) Model result from Feni OW1...... 191

5.17.B Comparison of (a) Manual and (B) Model result from Feni OW2...... 192

5.17.C Comparison of (a) Manual and (b) Model result from Feni OW3...... 193

5.18.A Comparison of (a) Manual and (b) Model result from Nabinagar OW1...... 194

5.18.B Comparison of (a) Manual and (b) Model result from Nabinagar OW2...... 195

5.18.C Comparison of (a) Manual and (b) Model result from Nabinagar OW3...... 196

5.19 Response of the simulation with different values of sensitive parameters...... 197

5.20 Distribution of transmissivity in the study area...... 216

6.1 Location map showing the step testing wells...... 221

xi Fig. Page

6.2 Step-drawdown test; Jacob solution for Devidwar well...... 228

6.3 Step-drawdown test; Jacob solution for Laksam well...... 229

6.4 Step-drawdown test; Jacob solution for Chandpur well...... 231

6.5 Specific drawdown vs. discharge plot for B'Baria well...... 233

6.6 Specific drawdown vs. discharge plot and yield- drawdown plot for Nabinagar well...... 234

6.7 Specific drawdown vs. discharge plot for Devidwar well...... 236

6.8 Specific drawdown vs. discharge plot for Burichong well...... 237

6.9 Specific drawdown vs. discharge plot and yield- drawdown plot for Chandina well...... 238

6.10 Specific drawdown vs. discharge plot for Kotwali well...... 240

6.11 Specific drawdown vs. discharge plot for Laksam well...... 242

6.12 Specific drawdown vs. discharge plot and yield- drawdown plot for Chandpur well...... 243

6.13 Step-drawdown test; Rorabaugh solution for Chandina well...... 245

6.14 Step-drawdown test; Rorabaugh solution for Chandpur well...... 247

6.15 Step-drawdown test; Rorabaugh solution for (a) Laksam well and (b) Nasirnagar well...... 249

6.16 Step-drawdown test; Eden and Hazel solution for Devidwar well...... 251

6.17 Step-drawdown test; Eden and Hazel solution for Laksam well...... 252

xii Fig. Page

6.18 Step-drawdown test; Eden and Hazel solution for Chandpur well...... 253

6.19 Yield-drawdown plot for all sites...... 260

6.20 Theoretical and actual plot of specific capacity vs. transmissivity forall tests...... 264

7.1 Map showing the quality welllocations ...... 269

7.2 Hydrochemical contour map of total dissolved solids (mg/L)...... 281

7.2(a) Modified contour map of total dissolved solids (TDS) in mg/L...... 283

7.3 Hydrochemical ratio distribution of sodium to total cations...... 284

7.4 Pattern distribution of major hydrochemical constituents...... 286

7.5 Piper diagram showing the hydrochemical distribution of ground water samples in terms of major ion percentages. Size of symbol is proportional to TDS (mg/L)...... 288

7.6 Map showing the selected flow lines from the Figure 4.5...... 289

7.7 Variation in ground water chemistry (arrow represent sequential directions of flow)...... 291

7.8 Classification of ground water types using the expanded Durov diagram: I, Ion exchanged waters; II, Old brackish water with some reverse ion exchange...... 293

7.9 Map showing the distribution of two water types. . . . 295

7.10 Plot showing the linear relationship between Calcite and Dolomite SI value...... 301

7.11 Plot showing the random distribution of Calcite and Siderite SI value...... 303

xiii Fig. Page

7.12 Plot showing the range of combined sodium and salinity hazard for classification of irrigation water quality...... 308

8.1 Hydrograph showing the base-flow and surface run-off component...... 319

8.2 Hydrograph showing the base-flow and surface run-off component...... 320

8.3 Hydrograph showing the base-flow and surface run-off component...... 321

8.4 Hydrograph showing the base-flow and surface run-off component...... 322

8.5 Map showing the subsurface peripheral inflow and outflow zones...... 325

8.6 Hydrograph showing the base-flow and surface run-off component...... 339

8.7 Hydrograph showing the base-flow and surface run-off component...... 340

xiv LIST OF TABLES

Table Page

1.1 Measured rate of infiltration through various types of clay...... 11

2.1 Geological succession and aquifer potential...... 37

4.1 Comparison of hydraulic gradient in the two seasons...... 81

4.2 Volumetric changes covering the entire region.... 8 9

5.1 Pumping test analysis results (analytical) of FeniWell; (a) Time-Drawdown and (b) Distance-Drawdown...... 110

5.2 Pumping test analysis results (analytical) of Nabinagar Well; (a) Time-Drawdown and (b) Distance-Drawdown...... 119

5.3 Pumping test analysis results (analytical) of B'Baria Well; (a) Time-Drawdown and (b) Distance-Drawdown...... 131

5.4 Pumping test analysis results (analytical) of Daudkandi Well; (a) Time-Drawdown and (b) Distance-Drawdown...... 137

5.5 Pumping test analysis results (analytical) of Burichong Well; (a) Time-Drawdown and (b) Distance-Drawdown...... 142

5.6 Pumping test analysis results (analytical) of Chandina Well; (a) Time-Drawdown and (b) Distance-Drawdown...... 148

5.7 Pumping test analysis results (analytical) of Kotwali Well; (a) Time-Drawdown and (b) Distance-Drawdown...... 155

5.8 Pumping test analysis results (analytical) of Barura Well; (a) Time-Drawdown and (b) Distance-Drawdown...... 160

xv Table Page

5.9 Pumping test analysis results (analytical) of Haziganj Well; (a) Time-Drawdown and (b) Distance-Drawdown...... 166

5.10 Pumping test analysis results (analytical) of Chauddagram Well; (a) Time-Drawdown and (b) Distance-Drawdown...... 171

5.11 Pumping test analysis results (analytical) of Senbagh Well; (a) Time-Drawdown and (b) Distance-Drawdown...... 177

5.12 Aquifer test results of Feni Well; (a) Numerical results and (b) Overall comparison of results obtained by all the methods...... 203

5.13 Aquifer test results of Nabinagar Well; (a) Numerical results and (b) Overall comparison of results obtained by all the methods...... 204

5.14 Aquifer test results of B'Baria Well; (a) Numerical results and (b) Overall comparison of results obtained by all the methods...... 205

5.15 Aquifer test results of Daudkandi Well; (a) Numerical results and (b) Overall comparison of results obtained by all.the methods...... 206

5.16 Aquifer test results of Burichong Well; (a) Numerical results and (b) Overall comparison of results obtained by all.the methods...... 207

5.17 Aquifer test results of Chandina Well; (a) Numerical results and (b) Overall comparison of results obtained by all.the methods...... 208

5.18 Aquifer test results of Kotwali Well; (a) Numerical results and (b) Overall comparison of results obtained by all.the methods...... 209

5.19 Aquifer test results of Barura Well; (a) Numerical results and (b) Overall comparison of results obtained by all.the methods...... 210

5.20 Aquifer test results of Haziganj Well; (a) Numerical results and (b) Overall comparison of results obtained by a'll the methods...... 211

xvi Table Page

5.21 Aquifer test results of Chauddagram Well; (a) Numerical results and (b) Overall comparison of results obtained by all the methods...... 212

5.22 Aquifer test results of Senbagh Well; (a) Numerical results and (b) Overall comparison of results obtained by all the methods...... 213

6.1 Comparison of step-drawdown test results...... 255

6.2 Verification of Lennox (1966) conditions for obtaining good results...... 258

6.3 Quantitative assessment of well efficiency factor...... 261

6.4 Specific capacity data at 100 minutes and 1000 minutes for all the pumping wells...... 265

7.1 Results of chemical analysis of ground water in the Comilla-Noakhali region (1976-1987)...... 272

7.1(a) Summary of ionic-balance and comparison of TDS...... 275

7.2 A modified form of the Phreeqe model calculated result output for well: 144...... 297

7.3 Summary of saturation indices of certain mineral matrix...... 299

7.4 Comparative tabulation of potable water quality in terms of various ions with selected international standards...... 304

7.5 Comparative study of the irrigation water quality in terms of various types of hazards...... 310

8.1 Sub-surface Inflow of ground water along various Zones across the boundary...... 327

8.2 Separation of various soil moisture components using the Grindley model (1969)...... 331

8.3 Estimated crop coefficient (Kcrop) for various kinds of rice in Comilla-Noakhali region...... 334

8.4 Separation of various soil moisture components using the Agnew model (1982)...... 335

xvii Table Page

8.5 Subsurface Outflow of ground water along various Zones across the boundary...... 343

8.6 First ground water budget using the I. value calculated by the Grindley (1969) and Agnew (1982) model...... 347

8.7 Second ground water budget using the I. value calculated from the ground water fluctuation contour map...... 348

xviii LIST OF APPENDICES

Appendix Page

4.1 Seasonal water level measurements used to draw various types of contour maps...... 370

5.1 Pump test data for all test sites...... 374

5.2.1 Rushton numerical (Radial Flow) model...... 384

5.2.2 Model data plotting program...... 388

5.2.3 Program to draw Time Drawdown Type Curve plot...... 291

5.2.4 Program to draw Time Drawdown Straight Line plot...... 392

5.3.1.A Comparison of (a) Manual (b) Model results from B'Baria OW1...... 394

5.3.1.B Comparison of (a) Manual (b) Model results from B'Baria OW2...... 395

5.3.1.C Comparison of (a) Manual (b) Model results from B'Baria OW3...... 396

5.3.2.A Comparison of (a) Manual (b) Model results from Daudkandi OW1...... 397

5.3.2.B Comparison of (a) Manual (b) Model results from Daudkandi OW2...... 398

5.3.2.C Comparison of (a) Manual (b) Model results from Daudkandi OW3...... 399

5.3.3.A Comparison of (a) Manual (b) Model results from Burichong OW1...... 400

5.3.3.B Comparison of (a) Manual (b) Model results from Burichong OW2...... 401

5.3.3.C Comparison of (a) Manual (b) Model results from Burichong OW3...... 402

5.3.4.A Comparison of (a) Manual (b) Model results from Chandina OW1...... 403

xix Appendix Page

5.3.4.B Comparison of (a) Manual (b) Model results from Chandina 0W2...... 404

5.3.4.Cl Comparison of (a) Manual (b) Model results from Chandina OW3...... 405

5.3.4.C2 Comparison of (a) Manual (b) Model results from Chandina OW3...... 406

5.3.5.A Comparison of (a) Manual (b) Model results from Kotwali OW1...... 407

5.3.5.B Comparison of (a) Manual (b) Model results from Kotwali OW2...... 408

5.3.5.C Comparison of (a) Manual (b) Model results from Kotwali OW3...... 40 9

5.3.6.A Comparison of (a) Manual (b) Model results from Barura OW1...... 410

5.3.6.B Comparison of (a) Manual (b) Model results from Barura OW2...... 411

5.3.6.C Comparison of (a) Manual (b) Model results from Barura OW3...... 412

5.3.7.A Comparison of (a) Manual (b) Model results from Haziganj OW1...... 413

5.3.7.B Comparison of (a) Manual (b) Model results from Haziganj OW2...... 414

5.3.7.C Comparison of (a) Manual (b) Model results from Haziganj OW3...... 415

5.3.8.A Comparison of (a) Manual (b) Model results from Chauddagram OW1...... 416

5.3.8.B Comparison of (a) Manual (b) Model results from Chauddagram OW2...... 417

5.3.8.C Comparison of (a) Manual (b) Model results from Chauddagram OW3...... 418

5.3.9.A Comparison of (a) Manual (b) Model results from Senbagh OW1...... 419

\ xx Appendix Page

5.3.9.B Comparison of (a) Manual (b) Model results from Senbagh 0W2...... 420

5.3.9.C Comparison of (a) Manual (b) Model results from Senbagh OW3...... 421

6.1 Program to analyze step-drawdown tests (Eden and Hazel method)...... 422

7.1 Program to plot trilinear diagram...... 424

7.2.1 (a) Plot showing constituents of ground water samples in terms of major ion percentages, (b) Piper-Hill (1944) sub-division for classification of ground water types...... 427

7.2.2 (a) Plot of the constituents of ground water samples in terms of major ion percentages, (b) Back's (1961, 1966) classification diagram for anion and cation facies...... 428

8.1 Program to draw river discharge hydrograph...... 42 9

8.2 Program to separate base-flow from hydrograph...... 430

xxi CHAPTER 1 INTRODUCTION

1.1 Purpose and Scope.

1.2 Acknowledgements.

1.3 Size and Location of the Project Area.

1.4 Physiography and Topography.

1.5 Soil Type and Characteristics.

1.6 Climatic Conditions.

1.7 Vegetation and Land Use.

1.8 River System.

1.9 Well Numbering System.

1.10 Previous Studies. 1.1 Purpose and Scope:

The south-eastern part (Comilla-Noakhali region) of Bangladesh includes some of the best agricultural land in the country which produces significant amounts of crops thereby playing a vital role in alleviating part of the serious food shortages of the nation. Although there is too much water in Bangladesh during summer time

(May-October), which occasionally causes floods, being an area that enjoys tropical monsoonal climatic conditions, it also suffers serious shortages of surface water during the winter period (November-April). This is because of prolonged dry conditions when normal rainfall virtually ceases and surface-water flow dramatically reduces to its lowest level. At that time the ground water resource is the only alternative source of irrigation water to ensure normal crop production. As a result, huge amounts of ground water are withdrawn seasonally from underground storage.

Another important cause of concern is the occurrence of poor quality and saline ground water in several locations which poses a serious threat to the quality of the existing ground water resources. All these background problems have encouraged the author to carry out a detailed hydrogeological study using the latest

available conventional and selected numerical techniques to extract as much

information as possible. The purpose of the study is to evaluate the present state

of ground water potential of these finite resources, to devise a possible solution as

to how they can best be utilized for irrigation, and to maximise their potability

without disturbing the ecological balance. More importantly, there is a need to

understand the extent of occurrence and the pattern of distribution of the existing

saline ground water problem within the study area.

The entire research work is based on, firstly, the collection of pre­

existing hydrogeological data, and secondly, on subsequent field sampling done

during two seasonal visits to the project area.

2 1.2 Acknowledgements:

The author extends his particular gratitude to his supervisor Mr. Glyn

P. Jones for excellent hydrogeological tuition and expresses sincere thanks for his guidance, patient explanation of the more difficult concepts, and above all for spending valuable time correcting the manuscript.

The author also expresses his gratitude to Dr. G. T. K. Pitman, the former World Bank adviser for the Bangladesh National Water Planning Project, for his encouragement to take up a Bangladeshi project and more importantly for playing the key role in supplying the existing relevant data.

Special and heartful thanks are due to Mrs. Susan White for her whole­ hearted co-operation from the very beginning of the M.Sc./Diploma course in all respects, particularly her skilful computing lessons which have played a vital role during the computer analysis of most of the data.

Sincere thanks are due to Dr. J. M. McArthur for discussions of the hydrochemical data analysis. Thanks and acknowledgements are also extended to

Dr. Thabit Madhi-Bashi, one of author’s colleagues for his helpful computing assistance.

The Association of Commonwealth Universities are owed extra special

thanks for selecting the author as one of their Commonwealth Scholars in the first place, and their subsequent financial support.

The co-operation of all fellow research workers is greatly appreciated, particularly that of Mr. Masoud Al-Ahmadi for use of the hydrochemical Phreeqe model.

All academic and departmental staff who extended their support deserve

special thanks, particularly, A. T. Osbom, for his assistance during the chemical

analysis of water samples and Janet Baker and Colin Stuart for their help during

the preparation of some of the drawings.

3 Finally, the author acknowledges with great pleasure, the support and encouragement that he has received from his wife, Mrs. Rukhsana Mahabub, when it was most needed.

1.3 Size and Location of the Study Area:

The present study includes the former Greater Comilla and Noakhali districts, excluding the off-shore islands, and occupies an area of some 10,223 sq. km. (about 3942 sq. ml.). It is of elongate shape and lies between Latitudes 22°

45’ and 24° 16’ N and Longitudes 90° 30’ and 91° 34’ E. To the east the area shares a common boundary with the Tripura States of India; to the west, south-west and north-west it is bounded by the Meghna river; to the north by the Madhabpur upazilla of Sylhet district, and finally to the south by the joint Meghna and Feni estuary that leads to the Bay of Bengal (see Fig. 1.1). The area is separated from the capital city of Dhaka by the Meghna river. The shortest distance between Dhaka and the study area (Daudkandi) is about 35 miles (60 km) and is linked to the capital by both road transport and rail.

1.4 Physiography and Topography:

The study area constitutes the south-eastern part of the alluvial Bengal deltaic plain, the largest in the world. The major sections of this part of the delta are formed of relatively older deltaic sediments which have developed a coastal plain along the western and south-western margins. The sequential distribution of various parts of the delta from the point of view of surface configuration, its relative position and as well as its genetic variability are so well developed that it has been divided into a number of physiographic units (Fig. 1.2) as follows:

Madhupur tracts (1), Noakhali-Chittagong Coastal Plain (2), Old Meghna Estuarine

Flood Plain (3), Middle Meghna Estuarine Flood Plain (4) and Young Meghna

4 un o

CD

Ll J CO Q. o in LEGEND

International boundary

Major physiographic sub-division 1, 2, 3, 4, 5

12 Mil I

li n KM

( % i

^ 5 ESTUARINE

B T1 „ ^ FLOOD P L A I N 5

BAY OF B E N G A L

90*)d

Fig. 1.2: Map showing the distribution of major physiographic sub-divisions (after: Pitman, 1985). Estuarine Flood Plain (5). Of these sub-divisions, the various flood plain units make up about 85 percent of the total land surface.

Physiographically, the area is bounded on the east by the Tertiary rocks of the Tripura Hills of India and by a part of their northern continuation into

Bangladesh, the Raghunandan Hills; On the west the Meghna river forms the natural boundary; which to the north is formed by the hills and plain of Sylhet basin, and on the south jointly by the Meghna and Feni estuaries leading to the Bay of

Bengal. From the eastern Hills, the area gently slopes in all other directions. The land is low-lying with elevations of the surface ranging from 25 ft (<8 m) above msl in the east to around 5 ft (<2 m) above msl in the south-west. The morphometry is greatly influenced by the mighty Mehgna river which defines the present arcuate shape of the area.

The Lalmai Hills are the only relic of previous geological activity that emerges like an island in the dissected tract of the alluvial plain. It is located 5-

10 miles west of Comilla town and is approximately 12 miles long with a north- south elongation. They are also called the ’red hills’ because of the highly oxidized surface soil cover and lateritic nature which is thought to be of Pliocene to

Pleistocene age. The Lalmai Hills have a flat top which gently slopes in the east but forms a scarp in the west.

1.5 Soil Type and Characteristics:

The vast majority of the soils have developed on a flood plain background and have been classified previously by various authors (Pacheco, 1970;

Islam, 1973) on the basis of physiographic units taking into account the dominant composition material, texture and degree of induration. A different approach has been adopted in the present study to classify soil types as adequate for our purposes. All the soils developed on different flood plains which were previously

7 identified as belonging to different series have been grouped together under the general name ’Flood Plain Soils’ since they consist of almost similar materials. The soils developed on the ’Lalmai Hills’ and the adjacent ’Piedmont plain’ are also easily separable. The different series recognized previously for the Lalmai Hills area are grouped as ’Hill Soils’ and the various series recognized in parts of

Piedmont Plain are collectively called as ’Piedmont Soils’. Brief descriptions of these three different groups of soil are presented below.

1.5.1 Flood Plain Soils:

The various flood plain deposits (Old Meghna Estuarine Flood Plain,

Middle Meghna Flood Plain, Young Meghna Estuarine Flood Plain and Noakhali-

Chittagong Coastal Plain) are characteristically developed on similar types of gently undulating topography consisting of broad flood plain ridges and shallow basins.

Most ’ridge soils’ are silty loams with some clay; they are predominantly light grey to very pale brown in colour and are comparatively more friable than the basin soils. Basin soils, on the other hand, are mostly clayey loam in texture with some silty loam, and range in colour from olive to dark grey to pale brown. At the basin edges the colour grades to greyish-brown. Both ridge and basin soils:

a) in most places have developed two-layer characteristics. The top layer is neutral in reaction when flooded but mainly becomes acidic when dry. The lower layer is mainly neutral to moderately alkaline in reaction;

b) show varying degree of mottling of yellow and brown colour; and

c) are richer in plant nutrients in comparison with hill soils and piedmont soils; therefore the flood plain soils have higher potential for cultivation.

1.5.2 Piedmont Soils:

The Old Piedmont soils have developed as narrow belts both along the

8 piedmont plain associated with the eastern foot hills distributed along the common

India-Bangladesh border and also along the base of the Lalmai Hills. The soil consists of unconsolidated silty clays and loams of yellowish-brown colour. In the better drained areas, the soils are almost entirely composed of red and yellow clay.

The more recent piedmont soils have developed in the depressed Comilla basin located in between the Lalmai Hills and the Eastern border hills. These soils originated on outwash material. On gently sloping areas they takes the form of pale brown clay; on flat areas grey silty-clay to clay and in the centre of depression the soils are dark grey clays.

1.5.3 Hill Soils:

The soils which have emerged particularly on the top and along the slopes of Lalmai Hills are described using the term ’Hill soils’. The hills have a flat top and steep sided gullies. Dark-red clay soils have developed on the flat summit of the Lalmai Hills. Along the slopes the soil grades to a mixed red-brown and brown clay loam and yellow-brown sandy loam. In the depression of the

Lalmai Hills the soil consists of alternate layers of pale brown sandy clay, clay and loam. These hill soils are strongly acidic, low in plant nutrients and suffer from drought in the dry season.

All three types of soils:

1) are subject to heavy rainfall; the flood plain usually becomes flooded both by rain water and flood water, the piedmont soil usually is flooded only by rain water, and the hill soil never becomes flooded;

2) appear to be rich in weatherable minerals.

The infiltration rates through the different types of soil materials have been measured by McDonald and Partners, 1985 (Table 1.1).

9 Table. 1.1: Measured rate of infiltration through various types of clays.

Soil texture Infiltration rate (m/d)

Dry Moist

1) fine sandy loam 0.48 - 2.40 0.048 - 0.249 2) silty loam 0.48 - 2.40 0.048 - 0.192 3) loam 0.48 - 2.40 0.396 4) silty clay loam 0.48 - 2.40 * 0.048 - 0.120 5) clay loam 0.48 - 2.40 * 0.084 6) silty loam 1.80 * 0.048 - 0.072 7) Basin clay 0.84 - 1.92 * 0.024 - 0.072

* increased rate due to soil cracking

The infiltration rate ranges from 24 to 192 mm/day. The soil storage co-efficient within the study area ranges from 5 to 6 percent but in the root zone this increases up to 25 percent.

1.6 Climatic conditions:

The entire Bengal deltaic plain enjoys a tropical monsoonal climatic condition, and the study area is no exception. It is characterized by moderate to high temperature, heavy rainfall, seasonally dry conditions and marked changes in each at different times of the climatic cycle. The year-round changes in the climatic pattern are marked by two primary and two secondary transitional seasons. The primary monsoon (or rainy) season is followed by the secondary post-monsoon transition season and again the primary winter (or dry) season is followed by the secondary pre-monsoon transition season.

The Monsoon, the longest of all the seasons, extends from May through September. During this period, the area receives more than 80 percent of its total annual rainfall. The Monsoon rain is not stormy but frequent, heavy and uneven and very often continues for a long time, usually from a couple of days to several days. The longer and heavy rainfall is frequently associated with floods.

10 High temperatures and high humidity levels prevail throughout this season.

The Winter begins in November and continues until the beginning of

March, and is characterized by long dry sunny spells associated with cool northerly breezes. This period is almost rainless except for some very light scattered showers which seldom exceed 5 percent of the total annual rainfall. During this time of the year humidity falls to its lowest value and the temperature remains at a pleasant level.

The Pre-monsoon transition season, March-May, is unpleasantly very hot and characterized by thunder-storms and squalls, called ’Nor’westers’, with heavy localized rainfall and hail. Both the temperature and humidity levels rise to their annual maximum levels.

The Pre-winter (Post-monsoon) transition season covers the period between late September and early November which is moderately warm and humid.

The temperature and humidity levels gradually decline and the season is marked by unstable atmospheric condition. During this time of the year, rapid changes in climatic conditions takes place with decreasing rainfall. The changing climatic conditions during pre-monsoon and pre-winter transition seasons induce thunder­ storms and cyclones in the Bay of Bengal which are very often catastrophic for the country.

Rainfall: The isohyetal map (Fig. 1.3) has been prepared using long-term mean annual rainfall (1951-1985) to show the rainfall distribution pattern over the area.

It may be seen that the highest amounts of rainfall (>3200 mm) occur in the south­ eastern part of the study area bordered by the Bay of Bengal. The lowest amounts of rainfall (<2200 mm) are distributed in a curved band which initially shows a north-west to south-east trend in the upper middle part and gradually swings in a south-westerly direction and finally maintains that trend into the Meghna river as

11 LEGEND

International boundary

Isohyets 3000

« HILE

BAY OF BENGAL

90*

Fig. 1.3: Isohyetal map on the basis of long-term annual rainfall (1951 - 1985) a result of which rainfall distribution again increases in north-west and northerly directions.

1.7 Vegetation and Land Use:

In the past, the hilly areas used to be covered by tropical forest but this

has almost completely disappeared because of massive deforestation by the local people to meet the acute demand for fuel. The hills are thus left with permanent

grasses (locally called ’uri’), thorny bushes, shrubs and various kinds of large

tropical fruit trees. Exceptionally, small areas have been planted as deciduous forests

controlled by the public sector. The elevated lands (both natural and man-made)

which are not usually flooded have a dual usefulness; a minor part is used as

homestead land, while the major part is used for cultivation. Most commonly, the

flooded lands are devoid of any vegetation except the low and medium flooded

areas on which temporary grass vegetation develops during the intervening dry

season but is washed away by the next seasonal flooding.

Other than the homestead lands and hilly areas having high slopes, the

entire land area is under cultivation to varying degrees. The crop distribution,

cropping pattern, and cultivation practices are mainly governed by the topography,

depth and duration of flooding, availability of dry period irrigation and partly by

the salinity of the area. The historical cropping pattern was to produce single or

double crops, mostly rice, both because of monsoonal flooding and serious shortages

of irrigation water during dry season. But the availability of ground water irrigation

is rapidly converting the cropping practices to a triple cropping pattern. This

facilitates year-round production of crops and at the same time makes it possible

to bring more and more lands under full-scale cultivation which previously had to

remain as fallow during the dry season.

13 Rice is by-far the most important and extensive food crop grown in the area. Various kinds of rice are produced at different times of the year depending on their degree of tolerance to the prevailing climatic conditions. Traditionally, the rice varieties are called Aus, Aman and Boro/irri. Aus is broadcast as seed in the fields during the months from March until May, and harvested between July and

September. Transplanted Aman seedlings are introduced into the puddled ground between July and September, but broadcast Aman is sown in March and April and both varieties are harvested during the months of November and December.

Boro/Ini is transplanted in December or January and harvested in April or May.

Jute, the major cash crop, and Chilies are grown extensively in the western part of the Chandpur and Noakhali area. Betel-nut and Coconut are widespread in

Chandpur and the northern part of Noakhali area. Sugar-cane is locally important.

The adjoining homestead and man-made high lands are continuously used to produce both the rabi (winter varieties) and kharif (summer varieties) crops and vegetables.

1.8 River system:

The surface water distribution is mainly controlled by the large Meghna river and six other small but important perennial rivers (Fig. 1.4) which combine to form the Meghna river system. The Mehgna it-self is formed by the confluence of two small but important rivers, the Surma and the Kusiyara, beyond the north of study area and both these rivers originate in the Meghalaya and Assam Hills in the north-west part of India. All other perennial rivers-the Titas, the Buri, the

Gumti, the Dakatia, the Little Feni and the Muhuri river leading to Feni river have their source in the eastern Tripura hills of India and depending on their direction of slope, they flow in north, west and southwardly directions and eventually most of them merge with the Meghna river. All these streams have numerous branches

14 91* 00

LEGEND

International boundary

Channels

a) Primary

b) Secondary

IJ Mil E

Fig. 1.4: Distribution of major primary and secondary rivers in the study area. in the form of tributaries and distributaries and by means of these all the rivers are connected with each other, thereby creating a criss-cross network producing different drainage patterns depending on surface topography and land forms.

Three different but distinct drainage patterns may be recognized in the study area. In the eastern part, the streams are typically dendritic; in the central part they are rectangular, and in the western part over the Meghna flood plain areas the streams are basically of a braided type. The development of rectangular drainage patterns in the central part is largely due to artificial activities undertaken to improve the irrigation channel network. All the branching tributaries and distributaries remain active during the monsoon but most of them become dry during the winter season. Detailed geological and geomorphological studies (Morgan

& McIntyre, 1959; Bakr, 1976) have revealed that some of the rivers, particularly the Meghna, Titas, Gumti and Dakatia have shown significant changes in their courses during the last few hundred years. This indicates that the Meghna river system has been unstable for quite a long time. All these rivers carry enormous loads both in suspension as well as bed-load especially during monsoon, when these loads are carried away very quickly by strong currents during a sudden rise of flood flow. Then on their route, a considerable amount of erosion and scouring takes place; this phenomenon also encourages the channel shifting processes. During every major channel shifting event, there are left behind typical landscapes like abandoned meanders, ox-bow lakes and elevated sandy ridges, the remains of levees, now mostly filled-in. The Comilla-Noakhali region has been built up by the deposition of these huge amounts of sediment carried by all the rivers of the Meghna river

system.

1.9 Well numbering system:

Most of the maps used in this study to illustrate the hydrogeological

16 conditions were produced in a modified form from two basic base maps. The first base map was prepared to show the distribution of the available identifiable lithological logs (see Fig. 2.7) and subsequently lithological cross-section maps

(Figs. 2.8 to 2.12) were constructed using these locations. The numbering system of these lithological distribution map is done on an upazilla basis (an upazilla is a secondary administrative sub-division). In doing this, the number of available lithological logs for each upazilla was identified and then located in its correct location. Then the wells belonging to a particular upazilla were numbered in such a way that the well located at the northernmost point is identified as well 1 with the number increasing towards the south; for the well located at the southern most point the maximum number is allocated. This system of well numbering is repeated for all the upazillas.

The second and the most important master base map was prepared to show the wells or the water level measuring stations (Fig. 4.2), pump test wells

(Fig. 5.1), step-drawdown test wells (Fig. 6.1) and the quality sample wells (Fig.

7.1). Firstly, all these wells were correctly plotted using a different symbol for different types of wells for their easy identification. Then the wells were numbered, also from north to south, but regardless of types of wells and the upazilla boundary.

The entire study area was considered specifying the northern-most well as well 1 and progressively increasing the numbers towards the south with the southern-most well identified by the maximum number. During the analysis of a particular type of well, a new sub-base map was prepared from the master base map simply by deleting the other kinds of wells. Therefore, it is important to remember that the maximum number that is read in every sub-base map has arisen because of the cumulative aggregate of all types of wells in the master map. 1.10 Previous Studies:

This detailed hydrogeological study is the first of its kind that takes into account most aspects of evaluation technique, thoroughly and systematically.

A fair amount of hydrogeological work has been done for the northern part of study area covering Comilla district, either with Comilla being the project area or as part of a bigger project area. Two such studies that delineated the general hydrogeological conditions were one prepared by a United Nations team (1981) for

Comilla district only, and a second prepared by IDA with the assistance of the

British Overseas Development Administration (ODA) which included Comilla as part of a bigger area. This study looked in some detail at the ground water potential for irrigation and was completed by McDonald & Partners (1986). No such work had been done for the Noakhali district which also suffers from a serious shortage of basic essential data for better assessment of the ground water potential.

Three different reconnaissance studies to assess the general hydrogeological conditions of the entire country have been completed with the assistance of various international agencies, and these provided some useful information about conditions in the present study area. The first was done by the

UN ground water survey (1982) and in 1985 the World Bank carried out another such study. The most up-to-date multi-disciplinary ground water related work was conducted by the Bangladesh National Water Planning Project (1986) under the supervision of Dr. Pitman. All the above-mentioned works necessarily grossly idealized and simplified the prevailing complex situation.

Reconnaissance soil studies for the area were carried out by FAO

(1970) for most of the present study area, and the northern part was also studied by the Soil Resources Research Institute (SRDI, 1973). Some physical properties of the soil were experimentally established by SRDI (1977) and McDonald &

Partner (1983) during the preparation of water balance studies. In addition, a wide

18 range of published and unpublished literature has been reviewed and relevant information extracted to make the present research work more meaningful.

19 CHAPTER 2 GEOMORPHOLOGY AND GEOLOGY

2.1 Introduction.

2.2 Major Geomorphic Units.

2.2.1 Lalmai Deltaic Plain.

2.2.2 Chandina Deltaic Plain.

2.2.3 Meghna Flood Plain.

2.3 Regional Geology.

2.4 Surface Geology and Stratigraphy.

2.4.1 Dupitila Formation.

2.4.2 Madhupur Clay Formation.

2.4.3 Chandina Formation.

2.4.4 Flood Plain Deposits.

2.5 Geologic Cross-Sections.

2.6 Major Structural Trends. 2.1 Introduction:

The Bengal basin, of which Bangladesh is a part, is bordered to the north by the Himalayan foot hills and Shillong plateau, a large elevated uplifted faulted block of Pre-Cambrian basement rocks with an area of Cretaceous and Tertiary shelf sediments. To the west the boundary is formed by the outcropping Pre-Cambrian basement of the Indian shield which is popularly known as the Indian Platform. The eastern margin is bordered by hills of the NNW-SSE and N-S trending frontal folded zones of the Neogene phase of the Arakan-Yoma orogenic belt (Fig. 2.1).

Bangladesh lies at the head of the Bay of Bengal and occupies the central and eastern part of the Bengal Basin, a major geosynclinal feature which began to form in the Late Cretaceous period (approx. 70 million years ago) where down-warping is believed to have been continuous with and analogous to the Sub-

Himalayan fore-deep of the Ganges basin and continues subsiding today (Alam,

1972). Sediments washed from the surrounding hills have filled this geosynclinal basin to depths exceeding 18 kilometres in the southern mainland and the offshore islands (Barisal-Patuakhali-Hatiya region). On the basis of the information obtained from deep drilling (done for oil and gas exploration) and geophysical investigations, the thickness contour map of the sedimentary cover of the Bengal Geosyncline

(Fig. 2.2) has been prepared by Mirkhamidov and Mannan (1981) and in two cross- section (Fig. 2.3) the shape and size of the Geosyncline has been demonstrated and different geological formations up to a depth of many kilometres have been identified.

Subduction of the Indian continental plate by north-ward movement beneath the Tibetan plate resulted in down-warp of the Indian continental crust to depths greater than 25,000 ft (7,600 m) south of and adjacent to the

Himalayan front range (the Siwalik Hills). Simultaneously, westward propagation of

21 9 0

NEPAL fO*«-Ofc£p A

ILLO NG

•.SOUTH SHILLONG ^SHELF _

SYLHET TROUGH

Dhaka *»

|HATIYA\ I \VwEST Z O N E . \ \ y . y !TRj&UGH V J V v ^ ^ tAST ZONE

L E G E N U BENGAL Axis of folded structures

Boundary of tectonic zone

Study Area (After D. K. Guha, slightly modified, 1978)

9 6

Fig. 2.1: Location of study area in tectonic map of Bangladesh. 96 Miles

Study Area

Thickness in metres

9

§

Fig. 2.2: Estimated thickness contours of sediments in the Bengal Basin (Source: Mirkhamidov & Mannan, 1986). SE NW Section A - A

0 10

cu w MANTLE

sw Section B - B’ B o 10

CRUST MANTLE

Formation/ Aquifer Potential Age Group. Deep Shelf Basin U. Miocene Tipam, Dupitila ( Holocene M. Clay & Alluvium Good Good

Miocene Surma None Mod. to Limited

M. Miocene Sedimentary I Oligocene Jainta - Barail None Limited

none None Cretaceous Rajmahal trap Good sst. Volcanic ash None

Permian Gondwana None Limited

Igneous/ Precambrian Granite - None None Metamorphic gneiss

Fig. 2.3: Geological cross - section along selected lines across the Bengal Basin (after: Pitman, 1985). the Arakan-Yoma orogenic belt progressively narrowed the seaway east of the

Indian continental plate as it moved northward (Jones, 1985).

The tectonic elements of the Bengal Basin (Figs. 2.1 and 2.4) can broadly be divided into Shelf, Slope or Hinge, and Bengal fore-deep or Basin fore-deep areas (Bakhtine, 1966; Holtrop and Kiser, 1970; Guha, 1978; and Alam,

1985). The shelf in the north and north-west is characterized by comparative stability and reduced sedimentary cover. The geosynclinal Bengal fore-deep in the south and south-east has greater tectonic mobility and a very thick sedimentary infill. Jones (1985) suggested from an interpretation of aero-magnetic data (Fig. 2.5) that the Bengal fore-deep is concave eastward reflecting the topography of the

Tripura Hills and accounting for both the Surma basin down-warp and the present position of the Meghna-Brahmaputra estuary. These two units are separated by a hinge zone running in a NE-SW direction through the middle of the basin.

Most of present-day Bangladesh comprises a gently-sloping surface formed by Recent and ancient delta and alluvial plains of the Ganges,

Brahmaputra and Meghna rivers with their numerous tributaries and is underlain almost exclusively by poorly-consolidated and/or unconsolidated deposits of Tertiary and Quaternary ages. This huge sub-aerial delta has been found to grade offshore to the world’s largest submarine fan complex that extends over 3,000 kilometres south to 10°S latitude beneath the Indian Ocean (Curry and Moore, 1974).

2.2 Major Geomorphic Units:

The study area surface shows a general slope towards west, south-west and south-eastern directions. The land is generally flat in nature and the degree of flatness increases along with a decrease of surface irregularities in the direction of slope, except for the north-south elongated Lalmai Hills, which are relics of a previous large-scale ancient Lalmai anticline.

25 INDIA

SHILLONG PLATEAU

SUHUA BASIN

TRIPUPI 7h U l 's

INDIA

48 0 48 96 Miles '------1------1______i

Fig. 2.4: Generalized geology of Bangladesh and adjoining areas (Sources:- Holtrop & Kiser, 1970; Alam, 1985; Jones, 1985). 96 Miles

Fig. 2.5: Depth to Basement in Bangladesh (Source: Aeromagnetic Survey, O.D.A, 1980; Jones, 1985). According to M. A. Bakr (1976) the area can be divided into three major geomorphic units (Fig. 2.6) on the basis of their lithological characteristics, drainage patterns, degree of artificial modification, relative position

to one another, degree of modification by denudation processes and the degree of

induration. From east to west these morphological units are:- (1) Lalmai Deltaic

Plain, (2) Chandina Deltaic Plain and (3) Meghna Flood Plain. Brief descriptions

of these units are presented below:

2.2.1 Lalmai Deltaic Plain:

The Lalmai deltaic plain fronts the Tripura Hills and slopes

gently towards the west. The land forms developed by this formation are of a

terraced type and gently rolling. The drainage pattern is subsequent and dendritic.

Its present disposition suggests that it has been uplifted and occurs at elevations

ranging from 20 ft (>6 m) to over 100 ft (>30 m) above mean sea level (msl).

Bakr (1976) believes that the Lalmai deltaic plain (also called the Lalmai terrace

by Morgan and McIntyre, 1959) along with other terraces may be related to the

penultimate major (fourth) stage of Himalayan upliftment. It may be recalled that

the Himalayas mountain chain was brought to its present position by five major

stages of uplift and the indications suggest that the Himalayan orogeny is still

active. It has been concluded that large parts of this plain have been eroded and/or

covered by younger sediments. The shape of the Lalmai Deltaic Plain in the study

area is arcuate with convexity westward, which is also an indication that the

formation was laid down in a deltaic environment. The sediments underlying the

synclinal depression between the Tripura and Lalmai Hills also suggest the existence

of an inlet or tidal channel reaching Comilla town in the past which has

disappeared because of the artificial modifications to the plain by uplift. According

to Morgan and McIntyre (1959) the Lalmai deltaic plain has not been folded but

28 '(9Z.61 ‘-D^a :J3UV) ^Pn^s 3lP J° ^SopsQ :g'z ‘§ij

OE 06

Q

31IW Zt

N IV Id 31*1130 IVW1V1

NOIlVWaOJ NIVId VNIQNVH3 3IV113Q VNIQNVH3

11S 0 d 3 a N IV Id N IV Id 00013 00013 VNHD3W

S 0 N3 0 31

OE o06 is broken into a number of faulted blocks as a result of earth movement and some of these blocks are slightly tilted in the western edge of the study area producing a fault scarp of 3 to 10 metres (10 to 30 ft) in height. Dendritic patterns of drainage are characteristic throughout the plain.

2.2.2 Chandina Deltaic Plain:

The distinctive flat-lying surface that surrounds the Lalmai Hills and extends towards the Meghna flood plain and which has relatively lower elevation has been given various names by different authors:- M. A. Bakr (1976) and H. R. Khan (1978) refer to it as the Chandina deltaic plain whereas it is called the Tippera surface by Morgan and Mcintyre (1959). It is a flood plain long since abandoned by flowing rivers, where the original topography has almost disappeared and the surface features have been modified by man’s action. In particular, the drainage system has been transformed into a rectangular pattern primarily for irrigation purposes. The surface is weathered but not to such a depth as in the

Lalmai plain. It is slightly more elevated than the western flood plain but much lower than the eastern Lalmai deltaic plain. Bakr (1976) suggests that the elevation ranges from 10 ft (>3 m) to 25 ft (>7 m) amsl, and the differential elevation between the Chandina deltaic plain and the younger Meghna flood plain probably ranges from 4 (>1 m) to 6 ft (<2 m) (Morgan & McIntyre, 1959). The elevation of the Chandina deltaic plain (Tippera surface) is probably due to Recent activation of the pre-existing blocks in the area. It would appear to form a relatively stable block which is slowly being eroded by the Meghna and its tributaries. The geological formation that makes up this plain is called the Chandina Formation.

30 2.2.3 Meghna Flood Plain:

This flood plain is the result of the present day depositional activities of the Meghna and its numerous tributaries which have criss-crossed the whole area and result in a network structure of merging and branching channel bars, meander bars, and levees and other old stage characteristics. The delta building process is still continuing, and elevations range from less than 5 ft (<2 m) to about

20 ft (>6 m) amsl. The boundary between the Chandina deltaic plain and the

Meghna flood plain can only be approximately drawn since the morphological change at their junction is gradual.

2.3 Regional Geology:

The Bengal fore-deep is the result of rapid deposition and

contemporaneous regional subsidence, with very little internal deformation of the

sedimentary sequences created during most of Miocene and much of Pliocene times.

The uplift and gentle folding of the eastern margin of the Bengal fore-deep

increases in intensity eastward. This is primarily due to the westward advancement

of the Arakan-Yoma orogenic belt producing north-south trending folds and thereby

dividing the fore-deep zone into an eastern folded flank and a western unfolded

flank. Because of the basinal configuration, the unfolded flank is again subdivided

from north-west to south-east into (a) the Faridpur Trough, (b) the Barisal-Chandpur

gravity high and (c) the Hatiya Trough.

The present study area occupies the north-eastern part of the

Barisal-Chandpur gravity high, the western part of the unfolded flank and the

northern part of the Hatiya Trough (Figs. 2.1 and 2.4). No basement rock crops out

within the study area (or in any part of Bangladesh as a whole) and thus all the

surface and subsurface geology consists of these Recent geosynclinal deposits.

31 2.4 Subsurface Geology and Stratigraphy:

The Lalmai Hills are the only outcrop area where all the rock types are exposed that make up the sub-surface geology down to a depth of several hundred metres. At the outcrop, the relationship between the older and younger rocks becomes clearer and the lithological variations are better defined. The oldest geological formation exposed here is the Dupitila Formation which blankets the entire study area and beyond in all directions as a thick sub-surface layer. It is exposed in the northern Sylhet Hills and Tripura Hills to the east of India; both the outcrops are located outside the study area. On the erosional surface of this formation, the younger Madhupur Clay Formation is unconformably deposited. It is reported by several workers (Morgan & McIntyre, 1959; Bakr, 1976; and others) that most probably, in the past, the Madhupur Clay must have been distributed over a much larger area but because of its long exposure its lateral extension has seriously been disrupted as erosional activity has removed a major part leaving behind the disconnected, individual segments of Madhupur Clay which lie covered by the younger formations. Remnants of the Madhupur Clay were encountered and identified in some of the drilled holes and are located in the geological cross- sections (Figs. 2.8 to 2.12).

The principal geological formations (Fig. 2.6) which make up this part of the delta down to an investigated depth of around 500 ft (150 m) are described below with the youngest at the top:

4) Meghna Flood Plain Deposits

3) Chandina Formation

2) Madhupur Clay Formation and

1) Dupitila Formation.

The Madhupur Clay Formations and the younger formation correspond to the geomorphic sub-divisions. The Dupitila Formation and the

32 Madhupur Clay Formation belong to the Madhupur Group and these formations were formed during Plio-Pleistocene times. The Chandina Formation and the Flood

Plain deposits are Holocene deposits. The surface and sub-surface boundaries of these formation have not yet been established firmly. The lack of horizontal continuity as a result of a complex intermixing and rapid facies changes made it extremely difficult to attempt a straight forward sub-division.

Along with the available surficial information, 367 borehole lithological logs (Fig. 2.7) have been analyzed to prepare a modified correlation of the lithological units. However, since the maximum depth of the borehole logs seldom exceeds 125 m (400 ft) it was felt that the maximum deposit depth was much greater, at least in some places in the south. The number of well logs available for the south and south-western parts is much too low to reconstruct an accurate distribution of the sub-surface lithology. Other problems include the poor distribution of some of the data points on the map, repitious well logs, and poor description of the sediments encountered. With all those problems in mind, a detailed description of the lithological units is presented below to facilitate correlation.

2.4.1 Dupitila Formation:

This geological formation is exposed only in the Lalmai Hills but has been encountered in every bore hole drilled in the study area. The unit is dominantly sandy and is grey to yellowish-grey in colour. A typical characteristic of this formation is its gradation in grain size, being finer at the top and coarsening with depth (Figs. 2.8 to 2.12). It consists of very fine to fine sand, silty sand and a mixture of different kinds of sand with occasional intercalations of silt and clay.

Usually, the lower part is composed of medium to coarse sand associated with pebbles and gravels. Since the overlying formation is unconformably deposited on

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T the erosional surface of the Dupitila Formation, in many places therefore the uppermost finer sandy fraction is missing. Within these sandy deposits, predominant mica and quartz grains are noticeable. This formation has been encountered throughout the region at varying depth. The thickness of the unit is variable and cannot be determined because in most of the cases the borehole was not taken down to the base of this formation.

2.4.2 Madhupur Clay Formation:

The Lalmai Deltaic Plain is underlain by the Madhupur Clay

Formation which unconformably overlies the tilted Dupitila Formation of Plio-

Pleistocene age. The Madhupur Clay consists of reddish-brown or yellowish-brown

clay and sandy/silty clay, a host of highly oxidized red deposits. Ferruginous

nodules are encountered at places within this formation which is generally

unconsolidated and flat lying. The Madhupur Clay is exposed at the base of the

Tripura Hills and on the slopes and ridges of the Lalmai Hills (Fig. 2.6). It was

presumably laid down by the ancient streams draining the Tripura and Assam Hills

to the north and north-east. On the other hand, because of their older age, they are

characteristically more compact and weathered than the other younger deposits.

Though this clay is massive, occasionally it becomes mottled and vesicular and an

interesting feature of the unit is that it is compact when dry but becomes very soft

when wet. The clay is occasionally intercalated with very fine sand and silt. The

thickness of the formation is highly variable and in many places the unit is missing

as it has suffered long exposure to erosion.

2.4.3 Chandina Formation:

The geological unit that forms the Chandina deltaic plain is

called the Chandina Formation. It is composed of silt, silty clay, clay and very fine

35 sand. The sediments of these units are lithologically similar to those of the Recent flood plain deposits except that the Chandina Formation is comparatively more compact and oxidized. The sediments of the Chandina Formation, according to

Morgan and McIntyre (1959), are alluvial deposits but later studies provide enough evidence for a brackish, marine and/or estuarine origin. The brackish water origin of these sediments is provided by the presence of flora content, different types of organic matter and soil formation. However, these deltaic sediments are underlain by thick sandy layers of coarse or medium-grained sand, frequently with pebbles and gravels. The formation extends from the surface to a depth of over 100 ft (Fig.

2.6).

2.4.4 Flood Plain Deposit:

These alluvial sediments were deposited by the present day

Meghna river and its numerous tributaries during Post-Recent and Contemporary times. The materials laid down are silts, silty clays, clays and sands similar to those of the Chandina Formation except that the Flood Plain deposits are comparatively more loosely consolidated, and typically grey to yellowish grey in colour. The geological succession in Table 2.1 briefly outlines the ground water potentiality of the different geological formations.

2.5 Geologic Cross-Sections:

A number of geological cross-sections have been prepared in different directions covering most of the study area on the basis of the available lithological logs (Fig. 2.7). The cross-sections were prepared along the *A-B, B-C,

C-D, E-B and F-G’ lines (Figs. 2.8 to 2.12). These sections have been prepared with reference to mean sea level (msl). Except for very few, most wells were drilled to a depth less than 125 m (400 ft) with a majority being drilled to a depth "3 ■n oo * s ^ c c o b •- t> *n — CJ <3 4J 6/5 O u i) y U a 8.1 ‘ ■ £ J 3 « . C/l Crt MU g»2 I » * 5 E .- o 2 s - * C J J Z VI E~ 2 C/5 C3 V) ” n S n c « 1e - "2 = n s - .s Jcj2 = u « n g S E ZD o CX tu ^ W .2 O M >“>.£ > cfl-i= T3 3) .2 £ '5 £

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A computer program was available in the Department which had been written originally for the presentation of geological sections at outcrops and primarily used by research students in Sedimentology and Petrology. This program was modified to prepare and present borehole log cross-sections for the wells used to correlate the lithology and to identify the extent of the major units (Figs. 2.8 to

2.12).

a) Geological Cross-Section ’A-B’: (Fig. 2.8)" starts from south eastern boundary of the study area and extends towards north almost touching the India-

Bangladesh border. It includes Sonagazi 4, Sonagazi 2, Feni 19 and Feni 15 wells which were drilled through the Meghna Flood Plain Deposits at the surface. At the northern end it includes Chauddagram 11 and Chauddagram 4 which were drilled through the exposed Madhupur Clay Deposits and wells Feni 7, Feni 2,

Chauddagram 20, Chauddagram 19, Chauddagram 16 and Chauddagram 12 in between which were drilled through the Chandina Formation.

From this section it appears that a layer of silt and clay, occasionally with very fine sand, is present everywhere and its thickness is lowest in the centrally located Chandina Formation and gradually increases to either sides.

Below this unit there is a dominantly sandy layer, 50 to 70 metres thick, which includes occasional gravels and pebbles at its base. In turn this sandy layer is bounded by another clay/silt layer at the bottom which is present in most of the wells at a depth of between 80 to 100 metres.

b) Geological Cross-Section ’B-C’: (Fig. 2.9) is the northern continuation of

’A-B’ cross-section line which is extended from Chauddagram to the central part

38

COMILLA - 26 COMILLA - 18 COMILLA - 3 BURICHONG - of the Brahmanpara upazilla. Except for Chauddagram 4 well, which is drilled on the exposed Madhupur Clay Formation, all other wells belonging to this section encounter the Chandina Formation at the surface. Here the Chandina Formation seems to be more clayey and its thickness is more variable. The sub-surface presence of Madhupur Clay has been identified in Comilla 26 and Comilla 23 wells. The well-defined lower bounding clay/silt layer that was identified in the

’A-B’ cross-section at a depth of about 80 to 100 metres has not been found to a depth of 110 metres. This indicates a gradual plunging of the clay layers towards the deeper part and implies a much deeper occurrence of the clay/silt layer at a depth not yet drilled. The present distribution of both the upper and lower bounding clay allows the intermediate sandy layer to become thicker.

c) Geological Cross-Section ’C-D’: is the third and the concluding segment

(Fig. 2.10) of the longer ’ABCD’ cross-section line which is extended from central

Brahmaputra to the northern end of Nasimagar upazilla marked by the Meghna river. The Sarail 11, Sarail 5 and Sarail 1 wells encounter the flood plain deposits as the uppermost layer but all other wells lying along the section were drilled through the Chandina Formation. The uppermost finer layer of clay and silt with fine sand is present throughout the entire length of the section. This layer is thickest in the middle and its thickness gradually reduces towards either end of the section to as low as 3 m (Brahmanpara 2). In general, the upper clay/silt layer in this section is some what thinner than the other two previous sections of the ’ABCD' cross-section line indicating the occurrence at shallow depths of the middle sandy layer. One special feature of this sandy layer in this section is that in several places multiple clay/silt layers are present in the form of lenses. In Kasba 14 and Kasba

12 wells the intermediate clay/silt layer is thought to be of Madhupur Clay type.

The occurrences and distribution of the lower bounding clay/silt layer has been

41 5 N=a :l-:l i encountered at a depth of about 100 metres in Kasba 12. Beyond that, in a northern direction, it has not been encountered even at a depth of 120 metres, suggesting a deeper occurrence along that direction.

d) Geological Cross-Section ’E-B’: is a NE-SW section (Fig. 2.11) and is located in the lower part of the study area extending from the Chauddagram upazilla to the south-western boundary of Laksmipur upazilla which is demarcated by the

Meghna estuary. In the south-west it includes wells Laksmipur 4 and Laksmipur

1 in which the uppermost layer is flood plain deposits. In the wells from Chatkhil

1 to Chauddagram 7 the surficial cover is the Chandina Formation and at the extreme north-east end the exposed Madhupur Clay Formation represents the topmost layer in Chauddagram 6 and Chauddagram 4 wells.

The topmost clay/silt layer is relatively thin in the middle portion but gradually thickens either direction. The thickness of the Flood Plain

Deposits sharply increases in the flood plain Laksmipur area beyond Chatkhil 1 well which rises to as high as 328 ft (100 metres). Several inter-bedded fine sandy layers have been identified within this thick surficial clay/silt layer. A deep drilling to a depth of 350 metres (Laksmipur 4) suggests that there is a marked change in lithology with the increasing supply of finer sediment. Other than the occurrence of sandy layers at different depth horizons from 100 to 140 m, 165 to 185 m and between 195 to 205 m the entire lithology is dominated by finer materials.

Therefore, it is difficult to say for certain that in this part of the study area which particular sandy layer is the extension of the main aquifer. Alternatively, because of the supply of finer material at different times the thicker aquifer may have been divided into several horizons or it may be that the main aquifer located at shallow depth in the northern part has plunged to much greater depth and has not been encountered in the boreholes in the southern part particularly at the Laksmipur 1

43 CHAUDDAGRAM - u d 3 2 1 2 3 5 ' ^ k

1 P 3 e 8 U o U & 8 s ;

3 I 3 3 " T 1 93 well. To answer these questions correctly, much more subsurface information is essential for the entire southern part of the study area. It is not clear that the clay/silt layer encountered in Laksam 15 well at a depth of 90 metres is the lower bounding clay/silt or not, since it has not been encountered in any of the wells located in the south at this depth.

e) Geological Cross-Section ’F-G’: is an east-west line (Fig. 2.12) chosen at about the middle part which roughly divides the study area into two halves and covers the Comilla town (Kotwali upazilla), northern minor part of Barura, and most part of Chandina and Daudkandi upazilla. Only the Daudkandi 4 well has been drilled through the Flood Plain Deposits. In all other wells from the Daudkandi 8 well to the other end of the section the uppermost covering layer is the Chandina

Formation except for Comilla 16 well which is reported to be drilled in the area where the Dupitila Formation is exposed. The formation is dominated by sandy sediments and the entire drilled depth is characterised by this material. In this well the top clay/silt layer and the bounding clay/silt layer is absent although present in the nearby wells on either side. The intermediate clay/silt layer at the Comilla 14 well could be of Madhupur Clay type.

The thickness of the upper clay is variable. It shows the highest thickness at the Chandina 3 well but at the same time the clay/silt layer in this locality also contains a considerable amount of fine sandy material which is thought to be one of the characteristics of the Chandina Formations. The thickness of this layer decreases to either side of the Chandina 3 well. After a sudden decrease in thickness at the Daudkandi 8 well in the west the thickness again increases into the flood plain. The upper clay/silt layer along this section beyond the Comilla 16 well in the east is particularly dominated by clayey materials. None of the wells on this section were drilled to find and locate the depth of the lower bounding Q. CO Fig. Fig. 2.12: Correlation of lithological units along the line clay/silt layer therefore the thickness of the sandy layer is really not known.

Comments:

From the foregoing discussion it can be concluded that the entire area except for the Lalmai Hills is covered with a clay/silt layer of varying thickness. In general the clay/silt layer is more silty in the west and more clayey in the east. This layer also sometimes contains fine sandy materials in several places. The thickness of this covering layer seems to increase in south-west and southern directions especially into the flood plain deposit area, though this pattern is interrupted in many places. In this south and south-western part, the upper clay/silt layer is very thick but its continuity is interrupted by several intermediate finer sandy layers. Another clay/silt layer has been identified more clearly in the upper and eastern part at a depth between 80 and 90 metres (Fig. 2.9 and Fig.

2.12). This bounding clay layer seems to plunge to a much greater depth in west, south-west and western directions as it has not been found at a greater depth in those parts of the area. The second clay/silt layer is described here as the lower bounding clay/silt layer since between lies a considerably thick intermediate sandy layer which extends throughout the area. This sandy layer is more distinct and sandy and contain relatively coarser grains along the eastern ’A-B’ and *B-C’ section and centrally located *F-G’ section but the sandy layer seems to contain more clay/silty materials and some times is separated into layers by lenses of clay/silt materials along the ’C-D’ section in the north and ’E-B’ section in the south-western part. Though the finer sediments contain a certain portion of the sandy layer in the south and south-west and are more divided by inter-bedded clay/silt layer yet the thickness of the sandy layer seems to increase in this section.

47 2.6 Major Structural Trends:

The mountain building processes during the late Tertiary Period

(Miocene and early Pliocene) have played the most important role in producing significant structural changes in and around the study area, especially along the border area (folded flank of the Bengal fore-deep) and further east in India. It is also the period when the major upheaval of the mighty Himalayas occurred. As a result, a large number of folds and faults were created, most of them having a general north-south trending orientation in which the Tertiary sediments have been compressed into folds parallel to the eastern Arakan-Yoma geanticline, which also has north-south trending structure (Fig. 2.13). Because of this upheaval, the landmass was exposed to erosional activity for a considerably longer period, hence the combined denudation processes have significantly levelled the surficial expression of these structural features. On the erosional surface of the Tertiary sediments, the Madhupur Group of sediments was deposited under transitional, brackish marine to estuarine or fluvial environments. As a result, all these Tertiary structures have been buried underneath the Quaternary sediments, except for the

Lalmai Hills, the remnants of the previous larger Lalmai anticline. The area is still technically active supported by various occurrences of earthquakes and sudden changes of river courses. A detailed geophysical study revealed a lot of information about these structural features which seem to have little or no control at all over the sediments which covered them. It has been found that these structures are similar to those Tertiary structures exposed on the surface in the adjacent northern and eastern regions. The folds are simple and vary from closed structures with wide flat crests and gentle flanks to gentle flat crested, steep sided, box like structures and are typified by their ’en echelon’ position. The width of the synclines is greater than that of the anticlines and varies from 15 to 20 kilometres, whilst fold amplitudes range from 200 to 3500 metres. The folds are asymmetrical and in most

48 LEGEND

TERTIARY STRUCTURES:

FOLDS

FAULTS

International boundary

Primary river channels

I I MILE

20 KM

BAY OF B E NGAL

Fig. 2.13: Distribution of major structural trends (compiled from Bakr, 1976 & MacDonald & partners, 1986). cases the eastern limbs is the steeper. Huge amounts of gas reserves have been discovered within some of these buried folds distributed in the northern (Titas

anticline), north-eastern (Bakhrabad anticline) and south-eastern (Begumganj

anticline) part of the study area. The seismic studies in particular have successfully

identified a number of major deep seated transverse faults (Fig. 2.13), some of

which have cut and displaced some of the folds. In some of the synclines the faults

are found to behave like axial thrust faults. A majority of these fault planes shows north-south extension.

Lalmai Anticline:

The Lalmai anticline (Fig. 2.6) which caused the Lalmai Hills is 12 miles long and has an average elevation of about 100 feet above the sea level.

It is bounded by a series of parallel faults and the whole hilly area is surrounded by the Chandina Deltaic Plain (M. A. Bakr, 1976) or Tippera surface (Morgan and

McIntyre, 1959). These hills are gently sloping to the east but the western flanks

are cliff-like (Fig. 2.6 and 2.13).

50 CHAPTER 3 HYDROGEOLOGY

3.1 Historical Development of Wells.

3.2 Aquifer System and Classification.

3.3 Main Aquifer:

3.3.1 Upper Confining Layer.

3.3.2 Physical Characteristics and Extent.

3.3.3 Aquifer Thickness.

3.3.4 Aquifer Nature.

3.4 Deep Aquifers.

51 3.1 Historical Development of Wells:

An organised effort to increase the development of ground water in Bangladesh was initiated in 1966 primarily for irrigation and also to enhance the availability of potable water in the rural areas. Also, there was the extension of municipal water networks in the important urban areas. The Ground

Water Circle (GWC) within the Directorate of Hydrology of the Bangladesh Water

Development Board (BWDB) is the present day national organization responsible for ground water development and management. More systematic and large scale

studies of ground water resources began in the early 1970’s, though the earliest

small scale hydrogeological data collection programme had started as early as 1961 with the measurement of water levels on a monthly basis for 147 wells distributed

throughout Bangladesh. A regular nation-wide measurement of the water table on

a weekly basis was started in the 1970’s by BWDB. Thereafter along side the

BWDB, ground water development programmes were carried out increasingly by

several other organizations like Bangladesh Agricultural Development

Corporation (BADC), Bangladesh Krishi Bank (BKB), Department of Public

Health Engineering (DPHE), and Bangladesh Rural Development Board

(BRDB), gradually by putting down more and more deep tube wells every year.

The BADC and BKB were primarily interested in irrigation, while BWDB, DPHE

and BRDB were more concerned with potable water.

The initial wells were mainly of shallow tube well

(STW) type and were restricted to between 80 and 180 feet in depth. The

structure is 4 to 6 inches in diameter with a suction lift centrifugal pump

mounted on the surface which usually provides a discharge of 15 1/s (130 m3/d)

and a capacity to irrigate 8-15 acres of crop land. Many of them are no longer in

use. Gradually increasing irrigation demand has made the installation of deep tube

wells (DTW) more popular than the shallow tube wells (STW). Most deep tube

52 wells are installed to a depth between 180 (55 m) and 400 feet (122 m) though some test holes may be installed down to a depth of 1200 feet (>365 m). The deep tube wells are drilled mainly by reverse circulation methods. In almost every case the upper 80 feet (24 m) is cased with 1.16 feet (0.35 m) diameter pipe to accommodate the pump and there after the entire length is kept constant with 8 inch (200 mm) diameter pipe. It is fitted with a turbine pump usually set at a depth between 50 (15 m) to 80 feet (24 m) which in most cases has a discharge of 58 1/s (5000 m3/d). Except in the urban areas, all the deep tube wells are used primarily for irrigation purposes. The wells are usually pumped for some 800-1600 hours during the winter (dry) season and a single DTW irrigates about 40-60 acres of cropland. In most cases the crops are rice but every year increasing amounts of other crops and vegetables are grown, particularly during the winter period using the ground water resources.

The earliest installation of ground water wells in the Comilla-

Noakhali region was documented during 1968/69 and since then the cumulative number of DTW’s is constantly increasing, mainly for irrigating croplands. Until

September 1985, the present study area alone had a total number of 1961 deep tube wells (1786 deep tube wells in Comilla and 135 deep tube wells in Noakhali districts) and 95 permanent observation wells (60 in Comilla and 35 in Noakhali) which indicates quite a significant amount of progress in ground water resources

study (Pitman, 1985). Because of insufficient information regarding location the majority of the wells could not be identified in the lithological maps (Fig. 2.7).

Though Bangladesh as a whole is criss-crossed by hundreds of

small and several major rivers and receives rainfall at rates among the world’s highest yet the country suffers a severe shortage of water. Some 60% of 19 million acres of excellent cropland lies fallow for about 5 months during the dry season,

a consequence of the monsoonal climatic condition.

53 3.2 Aquifer System and Classification:

To acquire detailed comprehensive knowledge about the hydrogeological conditions and the occurrence of ground water both at shallow depth as well as at the much greater depths in this deltaic geosynclinal basin, a nation-wide investigation was carried out by Jones of Louisiana University, U.S.A. in 1985. In his investigation he studied the nature and extent of the aquifer down to a depth of 6,000 feet (1800 m). To accomplish this work he accumulated and used all the available records of ground water related work which had been done by every related organization. This included the records available in the Ground

Water Circle (GWC), BWDB (the agency responsible for nation wide development and research of Ground water resources) and complementary to these some more geophysical logs like the electric logs, gamma-ray logs, caliper logs etc. for some

20 oil and gas wells from Bangladesh Oil Gas and Mineral Corporation (BOGMC).

Eventually after careful evaluation, the occurrence of six well-defined potential aquifers was identified (Figs. 3.1 and 3.2) within the investigated depth. In his report they were numbered with the shallowest as aquifer 1 and the aquifer number increasing with increasing depth marking the deepest aquifer no 6.

All these aquifers have a crescent-like shape with convexity downwards giving maximum depth for these aquifers in the central part (Dhaka) of the Bengal fore­ deep. Gradually the depth decreases in western and eastern directions, more rapidly to the east where ultimately the aquifers become exposed in both the Chittagong

Hills and beyond in the Tripura Hills (India).

All six aquifers either entirely or mostly contain fresh ground water except in a few places. A small part of aquifers 2, 3, 5 and 6 are affected by salinity along the southern coastal area of Barisal and Noakhali which lies beyond the study area. Aquifer 4 in the vicinity of Lalmai 2 well (Fig. 3.2) is also affected by salinity on a limited scale. [3A3| B3S UB3UI A\0J3q J33J UI q]d3Q

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o main aquifer and the deeper aquifers of Bangladesh (After: Jones, 1985). A^48A rvi Fig. Fig. 3.2: Geological cross-section along ’ C - D ’ line showing the distribution of both the 48^13642

joujsip psung Z - IPBlnW - BIZJH

pujsip psrreg ZZ} H3 l«streg

l _ J

pA 3J B3S UB3UI A\O pq S3IJ3UI UI qidSQ The uppermost aquifer (aquifer 1) depending on its geological and geographical location, changes its nature from unconfined to leaky confined and then to fully confined conditions and is mostly recharged by direct infiltration of the surface precipitation. Additionally, considerable amounts of recharge come from the outcrop in the eastern hilly areas as horizontal flow (Fig. 3.3). The separation of aquifer 1 and aquifer 2 is neither uniform nor continuous, therefore in several places the division is arbitrary as a result of which the lower (aquifer 2) in several locations where the separating layer has either pinched out or become very thin receives a certain amount of vertical flow and behaves as part of aquifer 1.

However, the main source of replenishment for aquifer 2 is lateral horizontal flow.

As a consequence of this situation the nature of aquifer 2 ranges from confined to leaky-confined. All the four remaining deeper aquifers reflect true confined conditions as they are sandwiched between thick clay/shale layers and are entirely recharged by lateral horizontal-flow from precipitation on the outcrops in the eastern hilly areas where all these deeper aquifers are exposed to heavy rainfall (see rainfall distribution map, Fig. 1.2).

The present work is entirely devoted to the delineation of the ground water resources potential of aquifer 1, since the depth considered in this study rarely exceeds 500 feet (>150 m) (data below this depth are not available) and only in few cases does the recorded depth of the available lithological log exceed 1000 ft (300 m). The wells having this greater depth are concentrated in the southern Laksmipur, Begumganj and Noakhali upazillas where the estimated depth of the base of aquifer 1 is well above 1000 ft (300 m). All over the studied area, aquifer 1 is covered by a clay/silt layer of varying thickness which has created an aquifer condition that ranges from leaky confined to fully confined. A detailed description of the nature of aquifer 1 is given in the following section.

57 UJ PL J3 8 S. SB E &E r - H D JC o ^-4 O J? O E *d CJtLi SU h Q fe

CN CO

c r

c * > § ’I

Cl 3 3 Main aquifers:

33.1 Upper Semi-Confining Layer:

The surface clay/silt layer contour map (Fig. 3.4) was prepared using most of the available lithological logs to minimise confusion and to obtain a better description of the overlying semi-confining layer. Though the thickness contour map shows considerable variations, yet it reveals quite a lot of information about the thickness pattern and the distribution of this aquiclude.

The map suggests the general presence of a clay/silt

layer all over the study area which is also reflected in several geological cross-

sections (Figs. 2.8 to 2.12). This aquiclude, depending on its thickness and

lithological characteristics and recharge ability, gives rise to the range from leaky

confined to fully confined conditions.

The thickness contour map is characterized by two

centrally-located closed-type low thickness areas separated by higher thickness in

all other directions. The smaller closed low thickness area is confined in the

north-central area covering most of Devidwar and parts of Burichong and

Banchharampur upazillas. The larger closed thickness area is located in the

south-central area covering most parts of Barura and Laksam and part of

Nangalkot upazilla. Towards its southern edge, this low thickness area extends

across the study area along a NW-SE strip covering part of Matlab Bazar,

Haziganj, Sharasti, Begumganj, Senbagh, Dagonbhuiya and Sonagazi upazillas,

separating the south and south-western part as the largest higher-thickness area.

Apart from these closed areas, the thickness also decreases towards the west in the

north-western part along the Meghna river bank covering part of Sarail and

Nabinagar upazillas to give one of the lowest thicknesses encountered in the area.

A distinct increase in thickness is encountered in three

different areas separated by intermediate low-thickness areas. In the north the

59 international b o u n o a r t

UPAZILA ADMINISTRATIVE BOUNOART

P R f M A R Y R IV E R C H A N N E L

BOREHOLE LOCATION

Thickness in feet

L MILE

12 KM 16

iNPA R A

1AUDKANOI

CHANQINA os "I

IILLA

'ey i..

MATLAB BAZAR | KA?HUJ

H A Jli

[ L A K S A l

iAZI

Ialo tc

IAIHCI WPUR

BEGUMGANJ

iGAZI IPANH HUAAHTCl

Fig. 3.4: Thickness distribution of the surficial clay/silt (aquiclude) layers. thickness estarts rising to the north of Nasirnagar upazilla and continues to do so beyond the study area towards the Sylhet basin. In the mid-western part, the thickness increases towards the west covering part of Banchharampur, Homna,

Chandina and Kasha upazillas though the highest thickness is encountered in the

Daudkandi area (>210 ft) and continues increasing into the Meghna river. Notably, the thickness of the aquiclude increases enormously in the south and south-western part of the study area and keeps on increasing towards the Meghna estuary where the thickness exceeds 350 ft in Laksmipur upazilla and 400 ft in Noakhali sadar upazilla before ultimately continuing into the Bay of Bengal. In this part of the project area, the aquiclude characteristically includes several thin layers of fine to medium sand and all these sand inter layers have limited aquifer potential. However, the extension of these inter-bedded sand layers within the aquiclude is not clearly known because of insufficient lithological information.

3.3.2 Physical Characteristics and Extent:

A detailed lithological study has been carried out using all the available and identifiable lithological logs to define and correlate the aquifer.

It appears from such work that the aquifer is distributed throughout the project area and beyond as a continuous thick layer of sand. It is unconsolidated and moderately sorted in nature. In most places the aquifer is identified as a thick single unit but in some places, especially in the Lalmai deltaic plain area and in the southern part (Figs. 2.8 to 2.12), the aquifer is separated into two or more layers by the Madhupur Clay Formation and inter-bedded clay/silt layers, respectively. The south-western, western and southern parts of the study area are less well known because of limited lithological information. In the southern part, the aquifer is situated at much greater depth and the thickness of the aquifer also varies over small horizontal distances which is clearly revealed in the thickness contour map

61 (Fig. 3.5).

More sub-surface lithological information is needed for

a clear delineation of the aquifer nature, especially for the southern part. Yet certain

characteristic changes in lithology can be recognised. The lithological logs which

were used to prepare geological cross-sections (Figs. 2.8 to 2.12) clearly

demonstrate a gradation in grain size in the aquifer material with the finer being at

the top and the grain size gradually increasing towards the base of the aquifer.

This gradation is less, clearly defined in the southern part though it can be

recognised vaguely. The aquifer can be divided roughly into three main parts: 1)

an upper finer part mainly composed of finer sand with little medium sand, 2) a

middle part mainly composed of medium-grained sand finer at the top and coarser

at the bottom and (3) a basal main part which is composed of medium to coarse

sand occasionally with gravels and pebbles. These three parts of the aquifer must

not be confused with the subdivisions of the previously recognised aquifer 1.

3.3.3 Aquifer Thickness:

The thickness contour map (Fig. 3.5) has been prepared

using all the available borehole log information to demonstrate the natural thickness

distribution of the aquifer all over the project area. It also reveals the prevailing

trend of change in the thickness of the aquifer.

The thickness distribution of the aquifer in the relatively

narrow northern part is quite different from that in the larger southern part. In the

northern part, the general thickening of the aquifer occurs from east to west

centring the B’Baria area, while in the southern larger part the aquifer represent

a three-fold increase. All these changes were found beneath the west ward wedge-

shaped 300 ft contour extending towards the Nabinagar area from the Akhaura

area. In the southern part, the thickness of the aquifer decreases in west and south-

I. tI

62 91 30

INTERNATIONAL BOUNOART

UPAZUA administrative BOUNOART

p r i m a r y r i v e r c h a n n e l

BOREHOLE LOCATION

Contour interval 50 ft,

INPARA

JAUOKANOI o

I h a J d o a g r a m

lA N G A L K O T C

s o n a g a V i

Fig. 3.5: Thickness distribution map of the main aquifer western directions over the region covering Daudkandi, Chandpur, Haimchar and

Raipur upazillas until it encounters the elongated 250 ft contour line wedging towards north-east directions. From this 250 ft contour line a thinning of the aquifer has been recognized in a south-eastern direction along a thin band covering parts of Senbagh, Begumganj and most of Sonagazi area. This 250 ft wedge shaped contour gradually opens-up towards the south, sharply increasing the aquifer thickness towards the Meghna estuary. At the southern extremity of the Noakhali region, the thickness of the aquifer exceeds 445 ft and appears to be increasing farther into the deeper sub-surface part beyond the limits of the mainland.

The aquifer reaches a thickness less than 150 ft only in two small areas. In the north, it covers the central part of the B’Baria upazilla where the lowest thickness obtained is about 114 ft and in the south-west it covers parts of Chandpur, Raipur and most parts of Haimchar upazilla where the lowest thickness encountered is as low as 82 ft. With these exceptions, the entire aquifer shows a thickness of more than 200 ft which controls and regulates the ground water resources in that region.

The need for more borehole logs was particularly felt for most parts of the southern region of the study area. On several occasions the entire upazilla has only one single borehole log (namely, Haimchar, Faridganj, Ramganj,

Raipur and Chatkhil upazilla). In other instances, four lithological logs (from

Laksmipur, Companiganj, Parshupram, Dagonbhuiya and Chhagalnaiya upazilla) and five lithological logs (from Begumganj, Sonagazi and fulgazi upazilla) were available for the sub-surface interpretation. The absence of this essential lithological information has forced limitations on the interpretation of the aquifer system with gross simplification of the complicated distribution in the southern part. When more sub-surface information would becomes available, the appearance of the thickness contour map could change significantly.

64 3.3.4 Aquifer Nature:

It is apparent from the preceding sections that a thick sandy aquifer is present throughout the entire project area and beyond (Fig. 3.5).

It is also obvious that the aquifer is overlain by a clay/silt layer of variable thickness (Fig. 3.4) covering the entire extent of the aquifer. Underneath the thick main aquifer there is another clay/silt layer (Figs. 2.8 to 2.12) which is not as prominent as the upper semi-confining layer and also not clearly revealed from the present interpretation of lithological logs though was more clearly interpreted by

Jones (1985, Fig. 3.1 and 3.2).

The presence of the overlying aquiclude and the lower bounding clay layer suggest a confined aquifer condition. But it has been found that a considerable amount of recharge takes place through the upper confining layer in the form of deep percolation of infiltrated water in addition to the recharge from lateral horizontal flow originating in the eastern hilly region beyond the Bangladesh-

India border. Such vertical flow conforms to the definition of a leaky-confined condition. This typical nature of the aquifer is more thoroughly tested in chapter-

5 (aquifer test analysis) where the hydraulic parameters suggest a fully confined condition for the smaller south-eastern part and leaky-confined conditions for the rest of the studied area.

3.4 Deep Aquifers:

On the basis of the Jones (1985) classification (Section

3.2) aquifers 3 to 6 inclusive are considered as the deeper aquifer series (Figs. 3.1 and 3.2). All these four major aquifers shows strong to very strong artesian characteristics. Using borehole geophysical techniques Jones demonstrated that in those areas for which information is available, ground water is fresh at depths greater than 1500 m (5000 ft) in the eastern part of the Surma basin and at depths

65 greater than 1200 m (4000 ft) throughout north-eastern Bangladesh, north of the confluence of the Meghna and Padma rivers. Throughout most of the Bengal fore­ deep, fresh ground water occurs at depths greater than 600 m (2000 ft). The maximum depth of occurrence of fresh ground water in the south-eastern part (Feni

and Chauddagram upazilla) is more than 600 m (2000 ft) underneath the present project area and this depth increases to more than 760 m (2,500 ft) in the northern part (B’Baria and Muradnagar upazilla) of the study area.

As mentioned previously, the only source of

replenishment for these deeper aquifers is from the lateral horizontal flow via the

outcrop section, and it has also been found that because of the basinal configuration

the depth of the aquifers increases from both eastern and western sides towards the

central part of the basin in the vicinity of the capital city of Dhaka (Kamta 1 well)

where the depth to fresh ground water is more than 1000 metres (Figs. 2.3 to 2.5).

It follows that the artesian head also increases for deeper aquifers with increasing

depth of burial. The area of outcrop of the deeper aquifers in the Tripura and

Chittagang Hill Tracts occurs at increasingly higher altitude eastwards from the

margin of the deltaic plain. Therefore, it is more likely that the artesian head also

increases with depth because of increased overburden pressure which makes positive

contribution in making the aquifer condition more and more strongly overflowing.

An interpretation of this artesian head in terms of Ghyben-Herzberg relationships

has been made which shows that when the depth of the fresh ground water is 600

m (the depth of fresh ground water underneath the present project area) then the

fresh water head (potentiometric head) in the aquifer should be at least (600/40) =

15 m (50 ft) above sea level. The maximum altitude around the project area is less

than 12 m (40 ft) which is less than the altitude of the potentiometric surface.

When the altitude of the land surface is lower than the altitude of the potentiometric

surface then the penetrated well in that aquifer should have an overflowing artesian

6 6 condition.

The difference between the altitude of the potentiometric surface and the altitude of the land surface is called the closed- in artesian pressure. If the difference is positive then it is called the closed-in artesian pressure at the land surface and higher number indicates a stronger artesian overflowing conditions. Jones demonstrated that natural overflowing conditions prevail almost any where to the east of the Brahmaputra River in the

deltaic plain for aquifers ranging from 3 to 6. For this particular well depth and

altitude condition the closed-in pressure at the land surface is (15-11.6) = 3.4 m

(11.16 ft) indicative of an overflowing condition.

A rough calculation can be made to demonstrate

theoretically how much water would be available from an over-flowing well

installed at a depth of 600 m (2000 ft) below sea level. If the well is 8 inch in

diameter and with a measured specific capacity of 0.05 ft3/sec/ft, then the rate of

artesian flow of the well would be:

= 11.16 x 0.05 ft3/sec = 0.558 ft3/s e c = 48211.2 ft3/d

= 1365.2 m 3/d = 15.7954 1/s [1 m 3/d = 0.01115 1/s]

= 300344 gpd [1 m3/d = 220 gpd] = 208.6 gpm.

This amount of flow minus the frictional losses would

be sustained by the well if a balance can be maintained between recharge and

withdrawal by means of an efficient water management. This, of course, is based

on a clear understanding of the hydrogeological regime.

67 CHAPTER 4 GROUND WATER FLOW

4.1 Water Level Monitoring System.

4.2 Water Level Data Used

4.3 Ground Water Level Fluctuation.

4.4 Water Table Contour Map and

Flow-Net Analysis.

4.4.1 Introduction.

4.4.2 Low Elevation.

4.4.3 High Elevation.

4.4.4 Annual Fluctuation Map.

4.5 Replenishment Calculation.

4.6 Comments on Ground Water Movement

and Flow Pattern. 4.1 Water Level Monitoring System:

The application and use of ground water in Bangladesh started

on a small scale as early as the 1960’s because of increasing demand for a variety

of purposes e.g - municipal, irrigation and industrial. Initially a directorate of the

then Water and Power Development Authority (WAPDA) was responsible for the

development, monitoring and application of both surface water and ground water.

With the passage of time and because of the inadequacy of surface water during the

dry season (winter period), the need and demand for ground water has become of

paramount importance both for increased nationwide irrigation practices and to make

available more ground water for drinking purposes. To ensure the better

management of water resources a separate organization called Bangladesh Water

Development Board (BWDB) was formed in the early 1970’s. A ground water

division has been established within the major Hydrology sub - division of the

greater BWDB establishment and has built up a good data storage section.

A second major organization which deals entirely with the

irrigation usage of both ground water and surface water is called the Bangladesh

Agricultural Development Corporation (BADC). Their data storage programme is

more irregular and at the same time monitoring is also not continuous. Therefore

most interpretation is mainly based on the BWDB data.

The most efficiently, organized and up-to-date computer based

data storage centre has been created by the Master Plan Organization (MPO) under

the Ministry of Irrigation, Water Management and Flood Control. This organization

is dedicated to preparing the National Water Planning Project under the advice of

Dr. G.T.K. Pitman, with the overall supervision of the Harza Engineering Company

International, a U.S. consulting engineering firm. The MPO has collected-collated

basic water-related data from every possible public and private organization involved

in water related projects. Most of the ground water data for the present work were

i fi

69 taken from the MPO with the direct help of Dr. Pitman, though the data centre is mainly based on BWDB data. Lately the MPO itself has expanded its own data generating network by installing its own permanent monitoring wells and by other means.

In the 1960’s the water level measurements were necessarily taken from shallow and hand-dug wells but since the early 1970’s these have been replaced by purpose-built deep boreholes. By September 1986, there were about 95 monitoring wells drilled by BWDB scattered throughout the present project area, from which water levels were and still are measured systematically and regularly once a week. The monitoring of ground water is essential for any assessment of the origin and movement of ground water and the nature of the aquifer system. Regular monitoring over long periods of time is vital to identify and control the effects of dry and wet years, if present.

As in many other parts of the country, the monitoring wells are constructed in the elevated ground of the villages and urban areas usually above the maximum flooding level to avoid the inundation and contamination of the well.

Thus the water level (piezometric surface) does not rise above the ground level.

4.2 Water Level Data Used:

Changes in ground water level with time and space as a consequence of both long term and short term changes of ground water level due to both natural and artificial causes are demonstrated in several sections of this chapter. Long term changes in ground water level i.e. the changes of ground water level with time are explained using continuous eleven years data (from 1976-1986) and are presented in section 4.3 in the form of long term ground water fluctuation

(Fig. 4.1).

70 The short term changes preferably called the changes of ground

water level in space are explained using the weekly measurement of ground water

level data for all the piezometric wells for the year 1985. Different types of contour

map, fluctuation map and flow net maps were constructed to highlight the

interpretation of the changes of water level in space. All the interpretation, both

qualitative and quantitative assessments, including the behaviour of flow patterns are

based on the 1985 data.

4.3 Ground Water Level Fluctuation:

The preparation of a ground water level fluctuation diagram is

one of the standard methods of presenting long term changes of ground water level

to demonstrate the changing behaviour under prevailing conditions. The diagram of

figure 4.1 was prepared using the data recorded from January, 1986 to the end of

December 1986. Three different monitoring wells were chosen to represent

fluctuations from the area as a whole; these are monitoring wells 4, 58 and 142.

The upper limit of this fluctuation graph coincides with the

measuring point level of monitoring well 4 (solid line) and the graduation scale

for this graph is also prepared with respect to this well. The measuring point level

for monitoring well 58 is actually at the 4 m marked level in the vertical scale. In

the same way the measuring point level for the monitoring well 142 is actually

0.5 m above the upper bounding line of the figure. The measuring points for

monitoring wells 58 (lower) and 142 (upper) is presented as broken lines and

essentially indicate that maximum water levels come close to the surface. A brief

description about the water level behaviour for each of these wells is presented

below:

i i;

71 FIG: 4*1: GROUNDWATER LEVEL FLUCTUATION (S3JJ3UI) SOtJJOS O IJ3UIOZ3Xd JO qjd3Q 3 d j q O J d X 3 Z O I U 3 .I J OX S O J J t O S ) I U 3 J J 3 S ( • ( • 3 3 3 3 s ans xquosd dsa s jd q o j oxjqsuiozsxd s n ja B so ) Well Number 4: This well is located in the extreme northern part of the project

area. It is mainly used for irrigation purposes but occasionally the villagers use the

well as a source of potable water. This well shows no consistent long-term decline

in ground water level during the last ten years. The rise of maximum water level

in different years seems to be variable in nature therefore the incremental changes

(Table 8.10) with respect to the previous years sometimes are positive and at other

times become negative. An examination of the seasonal rise of maximum water

level during the last ten years (Fig. 4.1) reveals the following facts. There was a

steady decline of maximum water level for four years from 1975-76 to 1979-80

but during the next two water years (1980-81 and 1981-82) a rise of maximum

water level was recorded. A brief fall of maximum water level in 1982-83 water

year is followed by a rise during the next two water years (1983-84 and 1984-85)

and again a fall in maximum water level is noticed during the 1985-86 water year.

This alternate rise and fall of maximum water level is not at all affected by the

continuously rising number of irrigation wells which is responsible for a steady

increase in ground water withdrawal. This indicates that the amount of withdrawal

is low in comparison with the perennial yield to be revealed by the response of

ground water level.

Well Number 58: Monitoring well 58 is chosen as representative of the east-central

part of the project area. It is installed in the highly populated Comilla town area.

Because of the dense population in and around Comilla there is a great demand for

ground water for both municipal and agricultural purposes which explains why the

Comilla area (more specifically Kotwali thana) has the highest concentration of

wells. Like many others, well 58 is under constant use throughout the year to meet

the ground water requirements. Because of excessive annual abstraction this well

produces the maximum amount of fluctuation (7.0 m or >23 ft). Like the well 4 i I

73 an examination of the maximum water level during the last ten years (Fig. 4.1) reveals the following information. A steady decline of maximum water level was recorded for a period of four years from 1975-76 to 1979-80 and thereafter

maximum water levels recorded a rise for the next two water years (1980-81 and

1981-82) followed by a brief fall during the 1982-83 water year. A substantial rise

in maximum water level was recorded during the 1983-84 water year. Although not

high enough to reach the level of 1976-77 water year it was higher than during the

last six years of record and was followed by a decline of maximum water level

during 1984-85 and 1985-86. These alternate declines and recovery of maximum

water level are a positive indication that the seasonal dry period overdraft of ground

water storage is recoverable in spite of the heavy withdrawal of ground water which

is primarily a consequence of the existing management of ground water resources.

The amount of fluctuation has also substantially increased locally as a result of

increased withdrawal which has caused the lowering of ground water levels and can

be regarded as a local phenomenon rather than of regional significance. This effect

can easily be understood from the opposite behaviour of the maximum water level

in the other two wells. The lowering of the water table also emphasises that the

amount of ground water withdrawal is greater than the seasonal replenishment.

Well Number 142: is located in the extreme southern part of the study area in

Noakhali town (Sudharam thana). The number of wells throughout the greater

Noakhali district in the south is much lower than the other parts to the north. In

some of the upazillas in the greater Noakhali district there is only one deep ground

water well and they are mainly used for municipal purposes as sources of potable

water. Ground water irrigation in the south takes place on a much smaller scale,

there-by suggesting a much lower abstraction. All these facts are revealed in the

form of the long term fluctuation (Fig. 4.1) for well 142. This shows a small but continuous steady rise in maximum water levels during the six years from 1979-

80 to 1985-86 in spite of the limited seasonal amount of artificial withdrawal of ground water. The seasonal dry period losses are fully recharged during the following wet period where the replenishment at the same time increases the perennial yield from this particular well.

4.4 Water Table Contour Maps:

4.4.1 Introduction:

Until August 1985, there were in the project area about 95

BWDB monitoring wells (Fig. 4.2) in which ground water levels were constantly monitored. Ground water level measurements from all these wells have been used to construct various potentiometric maps (e.g-water table contour map of minimum elevation, water table contour map of maximum elevation, and annual fluctuation map) as well as the construction of major flow direction maps for both periods of minimum and maximum elevation. In two of the monitoring wells (Well 60 in

Comilla town and Well 144 in Noakhali town) the water levels have been recorded continuously using an automatic recording device, but in all other piezometric wells the ground water levels were measured manually once a week.

The initial depth measurements to the water table are made not from ground level but from a convenient elevated point called the measuring point

(MP). The height from the ground level to the measuring point is commonly called the parapet The parapet height was carefully taken into consideration when the depth to the water table was converted into elevation (Appendix. 4.1) for the preparation of different types of potentiometric maps. The initial measurements were made in metric units and the depths are expressed in metres. The contours were drawn using a one metre interval, Each contour line represents the point of equal elevation.

75 Using the standard procedure of construction with the flow lines perpendicular to the equipotential lines and the direction of flow from higher elevation (potential) to lower elevation (potential), a flow net was produced. An idealised flow net will produce many ’squares’ depending on the number of flow lines and equipotential lines. The square appearance of a flow net tends to be distorted and is modified into a rectangular shapes depending on the degree of complication of the flow pattern which also largely depends on the inherent complex distribution of the water bearing system.

An interpretation of a water table contour map can reveal several useful features of the properties of ground water. The most useful are: a) it allows measurement of the hydraulic gradient which is a measure of the ground water potential, b) it allows the location of the best possible sources of ground water supply-using the assumption that a wider contour spacing represents a decreasing hydraulic gradient, which in turn suggest a more permeable condition and hence is a better ground water source, and c) a flow net can only be constructed from a completed contour map which enables the identification of the major flow direction.

4.4.2 Minimum Elevation Contour Map:

The contour map of minimum elevation (Fig. 4.2) has been prepared for one of the most dry periods (March, 1985) data. During this period of the year the water table reaches its minimum elevation as a result of a long dry sunny winter (November to March) which is a consequence of the monsoonal climate. At the same time, a maximum amount of ground water is also withdrawn from ground water storage.

A minimum elevation as low as -1 m is recorded at well 79 and less than +1 m at well 8. At the same time a maximum elevation of the

76 ■» i‘| od I 57]j3 F I G:-4-2: WATER TABLE CONTOUR MAP OF MINIMUM ELEVATION INItftNAMONAl BOUNOART ( DRY PERI ODJ MARCH 1 985. U i A H S l L i 1 /

iuhop » G wo ouAiinr s t a i i o n s (UNDP. baoc) ouAinr. pic jo w m s unop ouAtiii• Pina wcus

BAOC OUAUTT » PUMP TfST U ( ( U

W HILC

c r Elevation in metres

A '

L a

Hydraulic gradient measuring potentiometric surface greater than +6 m is recorded at wells 2 and 13, and greater than +7 m at well 52. In the north, well 8 produced the lowest elevation measurement being located somewhat in between wells 2 and 13, and both these wells showed the maximum elevation. Well 79 in the east-central part gave the lowest elevation measurement even being located adjacent to well 52 which produced the other maximum elevation. This abnormal close disposition of two extreme elevations should not in theory occur under normal circumstances.

It is apparent from knowledge of geomorphology and geology that the area has a gently sloping land surface and the present studied aquifer has not suffered any major structural evolution. The eastern boundary has a higher elevation and from there the land surface gently slopes in all other directions until it meets the Meghna river. It is also an established fact that the ground water table is a subdued replica of the land surface, therefore any major changes in morphology should also be reflected in the water table. Since such major changes in the morphology seem to be absent, and since all the wells under consideration

(Nos. 2, 8, 13, 52, 79 and 99) are located along the eastern elevated section therefore the wells 8, 79 and 99 should have produced higher ground water elevation than the measured value. In view of the above interpretation, a further checking of surface topography and surface elevation including the depth measurement of the water table is recommended during any future study which may significantly reduce the complication of the flow behaviour because the possibility of erroneous measurements-either of water level or elevation can not be discounted, though no proof is available.

The construction of a flow net showing flow directions (Fig.

4.3) provides useful information about the response of ground water and also its possible relationship with river flow. Although the constructed flow pattern is very complicated and makes extremely difficult any analysis of the possible relationship

78 war »7]Trf I 9?p FIG:-4-3: MAJOR FLOW DIRECTION BASED ON MINIMUM ELEVATION I N T I R N A 1IONAI BOUNDARY CONTOUR MAP. C H A N N t l S

./ —

AUTO PIEZONfTRIC V U IS

u n o p o u a u t y s t a t i o n s

(UNDP • GWC 1 OUAlirr s t a t i o n s lUNDP.BAotiouAiiTr. p i t z o w m s O?

BAOC OUAIITY* PUMP TEST WCllS

IBADC • GWCIOUAIITY • PICZO.WEUS

II HUE

li 20 KM between the ground water and surface water, useful information can still be obtained. In the northern region, the northern part of the Titas river behaves like a gaining stream while the southern part that merges with the Meghna river provides clear indication of a losing stream. The contribution to or from the Gumti river is some what unclear. The upstream part of the Dakatia and most parts of the

Little Feni rivers show clear indications of a losing stream. The flow pattern of the

Noakhali canal provides clear indication of a gaining stream.

There is a clear contrast in the distribution of contours between the eastern and western parts of the studied area. The contours in the western part are sparsely (thinly) distributed in comparison with those of the eastern part. The extreme closeness of the contours around Comilla town (wells 49, 52 and 60) is mainly because of excessive withdrawal of ground water from storage rather than because of poor aquifer conditions. The hydraulic gradient has been calculated for five different locations (Table 4.1) covering the main contrasting regions indicated in Fig. 4.2. Locations A, C and E were selected from the eastern densely distributed contoured area. On the other hand locations B and D were chosen from the sparsely distributed contoured area. The maximum and minimum hydraulic gradient values are recorded respectively at locations C and D which have a difference of more than two orders of magnitude. A number of reasons could be advanced to account for the steeper gradient in the eastern region and particularly at location C (around

Comilla town). Firstly, the town is a densely populated area which has a high demand for water for municipal purposes all the year round. Secondly, the urban area is surrounded by highly fertile crop lands which also require constant irrigation during the dry season for which the major source is ground water. Thirdly, a considerable amount of ground water is also abstracted for industrial purposes.

80 Hydraulic gradient Period Location dh/dl = i Ratio

D A 3 • 2 6 X lo I *, 3o R Y ~ 4 B | . 0 9 X 10 1 » 9140 Pn , -3 E C | • 27 X 10 I 7-9 a R - 5 1 D 7- IS X 1° 1°. 13930 0 r* D E 2 - 86 X 10 1 % 3500

W - 4 A 3-18 X 10 1 ». 3140 E T B 2- 0% X 10 1 * 47 80 P E C 3-50 X 10 4 1 * 2860 R -4 1 D 2 • 75 X 16 ' 1 3 &40 0 D E 2 • 72. X lo ' I*. 3 680

Table. 4.1: Comparison of hydraulic gradient in the two seasons. Because of all these demands the area has the highest concentration of deep tube wells (DTW) and shallow tube wells (STW) which abstract large amounts of ground water every year, especially during the dry season.

As a consequence the hydraulic gradient sharply increases within the zone of influence of this cluster of wells.

On the other hand, the crop lands in and adjacent to the flood plain areas in the western regions require smaller amounts of ground water or none

at all for irrigation as substantial quantities of surface water is available for this

purpose. As a result, only a small number of deep tube wells have been installed

in this part of the project area and a smaller fraction of the ground water resource

is withdrawn during summer, which is also reflected by the contour distribution.

4.4.3 Maximum Elevation (Wet Period) Contour Map:

The water table contour map for maximum elevation (Fig. 4.4)

has been prepared using the water table measurements for August, 1985 when the

maximum amount of rainfall occurs. During this period of time the highest possible

amount of recharge takes place and in a few cases, particularly close to the flood

plain area, some land surface occasionally becomes inundated.

During this wet period minimum elevations of <0 m have been

recorded at wells 8 and 99 whereas elsewhere the minimum elevations are >4 m

in all other places except the south-western Haimchar, Faridganj, Raypur and

Laksmipur areas. Here the elevation progressively decreases to <2 m which is

expected and logical since the land surface elevation decreases towards the west.

The general direction of flow (Fig. 4.5) obtained from flow net

analysis is much improved and less complicated in comparison with the flow net

map analysis for the dry period. In this map the general flow is more clearly

defined. An interesting feature about the ground water flow is observed within the

82 F IG'.-4-4: WAT E R TABLE CONTOUR MAP OF MAXIMUM ELEVATION (WET PERIOID) IN K RNATIONAl 60 UN DART AUGUST, 1985. CMANNfl j,

ppima «y M...... SCCONOAflT i j VCLL LOCATION

Pit TOMf TRIC w( US

AUTO PUTOMfTRIC writs PUMP U ST Wf11 S

pic to .* p.r. writ s UNOP OUAIITT STATIONS owe QUALITY STATIONS BAOC OUAlIlt STATIONS iunop * o wo ouAiinr stations IUN0P* BAOCI OUAUTY. PIC70 W(llS UNOP OUAIITT* PIC7Q. wens owe QUALITY »PIC70. Will S BAOC OUAIITT* PUMP If ST WfllS 5WC QUALITY' AUTO. Plf TO. WILLS

(baoc • gwciouaiity • pir/o.wciis

UNOP QUALITY• P.T. »PICTO. WCUS

l o L I Until

(, 0 I | I! H to™

Elevation in metres

Hydraulic gradient measuring p o in ts A, B, C, D and E AY OF B E N G A L ff FI G : - 4-5:M AJOR FLOW DIRECTION BASED ON MAXIMUM ELEVATION CONTOUR MAP.

UNOP 0 U*111 r STATIONS

IUNOP • 0 WO QUAlinr STATIONS IUNOP . BAOCI OUAIITY. PltfO WCUS o r~ owe ouAiur • pino. wcus BAOC OUAllTrt PUMP If ST Wflis

laADC'GwoouAtiTr • picto. w cus

12 MIL C

20 km

a*

(Ow—> 4 m closed contour surrounding the Nabinagar and Muradnagar areas in the north­ west (see Fig. 4.4). Here it looks as if ground water is pouring in from all directions. This 4 m contour surrounds the down stream part of the Gumti river suggesting the river is being fed by the ground water but the reverse is true for the upstream part of the same river. Previously the relationship of the Gumti river with the ground water was quite unclear in the dry period flow-net map (Fig. 4.3). The wet period flow-net map shows the Titas river to have characteristics of a losing stream throughout its entire length. The downstream section of the Dakatia river and most parts of the Noakhali canal show the characteristics of a gaining river. The losing characteristics of the Little Feni river are consistent with the dry period flow- net interpretation. The Feni river in the light of this flow-net analysis has characteristics of a gaining river.

The equipotential lines are much more uniformly distributed and the spacing of the contours all over the project area is somewhat similar. Even in the urban areas (around Comilla town) the contour spacing has also increased significantly to give a better co-ordination with the other areas. The hydraulic gradient has been calculated for five different locations (Table 4.1) which are close to those considered previously. The wet period values are remarkably close to each other and they are also fairly small. Such a close correlation in hydraulic gradient suggests a similar distribution of resource potential in different regions. It also indicates that the entire or most parts of the aquifer is well connected and the permeability does not change abruptly. This in turn also indicates that the lithological variation is minimal. An increase in contour spacing, particularly in urban areas (around Comilla town), indicates some augmentation in ground water storage during the summer time.

85 4.4.4 Annual Fluctuation Map:

The fluctuation in ground water elevation has been determined at the points of intersection by subtracting the elevation of minimum water table contours (Fig. 4.2) from the elevation of the maximum water table contours (Fig.

4.4) by superimposition of the two maps with additional fluctuations obtained as the difference between dry and wet periods in all the available wells. The resultant data were used to prepare the annual fluctuation map (Fig. 4.6) for the year 1985.

The use of both types of fluctuation values allowed a greater number of points to be taken into consideration for the better preparation of the map and the more accurate the contours are drawn so also will be the interpretation.

The maximum amount of fluctuation (>10 m) is recorded around the Comilla town where the maximum amount of ground water is withdrawn during dry period. The minimum amount of fluctuation as low as zero (0) m is recorded in the northern part of Nasimagar area. Further north, close to the boundary, an area of negative fluctuation (-1 m) is recorded which implies a rise in water level during dry period. This seems to be unlikely on the basis of the prevailing condition, when the water table elevation is expected to be declining.

A possible explanation for the rising water table could be that more water is coming into storage via horizontal flow and deep percolation as well as from the effluent Titas river than the amount of water that is flowing out naturally and/or taken out from storage by pumping through the existing large number of wells.

The changing fluctuation pattern in the north is quite different from those in the south. In the north, the maximum fluctuation is intermediate and gradually decreases in all directions. However, for the larger southern part the reverse is true i.e.-the central part gave rise to the lowest fluctuation and increases on all other direction except the south-eastern narrow strip where the fluctuation decreases into the Feni river, which itself behaves as a gaining river. The change

8 6 FIG:-^-6: CONTOUR MAP SHOWING HOEHDS ANNUAL FLUCTUATION FOR 1985. IN T[ RNATIONAl BOUNOARY C HA NNCL S

PRIMARY

scconoary

Will LOCATION

rlf 70MC TRIC WILLS

AUTO P1f70H[TRlt WCUS PUMP TfST WCUS

pir7o-«p-r- w c u s

UNOP QUALITY stations owe QUALITY STATIONS BAOC OUAUTY STATIONS

IUNOP . g wo ouAiinr stations IUNOP . BAOCI OUAUTY# piezo WCUS UNOP OUAlirr* PIC7Q. WCllS GWC QUALITY • PIC 70- WCLLS BAOC OUAUTY * PUMP Tt ST WCUS OWC QUALITY • AUTO. PIC70. WCLLS I8A0C • GWCIOUALI IY * PIC70.WCUS UNOP QUALITY• P.f.• PIC70- WCllS

I? Milt

8 W U 80 KH

Fluctuation in metres.

BAY OF BENGAL in fluctuation is large in the Comilla town area and consequently the gradient of the increasing fluctuation is also very high in the town area. The contour spacing of the annual fluctuation contour map increases in west, north-west and south-western directions, in similar fashion to the contour spacing of the dry period elevation contour map (Fig. 4.2).

In all locations the increased amount of fluctuation has coincided with the higher amount of ground water withdrawal. A high withdrawal is not necessarily harmful for the aquifer. In fact a controlled high withdrawal in relation to the annual recharge makes more ground water available for use. On the other hand, the excess amount of recharge which was previously unable to be taken into storage because of early saturation could now be accepted by the aquifer by virtue of the creation of more space by excessive withdrawal.

4.5 Replenishment Calculation:

The yearly replenishment for the year 1985 is calculated using the prepared fluctuation contour map (Fig. 4.6). The replenishment is calculated in the form of volumetric changes multiplying the area involved by the average fluctuation. Since the amount of fluctuation ranges from -2 m to +11 m and the map has a contour interval of 1 m, the volumetric changes between every two consecutive contours were calculated separately to obtain better results which are displayed in Table 4.2.

The total volumetric change in the contours between the extremes of -2 and

+11 m is equivalent to some 28,500 million [= 2.85335 x 10+1° m3 ].

Finally the total amount of recharge in the form of effective infiltration (Ic) is calculated using the following relationship:

1) Ie = [(Wy x Sy)/a] to get the results in terms of height in (mm/year), and

2) Ie = (Wy x Sy) to get the results in volume in (m3/year).

8 8 Contour Area between Average Volumetric interval contours fluctuation change (Wy) (m) (m2) (m) (m3)

- -2 -+o - ( S-95* lc? IS l-3 4 3 x lo J. - 1 -U O 1 • So X lo 0-5 9 .000X lo

0 f© 41 5 - 4 9 x l o 8 0 - 5 2- 445X lo

9 -+ I h> -t2 1 - 7 S x 'o 9 1-5 2. 640 X lo

. >o ■+ 2 it> 4- 3 4 -1 5 x w 9 2 - 5 [. 03% X lo

9 4 3 4 4 2-26 * lo9 3 - 5 7 . 910 X to

9 -f 4 + 5’ 6 .4-2 x 10s A '5 2-889 X lo

-1-5 4-£> 1- 61 x los 5 - 5 £ - 8 5 5 X 10

, 8 -+ 6 -to 4 4- I.34 X lo8 6 - 5 §.410 x lo

-1^ fo i S 9 - ? 2 X I <4 7-5 ? -2 9 o X lo

, 8 4 S iro -+9 7 - 4 0 X lo^ « '5 £. 290 X 10

4 9 -fo 4 \0 5 • 02 X lo7 9 - 5 4 . ? 6 9 X 10s

4 lc> {-o -Ml 5- 66 x lo? lo- 5 5 . 943 X 10

10 lo — T O T FV L I-02235X 10 2.. 8 5 33SX lo

Table. 4.2: Volumetric changes covering the entire region. where,

Wy = total volumetric changes = (2.85335 x 10+1° m3 ).

a = area over which recharge occurred = (1.02235 x 10+1° m2 ) and

Sy = specific yield = 20 percent.

The specific yield can be determined directly by analyzing pumping test data when the aquifer is unconfmed; in this case the late storativity is equivalent to the specific yield. But when the aquifer condition is other than unconfined, which is true for the present study area, then the specific yield cannot be determined from pumping test data because in these circumstances the aquifer can not be dewatered. Hence, the specific yield has to be determined in an alternative fashion. The commonest way, however, is to determine from the porosity analysis result where the volume of linked porosity is taken as equivalent to specific yield.

Unfortunately neither the actual porosity of the aquifer material nor the specific yield has been estimated by any other means. In these circumstances one can experimentally establish a value of specific yield. Three different sources were considered before selection of a reasonable value of specific yield justifiable for the existing lithological conditions which are a mixture of different types of unconsolidated sands and gravels (Section 3.3.2). The specific

yield determined by Poland et. al. (1959) for sand, sand and gravel, and gravel and

sand is about 20 percent. In another study Walton (1970) experimentally established that the specific yield for the present type of materials ranges from 15 to 25 percent

and this is reprinted by Driscoll (1987) in Johnson divisions book ’Groundwater

and Wells’. In another instance, Fetter (1980) has compiled the value of specific

yield from a large number of samples distributed in various geographic locations,

where it is found that the value of specific yield ranges from 20 to 35 percent for

sands and gravels with an average of 25 percent. The average of these three

90 published accepted values of specific yield is about 22 percent but to be on the safe

side a specific yield value of 20 percent has been selected to calculate the ground water replenishment and other parameters in the subsequent chapters. Using this

specific yield value the calculated value of effective infiltration (Ie) in both forms

are:

Ie = [(Wy x Sy) / a] = [{2.85335 x 10+1° x 0.20} / 1.02235 x 10+1° ]

= 558.22 mm = 5.71 x 10* m3.

4.6 Comments on Ground Water Movement and Flow Pattern:

From the foregoing analysis of various water table contour

maps and flow direction deductions, it can be concluded that in general ground

water flow directions are mainly towards west, south-west, north-west and south

with few exceptions where the flow of ground water is found to be towards

eastern directions. This flow pattern has developed because of variable sloping

directions of the land surface. The following comments can be made on the basis

of analysis of various aspects of ground water flow:

1) all the perennial rivers maintain a direct relationship with the ground water.

Most of them in their downstream sections show characteristics of a gaining river

and the upstream sections show characteristics of a losing river, except the Little

Feni river which shows the reverse characteristics. This feature is revealed in both

the dry period and wet period flow net maps.

2) the uniform distribution of contours in the contour map (Fig. 4.4) suggest

that enough water is available during the wet period and the ground water storage

is full to its capacity. At the same time, it may also indicate that this uniform

nature of the contours all over the places may also indicate minimal lithological

variation. 3) the general concept that increasing spacing of the equipotential lines means smaller hydraulic gradients which in turn suggest greater ground water potential has again been proved to be true. But one has to be careful that an aquifer having good ground water potential can also produce a higher hydraulic gradient resulting in close contour spacing because of excessive withdrawal from storage.

4) the higher elevation (which also coincides with the higher fluctuation) of the water table around Comilla town to some extent could well be due to the partial blockage of ground water flow by the north-south trending Lalmai Hills located in the west of Comilla town, the only relics of the Tertiary structure.

5) the annual fluctuation is at a maximum near the places from where maximum amount of ground water is withdrawn during the dry period i.e.-amount of fluctuation maintains a direct relationship with the amount of withdrawal, which suggests that the minimum levels are not natural, but instead are accentuated by pumping effects. What is significant is that the seasonal replenishment commonly restores water levels to their natural maxima, this being indicative of high value of effective infiltration.

92 CHAPTER 5 AQUIFER TEST ANALYSIS.

5.1 Introduction

5.1.1 General Information.

5.1.2 Well Structure.

5.1.3 Hydraulic Properties.

5.2 Analytical Solution.

5.2.1 Validity of Measurement.

5.2.2 Selection of Methods.

5.2.3 Presentation and Discussion of Analyses.

5.3 Numerical Solution.

5.3.1 Radial Flow Model.

5.3.2 Presentation of Analyses.

5.3.3 Discussion in Results.

5.4 Comparison of the Results.

5.4.1 Comparison of Individual Sites.

5.4.2 Overall Comparison.

93 5.1 Introduction:

5.1.1 General Information:

Being a part of a deltaic plain, the study area shows rapid facies changes along with characteristic lack of lateral continuity. This characteristic change in lithology is reflected in the rapid changes of aquifer condition from confined to semi-confined over very short distances even from one observation well to another at the same pumping well site.

A total of fourteen pump tests (see Fig. 5.1) were carried out by the

Bangladesh Water Development Board (BWDB) in and around the present project area. Eleven of them are constant rate tests i.e. the well was pumped for a considerable period of time at a constant discharge rate; such a test is often called an aquifer test. Seven of them are step-drawdown tests (over-lapping in some of the wells) i.e. the well was pumped at successively greater discharges for relatively short periods of time. Such a pumping test is sometime called a well test. During the pumping test session three to four observation wells (OW) were used with the pumping well where the change in water level (drawdown) was also measured.

These various drawdown-data measurements in the OWs facilitate the adoption of both time-drawdown and distance-drawdown solutions in the analysis of the important hydraulic parameters such as transmissivity (T), storativity (S), hydraulic conductivity (K), leakage factor (L), and others depending on the hydrogeological nature of the aquifer (i.e. whether it is confined, leaky-confined or unconfined). All these aquifer parameters provide vital clues about the storage as well as the transmitting properties of the aquifer. The drawdown data from the pumping wells have not been used to analyze any of the hydraulic parameters since drawdown data for several OWs are available.

When the well is pumped during the aquifer test the position of the potentiometric surface declines with time producing the drawdown response which

94 TJTeT

I N Tt MAYIONAl IOUNOAAT

Will. LOCATION

Site of tests

ar

Devidw

Baud k Buricfmjg*

Ch.mdina

B a r u r

L a ks a mi m

eni

S e n b a g h

BAY OF BENGALI

Fig. 5.1: Map showing the location of aquifer testing wells. is measured in the pumping well and in the nearby observation well at specified times. This recorded time-drawdown data allows the utilisation of various analytical and numerical methods for calculating the hydraulic parameters.

5.1.2 Well Structure:

From the top to the bottom of the hole the well is given a metallic structure for all cases in the study area because of the unconsolidated nature of the aquifer. Depending on the shape, size and use of the well, the total structure is divided into five different segments (Fig. 5.2). According to their position from top to bottom they are:

(1) Housing pipe: In most cases the housing pipe is around 80 feet (about 24 metres) in length with a width of 14 inches (about 36 cm). It is wide enough to accommodate a turbine pump.

(2) Reducing Socket: This part connects the housing pipe to the bottom part of the well pipe and at the same time reduces the well radius to the desired limit.

Usually the vertical length of the reducing socket is around 2 feet (0.61 m) in length.

(3) Blind pipe, Strainer and Bail Plug: From the reducer to the bottom of the well, the structure maintains a constant diameter in most of the wells; it is 0.25 ft

(0.08 m) except for a few instances when it is 0.33 ft (0.1 m). Depending on the presence of prospective aquifer horizon(s), single or multiple strainer (screen) segments are set against the best horizon(s), rather than placing strainers throughout the entire length of the aquifer, in order to minimise the well construction costs and to increase the performance of the well. Except for the lowest 5 or 10 ft (1.5 or

3.0 m), depending on the depth of the well, the entire well fixture length is completed with blind pipe. The bottom 5 ft (3.0 m) is called the bail plug which marks the physical end of the well.

96 V

Housing Pipe

— K - — a

K z z y * Reducing Socket

B l i n d P i p e

S t r a i n e r

Blind P i p e

S t r a i n e r

Bail Plug

Fig. 5.2. Generalised structure of the constructed wells. During the construction of the well in almost all cases the entire thickness of the aquifer was utilised to avoid partial penetration effects.

5.1.3 Hydraulic Properties:

The most important hydraulic properties of a potential aquifer are twofold in number. Firstly, the storage capacity (i.e. the water bearing formations should be capable of holding sufficient quantity of ground water within the pore spaces) which is reflected by a property called storativity (S) and is dimensionless.

Secondly, the yielding capacity (i.e. the water bearing formation(s) should be able of transmitting a sufficient quantity of ground water through the linked porosity) and this property is represented by the parameters known as transmissivity (T) and hydraulic conductivity (K).

Storativity is defined as the quantity of water that an aquifer releases from or takes into storage per unit surface area of aquifer per unit change in the component of head normal to the surface. Two important properties are related to the storage function which are porosity (more precisely the linked porosity) and specific yield (Sy). Porosity is an index of how much ground water can be stored in a saturated medium, and specific yield is a measure of how much water can actually be taken out from that storage. The coarser the sediment the higher will be the specific yield. The storativity of an unconfined aquifer (equivalent to their specific yield) ranges from 0.01 to 0.30 while the storativity of a confined aquifer is much lower because it is not drained during pumping (hence specific yield can not be determined) any water released from storage is obtained primarily by the compaction of the aquifer and expansion of the water. In a confined aquifer, water is always stored under high pressure and because of pumping this pressure is reduced to some extent which allows the water to expand though the aquifer is not dewatered. Typical storativity values of a confined aquifer range from 10 '5 to

98 10-3.

The hydraulic conductivity (permeability) indicates the quantity of water that will flow through a unit cross sectional area of a porous medium per unit time

under a hydraulic gradient of 1 (100 percent) at a specified temperature. A

hydraulic gradient of one means a head fall of 1 ft or 1 m for every 1 ft or 1 m

of flow travel. The common range of K is generally from 10 to 5000 gpd/ft 2 in the

English units system (or 0.5 to 200 m/d in the metric system of units) for natural

aquifer materials (Freeze & Cherry, 1979). The transmission of water through the

entire thickness of the aquifer is more informative than the flow through the unit

area of the aquifer. Theis (1935) introduced the concept of ’transmissivity* by using

the product of K and b as a single term defining it as the rate of flow through the

vertical section of an aquifer one feet (or other units) wide and extending the full

saturated thickness of an aquifer under a hydraulic gradient of 1. It is expressed as

m3/d/m or simply m2/d accordingly to the metric system and in the English unit

system it is gpd/ft or fti/d.

Among the several methods available for the determination of hydraulic

parameters, the results obtained by analyzing pumping test data are the most

accurate. When a well is pumped at a constant rate for a known time an

exponential decrease in water table (or piezometric surface) takes place within the

well and adjacent aquifer unless it intercepts a boundary (such as faults, rivers etc.)

or induces a vertical flow of water through the overlying semi-pervious confining

layer or receives gravity drainage equal to the amount of water being pumped from

the bore hole. The horizontal distance up to which the lowering of water level takes

place is called the zone of influence. The change in water level at a point during

pumping is called the drawdown (s). This when plotted against time, either

arithmetic scale or log-log scale, provides several values which then can be inserted

into various analytical formulae developed by Theis, Jacob, Hantush, Walton, De

99 Glee and others. For confirmation purposes, a numerical technique can also be used to calculate various hydraulic parameters depending on the type of aquifer.

5.2 Analytical Solution:

5.2.1 Validity of Measurement:

During the conduct of pumping tests in the study area, three observation wells were used for every test site to obtain more accurate results. The distance to the observation wells from the pumping well was limited to between 50

and 1000 ft, and varies from one well site to another.

A careful study of the time-drawdown data plots of all 33 observation

wells reveals various discrepancies within the data proper, and ignorance of these

facts could have produced misleading results.

Good quality data when plotted on semi-log paper or on double

logarithmic paper, should give a progressive increase in drawdown or a decrease in

the case of recovery. This rule is not maintained in two cases. Firstly, the short

time increase and decrease in drawdown during the first 30 minutes observed at

Burichong O.W. at r = 100 ft (30.48 m) in Fig. 5.8.A and Kotwali O.W. at r = 400

ft (121.92 m) in Fig. 5.10.C. These irregularities could be due to inefficient

measurement of data or could be due to rapid changes in sedimentary facies i.e.

alternating thin bands of clay/silt lenses within the aquifer. It is not due to an

uncontrolled rate of pumping because this effect is absent in other observation

wells. Secondly, the long-term fluctuation (increase and decrease) in drawdown

and/or recovery through-out the entire length of pumping session seen in Nabinagar

O.W., at r = 400 ft (121.92 m) Fig. 5.4.B; r = 1000 ft (304.8 m) Fig. 5.4.C; and

Kotwali O.W., r = 50 ft (15.24 m) Fig. 5.10.A and r = 400 ft (121.92 m) Fig.

5.10.C suggest that this could be due to inefficient measurement of data or more

likely to slight variations in pumping rate.

100 The unexpected sudden rises in drawdown seen in Daudkandi O.W., r

= 150 ft (45.72 m) Fig. 5.7.B; Chandina O.W., r = 50 ft (15.24 m) Fig. 5.9.A;

Chandina O.W., r = 150 ft (45.72 m) Fig. 5.9.B; Chandina O.W., r = 400 ft

(121.92 m) Fig. 5.9.C1 and Barura O.W., r = 150 ft (45.72 m) Fig. 5.10.B when the wells were attaining steady state conditions indicates interference drawdowns due to the pumping of a neighbouring well. Some rises in water level return to their steady state conditions, indicating that the interference wells were pumped only for a short time and then stopped before the cessation of the pumping test session.

The cone of influence should produce a greater drawdown in the nearer observation wells and a smaller drawdown at the farthest wells. This rule is maintained for the two O.W. [r = 150 ft (45.72 m) Fig. 5.9.B and r = 400 ft

(121.92 m) Fig. 5.9.C] of the Chandina test site, but a surprisingly small drawdown was recorded at the well at r = 50 ft (15.24 m) (Fig. 5.9.A) which is smaller than the recorded drawdown for the farthest observation well. Therefore the time- drawdown data of the nearest observation well cannot be used for calculating the hydraulic parameters.

A negative drawdown is only expected in the presence of a barrier boundary condition. How many times the plotted data will change gradient will depend on the number of boundaries in the vicinity of the well site. The drawdowns produced at the Barura O.W. with r = 50 ft (15.24 m) Fig. 5.1 l.A indicate the presence of a double boundary condition whereas the observation wells with r = 150 ft (45.72 m) Fig. 5.1 l.B and r = 400 ft (121.92 m) Fig. 5.11.C at the same pumping site produce no negative effects. If it were a true boundary condition then all the observation wells should have the same effect. Alternatively, it might be that a true boundary condition exists which is present close to the affected observation well and the unaffected wells are present on the opposite side of the pumping well from the boundary. Since the lay out of the test wells is not

101 available, this problem cannot be resolved, and also suggests that the data from r

= 50 ft (15.24 m) cannot be used for the final calculation of hydraulic parameters.

With all these difficulties in mind, the pump test data were analyzed using several types of solution to avoid confusion.

5.2.2 Selection of Methods:

It is desirable that a pumping test should be continued until steady state flow conditions have been reached i.e. the recharge to the aquifer is equal to the pumping rate. In practice it is found that a steady state condition cannot be reached for all types of aquifer condition. It is very difficult for example to achieve a steady

state condition for a truly confined aquifer because no actual dewatering takes place.

Also constraints on time and costs mean that most pumping tests have a duration

shorter than ideal. An advantage of longer pumping of well is that it may reveal the presence of boundary condition previously unknown.

The drawdowns observed in each well and/or piezometer during

pumping are then plotted against the corresponding time either on a semi-log paper

or on a double logarithmic paper to produce time-drawdown or distance-drawdown

curves. Analytical solutions are of two basic types (a) time-drawdown and (b)

distance- drawdown solution both of which can be analyzed by the straight-line

method (semi-log plot) and the type curve method (double-log plot). A few methods

such as that of Hantush (1956) require both time-drawdown and distance-drawdown

data for all the piezometers. For the present project, time-drawdown and distance-

drawdown solutions were both applied to analysis of the data since one method is

complementary to the other.

The shape of the time-drawdown plot (both straight-line and type-curve

method) provides important guidelines for understanding the nature and condition

(whether confined, semi-confined or water table) of the aquifer. A confined aquifer

102 condition produces a steep curve with constant gradient. A leaky confined condition initially produces a steep curve with high constant gradient which with increasing time gradually flattens so that if the duration of pumping is long enough then it reaches a steady-state condition. An unconfined aquifer, on the other hand, produces

a plot with three distinct segments. The first segment is analogous to the curve of

a confined aquifer since initially water is released instantaneously from storage by

the compaction of the aquifer and by the expansion of water. The second segment

shows a decrease in slope because of the replenishment by gravity drainage from

the horizon above the depression cone. The third segment again shows a rise in

the gradient and maintains a slope almost similar to the first segment. If the time-

drawdown is plotted on double logarithmic paper then the first and third segments

closely conform to the Theis type-curve when it reaches an equilibrium between the

gravity drainage and the rate of pumping.

In the light of knowledge of the geology and the above mentioned

aquifer responses, the data plots produced for all the pumping test sites suggest

leaky confined condition except in two wells (Feni well 117 and Senbagh well 130).

After a careful screening, the Theis (1935) and Jacob & Cooper (1946) non-steady

state solutions were used to analyze the confined condition. The Walton (1962) and

Hantush (1956) non-equilibrium and De Glee (1930,1951) equilibrium methods were

used to analyze the leaky confined conditions. Though each method is based on the

Theis formula, every solution has additional conditions to fulfil. Yet some basic

assumptions are common to many method of solutions:-

(1) the aquifer has an infinite lateral extent,

(2 ) the aquifer is homogeneous, isotropic and of uniform thickness over the area

influenced by pumping,

(3) prior to pumping, the potentiometric surface is nearly horizontal over the area

influenced by pumping,

103 (4) it should be an efficient pumping well and pumped at a constant rate,

(5) the pumping well penetrates the entire thickness of the aquifer and receive

water by means of horizontal flow, and

(6 ) the well diameter is infinitely small i.e. the storage in the well can be

neglected.

A brief outline of the methods used are given below:

Theis Method:

The non-steady state solution was first introduced by C. V. Theis

(1935) and derived from an analogy of ground water flow with that of heat conduction. In doing that he took into account the related parameters of pumping duration and the storativity of the aquifer. This is a type curve solution so that the time-drawdown data is plotted on double-logarithmic paper and requires matching of the data with a specially prepared Theis type-curve to obtain values of W(u), u, t and s which are known as the ’match point’ co-ordinates. The formulae he developed to calculate the transmissivity (T) and storativity (S) are:

Q W(u) 4 T t u X = ------and S = ------4 n s r2

This solution needs to satisfy the following conditions and general assumptions;

(1) the aquifer is confined i.e. the water bearing zone is bounded by

impervious layers both at top and at bottom,

(2 ) the flow to the well is unsteady i.e. the drawdown difference with time is not

negligible nor is the hydraulic gradient constant with time, and

(3) the water removed from storage is discharged instantaneously with the

decline of head.

104 Jacob and Cooper Method:

This method is also based on Theis method but it depends on the relationship that when sufficient time has elapsed for a discharging well then the drawdown at a fixed distance increases approximately in proportion to the logarithm of time since the pumping started and decreases in proportion to the logarithm of the distance from the well.

Jacob’s approximation of the Theis formula in the form of the straight- line equations he derived employ both time-drawdown and distance-drawdown solutions for the calculation of T ’ and ’S’, provided the value of ’u’ remains less than 0.02. In this connection, to check that the value of ’u’ is appropriate requires the calculation of ’tfl’ which indicates how much time should elapsed before the method is valid for a particular set of data.

One technique requires the time-drawdown plot (semi-log scale) and uses the following formulae to calculate the hydraulic parameters:

0.183 Q T = ------x log (tA ) ds

2.25 T to 12.5 i2 S S ------and t,!------t2 T

The second technique uses a distance-drawdown plot (semi-log scale) and the following formulae to calculate the hydraulic parameters:

0.366 Q 2.25 T t X = x log (rj/rl) and S = ------ds (r0)2

Walton Method:

This type curve method for analyzing the hydraulic properties of a

105 leaky confined aquifer combines the ideas of Theis and Hantush in the preparation of a family of type curves depending on the degree of leakage. Along with the previous general assumptions this method must also satisfy the following additional limitations:

(1) the aquifer is semi-confined,

(2 ) the flow to the well is unsteady, and

(3) instantaneous removal of storage water takes place with the decline

of hydraulic head.

After obtaining a satisfactory match with one of the family of type curves the match point co-ordinates of W(u), u, s and ^ are recorded to calculate the following hydraulic parameters:

Q W(u) T = ------4 71 s

4Ttmu r S = ------and L = ------i2 (r/L)

Hantush Method:

Hantush (1956) developed several methods, some dedicated to steady

state conditions and others applicable for non-steady state conditions. Therefore

selection of procedures depends on the nature of aquifer. Two of his procedures

were adopted for analyzing the aquifer parameters.

Firstly, with his time-drawdown procedure, the accuracy of the results

depends on the extrapolation of the maximum drawdown value (smax) and the correct

positioning of the associated inflection point. This method requires fulfilment of all

the additional assumptions applicable for the Walton method.

Calculation of the different hydraulic parameters using the following

formulae requires values for r/1 and e ‘r/1 from a tabulation produced by Hantush

106 (1956):

2.303 si r e(r/1) Ko (r/L) = ------L = ------dSi (r/1)

0.183 Q 4 T t* 12.5 i*S T = ------x e( r/1) S = ------and ttl = ------ds; 2 r L T

The second procedure is a distance-drawdown solution using a straight line method for determining the hydraulic parameters which requires at least two observation wells (but greater the number of OW’s the better the results) as well as the time-drawdown data for each observation well. A second semi-log plot with the change of drawdown per log cycle of time over the distances of the observation wells is also required. This method requires all the same additional assumptions to be fulfilled as for Walton's method including the general assumptions.

De Glee Method:

Unlike the confined aquifer, a steady state condition can be achieved for a leaky confined aquifer after pumping the well for a long enough period of time when the discharge rate of pumping well equals the recharge rate from the overlying semi-pervious layer in the form of vertical flow. De Glee’s method of solution requires steady state drawdown for each observation well. As it is a distance-drawdown type-curve solution, a number of observation wells is always desirable to obtain more accurate results. The following extra conditions are needed to be fulfilled in addition with the general assumptions:

(1) the aquifer is leaky-confined,

(2 ) the flow to the well is steady state i.e. there is no change in

drawdown with time,

107 (3) the phreatic surface remains constant (drawdown of the phreatic

surface < 5 % of the saturated part of the semi-pervious layer)

so that leakage through the covering layer takes place in proportion

to the drawdown of the piezometric level, and

(4) leakage factor is more than three times the aquifer thickness i.e.

L = > 3b.

Unfortunately this method is incapable of giving any storativity value but the match point co-ordinates of K^r/L), r/L=l, and s allows T and L to be determined with the following equations:

Q T =s------x Ko(r/L) r/L = 1 or r = L. 2 71 s

5.2.3 Presentation and Discussion of analyses:

The result of the pumping test analysis for the project area are presented in this section individually and systematically from north to south (Fig.

5.1). Detailed calculations of one test result are presented below from each group

of aquifer conditions with the main calculations for the other test sites only the final results are tabulated. The Feni Pumping test site is selected to represent confined

condition and the Nabinagar pumping test site is taken as the representative of the

leaky-confined conditions. The pump test data are presented in Appendix. 5.1.

Theoretically speaking, the results of the analysis of a pumping test

obtained from the different methods of solution used should normally show little

variation. However, since a good agreement in the results very much depends on

the successful conduct of the test, the accurate measurement of time-drawdown data

is of utmost importance. The variation in the results also depends to some extent

on the variation of the lithology in the vicinity of the pumping and observation

wells. Since a frequent change in lithofacies is an important characteristic of the

108 sediments deposited under deltaic conditions, therefore a variation in the results from different observation wells at the same site may not be unexpected.

Feni Pumping Test Site:

The well has a depth of 191.58 ft (58.4 m) with a well radius (r) of

0.25 ft (7.6 m). During the pumping test, the well was pumped with a constant

discharge (Q) = 4574 m3/d (161,553 ft 3/d) for a period of 4300 minutes. (3 days).

The observation wells are spaced at distances of 50 ft (15 m), 400 ft (120 m) and

1000 ft (305 m) respectively. The estimated thickness of the aquifer is about 110

ft (33 m) and the overlying aquiclude has an estimated thickness of 82 ft (25 m).

Static water level (SWL) is 11.33 ft (3.45 m) below measuring point (bmp). The results of analysis of the pumping test data are summarised in Table 5.1.

1) NSS/NLC/Time-Drawdown Solution:

Feni O.W. (r = 50 ft):

(a) Type Curve Method:

The log-log plot of Figure 5.3.A(a) was used to obtain the indicated match

point co-ordinates for the calculation of the following hydraulic parameters:

Q W(u) 61553 x 1 T = ------= ------= 11687.25 ftVd 4 n s 4 7t 1.10

or 1090 m2/d.

K = T/b = 11687.25/110 = 106.25 ft/dor 32 m/d.

4 T t u 4 x 11687.25 x 5.2 X 0.01 S = ------= = 6 .8 x 10"4 . i2 (50)2 x 1440

109 SITE:- FENI WELL No:- 1 1 7

(a) SOLUTION:- TIME-DRAWDOWN

DISTANCE VALUES OF HYDRAULIC PARAMETERS OF METHOD T (m2/d) S(-) K=T/b (m/d) L (m) PIEZOMETER D’cJown RFC. ID'down RFC. D'down RFC. D'down RFC.

- - - - 5 0 f t . SL 9 3 0 - IT (-3) 2 S

1 5 . 24m . TC 1090 - 6&

- 4 0 0 f t . SL <8 9 0 - l-S.f-3) - 2 7 - -

- 121. 92 m. TC 9oo - 4<-4) - 3 2 - -

- 1 0 0 0 f t . SL 9 3 0 - S£>(-4) - 2 8 - -

3 0 4 . 8 0 m . TC - 9-5 (-4) - 2 t - - -

AVERAGE VALUES 9 4 0 - il (-$) - 2 9 - - -

INFERRED CONDITIONS FULLY CONFINED

( b ) SOLUTION:- DISTANCE - DRAWDOWN

METHOD VALUES OF HYDRAULIC PARAMETERS r(m) T (m2/d) s, (-) ^2 (') s, (-) K (m/d) L (m)

15-24 ------

- - - - SL (II) I2I - 9 2 - -

3 0 4 - 8 0 - - - - -

TC (SS) ------

- TC (NSS) - 11 9 0 - 6-(.(-4) - 3 G

SL (II) - II AO - a - 3 4 -

AVERAGE VALUES 11 =f 0 - ■ST (~f) - 3 5 -

INFERRED CONDITIONS FULLY CONFINED

Table. 5.1. Pumping test analysis results (analytical) of Feni Well; (a) Time- Drawdown and (b) Distance-Drawdown. (a) TYPE CURVE : TIHE'DRAWDOWN PLOT FENI PIEZO. WELL AT A DISTANCE R ' 50.0 FT Q ' 161553 FT3/D L0G10

LU Q = 161553 ftVd LlI IL r = 50.0 ft Z O3 3Q < CE a t = 5.2 mins

W(u) = 1

1/u = 100

110.0 ft

TIDE ((1INUTES)

(b) STRAIGHT LINE METHOD : TIME-DRAWDOWN PLOT

FENI PIEZO. WELL AT A DISTANCE R - 50.0 FT Q - 161553 FT3/D

Q = 161553 ftJ/d 10 r = 50.0 ft

12 to = 0.27 mins 13 ds = 2.95 ft

110.0 ft 15 16

16L -1 L0G10 TIRE (MINUTES)

Fig. 5.3.A : Aquifer test analysis for 0W 1 at Feni; (a) Type Curve and (b)Straight Line. (b) Straight Line Method:

The ’ds’ and V values were taken from the semi-log plot [Fig.

5.3.A(b)] to calculate the following parameters:

0.183 x Q 0.183 x 161553 T = ------= ------= 10021.76 ft7d ds 2.95

or 930 m2/d.

K = T/b= 10021.76/110 = 91.11 ft/d. or 28 m/d.

2.25 T to 2.25 x 10021.76 x 0.27 S = ------= ------= 1.7 x 10-3. r2 (50)2 x 1440

12.5 r2 to 12.5 x (50)2 x 1.7 x 10 3 tiI = ------= ------= 5.3 x 10'3 days T 10021.76

or 7.6 minutes.

Feni O.W. (r = 400 ft):

(a) Type Curve Method:

The match point co-ordinates of W(u), u, t and s are obtained from the log-log plot [Fig. 5.3.B(a)] to calculate the following hydraulic parameters:

Q W(u) 161553 X 1 T = ------= ------= 9813.72 ftVd. 4 n s 4 k 1.31

or 910 m2/d.

K = T/b = 9813.72/110 = 89.22 ft/d or 27 m/d.

4 T t u 4 x 9813.72 x 9.00 x 1 S = ------= = 1.5 x 10*3. r2 (400)2 x 1440

112 9.0CL 8 8.50: 6 6 3.50: 2.50: 3.00: 2 1.50: 1 . . . . . DRAUDOIJN (FEET 0 0 50 0 0 0 0 50 L 00 00 -2 1 - L0G10 Fig. -1 : : : : -1 : _ (b) STRAIGHT LINE HETHOD : TIME-ORAWDOWN PLOT : TIME-ORAWDOWN HETHOD LINE STRAIGHT (b) 5.3.B (a) : Aq : u i f e r t e s t a n a l y s i s f oa r t OW2 F e n i ; ( a ) T y p e C u r v e EI IZ. ELA ITNER 0. TQ- 653 FT3/D 161553 -Q FT 400.0 -R DISTANCE ATA WELL PIEZO.FENI a n d ( b ) S t r a i g h t L i n e . s 30 ft 3.08 = ds o 1. mins 19.0 = to r = 400.0 400.0 = r Q EI IZ. ELA ITNER 0. TQ-115 FT3/D 161553 -Q FT -400.0 R DISTANCE A AT WELL PIEZO. FENI TYPE CURVE TIHE-DRAWDOWN : PLOT = 161553 161553 = 110.0 ft ft ftJ/d TINE (I1INUTES) iE (NINUTES) TinE u) 1 = ) (u W mins 9.0 = t = 0. ft 400.0 = r Q 115 ftVd 161553 = 110.0 110.0 ft L0G10 L0G10 (b) Straight Line Method:

The ’ds’and V values were taken from the time-drawdown plot [Fig.

5.3.B(b)] to calculate the following hydraulic parameters:

0.183 Q 0.183 x 161553 T = ------= ------= 9598.76 ft7d ds 3.08 or 890 m 2/d.

K = T/b = 9598.76/110 = 87.26 ft/d or 27 m/d.

2.25 T to 2.25 x 9598.76 x 19 S = ------= ------= 1.8 x 1 0 \ i2 (400)2 x 1440

12.5 r2 S 12.5 x (400)2 x 1.8xl0 3 t,[ = ------= ------= 0.37 daysor540 mins. T 9598.76

Feni O.W. (r = 1000 ft):

(a) Type Curve Method:

The match point co-ordinates of W(u), u, t and s are obtained from the log-log plot [Fig. 5.3.C(a)] to calculate the following hydraulic parameters:

Q W(u) 161553 X 1 T = ------= ------= 9383.93 ft7d 4 n s 4 7i 1.37

or 870 m 2/d.

K = T/b = 9383.93/110 = 85.31 ft/dor 26 m/d.

4 T t u 4 x 9383.93 x 36.5 x 1 S = ------= ------= 9.51 x Id 4. r2 (1 0 0 0 )2

(b) Straight Line Method:

The ’ds* and ’to’ values were taken from the time-drawdown plot [Fig.

5.3.C(b)] to calculate the following parameters:

114 DRAWDOWN (FEET 1.50: 9.00L 6.50: G.OO: 5.50: 3.50: 2.50: 5.00: 3.00: 2 1.50: 1 -a L0G10 . . 50: 0 0 00 0 0 00 50: -i -1 : Fig. : : ^ STRAIGHT LINE nETHOD : TIHE-ORAWDOWN PLOT : TIHE-ORAWDOWN nETHOD LINE STRAIGHT ^ (a) 5.3.C EI IZ. ELA ITNER- QOOF -S53 FT3/0 Q-1S1553 FT IQOO.O -R OISTANCE AAT WELL PIEZO. FENI : Aq : u i f e r t e s t a n a l y s i s f oa r t 0W3 F e n i ; ( a ) T y p e C u r v e EI IZ. ELA ITNER-10. T -653 FT3/D Q-161553 FT 1000.0 -R DISTANCE AAT WELL PIEZO. FENI TYPE CURVE TIHE-ORAWDOWN : PLOT a n d ( b ) S t r a i g h t L i n e . ft 2.95 = ds o 5. mins 54.0 = to ft 1000.0 ft3/d = r 161553 = Q 1. ft 110.0 IE (HINUTES) TIME IE (HINUTES) TIDE \ _ - () 1 = W(u) mins t36.5 = ftJ/d 161553 = Q = 000 ft 1000.0 = r / = 1 = 1/u 1. ft 110.0 +-P L0G10 LOG 10 LOG 0.183 Q 0.183 x 161553 T = ------= ------= 10021.76 ft7d ds 2.95

or 930 m2/d.

K = T/b = 10021.76/110 =91.11 ft/dor 28 m/d.

2.25 T to 2.25 x 10021.76 x 54 S = ------= = 8.5 x 10"*. i2 (1000)2 x 1440

12.5 i2 S 12.5 x (1000 )2 x 8.5x10"* t,! = = 1.06 days T 10021.76

or 1526.7 mins.

2) NSS/NLC/Distance-Drawdown Solution:

Feni site:

(a) Type Curve Method:

The match point co-ordinates of W(u), u, s and r were taken from the

log-log plot [(Fig. 5.3D(a)] to calculate the following hydraulic parameters:

Q W(u) 161553 x 1 T = ------= = 12856.00 ft7d 4 n s 4 x 7i x 1.0

or 1190 m2/d.

K = T/b = 12856.00/110 = 116.90 ft/d or 36 m/d.

4 T t u 4 x 12856.00 x 200 x 1 S = ------8 .6 x 10"* . r2 8,300,000 x 1440

(b) Straight line Method:

The semi-log plot [Fig.- 5.3D(b)] of distance-drawdown data were used

to obtain the values of ds and r 0 for the calculation of following hydraulic

parameters: DRAWDOWN (FEET) 10 10 ° ' V i. ... qie ts aayi fr ei () ye uv ad b Srih Line. Straight (b) and Curve Type (a) Feni; for analysis test Aquifer 5.3.D. Fig. = 653 ft3/d 161553 = Q = 0 mins 200 = t () 1 = W(u) 0.0 7.0 6.0 4.0 5.0 2.0 3.0 .3 .6 .8 1.67 1000 3.08 400 5.46 150 ;.33 iO 3000 ft: ,300,000 s 485 ft 4.825 = ds ft3/d 161553 = Q t = 200 mins mins 200 = t 3 5.46 .33 5 40 1000 400 150 b FN TS ST: ITNE DADW SOLUTION DRAWDOWN - DISTANCE SITE: TEST FENI (b) (a) FENI TEST SITE: DISTANCE - DRAWDOWN SOLUTION SOLUTION DRAWDOWN - DISTANCE SITE: TEST FENI (a) TAGT IE LT DSAC - RWON PLOT DRAWDOWN - DISTANCE PLOT: LINE STRAIGHT YE UV: ITNE DADW PLOT DRAWDOWN - DISTANCE CURVE: TYPE 1.67 QAE F ITNE (FEET) DISTANCE OF SQUARE ITNE (FEET) DISTANCE » 0 20 ft 2100 = r0 0.366 Q 0.366 x 161553 T = ------= 12254.59 ft7d ds 4.825

or 1140 m 2/d.

K = t/b = 12254.59/110= 111.4 ft/dor 34 irf/d.

2.25 T t 2.25 x 12254.59 x 200 S = ------= 8 7 x 1(r> (r0)2 (2100)2 x 1440

3) Discussion:

Feni well is an ideal example of a non-leaky confined condition indicated by the results obtained from all the methods (Table. 5.1). Strikingly close results were obtained for T, S and K from all the different methods.

Maximum and minimum transmissivity values range from 1190 m2/d obtained by the distance-drawdown solution to 870 m2/d obtained by a time- drawdown solution for OW3.

Storativity values range from 1.7 x 10 ‘3 for OW1 to 6 .8 x 10"4 for both

OW1 and OW2.

The permeability values range from 26 m/d to 36 m/d.

Nabinagar Pumping Test Site:

The test well has a depth of 301.5 ft (92 m) and a well radius of 0.25 ft (7.62 cm). During the test programme, the well was pumped at a (Q)

= 2446 m3/d (86400 ft 3/d) for a time period of 4100 mins (2.85 days). The piezometers were placed at distances of 50 ft (15 m), 400 ft (122 m) and 1000 ft.

(305 m) from the pumping well. The observed thickness of the aquifer (b) is 140 ft (43 m) with an overlying aquiclude that has a thickness of 161.5 ft (49 m).

Pumping test results are summarised in Table 5.2. SITE:- N A BIN AGAR WELLNo:-9

(a) SOLUTION:- TIME-DRAWDOWN

DISTANCE VALUES OF HYDRAULIC PARAMETERS OF METHOD T (m2/d) S(-) K=T/b (m/d) L (m) PIEZOMETER D’down REC. D’down REC. D’down REC. D’down REC.

5 0 f t . SL 420 - S2

TC - - 1 5 .2 4 m . 3 6 0 - 61(H ) - 8 5 0 8

4 0 0 f t . SL 4 3 0 - 10 - 1108 -

121.92 m. TC 2 8 0 - 77(-4) - 7 - 4 0 6 -

1000 ft. SL 5 3 0 - 89(H ) - 12 - 5 8 3 -

TC - - 3 0 4 - 8 0 m. 410 - 9-4 (-4) - 10 7 6 2

AVERAGE VALUES - 4 1 0 - 73(H ) - l o 8 2 3 -

INFERRED CONDITIONS LEAKY CONFINED

( b ) SOLUTION:- DISTANCE - DRAWDOWN

METHOD VALUES OF HYDRAULIC PARAMETERS r(m) T ( m 2/ d ) s, (-) S2 (-) S, (-) K ( m / d ) L (m)

/5 - 24 3 5 0 8 * (-4) - - 2 3 7 f

SL (II) 121- 9 2 3 5 0 - 7-3 C 0 - % 3 7 (

3 0 4 - 9 0 3 5 0 - - « l( - 4 ) % 3 7-1

TC (SS) - 3 s o - - - % 6 0 4

TC (NSS) * ------

- - SL (II) - - - - -

AVERAGE VALUES 3 6 0 - s o ( - | - % 4 8 8

INFERRED CONDITIONS LEAKY CONFINED

Table. 5.2. Pumping test analysis results (analytical) of Nabinagar Well; (a) Time- Drawdown and (b) Distance-Drawdown. 1) NSS/LC/Time-Drawdown Solution:

Nabinagar O.B. (r = 50 ft):

(a) Type Curve Method:

The match point co-ordinates of W(u), u, t and s along with the (r/L) value obtained from the type curve plot [Fig. 5.4.A(a)] were used to calculate the following hydraulic parameters:

Q w(u) 86400 x 1 T = ------= ------= 3862.63 ft7d. 4 7t s 4 x 7i x 1.78 or 360 m 2/d.

K = T/b = 3862.63/140 = 27.59 ft/dor 8 m/d. r/L = 0.3 x 10'1.

r 50 L = ------= ------= 1666.67 ft. (r/L) 0.3 x 10 1

4 T ^ u 4 x 3862.63 x 14.3 x 0.01 S = ------= = 6.1 x 10-4. r2 (50)2 x 1440

(b) Straight Line Method:

The necessary parameters obtained from the time-drawdown plot [Fig.

5.4.A(b)] with the other values taken from the Hantush (1956) table of functions

specially prepared for this solution were used to calculate the following parameters:

2.303 x s4 2.303 x 6 .8 er/L Ko (r/L) = ------= ------= 4.54. dSi 3.45

e r/L = 0.987,r/L = 0.013,

r 50 L = ------= ------= 3846 ft. or 1172 m. (r/L) 0.013

120 Q 0 O 3 u. < 3 Q L UJ 2 l C I

10 DRAWDOWN (FEET 1: -1 -11 Fig. :. L0G1Q _ 5.4.A A NGRPEO WL TADSAC 5. TQ- 60 FT3/D 86400-QFT 50.0NAB -R DISTANCE AAT WELL INAGARPIEZO. STRAIGHT LINE HETHOD s TIHE-DRAWDOWN PLOT s TIHE-DRAWDOWN HETHOD LINE STRAIGHT Aq : u i f e r t e s t a n a l y s i s f o ra t OW1 N a b i n a g a r ; ( a ) T y p e C u r v e S = .5 ft 3.45 = dSi j 1. mins 16.0 = tj = 00 ft 50.0 = r = 60 ft3/d 86400 = Q a n d ( b ) S t r a i g h t L i n e . A N G R IZ. EL T DSAC R 5 F Q 60 FT3/D NAB INAGAR WELL PIEZO. 86400 DISTANCE AT 50 A - = Q FT - 0 R TYPE CURVE TIHE-DRAWDOWN : PLOT 4. ft 140.0 IE (HINUTES) TIRE IE (HINUTES)TIDE () 1 = W(u) mins 14.3 = t = 00 ft 50.0 = r A = 100 = lAi frVd 86400 = Q 17 ft 1.78 = 4. ft 140.0 /= 0.03 r/L= L0G10 L0G10 0.183 x Q 0.183 x 86400 x 0.987 T = x e'r/L = = 4523.38 ftVd. dSj 3.45 or 420 m 2/d.

K = T/b = 4523.38/140= 32.31 ft/d or 10 m/d.

4 T tj 4 x 4523.38 x 16 S = ------= = 5.2 x 10"*. 2 r L 2 x 50 x 3846 x 1440

12.5 r2 s 12.5 x (50)2 x 5.2 x 10^ t,! = ------= = 3.59 x 10'3 days T 4523.38

= 5.17 mins.

Nabinagar O.W. (r = 400 Ft):

(a) Type Curve Method:

The match point co-ordinates of W(u), u, t and s along with the (r/L) value obtained from the type curve plot [Fig. 5.4.B.(a)] were used to calculate the following hydraulic parameters:

Q w(u) 86400 x 1 T = ------= ------= 3055.77 ftVd. 4 n s 4 x n x 2.25

or 280 m 2/d.

K = T/b = 3055.77/140 =21.83 ft/d or 7 m/d.

4 T t. (u) 4 x 3055.77 x 14.5 x 1 S = ------= = 7.7 x 10-4. r2 (400)2 x 1440

(b) Straight Line Method:

The necessary parameters obtained from the time-drawdown plot [Fig.

5.4.B(b)] and the Hantush (1956) function tables were used to calculate the ORAUDOUN (FEET 9.00L 8.50 1.00 6-50: 6.00 5.50 £.50: 3.50: 3.00: 2.50: 1.50: 1 L0G10 . 00 50: 00 00 -1 Fig: : __ __ : __ 5.4.B (a) AIAA IZ. ELA ITNER £00F ' 60 FT3/D ' ' £00.0FTATAQ 86£00DISTANCERPIEZO. WELLNABINAGAR TAGTLN EHD : TIHETHODLINESTRAIGHT HE'DRAWDOWNPLOT : Aq : u i f e r t e s t a n a l y s i s f o r a t 0W2 N a b i n a g a r ; ( a ) T y p e C u r v e A I A A PEO WL A A ITNE - £00 T - 60 FT3/D NABINAGAR 86£00 - Q FT WELL PIEZO. DISTANCE AT £00.0 A - R TYPE CURVE TIHE-DRAWDOWN : PLOT a n d ( b ) S t r a i g h t L i n e . s = .5 ft 3.05 = ds, = 0. ft 400.0 = r = 60 ft3/d 86400 = Q 34 ft 3.45 = 4. mins 145.0 4. ft 140.0 IE (HINUTES)TIDE IE (HINUTES)TIDE () 1 = W(u) = 0. ft 400.0 ftVd = r 86400 = Q / = 1 = 1/u 4. ft 140.0 L0G10 L0G10 following hydraulic parameters:

2.303 x Si 2.303 x 3.45 er/L.Ko.(r/L) = ------= ------= 2.61 ds* 3.05 e'r/L = 0.89. and r/L = 0.11 (From the table).

r 400 L = ------= ------= 3636.36 ft. (r/L) (0.11)

0.183 x Q 0.183 x 86400 x 0.89 T = ------x e r/L = ------= 4613.73 ft7d. dSi 3.05

or 430 m 2/d.

4 T t* 4 x 4613.73 x 145 S = ------= ------= 6.4 x 10"* 2 r L 2 x 400 x 3636.36 x 1440

K = T/b = 4613.77/140 = 32.96. ft/d. or 10 m/d.

12.5 r2 s 12.5 x (400)2 x 6.4 x 10"* tjj = ------= ------= 0.27 days. T 4613 .73

= 399 mins.

Nabinagar O.W. (r = 1000 ft):

(a) Type Curve Method:

The match point co-ordinates of W(u), u, t and s and the matching

(r/L) value were taken from the type curve plot [Fig. 5.4.C(a)] to calculate the

following hydraulic parameters:

Q w(u) 86400 x 1 T = ------= ------= 4435.80 ft ft7d. 4 n s 4 x 7t x 1.55

or 410 m 2/d.

K =T/b = 4435.80/140 = 31.68 ft/d. or 10 m/d.

r 1000 L = ------= = 2500 ft. (r/L) (1000/0.4) DRAWDOWN (FEET -21 L0G10 3.60c. 2.40: 2.01 2.80: 1.80: 1.60: 3.20: 3.00: 2.21 1 1 -1 . . 0 2 00 80: 60: 40: 20 OCL Fig. -1 : : : ______^ STRAIGHT LINE HETHOD : TIHE-DRAWDOWN PLOT : TIHE-DRAWDOWN HETHOD LINE STRAIGHT ^ = 000 ft 1000.0 ft3/d = r 86400 = Q () 1 = W(u) = 60 mins 76.0 = t (a) / = 1 = 1/u 5.4.C 4. ft 140.0 : Aq : u i f e r t e s t a n a l y s i s f o ra t OW3 N a b i n a g a r ; ( a ) T y p e C u r v e NABINAGAR PIE20. WELL AT A DISTANCE R -1000.0R DISTANCE AAT WELL PIE20. NABINAGAR s = .2 ft 2.02 = ds, TTPE CURVE TIHE-DRAWDOWN 5 PLOT i 0 mi s in m .0 0 6 3 = ti FT3/D NABINAGAR 86400 - WELL Q PIEZO. FT DISTANCE AT A -1000.0 R = 000 ft 1000.0 = r = 60 ftJ/d 86400 = Q a n d ( b ) S t r a i g h t L i n e . 4. ft 140.0

IE (HINUTES)TIME IE (HINUTES)TIHE T Q FT 60 FT3/0 86400- /= 0.4 r/L= L0G10 L0G10 or L = 762 m/d.

4 T t. (u) 4 x 4435.80 x 76 x 1 S = ------= ------= 9.4 x 10A i2 (1000)2 X 1440

(b) Straight Line Method:

The necessary parameters were obtained from the time-drawdown plot

[Fig. 5.4.C(b)] and also from the Hantush (1956) function tables to calculate the following hydraulic parameters:

2.303 s, 2.303 x 1.60 er/L.Ko.(r/L) = ------= = 1.824 dSi 2.02 e*r/L = 0.733 and r/L = 0.31. (From function table)

r 1000 L = ------= ------= 3225.81 ft. or 983 m. (r/L) 0.31

0.183 x Q x 0.183 x 86400 x 0.733 T = ------= ------ds{ 2.02

= 5737.43 ft7d. or 530 m 2/d.

K = 5737.43/140 = 40.98 ft/d. or 12 m/d.

4 T t* 4 x 5737.43 x 360 S = ------= = 8.9 x 1 0 \ 2 r L 2 x 1000 x 3225.81 x 1440

12.5 x r2 x S 12.5 x (1000 )2 x 8.5 x 10 t,j—------= ------= 1.939 days. T 5737.43

or 2792 mins.

2) SS/LC/Nabinagar Distance-Drawdown solution:

126 (a) Type Curve Method:

The match point co-ordinates were obtained from the distance- drawdown Plot [Fig. 5.4.D(a)] to calculate the following hydraulic parameters: r/L = 1 or r = L = 1980 ft. or 604 m.

Q K0.(r/L) 84600 x 1 T = ------= ------= 3819.72 ft7d. 2 n s 2 x n x 3.60

or 360 m 2/d.

K = T/b = 3819.72/140 = 27.28 ft/d. or 8 m/d.

(b) Straight Line Method:

The necessary parameters were taken from the previous time-drawdown plots of all the observation wells and also from the distance-ds (per log cycle) plot

[Fig. 5.4.D(B)] to calculate the following hydraulic parameters:

L = dr/2.303 = 2803.3/2.303 = 1217.20 ft. or 371 m.

r/L = 50/1217.2 = 0.04, Ko.(r,/L) = 3.312 (table).

tJL = 400/1217.2 = 0.329, K^O^L) = 1.286 (table).

r3/L= 1000/1217.2 = 0.82, K J r ^ ) = 0.548 (table).

0.183 Q 0.183 x 86400 T = ------= ------= 3746.73 ftVd. ds0 4.22

or 350 m 2/d.

Q 86400 s.(1) = x K0.(r7L) = ------x 3.312 4 7t T 4 x n x 3746.73

= 1.835 x 3.312 = 6.08 ft. and from the plot the corresponding tj(1) value is© mins.

Q 86400 si(2) = x KO.(rTL) = ------x 1.286 4 7t T 4 x 71 x 3746.73

127 DISTANCE (FEET) 1,200 1,000 800 400 600 200 0.0 o £ Z Fig. 5.4.D: a n d ( b ) S t r a i g h t L i n e . b NBNGA TS ST: ITNE DA O SOLUTION N DOW DRAW - DISTANCE SITE: TEST AR NABINAG (b) A q u i f e r t e s t a n a l y s i s N a b i n a g a r s i t e ; ( a ) T y p e C u r v e TAGT IE LT DSAC - RWDWN NRMN ( ) PLOT s) (A INCREMENT N DOW DRAW - DISTANCE PLOT: LINE STRAIGHT = 60 ft3/d 86400 = Q = 10 mins 4100 = t = 90 ft 1980 = r a NBIAA TS ST: ITNE DA OWN SOLUTION N W DO DRAW - DISTANCE SITE: TEST INAGAR NAB (a) YE UV: ITNE DA O PLOT N DOW DRAW - DISTANCE CURVE: TYPE RWDWN NRMET (FEET) ENT INCREM N DOW DRAW ^

ITNE (FEET) DISTANCE s - 485 ft 4.825 - ds0 r 20. ft 2803.3 = dr = 60 ft3/d 86400 = Q = 10 mins 4100 = t 0 5 40 1000 400 150 50 34 96 67 3.33 6.71 9.69 13.42 5 40 1000 400 150

= 1.835 x 1.286 =2.36 ft. and from the plot the corresponding ti(2) value is 68.0 mins.

Q 86400 siC3) = x K0.(r7L) = ------x 0.548 4 n T 4 x n x 3746.73

= 1.835 x 0.548 = 1.01 ft. and from the plot the corresponding ti(3) value is 190.0 mins.

2 T ^ 2 x 3746.73 x 10.0 S1 = ------= ------= 8.6 x 10A r L 50 x 1217.2 x 1440

2 x 3746.73 x 190 S2 = ------= 7.3 x 10"*. 400 x 1217.2 x 1440

2 x 3746.73 x 190 S3 = ------= 8.1 x 10"*. 400 x 1217.2 x 1440

3) Discussion:

All the observation wells show the characteristics of a leaky confined

aquifer indicating minimum lithologic variation. The maximum amount of leakage

(L = 371 m) is obtained from the straight line distance-drawdown solution for

OW1 while the minimum amount of leakage (L = 1172 m) is given by SL time-

drawdown for the same well.

The transmissivity values obtained do not show any great deal of

difference except the single low value (280 m 2/d) obtained by the type curve time-

drawdown solution for OW2. The highest T value (530 m 2/d) is given by the

straight line time-drawdown solution for OW3.

Striking similarities were obtained in storativity values. The lowest

value (5.2 x 10"*) was obtained by the straight line time-drawdown solution for

OW1 and the highest value (9.4 x 10"*) is given by the type curve time-drawdown

129 solution for OW3.

The permeability values range from 7 m/d obtained by use of the type curve time-drawdown solution for OW2 to 12 m/d obtained from the straight line time-drawdown solution for OW3 (Table. 5.2).

B’Baria Pumping Test Site:

The well has a depth of 302 ft (92 m) with a well radius (r) = 0.33 ft (10 cm). During the test the well was pumped at a discharge (Q) = 76997 ft3/d

(2180 m 3/d) for a period of t = 3000 minutes (2.083 days). The observation wells were spaced at r = 50 ft (15 m), 150 ft (45 m), and 400 ft (122 m). The estimated thickness of the aquifer is 200 ft (60 m) and the overlying semi-pervious layer has a thickness of 102 ft (31 m). The static water level at the pumping well is 4.39 ft

(1.34 m) below the measuring point. The result of analysis of pumping test data are summarised in Table 5.3 calculated on the basis of the match point co-ordinates and other necessary parameters obtained from the relevant figures.

1) Time-Drawdown Solution:

(a) Type Curve Method: The match-point co-ordinates for OW1 (r = 50 ft),

OW2 (r = 150 ft) and OW3 (r = 400 ft) were obtained from the type-curve plots of Figures 5.5.A(a), 5.5.B(a) and 5.5.C(a) respectively.

(b) Straight Line Method: The necessary parameters for OW1, OW2 and OW3 were obtained from the time-drawdown plots of Figures 5.5.A(b), 5.5.B(b), and

5.5.C(b), respectively.

2) B’Baria Distance-Drawdown Solution:

(a) Type Curve Method: The match-point co-ordinates were obtained from the distance-drawdown log-log plot (figure not included).

130 SITE:- B* BARI A WELL N o:- 6

(a ) SOLUTION:- TIME-DRAWDOWN

DISTANCE VALUES OF HYDRAULIC PARAMETERS OF METHOD T (m2/d) S(-) K=T/b (m/d) L (m) PIEZOMETER D’down REC. D’down REC. D’down REC. D’down REC.

-- 50 ft. SL 95o - 11 (-3) - 16 -

15. 24m. TC 1020 - 6-3 (-$ 17 -- -

1 5 0 f t . SL 810 - ■K-3) - 13 - 6 lo - * -*> * 4 5 .7 2 m. TC 590 - - 1 o - IS3

400 ft. SL 1020 - - I? - - - * 121.92 m. TC A lo - 2S(-3) - 7 * - 203 -

AVERAGE VALUES 9 5 0 - 2-7(-3) - 16 - 6 (0

INFERRED CONDITIONS LEAKY CONFINE D

* Results not included

( b ) SOLUTION:- DISTANCE - DRAWDOWN

METHOD VALUES OF HYDRAULIC PARAMETERS r(m) T (m2/d) s, (•) s3 (-) S, (-) K (m/d) L (m)

- 15-24 2 0 M 1-6

SL (II) 45-72 2014 - '-5 (-3) - 3 4 1166

(21-92. 20 14 - - 10 (-3) 3 4 1166

TC (SS) - Z 3 0 - - - H % 32

TC (NSS) ------

SL (II) ------

AVERAGE VALUES <230 8-6 (-4) 2 4 loo 2

INFERRED CONDITIONS LEAKY CONFINED

Table. 5.3. Pumping test analysis results (analytical) of B’Baria Well; (a) Time- Drawdown and (b) Distance-Drawdown. 6.50_ G.00_ 2.50: 2 T.OO: 1.50:

. DRAWDOWN (FEET 50: 50: 00 0 0 L0G10 Fig. -7 : -1 b SRIH IEHTO :PLOT TIHE-DRAWDOWN HETHOD LINE STRAIGHT (b) 5.5.A () 1 = W(u) ft 50.0 = r = 0. ft 200.0 = b mins 5.2 = t ft5/d 76997 = Q A = 100 = lAi 05 ft 0.56 = Aq : u i f e r t e s t a n a l y s i s f o ra t OW1 B’ B a r i a ; ( a ) T y p e C u r v e * B RI IZ. ELA ITNER-00Q= FT3/D B* BAR =-50.0QR DISTANCE IAATA WELL PIEZO. s 135 ft 1.375 = ds = 0. ft 200.0 = b o 01 mins 0.17 = to ft 50.0 = r = 69 ftVd 76997 = Q a n d ( b ) S t r a i g h t L i n e . 'AI PEO WL A A ITNE -00 = 69 FT3/D B'BARIA WELL 36993 PIEZO. = Q DISTANCE AT A -50.0 R TYPE CURVE TIHE-ORAWOOWN : PLOT IE (niNUTES) TIDE IE (HINUTES)TIDE +> L0G10 L0G70 DRAWDOWN ( FEET 9.00L 1.50 8.50 : 0 0 . 8 6.50:___ 6.00 5.50: 5.00: 3.50 3.00 2.50 2.00 1.00 1.50 00 50 U o Ix L h— Q CC< 3 Q -7 l Fig. J ___

______1 1 - L0G10 -1 5.5.B () 1 = W(u) = . mins 7.3 = t ft 0.97 = s ft 150.0 = r = 0. ft 200.0 = b = 69 ft7d 76997 = Q A = 1 = lAi TYPE CURVE TIHE-DRAWDOWN : PLOT a) ( : Aq : u i f e r t e s t a n a l y s i s f o ra t OW2 B1 B a r i a ; ( a ) T y p e C u r v e ’AI IZ.ELA ITNER-T00F 191 FT3/D 16991-QFT-ATAT50.0 DISTANCER PIEZO.WELL B’BARIA TAGTLN EHD : TIHE-DRAWDOWNPLOTHETHOD LINE STRAIGHT = 5. ft 150.0 ftJ/d = r 76997 = Q = 0. ft 200.0 = b a n d ( b ) S t r a i g h t L i n e . 0. mins 108.0 ’BRA IZ.EL T DSAC R 100 T - 69 FT3/D 16991 B’ BARIA PIEZO.WELL - Q FT DISTANCE AT A 150.0 - R

+ + IE (HINUTES)TIHE IE (HINUTES) TIHE /= 0.25 r/L= L0G10 L0G10 (a) TYPE CURVE : TIHE-DRAUIDOWN PLOT B’BARIA PIEZO. WELL AT DISTANCE R - £00.0 FT 0=16991 FT3/D L0G10

i— Q = 76997 ft7d LU UJ U. r = 400.0 ft 3z QO 3< CC t = 33.0 mins Cl w(u) = 1

b = 200.0 ft

-1 TIDE (HINUTES) L0G10

STRAIGHT LINE HETHOD : TIHE-ORAUDOLIN PLOT

B’eARIA PIEZO. WELL AT DISTANCE R - £00.0 FT 0=15991 FT3/D

00 20i £01 601

aoi 4.001

1.201

1.6C1 Q = 76997 ftVd 1.801 r = 400.0 ft 2.001 15.5 mins 2.20i 2.£0i ds = 1.29 ft

2.601 b = 200.0 ft 2.801

3.00i

3.2Ci

3.£0i

3.60L -1 L0G10 TIDE (HINUTES)

Fig. 5.5.C. Aquifer test analysis for 0W 3 at B’Baria; (a) Type Curve and (b) Straight Line. (b) Straight Line Method: The necessary parameters were obtained from the previous time-drawdown plots of all the observation wells and the distance-ds

(drawdown per log cycle) semi-log plot (figure not included).

3) Discussion:

Both the type curve (TC) and straight line (SL) solution for OW1

(r = 50 ft) and the SL solution for OW3 (r = 400 ft) suggest a non-leaky confined condition whereas both the type curve and straight line solution for OW2 (r = 150 ft) and the type curve solution for OW3 produces enough leakage to qualify as a leaky confined condition. The highest leakage (L = 183 m) was calculated by the type curve time-drawdown solution for OW2 and the lowest leakage (L = 1166 m) was produced by the straight line distance-drawdown solution (Table. 5.3).

A high transmissivity (T) value (2014 m 2/d) is obtained by the straight line distance-drawdown solution with a low T value (410 m 2/d) given by the type curve time-drawdown solution for OW3, and these values are not included for further interpretation.

All the storativity values obtained for the different OWs indicate a confined condition. The highest storativity value (5.7 x 10'3) is given by a type curve time-drawdown solution for OW2 and the lowest value (1.6 x 10-4) is obtained by a straight line distance-drawdown solution for OW 1.

The maximum (34 m/d) and minimum (7 m/d) permeability (hydraulic conductivity) values correspond to the highest and lowest transmissivity values.

Daudkandi Pumping Test Site:

The well structure has a depth of 342 ft (104 m) with a well radius of

0.25 ft (7.6 cm). During the pumping test the well was pumped with an average discharge (Q) = 172785 ft3/d (4892 m 3/d) for a period of 1800 minutes (1.25 days).

135 The observation wells are spaced at 50 ft (15 m), 150 ft (45 m), and 400 ft (122 m) from the pumping well. The estimated aquifer thickness is 140 ft (40 m) which

is underlain by a semi-pervious layer of 195 ft (60 m) thick. S.W.L. = 8.08 ft. The

result of the analysis is present in the Table. 5.4 calculated on the basis of the

match-point co-ordinates and other necessary parameters obtained from the relevant

figures.

1) Time-Drawdown and Time-Calculated Recovery Solution:

(a) Type-Curve Method: The match-point co-ordinates for OW1 (r = 50 ft),

OW2 (r = 150 ft) and OW3 (r = 400 ft) were obtained from the type-curve plots

of Figures 5.6.A(a), 5.6.B(a) and 5.6.C(a), respectively.

(b) Straight Line Method: The necessary parameters for OW1, OW2, and OW3

were obtained from the time-drawdown plots of Figures 5.6.A(b), 5.6.B(b), and

5.6.C(b), respectively and the Hantush function tables.

2) Daudkandi Distance-Drawdown Solution:

(a) Type-Curve Method: The match point co-ordinates were obtained from the

distance-drawdown log-log plot (figure not included).

(b) Straight Line Method: The necessary parameters were obtained from the

previous time-drawdown plots of all the observation wells and the distance-ds

(drawdown per log cycle) semi-log plot (figure not included).

3) Discussion:

In addition to the time-drawdown data, the recovery data were also

available for this particular test site. The results obtained by analyzing both

drawdown and recovery data (Table. 5.4) suggest a leaky confined condition. The

recovery data suggests a lower leakage. The highest leakage (L = 192 m) is given

136 SITE:- DAUDKANDI WELLNo:-43

(a) SOLUTION:- TIME-DRAWDOWN

DISTANCE VALUES OF HYDRAULIC PARAMETERS OF METHOD T (m2/d) S(-) K=T/b (m/d) L (m)

PIEZOMETER D 'down RFC. D ’dow n RFC. D’down RFC. D ’down RFC. <0 50 ft. SL lo io 8 6 0 5oC-f) 24 2 0 8 o 2 50 5 * S' 'S o 15. 24 m. TC 770 - I 18 - 2 5 4 -

150 ft. SL 1170 loio 27 24 1758 4/6 I --- 45.72 m. TC 1090 - 26(-4)| ' 26 IMS -

400 ft. SL 1320 1030 3o(-4) 31 24 1999 581

TC 121.92 m. 1240 3s(-4) - 29 - 1219 -

AVERAGE VALUES 1100 970 4'4(-4)b'(-3) 26 23 1384 501

INFERRED CONDITIONS LEAKY CONFINED

* Results not included

( b ) SOLUTION:- DISTANCE - DRAWDOWN

METHOD VALUES OF HYDRAULIC PARAMETERS r (m) T (m2/d) S, (-) S:(-) S3 (•) K (m/d) L (m)

15-24 10 5 0 5 b (-4 ) - - 2 5 192

- SL (II) 45-72 1 0 5 0 1-7 ( - 4) - 2 5 192

121-92 10 5 0 - - «-5 (- 4) 2 5 192

- - - - TC (SS) 1 0 4 0 2 4 914

TC (NSS) ------

SL (II) ------

AVERAGE VALUES 1 0 5 0 - 5 1 (- 4 ) - 25 5 5 3

INFERRED CONDITIONS LEAKY CONFINED

Table. 5.4. Pumping test analysis results (analytical) of Daudkandi Well; (a) Time- Drawdown and (b) Distance-Drawdown. w DAUDKANDI PIEZO. WELL AT A DISTANCE R - 50.0 FT Q - 112185 FT3/D L0G10

h— UJ Q = 172785 ft5/d UJ li. z r = 50.0 ft O3 3Q CC< Q 10.7 mins

W(u) = 1

1/u =100

b = 140.0 ft

-1 TIHE (HINUTES) L0G10

STRAIGHT LINE HETHOD : TIHE'DRAWDOWN PLOT

DAUDKANDI PIEZO. WELL AT A DISTANCE R ' 50.0 FT 0 ' 112185 FT3/D

Q = 172785 ft3/d

10: r = 50.0 ft

tj = 4.3 mins 14 ds, = 2.85 ft

140.0 ft 11: iat

LOGIO TIHE (HINUTES)

Fig. 5.6.A : Aquifer test analysis for OW 1 at Daudkandi; (a) Type Curve and (b) Straight Line. 9.00c. 8.50: 5.50: 2 3.50: 3.00: 6.50: 1.50: 1 . . DRAWDOWN (FEET 00 00 50 L 00 -ll L0G10 -1 Fig. : : -1 (b) STRAIGHT LINE HETHOD : TIHE-DRAWDOWN PLOT : TIHE-DRAWDOWN HETHODLINE STRAIGHT (b) 5.6.B TYPE CURVE TIHE-DRAWDOWN : PLOT ^ ADAD PEO WL TADSAC 5. T 128 FT3/D 112185- QFT 150.0- R DISTANCE AAT WELL PIEZO. DAUDKANDI : Aq : u i f e r t e s t a n a l y s i s f o ra t OW2 D a u d k a n d i ; ( a ) T y p e C u r v e a n d ( b ) S t r a i g h t L i n e . A D A D PEO WL A A ITNE - 5. F Q 128 FT3/D DAUDKANDI 112185 - Q FT WELL PIEZO. AT 150.0 DISTANCE A - R IE (HINUTES)TIHE IE (HINUTES) TIHE () 1 = W(u) mins 18.0 = t = 5. ft 150.0 = r lAi =100 ftVd 172785 = Q S = .5 ft 2.45 = dSi | 1. mins 12.2 = t| = 775 ft’/d 172785 = Q 4. ft 140.0 82 ft 8.2 = 4. ft 140.0 5. ft 150.0 /= 0.04 r/L= LOGIO 1.50: 1 2.50: 2 6.50: 5.01 3.50: 3.00: 9.001 6 5.50: 4.01 8 . . . . 00 00 50: 00 00 50: 00 DRAWDOWN (FEET -ll Fig. L0G10 -1 : : : : ______-1 b SRIH IEHTO : TIHE-DRAWDOWNPLOTHETHOD LINE STRAIGHT (b) 5.6.C = 0. ft 400.0 ft3/d = r 172785 = Q () 1 = W(u) =4. ft =140.0 b / = 1 = 1/u i 4. mins 43.0 = ti , 27 ft 2.75 = s, = 0. ft 400.0 = r = 775 ft3/d 172785 = Q : Aq : u i f e r t e s t a n a l y s i s f o r a t 0W3 D a u d k a n d i ; ( a ) T y p e C u r v e ADAD PEO WL TADSAC 0. TQ-128 FT3/D FT112185-400.0Q-AT WELLDISTANCERA PIEZO. DAUDKANDI . mins 1.5 4. ft 140.0 a n d ( b ) S t r a i g h t L i n e . A D A D PEO WL A A ITNE - 0. F Q 128 FT3/D DAUDKANDI 112185 - Q FT WELL PIEZO. DISTANCE AT £00.0 A - R TYPE CURVE TIHE-DRAWDOWN : PLOT

IE (HINUTES)TIHE IE (HINUTES)TIHE /= 0.1 r/L= L0G10 L0G10 by the straight line distance-drawdown solution and the lowest leakage (L = 1999 m) is recorded by the straight line time-drawdown solution for OW3.

The transmissivity values obtained for all the observation wells employing all the methods shows little variation except that the lowest value (770 m2/d) obtained by the type curve time-drawdown solution for OW1 which is much lower than all other values. The highest transmissivity value (1320 m 2/d) is given by the straight line time-drawdown solution for OW3.

Storativity values obtained are representative of confined conditions. The highest and lowest storativity values ranged from 1.0 x 10'3 obtained by a type curve time-drawdown solution for OW1 to 1.7 x 1C1 4 obtained by the straight line distance-drawdown solution for OW2.

The permeability values show no great deal of difference and vary from

18 m/d obtained by the type curve time-drawdown solution for OW1 to 31 m/d obtained by the straight line distance-drawdown solution for OW3.

Burichong Pumping Test Site:

The test well was drilled a depth of 327 ft (100 m) with a radius (r)

= 0.25 ft (7.6 cm). During the testing session the well was pumped with a constant discharge (Q) = 76962 ft3/d (2179 m/d) and the test was continued for a period of

3000 mins (2.083 days). The observation wells were placed at r = 100 ft (30 m),

150 ft (45 m), and 250 ft (76 m). The aquifer has an estimated thickness (b) of 192 ft (60 m) and the thickness of the overlying semi-pervious bed (b’) is 135 ft. (40 m). The static water level is measured at 5.42 ft (1.65 m) below measuring point.

The test results are summarised in Table. 5.5 calculated on the basis of the match- point co-ordinates and necessary parameters obtained from the relevant figures.

141 SITE:- BURICHONG W ELL No:- U6 (a) SOLUTION:- TIME-DRAWDOWN

DISTANCE VALUES OF HYDRAULIC PARAMETERS OF METHOD T (m2/d) S(-) K=T/b (m/d) L (m) PIEZOMETER D’down m:c. D 'd iw n j Rl-C. I)'down iir-c. D ’down R I:.C.

¥ -*• i * % - - - 100 f t . SL 5 7 0 9-5 (-2) - lo £ 9

¥ *! TC - 3 0 - 4 8 m. 3 2 5 9-7(-2); - - 3 8

1 5 0 f t. SL 5 6 0 - *»H )j • 10 - \o%% -

- 4 5 . 7 2 m. TC 4 2 0 - 6-9(-4)j - 7 4 5 7 -

- 2 5 0 f t . SL 550 - 4 0 (-3) - 9 2 9 3 -

TC 7 6 .2 0 m. 4 9 0 • 4I(- 3) - 9 - 2 5 4 -

AVERAGE VALUES 5 0 5 - 2-3(-3) - 9 > 5 2 3 -

INFERRED CONDITIONS LEAKY CONFINED

* Results not included

( b ) SOLUTION:- DISTANCE - DRAWDOWN

METHOD VALUES OF HYDRAULIC PARAMETERS r(m) T (m2/d) s, (-) St (-) s3(-) K (m/d) L (m)

30-48 4 3 0 -? - - 7 148

- 7 SL OH 45-72 4 3 0 - 6-o (-4) 148

7 6-20 4 3 0 - - 9-2 (-3) ? 148

TC (SS) - 2 4 0 - - - 4 113

TC (NSS) ------

SL (II) ------

AVERAGE VALUES 2)40 - 4-9(13) - 6 131

INFERRED CONDITIONS LEAKY CONFINED

Table. 5.5. Pumping test analysis results (analytical) of Burichong Well; (a) Time- Drawdown and (b) Distance-Drawdown. 1) Time-Drawdown Solution:

(a) Type-Curve Method: The match-point co-ordinates for OW1 (r = 100 ft),

OW2 (r = 150 ft) and OW3 (r = 250 ft) were obtained from the time-drawdown

plots of Figures 5.7.A(a), 5.7.B(a), and 5.7.C(a), respectively.

(b) Straight Line Method: The necessary parameters for OW1, OW2, and OW3

were obtained from the time-drawdown plots of Figures 5.7.A(b), 5.7.B(b), and

5.7.C(b), respectively and the Hantush function tables.

2) Burichong Distance-Drawdown solution:

(a) Type Curve Method: The match-point co-ordinates were obtained from the

distance-drawdown log-log plot (figure not included).

(b) Straight Line Method: The necessary parameters were obtained from the

previous semi-log time-drawdown plots of all the observation wells and the distance-

ds (drawdown per log cycle) semi-log plot (figure not included).

3) Discussion:

The results obtained by using both time-drawdown and distance-

drawdown solutions for OW 1 are abnormally high and are not included for further

interpretation. Analytical results for other observation wells are reasonably

acceptable (Table. 5.5).

Highly variable leakage values (L) are obtained ranging from 113 to

1088 m for OW2.

I Confined storage values for the aquifer were obtained from all solutions I | for OW2 and OW3. The storativity values range from 4.4 x 10"*) for OW2 to 9.2

x 10-3 for OW3.

Little variation in transmissivity values were found with a range from

240 m2/d to 560 m 2/d.

143 w BURICHONG PIEZO. WELL AT A DISTANCE R - 100.0 FT Q - 16962 FT3/D L0G10

r/L= 0.!

Q = 76962 ft7d

2 100.0 ft O3 Q 3 1.75 ft cc< a t = 100.0 mins

W(u) = 1

192.0 ft

-2 -1 TIHE (HINUTES) L0G10

(b) STRAIGHT LINE HETHOD : TIHE-ORAUDOWN PLOT BURICHONG PIEZO. WELL AT A DISTANCE R - 100.0 FT Q - 16962 FT3/0

00 20:

60:

80: 1.00: 1.20:

1.60: Q = 76962 ftVd 1.80: r = 100.0 ft 2 .00: 2.20: 2.40:

2.60: tj = 255.0 mins 2.80: dSj = 1.48 ft 3.00:

3.20: 192.0 ft

3.60l -1 L0G10 TIHE (HINUTES)

Fig. 5.7.A : Aquifer test analysis for 0W 1 at Burichong; (a) Type Curve and (b) Straight Line. 6.50: 6 5.50: 8.50: 1.50: 5.00: 4.00: 3.50: 2 1.50: 3.00: 2.50: 1

. DRAWDOWN (FEETS . . 00 00 00 00 50: 00 L0G10 Fig. : : : : 5.7.B : Aq : u i f e r t e s t a n a l y s i s f o r a t 0W2 B u r i c h o n g ; ( a ) T y p e C u r v e i 2. mins 28.0 = ti s = .0 ft 2.50 = ds( m = .0 ft 6.70 = sm„ ft 150.0 = r = 66 ft3/d 76962 = Q UIHN IZ. ELA ITNER 100F ' 66 FT3/D ' 'Q 16962 150.0FT R AT ADISTANCE PIEZO. WELL BURICHONG TAGTLN EHD :PLOT TIHE'DRAWDOUN HETHODLINE STRAIGHT 33 ft 3.35 = 9. ft 192.0 a n d ( b ) S t r a i g h t L i n e . U I H N PEO WL A A ITNE - 5. F 3 192 FT3/D BURICHONG 16962. - WELL 3 FT PIEZO. DISTANCE AT 150.0 A - R IE HNTS L0G10 (HINUTES) TIDE IE (HINUTES)TIHE () l = W(u) = 2 mins .23 l = t = 5. ft 150.0 = r / = l = l/u = 66 ft3/d 76962 = Q .5 ft l.35 9. ft 192.0 /= O.l r/L= LOG10 3.60L 3.20: DRAWDOWN (FEET 3.00: 2.80: 2.80: 2 2 1 1 1 -7 . . . . .8C: L0G10 00 80: 60. 00 20 00 20 C 20 -1 0: Fig. -1 : : : : : ______b SRIH IEHTO :PLOT TIHE-DRAWDOWNHETHODLINE STRAIGHT (b) 5.7.C s = .3 ft 1.83 = ds, = 9. ft 192.0 = b mins 110.0 = tj = 5. ft 250.0 = ftJ/dr 76962 = Q : Aq : u i f e r t e s t a n a l y s i s f o ra t 0W3 B u r i c h o n g ; ( a ) T y p e C u r v e UIHN IZ. ELA ITNER-200F 66 FT3/D 36962 -QFT 250.0- ATADISTANCER WELL PIEZO. BURICHONG 15 ft 1.55 = U I H N PEO WL A A ITNE - 5. F Q 392 FT3/D BURICHONG 369G2. - Q WELL FT PIEZO. DISTANCE AT A 250.0 - R a n d ( b ) S t r a i g h t L i n e . IE (HINUTES)TIHE IE (HINUTES)TIHE () 1 = W(u) = 73 mins 17.3 = t ft 250.0 = r = 66 ft7d 76962 = Q / = 1 = 1/u 9. ft 192.0 /= 0.3 r/L= L0G10 The permeability values range from 4 m/d to 10 m/d.

Chandina Pumping Test Site:

The well has a depth of 295 ft (90 m) and the structure has a radius of 0.25 ft ( 7.6 cm). During the test the well was pumped with a discharge (Q) =

84662 ft3/d (2397 m 3/d) for a period of t = 3600 mins (2.5 days). Three observation wells were placed at 50 ft (15 m), 150 ft (45 m), and 400 ft (122 m) from the pumping well. The aquifer has an estimated thickness (b) of 135 ft (41 m) and the overlying semi-pervious confining layer has a thickness (b’) of 160 ft (50 m). Static water level = 11.04 ft (3.36 m) below measuring point. The results are summarized in Table. 5.6 calculated on the basis of the match-point co-ordinates and other necessary parameters obtained from the relevant figures.

1) Time-Drawdown and Time-Calculated Recovery Solution:

(a) Type-Curve Method: The match-point co-ordinates for OW1 (r = 50 ft),

OW2 (r = 150 ft), and OW3 (r = 400 ft) were obtained from the log-log plots of

Figures 5.8.A(a), 5.8.B(a), 5.8.Cl(a), and 5.8.C2(a), respectively.

(b) Straight Line Method: The necessary parameters for OW1, OW2, and OW3 were obtained from the time-drawdown semi-log plots of Figures 5.8.A(b), 5.8.B(b),

5.8.Cl(b), and 5.8C2(b), respectively and the Hantush function tables.

2) Chandina Distance-Drawdown Solution:

(a) Type Curve Method: The match-point co-ordinates were obtained from the distance-drawdown log-log plot (figure not included).

(2) Straight Line Method: The necessary parameters were obtained from the previous time-drawdown and time-calculated recovery plots of all the observation

wells and the relevant distance-drawdown and distance-recovery semi-log plots SITE:- CHANDINA WELL No:- 55

( d ) SOLUTION:- TIME - DRAWDOWN

DISTANCE VALUES OF HYDRAULIC PARAMETERS OF METHOD T (m2/d) S(-) K=T/b (m/d) L (m) PIEZOMETER D ’down RFC. D ’dnwn RFC. D’down RFC. O'down RF.C.

5 0 ft. SL 62 60 - 9 Hi) - 151 - - -

15.24m. TC 4 i? o - - 10! -- -

150ft. SL til 640 N-J W-3) N-l 16 M .1 >5?

TC 4 5.72 m. N.J 6 oo N.J HI 15 N-l I3J

400 ft. SL 1620 17 50 JSl-4) 7 5 $ 39 A3 /?6? 1340

121. 92. TC 1530 1650 9•<(-$ 7 -Oft 37 AO 1219 1219

AVERAGE VALUES 15 SO 1160 8 -3 0 M i 3S 2 9 IA93 7/2

INFERRED CONDITIONS LEAKY CONFINED

( b ) SOLUTION:- DISTANCE - DRAWDOWN

METHOD VALUES OF HYDRAULIC PARAMETERS r(m) T (m2/d) s, (-) S2 (-) s, (-) K (m/d) L (m)

15-2-4 5 10 N.J -- 12 91

SL (II) 4 5-72 5 io - * 5 (-3) - >2 91

121-92. 5 10 - - 5-5 (-4) 12 91

- TC (SS) 6 So - - - IG 3 51

- - TC (NSS) - - - - -

SL (II) ------

AVERAGE VALUES Goo - 4-5C-3) - 14 2 2 !

INFERRED CONDITIONS LEAKY CONFINED

Table. 5.6. Pumping test analysis results (analytical) of Chandina Well; (a) Time- Drawdown and (b) Distance-Drawdown. (a) i i r t L - u n v c. • i 11 ic.~unAiMuuMiv r l u i CHANDINA PIEZO. WELL AT A DISTANCE R - 50.0 FT Q - 84662 FT3/D

L0G10

Q = 84662 ft7d

r = 50.0 ft

s = 0.15 ft

t = 3.4 mins

W(u) = 1

UJ b = 135.0 UJ ft u_ z O3 3Q < -1 CCQ J

-a -1 TIHE (HINUTES) L0G10

^ STRAIGHT LINE HETHOO : TIHE-DRAWDOWN PLOT

CHANDINA PIEZO. WELL AT A DISTANCE R - 50.0 FT Q 84662 FT3/D

00

20:

6C:

80: 1.0C:

1.60: Q = 84662 ft7d

r = 50.0 ft 2 .0 0 : 2 .2 0 : to = 2.3 mins

2.40: ds = 0.23 ft 2.60: b = 135.0 ft 2.80:

3.00:

3.20:

3.6CL-1 L0G10 TIHE (HINUTES)

Fig. 5.8.A : Aquifer test analysis for OW 1 at Chandina; (a) Type Curve and (b) Straight Line. (a) TYPE CURVE : TIHE-DRAWDOWN PLOT CALC.REC.DATA CHANDINA PIEZO. WELL AT A DISTANCE R - 150.0 FT Q - 84662 FT3/D L0G10

r/L= 0.35

Q = 84662 ft3/d h“ UJ r = 150.0 ft UJ u . z Z 3 o 3Q t = 11.2 mins cc< Q W(u) = l

l/u = l

135.0 ft

-1 TIHE (HINUTES) L0G10

^ STRAIGHT LINE HETHOD : TIHE-DRAWDOWN PLOT

CALC.REC.DATA CHANDINA PIEZO. WELL AT A DISTANCE R - 150.0 FT Q - 84662 FT3/D

00 20:.

60: 80: 1.00: 1 .2 0:

Q = 84662 ft3/d 1.60: r = 150.0 ft 1.80: 2 .0 0 : smu = 2.74 ft

2 . 2 0 : = l .37 ft 2.40: tj = 68.0 mins 2.60: ds, = l.68 ft 2.80:

3.00 135.0 ft

3.20

3.60: -1 L0G10 TIHE (HINUTES)

Fig. 5.8.B : Aquifer test analysis for OW 2 at Chandina; (a) Type Curve and (b) Straight Line.

/ CHANDINA PIEZO. WELL AT A DISTANCE R - 400.0 FT Q - 846G2 FT3/D LOGIO

Q = 84662 ft7d t— uuu r = 400.0 ft u . 2 s = 0.41 ft O3 o r 3 t = 3.2 mins 2 a W(u) = 1

135.0 ft

-a -1 TIDE (HINUTES) L0G10

(b) STRAIGHT LINE HETH0D : TlflE-DRAWDOUIN PLOT

CHANDINA PIEZO. WELL AT A DISTANCE R - 400.0 FT C - 84662 FT3/D

00 20:

60:

80. 1. 00:

1.60: Q = 84662 ft3/d

r = 400.0 ft 2 . 0 0 : 2 . 2 0 : = 2.16 ft

= 1.08 ft 2.60: t; = 74.0 mins

ds, = 0.83 ft 3.00:

3.20: 135.0 ft

3.40L

3.60L

L0G10 TIDE (fUNUTES)

Fig. 5.8.C1 : Aquifer test analysis for OW 3 at Chandina; (a) Type Curve and (b) Straight Line. /

DRAWDOWN (FEET LOGIO 3.6CL 3.20. 2 2 1.80: 1 1 3.00: 2.80: 2.60: . . . . 0 2 0 0 0 2 0 0 80: 60:. 40: 20 L 00r F i g5. . 8 . C 2 :A q u i f e r t e s t a n a l y s i s f o ra t OW3 C h a n d i n a ; ( a ) T y p e C u r v e -1 : : : : ACRCDT HNIAPEO WL TADSAC 0. TQ-862 FT3/D WELLPIEZO.ATADISTANCE-R-400.0 84662 CHANDINA FTQ CALC.REC.DATA TAGTLN EHD : TIHE-DRAWDOWNPLOT HETHOD LINESTRAIGHT A C RCD T CAD N PEO WL A A ITNE - 0. F Q 862 FT3/DCALC.REC.DATA CHANDINA 84662 WELL - Q PIEZO. FT DISTANCE AT A 400.0 - R a n d ( b ) S t r a i g h t L i n e . S = .5 ft 0.75 = dSi , 5. mins 50.0 = t, = 0. ft 400.0 = r = 46 ftJ/d 84662 = Q 09 ft 0.90 = 3. ft 135.0 IE (HINUTES)TIME IE (HINUTES)TIHE () 1 = W(u) = . mins 2.3 = t A = 1 = lAi = .8 ft 0.38 = s = 0. ft 400.0 = r = 46 ft7d 84662 = Q 3. ft 135.0 /= 0.1 r/L= LOGIO LOGIO (figures not included).

3) Discussion:

The results obtained by analyzing the time-drawdown data for OW1 are abnormally high and misleading, therefore these results are not included in the final interpretation of the results (Table. 5.6).

For OW2 and OW3, both the time-drawdown and recovery data were available for analysis. But the time-drawdown data measured for OW2 are not amenable to analytical solution and therefore were not included. Recovery results for OW2 and the distance-drawdown result are much different from those obtained for OW3.

The leakage values (L) ranges from 91 m to 1340 m for OW3.

Transmissivity values range from 510 m2/d to 1750 m2/d for OW3 with recovery data.

Noticeable differences were found in the storativity values obtained by different methods of solution. The range of values are 8.9 x 10 '3 (obtained from recovery data) for OW2 to 5.5 x 10 "4 (obtained from drawdown data) for OW3.

Considerable variations were also observed in the permeability values obtained by different methods. They range from 12 m/d obtained from distance- drawdown solution to 43 m/d obtained from the time-drawdown solution for OW3.

Kotwali Pumping Test Site:

The well has a depth of 135 ft (41 m) and the structure was constructed with a radius (r) = 0.25 ft (7.6 cm). During the test the well was pumped with a discharge (Q) = 76982 ft3/d (2179 m 3/d) for a period t = 2960 minutes (2.06 days). The observation wells were placed at 50 ft (15 m), 150 ft (45 m), and 400 ft (122 m) from the pumping well. The estimated thickness of the aquifer b = 50 ft (15 m) while the thickness of the overlying aquiclude (b’) = 85 ft ( 26 m). Static water level (swl) = 4.54 ft (1.38 m) below measuring point. The results of pump test data analysis by various analytical methods are summarized in

Table. 5.7 calculated on the basis of the match-point co-ordinates and other necessary parameters obtained from the relevant figures.

1) Time-Drawdown Solution:

(a) Type Curve Method: The match-point co-ordinates for OW1 (r = 50 ft),

OW2 (r = 150 ft), and OW3 (r = 400 ft) were obtained from the log-log plots of

Figures 5.9.A(a), 5.9.B(a), and 5.9.C(a), respectively.

(b) Straight Line Method: The necessary parameters for OW1, OW2, and OW3 were obtained from the semi-log plots of Figures 5.9.A(b), 5.9.B(b), and 5.9.C(b), respectively and the Hantush function tables.

2) Kotwali Distance-Drawdown Solution:

(a) Type-Curve Method: The match-point co-ordinates were obtained from the distance-drawdown log-log plot (figure not included).

(b) Straight Line Method: The necessary parameters were obtained from the previous time-drawdown plots of all the observation wells and the distance-ds

(drawdown per log cycle) semi-log plot (figure not included).

3) Discussion:

The results obtained show all the characteristics of a leaky confined condition. Unusually low leakage values (L = 4572 m) were obtained for OW2 and the maximum leakage (L = 203 m) is obtained for OW3 (Table. 5.7).

The transmissivity values show noticeable differences among themselves. They range from 1040 m2/d obtained for OW2 to 320 m2/d obtained for SITE:- KOTWALI WELL No:- 59

(a) SOLUTION:- TIME-DRAWDOWN

DISTANCE VALUES OF HYDRAULIC PARAMETERS OF METHOD T (m2/d) S(-) K=T/b (m/d) L (m) PIEZOMETER D ’down RFC. D ’down RFC. D ’down RFC. D ’down RFC.

50 ft. SL % 10 - b-m - 53 - 1524 -

15.24m. TC 4 7 0 - 10 C-i) - 31 - 361 -

150 ft. SL 1040 - Ht-4) - 68 - 4572 -

45.72m. TC 790 - - 52 - 15 24 -

400 ft. SL 340 - 4-3 H - 23 - ZOJ -

121. 92m. TC 320 - 4S(-3) - 21 - 2 0 3 -

AVERAGE VALUES G30 - 1-2 (-5) - 41 - 7 6 g -

INFERRED CONDITIONS LEAKY CONFINED

( b ) SOLUTION:- DISTANCE - DRAWDOWN

METHOD VALUES OF HYDRAULIC PARAMETERS r (m) T (m2/d) s, (-) (-) Sj (-) K (m/d) L (m) - 15-24 440 21 (-3) - 29 3 3 9

SL (II) 45-72 4 40 - l-oC-3) - 2 9 3 3 9

121-92 440 - - A-A (-4) 2 9 339

TC (SS) - 5 o o - - - 3 3 3 9 0

TC (NSS) ------

SL (II) ------

AVERAGE VALUES 4 7 0 - (•2( 3) - 31 3 6 5

INFERRED CONDITIONS LEAKY CONFINED

Table. 5.7. Pumping test analysis results (analytical) of Kotwali Well; (a) Time- Drawdown and (b) Distance-Drawdown. DRAWDOWN (FEETS 8 9.00L 8.50: 6.50: G.OO: 5.50: 3.00: 2.50: 2 1.50: 1 1 1 - . LOGIO . . 00 00 00 00 50: Fig. -1 : : : 5.9.A Aq : u i f e r t e s t a n a l y s i s f o ra t 0W1 K o t w a l i ; ( a ) T y p e C u r v e OWL PEO WL TADSAC 00F -S8 FT3/D Q-1S982RAT50.0- FTDISTANCEA WELL PIEZO. KOTWALI TAGTLN EHD :PLOT TIHE-DRAWDOWNHETHODLINE STRAIGHT O W L PEO WL A A ITNE - 00 T -S8 FT3/D KOTWALI Q-7S982 FT WELL PIEZO. DISTANCE AT 50.0 A - R a n d ( b ) S t r a i g h t L i n e . IE HNTS LOGIO (HINUTES) TIHE TIME (HINUTES)TIME () 1 = W(u) = 00 ft 50.0 = b = 00 ft 50.0 ft3/d = r 76982 = Q / = 10 = 1/u = 00 ft 50.0 = b ft 3.75 = s, = 00 ft 50.0 = r = 68 ft7d 76982 = Q 20 mins 12.0 /= 0.04 r/L= LOGIO TTPE CURVE : TIHE-DRAWDOWN PLOT KOTWALI PIEZO. WELL AT A DISTANCE R - -150.0 FT Q - 16982 FT3/D LOGIO

Q = 76982 ft7d

r = 150.0 ft

s = 0.72 ft

W(u) = 1

co Uu = 10 LUUJ r/L= 0.03 u . b = 50.0 ft z3 ao 3< Qac

-1 TIDE (HINUTES) LOGIO

STRAIGHT LINE HETHOD : TIHE-DRAWDOWN PLOT

KOTWALI PIEZO. WELL AT A DISTANCE R - 150.0 FT Q - 16982 FT3/D

00

5 C l 1.00:

2 . 0 0 : 2.50: 3.00: 3.50:

4.00:___ Q = 76982. ft3/d

r = 150.0 ft 5.00:

5.50: 6.00: = 2.60 ft 6.50: 19.5 mins

ds, = 1.25 ft

8 .00: b = 50.0 ft 50:

9.00c. -1 LOGIO TIHE (HINUTES)

Fig. 5.9.B : Aquifer rest analysis for OW 2 at Kotwali; (a) Type Curve and (b) Straight Line. 3.40 3.60c. 2.80: 3.20: 3.00 2 1.80: 1.40: 1.60 1

T.OO: DRAWDOWN (FEET . . -a LOGIO 00 0 2 80: GO: 20 OCL -1 Fig. : _ _ : _ __ : __ 5.9.C 0 ft .0 0 5 = b 1 = W(u) t = 0. ft 400.0 = r / = 1 = 1/u ft’/d 76982 = Q (a) 0 mi s in m .0 0 8 = : Aq : u i f e r t e s t a n a l y s i s f o ra t 0W3 K o t w a l i ; ( a ) T y p e C u r v e OWL IZ. ELA DITNER-400F -S8 FT3/D KOTWALI WELLPIEZO.ATAD ISTANCE-R400.0 Q-"S982 FT STRAIGHT:HETHOD TIHE-DRAWDOWNLINE PLOT s = 2. ft 0 .1 2 = ds, = 50. ft .0 0 5 = b , 0 mi s in m .0 0 3 2 = t, = 400. ft .0 0 0 4 = r ft3/d 2 8 9 6 7 = Q O W L PEO WL A A SAC R £00 T -68 FT3/D KOTWALI WELL PIEZO. Q-36982 AT FT AD ISTANCE £00.0 - R TYPE CURVE TIHE-DRAWDOWN : PLOT a n d ( b ) S t r a i g h t L i n e . IE (HINUTES)TIHE IE (HINUTES)TIHE + + LOGIO LOGIO OW3.

The storativity values are representative of confined conditions. Most values are close together except the lowest value 4.8 x 10 '3 which was obtained for

OW3, the highest storativity value 1.4 x 10^ was obtained for OW2.

Like the transmissivity values, the permeability values also show marked differences. Maximum and minimum values calculated are 68 m/d and 21 m/d.

Barura Pumping Test Site:

The penetrated depth of the well is 305 ft (93 m) and the structure has an effective well radius of 0.25 ft (7.6 cm). During the test, the well was pumped for a period of 3000 minutes (2.083 days) with a constant discharge (Q) = 76982 ft3/d (2179 m3/d). The estimated thickness of the aquifer is 140 ft (40 m) and the thickness of the overlying semi-confining layer is 170 ft (50 m) The static water level at the pumping well is 5.08 ft (1.55 m). The piezometers were placed at distances of 50 ft (15 m), 150 ft (45 m), and 400 ft (122 m) from the pumping well. Test analysis results are summarised in Table. 5.8 calculated on the basis of the match-point co-ordinates and other necessary parameters obtained from the relevant figures.

1) Time-Drawdown and Time-Calculated Recovery Solution:

(a) Type Curve Method: The match-point co-ordinates for OW1 (r = 50 ft),

OW2 (r = 150 ft), and OW3 (r = 400 ft) were obtained from the log-log plots of

Figures 5.10.A(a), 5.10.B(a), and 5.10.C(a), respectively.

(b) Straight Line Method: The necessary parameters for OW1, OW2, and OW3

were obtained from the time-drawdown plots of Figures 5.10.A(b), 5.10.B(b), and

5.10.C(b), respectively and the Hantush function tables.

159 SITE:- B A R U R A WELL No:- 6 9

(aj SOLUTION:- TIME-DRAWDOWN

DISTANCE VALUES OF HYDRAULIC PARAMETERS

OF METHOD T (m2/d) S(-) K=T/b (m/d) L (m) PIEZOMETER D’down REC. D’down REC. D’down REC. D'down RE'C.

■4- * 50ft. SL 6 1 5 0 - 2 St-2) - 144* -- - * * 15.24m. TC IJ70 - 2 3 ( - l) - 41* - - -

SL 150 ft. 7 0 0 1060 5 - 9 ( - $ 2 - 3 ^ 1 6 2 5 3 5 2 7 6 2

TC a* 4 5.72m. A 6 0 9s o 3 - 5 H ) II 2 3 /I4 5 7 2

40 0 ft. SL 1170 1/50 3 - 5 H ) m 2 7 2 7 //0g 7 6 2 1 0 o TC 0 121-92. 1 4 6 0 fc-5 (-4 ) 34 2 1 5 0 5 4 0 6

AVERAGE VALUES mo 1 0 2 3 5 - ^ - 4 ) * 3 $ 2 2 24 6 2 6

INFERRED CONDITIONS LEAKY CONFINED

( b ) SOLUTION:- DISTANCE - DRAWDOWN

METHOD VALUES OF HYDRAULIC PARAMETERS r (m) T (m2/d) s, (-) S2 (-) s, (-) K (m/d) L (m)

15-24 Goo - - 14 t5 4

- SL (II) 4 5 -7 2 Goo 5 - 9 1 :4 ) - 14 154

121- 9 2 Goo - - 3 4 L-4) 14 154

TC (SS) - 2 6 o - - - 2 0 5 3 3

TC (NSS) ------

SL (II) ------

AVERAGE VALUES 7 3 0 - 4 1 i-4) - 17 3 4 4

INFERRED CONDITIONS LEAKY CONFINED

Table. 5.8. Pumping test analysis results (analytical) of Barura Well; (a) Time- Drawdown and (b) Distance-Drawdown. DRAWDOWN (FEET SOL . 3 3.20: 2.80: 2.60:___ 2.40: 2 2 3.00[___ 1 1 1.80: . . . . -11 LOGIO 0 0 20 00 00 60: 20 20 80: -1 Fig. : : : : : ___ __ (5) STRAIGHT LINE HETHOD : TIHE-DRAWDOWN PLOT : TIHE-DRAWDOWN HETHOD LINE STRAIGHT (5) 5.10.A = .2 ft 0.925 = s ft 50.0 ftVd = r 76982 = Q = . mins 3.4 = t () 10 = W(u) / = 10 = 1/u AUAPEO WL TADSAC 00F 192 FT3/D - 16982Q-FT 50.0 R DISTANCE AAT WELL PIEZO.BARURA 4. ft 140.0 :A q u i f e r t e s t a n a l y s i s f o ra t 0W1 B a r u r a ; ( a ) T y p e C u r v e A U A IZ. EL T DSAC R 00 T - 68 FT3/D BARURA 16982 - Q WELL FT PIEZO. DISTANCE AT A 50.0 - R TYPE CURVE TIHE-DRAWDOWN : PLOT s 07 ft 0.74 = ds o 2. mins 20.0 = to = 00 ft 50.0 = r = 68 ft3/d 76982 = Q a n d ( b ) S t r a i g h t L i n e . 4. ft 140.0

IE (HINUTES)TIHE IE (HINUTES) TIHE ++ L0G10 LOGIO 3.60L 3.20: 2.80: 2.60: 2 2 3.00: 1.80: 1.60: 1 1 DRAWDOWN (FEET . . . . -11 L0G10 20 00 20 00 8C: 6 4C: 2C: 00 CL -1 Fig. -1 : : : : 5.10.B (a) AUAPEO WL TADSAC 5. TQ 192 FT3/D 16982 --150.0RAQDISTANCEAT WELL FTPIEZO. BARURA TAGTLN EHD : TIHE-DRAWDOWNPLOTHETHOD STRAIGHT LINE 0 ft .0 0 4 1 = b u) 1 = ) (u W = 10 ns in m 1.0 = t = 12 ft 1.23 = s 1 ft .0 0 15 = r t d ft7 2 8 9 6 7 = Q :A q u i f e r t e s t a n a l y s i s f o ra t 0W2 B a r u r a ; ( a ) T y p e C u r v e /u= A U A IZ. EL T DSAC R 100 T - 68 FT3/D BARURA 16982 WELL - Q PIEZO. FT AT DISTANCE A 150.0 - R TYPE CURVE TinE-DRAUDOUN : PLOT a n d ( b ) S t r a i g h t L i n e . 1 TIHE (HINUTES)TIHE IE (HINUTES)TIHE = 16 ft 1.64 = ( s d j 9. ns in m .8 9 = tj 150. ft .0 0 5 1 = r t d ft7 2 8 9 6 7 = Q 74 ft 4 .7 1 = L= 0.4 0 = /L r + +++• 0 ft .0 0 4 1 L0G10 LOGIO TYPE CURVE : TIHE-DRAWDOWN PLOT BARURA PIEZO. WELL AT A DISTANCE R - 400.0 FT Q - 16982 FT3/D LOGIO

r/L= 0.4

Q = 76982 tf/d »- UJ Ll I r = 400.0 ft 2 3 crO 3< t = 3.1 mins QDC W(u) = 1 lft = 1

140.0 ft

-1 TIHE (HINUTES) LOGIO

STRAIGHT LINE HETHOD : TIHE-DRAWDOWN PLOT

BARURA PIEZO. WELL AT A DISTANCE R - 400.0 FT Q - 16982 FT3/D

oa 20: 40:

60:

80: 1.00:

1.60:_ Q = 76982 ft}/d

r = 400.0 ft 2.0C_ 2.20_

2.60_ t, = 29.0 mins

2.80_

3.00i_ 140.0 ft

3.60t -1 LOGIO TIHE (HINUTES)

Fig. 5.10.C : Aquifer test analysis for OW 3 at Barura; (a) Type Curve and (b) Straight Line. 2) Barura Distance-Drawdown Solution:

(a) Type Curve Method: The match-point co-ordinates were obtained from the distance-drawdown log-log plot (figure not included).

(b) Straight Line Method: The necessary parameters were obtained from the previous time-drawdown plots of all the observation wells and the distance-ds

(drawdown per log cycle) semi-log plot (figure not included).

3) Discussion:

The time-drawdown data recorded for OW1 is not amenable to analytical solution because of its negative draw-down characteristics (see section

5.2.1) and this well is therefore not included for further interpretation (Table. 5.8).

Drawdown and recovery data are available for OW2 and OW3. The results obtained by analyzing both types of data suggest an ideal leaky confined condition. Maximum leakage (L = 114 m) is given for OW2 and the minimum leakage (L = 1108 m) for OW3.

Comparatively high transmissivity values are recorded for OW3. But the lowest transmissivity value (460 m 2/d) is for OW2. On the other hand, the highest transmissivity value (1460 m 2/d) is for OW3.

The permeability values range from 11 m/d to 34 m/d and correspond to the highest and lowest transmissivity values.

Haziganj Pumping Test Site:

The depth of the pumping well is 391.66 ft (120 m) with a well radius

of (r) = 0.25 ft ( 7.6 cm). During the test the well was pumped at a discharge of

(Q) = 180273 ft3/d (5104 m 3/d) for a period of 3000 minutes (2.083 days). The

observation wells are located at distances of 50 ft (15 m), 150 ft (45 m), and 1000 ft (300 m) from the pumping well. The estimated thickness of the aquifer (b) is 120 ft (35 m) while the thickness of the overlying aquiclude (b’) is 265 ft ( 80 m).

Static water level is 13.21 ft (4.03 m) below measuring point. The analyzed results by the different analytical methods are summarized in Table. 5.9 calculated on the basis of the match-point co-ordinates and other necessary parameters obtained from the relevant figures.

1) Time-Drawdown Solution:

(a) Type Curve Method: The match-point co-ordinates for OW1 (r = 50 ft),

OW2 (r = 150 ft), and OW3 (r = 1000 ft) were obtained from the log-log plots of

Figures 5.11.A(a), 5.11.B(a), and 5.11.C(a), respectively.

(b) Straight Line Method: The necessary parameters for OW1, OW2, and OW3 were obtained from the semi-log plots of Figures 5.11.A(b), 5.11.B(b), and 5.11.C(b) and the Hantush function tables.

2) Haziganj Distance-Drawdown Solution:

(a) Type Curve Method: The match-point co-ordinates were obtained from the distance-drawdown log-log plot (figure not included).

(b) Straight Line Method: The necessary parameters were obtained from the previous time-drawdown Plots of all the observation wells and the distance-ds

(drawdown per log cycle) semi-log plot (figure not included).

3) Discussion:

The OW1 and OW3 show enough leakage to qualify as a leaky confined condition but OW2 does not produce any leakage and hence suggests a non-leaky confined condition. Maximum leakage (L = 381 m) was produced for

OW1 while the minimum leakage (L = 3048 m) was obtained for OW3 (Table.

165 SITE:- HAZ IGANJ WELL No:- 82

(a) SOLUTION:- TIME-DRAWDOWN

DISTANCE VALUES OF HYDRAULIC PARAMETERS OF METHOD T(rn2/d) S(-) K=T/b (m/d) L (rn) PIEZOMETER D’down REC. D'down REC. D'down REC. D’down REC.

- 5 0 f t . SL 1690 - 4-4(-a) - 4 6 1524 - * 1 5 - 2 4 m . TC 9 7 0 - a« (-4)- 2 6 - 3 8 ) -

1 5 0 f t . SL 166 O - 17 d-4) - 4 5 - - -

4 5.72 m. TC 10 - & o(-$ - 47 - - -

1 00 0 ft. SL 14 50 - - AO - 2.17?

304. 80m. TC (710 - 5-10 - 47 - 3 0 4 8

AVERAGE VALUES 15 30 - 4-5 0 - 4 2 - 2250

INFERRED CONDITIONS LEAKY C0NF INED

( b ) SOLUTION:- DISTANCE - DRAWDOWN

METHOD VALUES OF HYDRAULIC PARAMETERS r(m) T (m2/d) s, (-) s2 (-) S,(-) K (m/d) L (m)

15-24 I6IO 2-2 (-4) - - 4 4 ( 8 8 ?

SL (II) 4 5 - 7 2 I6IO - 8'3 (-5) - 4 4 1887

- 3 0 4 -8 0 I6IO - 3'9(r4) 4 4 1 8 8 7

TC (SS) - 12(0 -- - 3 3 1 3 7 2

TC (NSS) ------

SL (II) ------

AVERAGE VALUES 14 (O - 3-1 ( - 4 ) - 3 9 ( 6 3 0

INFERRED CONDITIONS LEAKY CONFINED

Table. 5.9. Pumping test analysis results (analytical) of Haziganj Well; (a) Time- Drawdown and (b) Distance-Drawdown. (a) lire. i*unve. s i me uriAwuuwrg rLU I HAJIGANJ PIEZO. WELL AT A DISTANCE R ' 50.0 FT Q ' 180213 FT3/D

LOGIO 5>

r/L= 0 .0 4 :

Q = 180273 ft*/d

r = 50.0 ft

t = 7.6 mins

W(u) = 1

1/u = 100

120.0 ft

L 0G 10TIDE (HINUTES) L0G10TIDE

STRAIGHT LINE HETHOD : TIHE-DRAWDOWN PLOT

HAJIGANJ PIEZO. WELL AT A DISTANCE R - 50.0 FT Q - 180213 FT3/D

Q = 180273 fp/d

10:__ r = 50.0 ft

= 4.55 ft

tj = 4.4 mins

ds, = 2.17 ft

120.0 ft 11: 18L -1 LOGIO TIHE (HINUTES)

Fig. 5.1 l.A : Aquifer test analysis for OW 1 at Hazigang; (a) Type Curve and (b) Straight Line. DRAWDOWN (FEET S. 8.50:. 8 3.50: 3.00: 2.50: 2 1.5C: 1 9.00c. LOGIO .00:_ . . 00 00 50: 00 00 -1 : Fig. : :_ b SRIH IEHTO :PLOT TIHE-DRAWDOWNHETHODLINE STRAIGHT (b) 5.11.B TTPE CURVE TIHE"DRAWDOWN : PLOT ^ AIAJPEO WL TADSAC 5. TQ- 823 FT3/D 180213-QFT- 150.0 WELLR ATA DISTANCE PIEZO.HAJIGANJ :A q u i f e r t e s t a n a l y s i s f o ra t OW2 H a z i g a n g ; ( a ) T y p e C u r v e o= . mins 0.1 to = ft 150.0 = r = 823 ft3/d 180273 = Q A IA J IZ. EL T DSAC R 100 T " 823 FT3/D HAJIGANJ 180213 WELL " PIEZO. Q FT DISTANCE AT A 150.0 " R a n d ( b ) S t r a i g h t L i n e . 2. ft 120.0 IE (HINUTES)TIDE IE (HINUTES)TIHE () 1 = W(u) mins 3.7 = t = .8 ft 0.78 = s ISO.ft = r = 823 ft3/d 180273 = Q 1/u 100 = 2. ft 120.0 LOGIO LOGIO DRAWDOWN ( FEET SOL . 3 3.40: 3.20: 3.00: 2.80: 2.60: 2 1.60: 1 1.80: 2 1 . . . . 0 0 0 2 0 0 80: 40: 20 60: 20 00 Fig. -1 a O 3 2 L u ui tr 3 o < : : : : : ______l -2 L0G10 b SRIH IEHTO :PLOT TIHE-DRAWDOWN STRAIGHTLINEHETHOD (b) -1 5.1 l.C. AIAJPEO WL TADSAC 000F 823 FT3/D 1000.0-R-FTQA 180273AT WELLDISTANCE HAJIGANJPIEZO. A q u i f e r t e s t a n a l y s i s f o r ( b ) S t r a i g h t L i n e . s = .0 ft 1.90 = dsj = 2. ft 120.0 = b i 100 mins 190.0 = ti = 000 ft 1000.0 = r = 823 ft3/d 180273 = Q 18 ft 1.80 = A IA J IZ. EL T DSAC R 10. F Q 827 FT3/D HAJIGANJ 1802*73 WELL - Q PIEZO. FT DISTANCE AT A 1000.0 - R i l U L r N W U U W A t r u - t n i i i c v n u L . c r i i IE (HINUTES)TIHE OW3 OW3 IE (HINUTES)TIHE at Hazigang; Hazigang; (a) Type Curve and () 1 = W(u) = 000 ft 1000.0 ft3/d = r 180273 = Q = 00 mins 10.0 = t ft 0.78 = s / = 1 = 1/u 2. ft 120.0 /= 0.1 r/L=

LOGIO 5.9).

Small variations were found in the transmissivity values calculated using various solutions except the lowest value of 970 m2/d obtained for OW1. The maximum T value (1710 m 2/d) is given for both OW2 and OW3.

Typical storativity values were obtained which suggest a confined condition. The values also shows little variation among themselves obtained by the different methods. Highest and lowest storativity values obtained are 8 .8 x 10-4 for

OW1 and 8.0 x 10 '5 for OW2.

The permeability values, like transmissivity values, also show little variation. The minimum K values 26 m/d is the only very low value but the other values are quite close to each other of which the maximum K value is 47 m/d.

Chauddagram Pumping Test Site:

The pumping well has a depth of 326.66 ft (100 m) which has a structural radius (r) = 0.25 ft (7.6 cm). During the test the well was pumped at a discharge (Q) = 86604 ft3/d (2450 m 3/d) for a period of t = 4290 minutes (3 days).

The observation wells were spaced at distances of 50 ft (15.24 m), 150 ft (45 m), and 1000 ft (300 m) from the pumping well. The aquifer has an estimated thickness

(b) of 241 ft (70 m) while the thickness of the overlying confining layer (b’) is about 95 ft (30 m). Static water level = 7.83 ft ( 2.39 m) below measuring point.

The analyzed results are presented in Table. 5.10 calculated on the basis of the match-point co-ordinates and other necessary parameters obtained from the relevant figures.

1) Time-Drawdown Solution:

(a) Type Curve Method: The match-point co-ordinates for OW1 (r = 50 ft),

OW2 (r = 150 ft), and OW3 (r = 1000 ft) were obtained from the log-log plots of

170 SITE:-CHAUODAGRAM WELL No:- 101

(a) SOLUTION:- TIME-DRAWDOWN

DISTANCE VALUES OF HYDRAULIC PARAMETERS OF METHOD T (m2/d) S(-) K=T/b (m/d) L (nn) PIEZOMETER D'down RF.C. D'down RF.C. D’down RFC. D'down RFC

- 5 0 f t . SL 2 3 0 - 2 0 (-2) - 3 - - * 15.24m. TC 2 o o - 2 3(-2) - 3 - - -

1 5 0 ft. SL 250 - 3 0(-3) - 3 - - -

45.72 m. TC 142 - IA(-3) - 2 - - -

1 0 0 0 f t . SL 3 2 0 - - 4 - - - - 3 0 4 . 80m. TC 210 - 19 (-3) - 4 - -

AVERAGE VALUES 240 - 3 - - -

INFERRED CONDITIONS FULLY CONFINE D

( b ) SOLUTION:- DISTANCE - DRAWDOWN

METHOD VALUES OF HYDRAULIC PARAMETERS r (m) T (m2/d) s, (-) S2 (-) s, (-) K (m/d) L (m)

15-24 ------

SL (II) 4 b 11 - — - - - -

304-80 ------

TC (SS) ------

TC (NSS) - 510 - 5-6 (-4) - 7 -

SL (II) £40 - 3'5(-4) - 11 -

AVERAGE VALUES 6S0 - 4-6 (-4 ) - 9 -

INFERRED CONDITIONS FULLY CONFINED

Table. 5.10. Pumping test analysis results (analytical) of Chauddagram Well; (a) Time-Drawdown and (b) Distance-Drawdown. Figures 5.12.A(a), 5.12.B(a), and 5.12.C(a), respectively.

(b) Straight Line Method: The necessary parameters for OW1, OW2, and OW3 were obtained from the semi-log plots of Figures 5.12.A(b), 5.12.B(b), and

5.12.C(b), respectively.

2) Chauddagram Distance-Drawdown Solution:

(a) Type Curve Method: The match-point co-ordinates were obtained from the distance-drawdown log-log plot (figure not included).

(b) Straight Line Method: The necessary parameters were obtained from the distance-drawdown semi-log plot (figure not included).

3) Discussion:

This is an ideal example of a non-leaky confined condition exclusively suggested by both the type curve and straight line method. Hence there is no leakage (Table. 5.10).

The distance-drawdown solution gave much higher transmissivities in comparison with the time-drawdown solution. The highest value of 840 m2/d was

obtained from the distance-drawdown solution by comparison with a low

transmissivity value of 142 m2/d determined for OW2 by a time-drawdown solution.

The storativity value 2.0 x 10 ‘2 obtained for OW1 is much too high for

a non-leaky confined condition. The values obtained by the time-drawdown solution

showed that storativity decreases with increasing distance of the observation wells.

The lowest storativity value 3.5 x 10"* is given by the distance-drawdown solution.

The maximum and minimum permeability values obtained are 11.0 m/d

and 2 m/d respectively. DRAWDOWN (FEET 14 12 10 18: 13: LOGIO Fig. -1 -1 : : (5) STRAIGHT LINE HETHOD LINE STRAIGHT (5) 5.12.A HUDGA I2.WL TADSAC -00F -60 FT3/D Q-86604 FTR-50.0 ADISTANCE AT WELL PIE20. CHOUDDAGRAH :A q u i f e r t e s t a n a l y s i s f o ra t OW1 C h a u d d a g r a m ; ( a ) T y p e C u r v e a n d ( b ) S t r a i g h t L i n e . CHOUDDAGRAH FT3/D WELL PIEZO. 0-88604 FT DISTANCE AT A R-50.0 TTPE CURVE TIHE-DRAWDOWN s PLOT = 00 ft 50.0 ftVd = r 86604 = Q s 65 ft 6.52 = ds = 4. ft 241.0 = b 40 mins 14.0 t TIHE-DRAWDOWN PLOT TIHE-DRAWDOWN

IE HNTS LOGIO (HINUTES) TIHE TIHE (HINUTES)TIHE =4. ft =241.0 b 1 = W(u) mins 9.8 = t = 00 ft 50.0 = r = 60 ftVd 86604 = Q / = 1 = 1/u 32 ft 3.2 = LOGIO (a ) TTPE CURVE : TIHE-DRAWDOWN PLOT CHOUDDAGRAH PIEZO. WELL AT A DISTANCE R - 150.0 FT Q-86604 FT3/D LOGIO

H UJ Q = 86604 ftVd iLi Ll. z r = 150.0 ft o3 o3 cc< a t = 6.9 mins

W(u) = 1

1/u = 1

241.0 ft

-1 TIHE (HINUTES)

(b) STRAIGHT LINE HETHOD : TIHE-DRAWDOWN PLOT CHOUDDAGRAH PIEZO. WELL AT A DISTANCE R - 150.0 FT Q-86604 FT3/D

+ +. ++

Q = 86604 ft5/d

10: r = 150.0 ft 11 16.0 mins

12: ds = 5.9 mins 13: b = 241.0 mins

15:

18:

-1 LOGIO TIHE (HINUTES)

Fig. 5.12.B : Aquifer test analysis for OW 2 at Chauddagram; (a) Type Curve and (b) Straight Line. DRAWDOWN ( FEET ) DRAWDOWN (FEET LOGIO 9 i i n 9.0GL 8.50: 8.01 6.5< 6.0i 5.50: 5.00: 3.50: 2.50: 2 1.50: 1 3.00: . . 0 0 00 50: 00 -1 Fig. : : __ 5.12.C HUDGA IZ. ELA ITNER10. TQ864 FT3/D FTQ-86604 R-1000.0 ADISTANCE AT WELL PIEZO. CHOUDDAGRAH STRAIGHT LINE METHOD : TIHE-DRAWDOWN PLOT : TIHE-DRAWDOWN METHOD LINE STRAIGHT CHOUDDAGRAH FT3/D WELL PIEZO. Q-86604 FT DISTANCE AT A R-1000.0 :A q u i f e r t e s t a n a l y s i s f o ra t 0W3 C h a u d d a g r a m ; ( a ) T y p e C u r v e o 170 mins 117.0 = to ft 1000.0 = ft3/dr 86604 = Q s 46 ft 4.67 = ds = 4. ft 241.0 = b a n d ( b ) S t r a i g h t L i n e .

i i (lNTS LOGIO TiriE (fllNUTES) ______IE (HINUTES) TIHE 1 - / L A t [ /

i

/

* — ------t '

--- > X .+ / 1 INI 1 I 1N 1 I 1 i . 4. t ! ft 241.0 = b ()= 1 = W(u) t mins 90.0 = s = 2.4 fts = r Q / 1 : 11/u =

looo.o= 864 ftVd 86604 = X t ; ft Mill pm LOGIO Senbagh Pumping Test Site:

The well has a depth of 295 ft (90 m) and the structure has an effective well radius of (r) = 0.33 ft (10 cm). During the test the well was pumped at a discharge (Q) = 86604 ft3/d (2450 m 3/d) for a period of t = 4100 minutes (2.85 days). The observation wells are located at distances of 50 ft (15 m), 150 ft (45 m) and 400 ft (122 m) from the pumping well. The estimated thickness of the aquifer

(b) is about 136 ft (40 m) while the thickness of the overlying aquiclude (b’) is 157 ft (48 m). Depth of static water level is 5.17 ft (1.57 m) below the measuring point.

All the observation wells were put down to a similar range of depths which is 247 ft (75 m). The analytical results are summarised in Table. 5.11 calculated on the

basis of the match-point co-ordinates and other necessary parameters obtained from

the relevant figures.

1) Time-Drawdown Solution:

(a) Type Curve Method: The match-point co-ordinates for OW1 (r = 50 ft or

15 m), OW2 (r = 150 ft or 45 m), and OW3 (r = 400 ft or 120 m) were obtained

from the log-log plots of figures 5.13.A(a), 5.13.B(a), and 5.13.C(a), respectively.

(b) Straight Line Method: The necessary parameters for OW1, OW2, and OW3

were obtained from the semi-log plots of Figures 5.13.A(b), 5.13.B(b), and

5.13.C(b), respectively and the Hantush function tables.

2) Senbagh Distance-Drawdown Solution:

(a) Type Curve Method: The match-point co-ordinates were obtained from the

distance-drawdown log-log plot (figure not included).

(b) Straight Line Method: The necessary parameters were obtained from the

previous time-drawdown plots of all the observation wells and the distance-ds

(drawdown per log cycle) semi-log plot (figure not included). SITE:- SENBAGH WELL No:- 1 3 0

(a) SOLUTION:- TIME-DRAWDOWN

DISTANCE VALUES OF HYDRAULIC PARAMETERS i§ OF METHOD T (m2/d) S(-) II (m/d) L (m) PIEZOMETER D ’down RF.C. D ’down RFC. D’down RFC. D’down RF.C.

50 ft. SL 69 0 - - 1? - 9 5 3 -

15.24m. TC 6 8 0 - 34 (~<) - 17 - 9 6 7 . -

1 5 0 ft. SL 7 8 0 - - 19 - 914 -

45.72 m. TC 7 5 0 - 3 0(-4) - IS - 6 5 3 -

400 ft. SL 9 9 0 - /•2(- 3) - 24 - 9 3 g -

121. 92m. TC 7 5 0 - 1-3 (-3) - IS - 6loo -

AVERAGE VALUES 7 ?o - - 19 - 8 4 4 -

INFERRED CONDITIONS LEAKY CONFINED

( b ) SOLUTION:- DISTANCE - DRAWDOWN

METHOD VALUES OF HYDRAULIC PARAMETERS r (m) T (m2/d) S, (-) S2 (-) S3 (-) K (m/d) L (m)

15-24 6 7 O 9-2(-3) - - 16 3 67

SL (II) 45 -7 2 6 7 0 - 6-0 (-3) - 16 3 67

121-92 670 - - 4 -5 (-3) 16 3 6 7

TC (SS) - 5 8 0 - - - 14 4 2 7

TC (NSS) ------

SL (II) ------

AVERAGE VALUES 630 - 6-6 (-3 } - 15 3 9 7

INFERRED CONDITIONS LEAKY CONFINED

Table. 5.11. Pumping test analysis results (analytical) of Senbagh Well; (a) Time- Drawdown and (b) Distance-Drawdown. DRAWDOWN (FEET 8 9.00L S.50 6.0C 5.50 3.50 5.00 4.00 2.50 2 3.00 1.50: 1 . LOGIO . . 00 00 00 50: 0(1 -1 Fig. -1 : : : b SRIH IEHTO : TinE-ORAWDOWNPLOTLINEHETHOO STRAIGHT (b) 5.13.A. w EBG IZ. ELA AQ-86804-50PIEZO.ATFT WELLDISTANCER SENBAGH Aquifer test analysis for at 1 W 0 Senbagh; (a) Type Curve and ( b ) S t r a i g h t L i n e . SENBAGH PIEZO. WELL AT A DISTANCE R AATDISTANCE WELL PIEZO.SENBAGH . i uun»L • II - 1AUI \ PLOT O L P I\I W U J IL U A I1 .-U IIIC I • L » n u u i_ i . . IE (HINUTES)TINE iE (fllNUTES)TinE 0 T -60 FT3/D G-86604 FT50 FT3/D () 1 = W(u) mins 4.2 = t 0.94 = s tf/d 86604 = Q = 00 ft 50.0 = r b = 136.0 136.0 = b 1 /u= j 56 mins 5.6 = tj = 00 ft 50.0 = r = 60 ft3/d 86604 = Q = 3.91 3.91 = 136.0 136.0 100 ft ft ft ft

LOGIO L0G10 ( a) TTPE CURVE : TIHE-DRAWDOWN PLOT SENBAGH PIEZO. WELL AT A DISTANCE R - "150 FT Q-86604 FT3/D LOGIO

Q = 86604 ft7d

r =150.0 ft

s = 0.86 ft

t = 66.0 mins

W(u) = 1

1/u = 100 I— uiU r/L= 0.07 ‘ Ll. 136.0 ft

o 3Q cc< a

-1 TIME (RINUTES) LOGIO

STRAIGHT LINE HETHOD : TIHE-DRAWDOWN PLOT

SENBAGH PIEZO. WELL AT A DISTANCE R - T50 FT Q-6E804 FT3/D

00

50i

Q = 86604 ft3/d

r = 150.0 ft

s, = 2.55 ft

tj = 2 3 .5 m in s

b = 136.0 ft

-1 LOGIO TIf1E (HINUTES)

Fig. 5.13.B : Aquifer test analysis for OW 2 at Senbagh; (a) Type Curve and (b) Straight Line. 8 7.50: 9.00L 8.50: 6.50: DRAWDOWN (FEET 6 5.50: 5.00: 4.50: 4.00: 3.50: 3.00: 2 2.50: 1.50: 1 . . . . LOGIO 00 0 0 0 0 0 0 50: 00 -1 -1 F i g5. . 1 3 . C :A q u i f e r t e s t a n a l y s i s f o ra t 0W3 S e n b a g h ; ( a ) T y p e C u r v e : : : : (a) EBG IZ. ELA ITNER-40F -60 FT3/D -FTQ-86604R400 DISTANCE A ATPIEZO. WELL SENBAGH TAGTLN EHD :PLOT TIHE-DRAWDOWN HETHODSTRAIGHTLINE = 60 ftVd 86604 = Q = 0. ft 400.0 = r j 100 mins 100.0 = tj s = .0 ft 1.30 = ds, 14 ft 1.40 = EBG IZ. ELA ITNER-40F -60 FT3/D -ATADISTANCER400FTQ-86604 WELL PIEZO. SENBAGH TYPE CURVE TIHE-DRAWDOWN : PLOT a n d ( b ) S t r a i g h t L i n e . 28 ft 2.80 = 3. ft 136.0

iE (HINUTES)TinE IE (HINUTES)TIHE () 1 = W(u) mins 9.0 = t ft 0.76 = s ft 400.0 ft7d = r 86604 = Q / = 1 = 1/u 136.0 136.0 ft /= 0.02 r/L= LOGIO LOGIO 3) Discussion:

Senbagh well is a typical example of a leaky confined condition (Table

5.11). Minimum variation between the results for different hydraulic parameters were found except for the unusually low leakage value (L = 6100 m) obtained for

OW3. The maximum leakage was L = 367 m.

The transmissivity values range from 990 m2/d obtained for OW3 to

580 m 2/d. Extreme permeability values of 24 m/d and 14 m/d correspond to the maximum and minimum transmissivity values.

The storativity values unanimously suggests a confined condition. The values range from 9.2 x 10 '3 for OW1 to 3.0 x 10“* for OW2. 5.3 Numerical Solution:

5.3.1 Radial Flow Model:

It is well known that the analytical solutions (both type-curve and straight line methods) are based on many simplified assumptions. It frequently happens that one or more of these assumptions are not valid and although the range of problems that can be analyzed by these classical solutions are impressive yet many features which are known to have a significant effect on the response of an aquifer cannot be included in the analytical solution. Where this is the case an alternative numerical method can be used known as the radial flow modelling technique. This method has the advantage that a variety of variables can be introduced in a single numerical solution. A full description of the numerical technique is available in several books and journals [Rushton and Chan (1976),

Jones and Rushton (1981), Rushton and Booth (1976) and Rushton and Redshaw

(1979)] however a brief outline is given below:

This method is based on a discrete space-discrete time approximation

to the differential equation of two-dimensional, radial, time-variant flow in the

aquifer. When analyzing pumping test data using a numerical technique, the flow

is assumed to be radial (Fig. 5.15). Depending on the nature of the problem two

alternative idealizations are adopted:

(1) For confined Situation:

In such situation the general three-dimensional differential equation is

integrated in the vertical direction and takes the following form:-

d dh d dh dh b.k,— +— b.ky— = S,.b------(5.1) dx dx dy dy dt

Where ,

b = aquifer thickness.

182 In many instances vertical flow of water occur into the aquifer (Fig. 5.14) which is called the inflow "q(x, y, t)*\ As a consequence equation (1) becomes: d dh b dh dh — b.kr— + — k , = S q(r,t) (5.2) dr dr r dr dt substituting r* = x 2 + y2 at the same time, which is known as the governing differential equation.

Rather than working in terms of ground water potential "h" , it is usually convenient to consider the drawdown ’s’ since s = (H - h) where ’H’ is the elevation of the rest water level. After this substitution, equation (5.2) becomes: d ds b ds ds b.k^— +— .k,.------= S + q(r,t) (5.3) dr dr r dr dt

which is known as the governing differential equation for a radial flow due to pumping under a non-leaky confined condition, where,

s = drawdown below an arbitrary datums,

r = radial co - ordinate,

b = saturated thickness of the aquifer,

K, = radial permeability,

t = duration of pumping,

S = storativity, and

q = inflow per unit area.

It has been pointed out by Rushton and Redshaw (1979) that when the radial ordinate is divided into a discrete mesh which increases logarithmically by

an amount of ’da’ then it is usually more convenient to analyze radial flow

towards a well.

Introducing the variable ’a’ such that a = logtr g. 15( . s et pae dicr e tme i t adi dit ncr i g sin a re c in e c n ista d l ia d ra ith w rid g e tim te re isc d - ace sp te re isc D ). (b 5 .1 5 . ig F Ti m e i. 14 : nfow de o ekg i a i aquifer. d e fin n o C a in leakage to due w flo In : 4 .1 5 Fig. (t-1 ) ) (t-1 i. .5a : ss Nu rcl ehiu fr ail lw flow radial for technique erical um N f o asis B : 5.15(a) Fig. j t ( ogart caly ( tr Rus on 1979). n to sh u R fter: (A lly a ic m rith a g lo l e v e L d n u o r G ( Levels Levels - ( ✓Piezometric ✓Piezometric e( nie aquifer). onfined del(C o m y r a d n u o B r e t u O ■t

» I 1 1 •r •r

\ ! \ I \ 1 \ I \ ! \ N \ - — \ V " - t \ ! ■N— r \ i \ r - \ l l \ I \ I \ I \ \ I \ I \ I i s ■^•Radius ______\ \ \ \ *1 Aquifer t I and substituting for it in equation (5.3) and multiplying through by r2 leads to the equation

d2s ds b.kr. = Si2. + qi2 (5.4) da 2 dt

A solution to equation (5.4) with appropriate boundary and initial

conditions can be obtained using the finite difference technique. The use of mesh-

spacing with a constant increment of ’da’ results in a fine mesh in the vicinity of

the well with the distance between mesh points becoming larger with increasing

radius. By considering a time increment from t to (t+dt) as shown in the Figure.

5.15 and using the backward difference approximation (fully implicit), the finite

difference approximation to equation (5.4) allows the expression to be written for

drawdown centred at nodes j as:

b.k, ts(j-i) ■ ^Sq) + s0+1)] (l+dl) da 2

Sr' — [s(j)>G-*io " sjJ + 9(t + dt/2) rj (5.5) dt

For an accurate representation at the smallest radius, according to Rushton

and Redshaw (1979), the initial time step should be kept very small and that can

be done by setting the initial value of the time step as:

0.0025 rw2Sc dt = ------(5.6) T

where ’Sc’ is the confined storativity and rw is the radius of the pumping well.

The finite difference method leads to a series of simultaneous equations.

These are solved efficiently by simple matrix routines.

(2) For Unconfined Situation:

When the vertical component of flow is significant then the differential

185 equation for radial flow towards a well takes the following form:

d ds b ds d2s ds — b.k— + — k,.— + b.lq— = S (5.7) dx dr r dr dzj dt

Where,

s = drawdown,

r = radial ordinate,

z = vertical ordinate,

k, & kz = radial and vertical permeability,

b = saturated aquifer thickness,

t = pumping time, and

S = storativity.

As in the confined situation, the radial mesh also increases logarithmically and in

addition the drawdowns are defined at the free surface and at distance ’Z = 0.25

m’ above the base of the aquifer, these drawdowns are denoted as sr and sb

respectively (Fig. 5.16). Using the two successive time steps of t and (t+dt) the

finite difference approximation for drawdown is written as:

SfU+i) “ Sf(j) Sf(j-1) " Sf(j) Sb(j) " S«j)

H U ffl H IV. V 0)

SIG. t+di) " sfG. 0 = ------+ qr/ (5.8) Tj

Where, 2.d.a 2 HUj = HLj = ----- b.kr

0.46875.b d.t Vj = ------, T = and K-rf S.q2

’q’ refers to the recharge per unit area. At present there are no exact analytical

186 D a t u m

_ a ___ D raw dow n

Free Surface ~2 5 m l

Fig. 5.16(a). Pictorial definition of drawdown Sf and Sb.

Fig. 5.16(b) : Problems involving variable saturated depth. solutions for time-variant unconfined radial-flow problems.

5.3.2 Presentation of Analysis:

The aquifer condition for all the observation wells was simulated with the time drawdown data (in some cases the recovery data) using the modified

Rushton Radial flow modelling program (Appendix. 5.2) to obtain the numerical solution.

With the modified Rushton radial flow program the well can be modelled using the exact distance of the observation well which brings more accuracy to the results. During the running of the model it was found that some parameters are more sensitive than the others. For confined condition the sensitive parameters are permeability (K) and storativity (S). For leaky confined conditions the sensitive parameters are permeability, storativity and the leakage factor (L). For unconfined conditions, permeability, storativity and the delay index (alpha) are important.

During the simulation exercise the model was run several times with different values for the parameters starting with the manually derived results. The parameters are fed into the computer in the form of a data file that is linked to the model with changes to values of hydraulic parameters made after every run with the aim of finding the closest possible match between the plot of the field time-drawdown data and the model interpretation. The plots with the trial values are displayed on a graphics terminal and the plots for the final results were printed for presentation when the best agreement was achieved. Crosses (+) represent the field data while the continuous unbroken line represent the model data plot. The simulated values of all the parameters are printed at the bottom of every numerical modelling plot.

The simulated final model plot along with the results and the model

188 plot produced by the best analytical results (some with straight line method and others with type curve method) with the results at the bottom of the plot for one observation well of a particular pumping test site are presented together to demonstrate the variation of the results obtained by the two different approaches.

The plots of the two representative test sites (Feni OW1 (Fig. 5.17.A), OW2 (Fig.

5.17.B) and OW3 (Fig. 5.17.C) and Nabinagar OW1 (Fig. 5.18.A), OW2 (Fig.

5.18.B) and OW3 (Fig. 5.18.C) are presented below and the plots for all other test sites are attached in Appendix. 5.3 as tabulated in the next page.

The movement of the model plot during simulation is controlled by changing the more sensitive parameters. An increase in K value, for example, decreases the gradient of the curve and vice versa (Fig. 5.19.a).

A change in the confined storativity value moves the curve either upward or downward without changing the gradient. A positive change takes the curve upwards while a negative change brings the curve downwards (Fig. 5.19.b).

A change in the leakage factor (BL) modifies the tail end of the curve (Fig. 5.19.c).

An increase in the BL value (lower leakage) produces a downward deviation whereas a decrease in BL value (higher leakage) moves the tail upwards. A variation in the Boulton delay index (alpha), modifies the wavy nature of the typical elongated S-shaped curve that represent the three section of a true water table condition (Fig. 5.19.d).

During simulation with the radial flow modelling the true well radius was used. A very large Rmajl was adopted to avoid any boundary effect. Lithological logs for the pumping wells were not available, and the length of screen was used as the effective aquifer thickness to run the model. It is also assumed that the well is 100 percent efficient. TEST SITE OBSERVATION WELL APPENDICES

OWL Appendix 5.3.1.A B’Baria OW2. Appendix 5.3. l.B OW3. Appendix 5.3.l.C

OWL Appendix 5.3.2.A

Daudkandi OW2. Appendix 5.3.2.B OW3. Appendix 5.3.2.C

OWL Appendix 5.3.3.A Burichong OW2 . Appendix 5.3.3.B

OW3. Appendix 5.3.3.C OWL Appendix 5.3.4.A OW2. Appendix 5.3.4.B Chandina OW3. Appendix 5.3.4.C1 OW3. Appendix 5.3.4.C2 OWL Appendix 5.3.5.A Kotwali OW2. Appendix 5.3.5.B OW3. Appendix 5.3.5.C OWL Appendix 5.3. 6 .A

Barura OW2. Appendix 5.3.6.B OW3. Appendix 5.3.6.C OWL Appendix 5.3.7.A

Haziganj OW2. Appendix 5.3.7.B OW3. Appendix 5.3.7.C

OW1. Appendix 5.3. 8 .A

Chauddagram OW2. Appendix 5.3. 8 .B

OW3. Appendix 5.3. 8 .C

OWL Appendix 5.3.9.A Senbagh OW2. Appendix 5.3.9.B OW3. Appendix 5.3.9.C STRAIGHT LINE HETHOD : TIHE-DRAWDOWN PLOT FENI PIEZOa WELL AT A DISTANCE R - 50c0 FT Q - 161553 FT3/D FIELD DATA INDICATED BY CROSSES RADIAL FLOW HODEL INDICATED BY CONTINUOUS LINE

. — '—* f T " F~ I 1 I I I 1 | . , , , .,, , t- T, .,T-r.,r,T T----i-- 1-.—i—i—r i i. 1 ? 3 ANALYTICAL SL: +■ 4 5 6 7 R a 10 11 12 1" " " ^ : 13 14 15 16 17 K= 91ol0899 *s= n o o n o SY= o10000 Rw= d250 Fmax- 200000:. JFIX- 1 18 ---- 1 ... i i j i i i il ----LPHA=1— i oOOOOOBi j i 11 ■-=- a 000001__1 1 1 1 1 1 1I ____ELLOS=1__ 1_ I1_dL_1_J-.JLOOO J_ RCH- oOOOOO ! 1 TIHE (HINUTis) 3 LOGIO

STRAIGHT LINE HETHOD : TIHE-DRAWDOWN PLOT (b) FENI PIEZOo WELL AT A DISTANCE R - 50-0 FT Q - 161553 FT3/D FIELD DATA INDICATED BY CROSSES RADIAL FLOW HODEL INDICATED BY CONTINUOUS LINE

. - 1—1 1 1 1 » I "■■■T T "f"T"TT -1 .l-1—i—till -- v t— -i" i' r i i i • ■ ' I-- 1- 1—i—r-i ■.

: = SYNTHETIC ; + \ + \

: : :

• : T«- :

: K= 91o50000 S- d0018Q SY= a 10000 RW= a250 RTiax= 200000:. j JFIXf 1... iiLPHA--1 . oOOOOOB i i i i i i oOOOOO IJELLOS= I dOOO RCH= D00000 : -1 TIHE (HINUTES) LOGIO

Fig. 5.17.A : Comparison of (a) Manual and (b) Model result from Feni OW1. DRAWDOWN ( FEET ) DRAWDOWN ( FEET 3 2n50 2 1d50L 3 loOOi o d □ 50: □ d 50 001 00 50 00 00 50 00 50 501 00 00 00 50: 00 -1

JI= 1 JFIX= j K= j ------: • - • ’ ' - • (a) F i g5. . 1 7 . B :C o m p a r i s o n o f ( a ) M a n u a l a n d ( B ) M o d e l r e s u l t

(b) FX 1 JFIX= K- 1 --- 3 8 81*25933 ,j. r — r T T | T 1— i— d AILFO OE IDCTD T OTNOS LINE CONTINUOUS BT INDICATED HODEL FLOW RADIAL CROSSES BT INDICATED DATA FIELD - R DISTANCE A AT WELL PLOT PIEZOo FENI : TIHE-DRAWDOWN HETHOD LINE STRAIGHT EI IZn EL T DSAC R - R DISTANCE A AT WELL PIEZOn FENI IL DT IDCTD T CROSSES BT INDICATED DATA FIELD TAGT IE EHD TH-RWON PLOT : TIHE-DRAWDOWN HETHOD LINE STRAIGHT AIL LWHDL NIAE B CNIUU LINE CONTINUOUS BT INDICATED HODEL FLOW RADIAL 50000 i _ j _ »i i from Feni OW2. I m ------^LPHA= oOOOOOB LPHA= S- ^ =00118 S^ 1 --- 0 oOOOOOB.- OOI 1 -- 1 i i._i_ 8 O 1

1 . x ST= ST= IE (HINUTES) TIHE IE (HINUTES) TIHE T olOOOO ST- 0 —1 o 000 I 00000 OOOOO --- olOOOO r — t ~ t — t ~ r i X X 1 LIELLOS= 'I JELLOS= I W o5 Rnnax= RW= o250 W n250 RW- — T “T £00*0 £ 00*0 V X -- \ T - 161553 - Q FT T - 161553 - Q FT 1 - d d rTTTT OOO OOO \ i V ... ANALYTICAL SL C = 000 ; □00000 RCH= RCH- Rnnax- ... SYNTHETIC T "" T "*11 T ! ' l \ LOGIO LOGIO 200000 00000 200000 > FT3/D FT3/D CE5 35a00 O

DRAWDOWN ( 3a50 FEET ) DRAWDOWN ( FEET 1 1 a 50 8a 6a 5a 3a 3a 8a la la 6a 5a 2a la la 9a CD

O -1 ; : : F i g5. . 1 7 . C :C o m p a r i s o n o f ( a ) M a n u a l a n d ( b ) M o d e l r e s u l t l L ---

» , EI IZo EL T ITNE -OOO T Q-T61553 FT R-lOOOoO DISTANCE A AT WELL PIEZOo FENI W K- FX 1 / 1 JFIX= = 85a29999 K= FX 1 JFIX- 1 -- 84o50000 l ___ 1 - Ii I 1 i I AIL LW OE IDCTD T OTNOS LINE CONTINUOUS BT INDICATED HODEL FLOW RADIAL CROSSES BT INDICATED DATA FIELD EI IZa EL TA ITNE "000 T T653 FT3/D GT161553 FT R"1000a0 DISTANCE A AT WELL PIEZOa FENI TAGT IE EHD TH'RWON PLOT : TIHE'DRAWDOWN HETHOD LINE STRAIGHT AILFO HDL NIAE B CNIUU LINE CONTINUOUS BT INDICATED HODEL FLOW RADIAL CROSSES BT INDICATED DATA FIELD TAGT IEHTO : IEDADW PLOT : TIHE-DRAWDOWN HETHOD LINE STRAIGHT 1 —i i i i i i

i v r from Feni 0W3. i a — kLPHA- oOOOOOB ---- LPHA= ...... = p00100 S= ^ aS^ 00095

I 1 — « — « i aOOOOOBL= l ii i —r~ i ■ i i r j

l I l l j i i 1 J l' —' —j i— '— j— ' l -J- 1 j TIHE (HINUTis) (HINUTis) TIHE -- T □10000 ST= T a ST- 10000 IE (HINUTES) TIHE OOO I oOOOOO ii i ,00000 1 1 ----- t i n r i i nr 1 — 1 l 1 J I —l- X i

ELS 1 HELLOS- a 000 IELLOS= 1 a 000 ------W a 250 RW= w d250 Rw= ■i— i i i —i i i— 1— V X i 11 1 1 i i " __ t i i i X i 111 X t 3 ------! \ ! X NLTCL TC ANALTTICAL RCH= oOOOOO oOOOOO RCH= mx 200000-, Fmax^ Rrnax- RCH= RCH= STNTHET 1 ___ r i1 “ i i i r ; X LOGIO i i i i i LOGIO oOOOOO x 200000 FT3/D C : IC - tt J DRAWDOWN ( FEET ) DRAWDOWN ( FEET '111 151 141 121 18 161 131 111 101 ^ F F >: j JFIX= JFIX= j ---- K- I = = l b SRIH LN EHD TH'RWON PLOT : TIHE'DRAWDOWN HETHOD LINE STRAIGHT (b) F i g5. . 1 8 . A :C o m p a r i s o n o f ( a ) M a n u a l a n d ( b ) M o d e l r e s u l t K= FX 1 JFIX- — L l . 1 1 1 .1 1 _l L 1 1— 3Zul3333 - r-r i i i i r - ■ r i- - r — 32d31000 AILFO OE IDCTD T OTNOS LINE CONTINUOUS BT INDICATED HODEL FLOW RADIAL CROSSES BT INDICATED DATA FIELD NAB INAGAR 1 AIL LWHDL NIAE B CNIUU LINE CONTINUOUS BT INDICATED HODEL FLOW RADIAL PLOT : TIHE~DRAWDOWN HETHOD LINE STRAIGHT FIELD DATA INDICATED BT CROSSES BT INDICATED DATA FIELD ' 50 R DISTANCE A AT NAB WELL PIEZOc INAGAR ) from Nabinagar 0W1. ■ > * i i i i * ■ > iLPHA= a . ... LPHA- LPHA- S- = o00052 S= . T PIEZOp o00046 -- i _« p t - p OOOOOB T OOOOOBL- - i i '1 r j i i _ i _i I i— _ i i _ _ I i i i < i > —T ELA ADSAC R “ R DISTANCE A AT WELL T, “”T" V —TTT T 1— T V" " T ” “ , T T i i .= X IE (HINUTES) TIHE ST= 3900 T olOOOO ST= IE (HINUTES) TIHE 3846p00000 \ \ 0 p 10000 0Q000I I II 1 i I i i I I j ^ + + IELLOS= I ---- ELS T HELLOS- Rw— v i i 111 1 1 i i i i 1 i i i i p 250 ------50p0 50p0 t JJ.il i . J J * p ~ ' p OOQ t p i i i r OOO ...... T _ 60 FT3/D _ 86400 Q FT 0 T Q FT ------RCH- RCH- Rmax= NLTCL SL ANALTTICAL RCH- na- 200000 Rnnax- STNTHET I “ ------.u_ + : + _ u . 1 1 60 FT 3/D 86400 LOGIO p 1 LOGIO ------oOOOOO OOOOO 200000;, 1 ---- 1 IC ---- — 1 1. 1 ,—1 j : j ■2o

5 3o50 I 6

<9 n 00 8 1 DRAWDOWN ( FEET ) DRAWDOWN ( FEET 6 5 4 4 3 8o50 2

2 1 I 9 8 4d a 8 I 6 6 5o 5 3d 2 In I la 3d 4d

d d D d d d d d d d d o o d d d d d d d d D d d

o i ,ooL ,50L ,ooL i , ooL ,50L ,00

50 50 00 00 50 OO 50 00 00 00 50 00 50 OO 50 00L 50L ooL ooL. 50L ooL. 50L ooL 50L 50L OOL 50L 50L o

(a) ji= i jfix= ------: K= 31o00000 ; F i g .5. 1 8 . B :C o m p a r i s o n o f ( a ) M a n u a l a n d ( b ) M o d e l r e s u l t JF 1 IX- K- 1 ------1 • • 32d95999 ------i « i i « i i » ! _ —1 I1 _ 1 FIELD DATA INDICATED BT CROSSES BT INDICATED DATA FIELD PLOT PIEZO NABINAGAR : TIHE-DRAWDOWN HETHOD LINE STRAIGHT AIL LWHDL NIAE B CNIUU LINE CONTINUOUS BT INDICATED HODEL FLOW RADIAL AILFO OE IDCTD T OTNOS LINE CONTINUOUS BT INDICATED HODEL FLOW RADIAL AIAA PIEZO NABINAGAR IL DT IDCTD T CROSSES BT INDICATED DATA FIELD TAGTLN HTO : IEDADW PLOT : TIHE'DRAWDOWN HETHOD LINE STRAIGHT i a vLPHA= from Nabinagar 0W2. LPHA= S= = 004ST= O00064 S= l— I I i, I < —i I, l » o00034 d ,0000061= OOOOOB i t i i % d d ELA ADSAC R- 0o F Q 86400 - Q FT 400o0 - R DISTANCE A AT WELL EL T DSAC R 400 T Q FT ' 400o0 R DISTANCE A AT WELL i j i TH (IUE) 3 (HINUTES) TIHE 1 SY= IE (HINUTES) TIHE 2800.000001 2800.000001 3636 X 1 1 1 1 1 1 1 1 1 J X 1» tit .-10000 d d IOOOO X 35986 35986 i _i_i « X i 1 » ii 1 r § j i j ij_f«I § « r WELLOS= WELLOS= JELLOS= I \ RW= Rw= X x+tfc_ N; d d250 250 V I d d OOO X OOO ______ANALYTICAL SL: ANALYTICAL RCH= RCH= Rmax= 200000: RCH= ra- 200000 Rrnax- TTEI j STNTHETIC , t X • » i « i LOGIO d LOGIO d OOOOO : 86400 OOOOO : : 0 FT3/D FT3/D *0 JIs1 iPA oOOB= 30000IELS 100 C= oOOOOO RCH= /iLPHA= 3300o000Q0 oOOOOOBL=IIELL0S= 1*000 1 JFIXs 3*60= 3 3o20L *•' ° I '-’'-n— 3*001 2 2 2*401 2*201 2*201 2*001 2*001 1*80:

DRAWDOWN 1 o ( 60:l*4oi FEET1*201 ) DRAWDOWN ( FEET 1*001 2 1 Id 3 3 2 2 2 I 2 3 3 I I d d = d *801 □ 60: □ uCO\ *00 d d d d d d d d d d d d , .801 ,60i ,40L : i 0 2

40|_K=_40

80: 60L 201 60i 20 00 80 40 60 £0 00 00 80: "I -1 b NBNGRPEO WL A ADSAC -000F Q 86400 - Q FT -1000*0 R DISTANCE A AT WELL PIEZO* NABINAGAR (b) JI= 1 JFIX= j ! - - - - - : - - ■ (a)

F i g5. . 1 8 . C :C o m p a r i s o n o f ( a ) M a n u a l a n d ( b ) M o d e l r e s u l t - 0900s. *00089 s=. 40*98000 K- 1 1f ■l-TTTTTT o AILFO OE IDCTD T OTNOS LINE CONTINUOUS BT INDICATED HODEL FLOW RADIAL CROSSES BT INDICATED DATA FIELD 1—i STRAIGHT LINE HETHOD : TIHE-DRAWDOWN PLOT PLOT : TIHE-DRAWDOWN HETHOD LINE STRAIGHT 00000 AIL LWHDL NIAE B OTNOS LINE CONTINUOUS BT INDICATED HODEL FLOW RADIAL CROSSES BT INDICATED - Q DATA FT FIELD -TOOOnO R DISTANCE A AT WELL PIEZO* PLOT NABINAGAR : TIHE-DRAWDOWN HETHOD LINE STRAIGHT I I ...... I I I I from Nabinagar OW3. y ^LPHA- *00000B = *00095 S= ---- rr 1 - ■ I—t t -, ,

t I. r t-r-r i i i I ------1 IE (HINUTES) TIHE olOOOO ST= T *00 w *250 Rw= *10000 ST- IE (HINUTES) TIHE 3225*39980 L 3225*39980 - __ T i —TTI I I i ■ ■ . j .

1 TT-TT'TT iiiiii ' '' i ■ ____ JELLOS= 1*000 ------^ w □250 Rw= » i»i ■ i i i i I 1 --- \ .. \ 1" !1 1 — T T T T ~t"~ r -r r ~t"~ -r r \ \ \ ____ = L ANALTTICAL SL: Rmax=+2P0000:.( C = *0.0000,RCH=j Rmax^+3f)0000: ”1 “ % STNTHETIC ■ ■ .iiiii + -- LOGIO r T Tr 1 T 1 1. LOGIO 86400 : i 0 FT3/D FT3/D Lower - S

F i g . - 5-19 (bj.

Higher-S con ♦ K / Higher-cc* K L o w e r - BL Higher-S uncon

v.% N.

H igher- BL

Fig. 5-19 ; Response of the simulation with different values of sensitive parameters. 53.3 Discussion in results:

The model plots themselves are self explanatory. The better the match the more accurate is the analysis. In some cases excellent matching was obtained but in others difficulties arise in obtaining good agreement between the model and field data plots.

B’Baria Well Site:

Excellent matching is obtained for OW1 (Appendix.

5.3.1.A) and OW3 (Appendix. 5.3.1.C) without requiring any leakage though a little leakage was essential for OW2 (Appendix. 5.3.l.B) in order to get the excellent match with the field condition. In the case of OW1 and OW2, the first few data measurements show higher drawdowns than the model, while the reverse is true for

OW3. No remarkable differences between K values are found. The storativity value for OW2 is one order of magnitude greater than the others but still valid for a leaky confined condition.

Nabinagar Well site:

A very good simulation is obtained for all three OWs

(Fig. 5.18.A, 5.18.B & 5.18.C) by introducing leakage for every well. For OW2

(Fig. 5.18.B) and OW3 (Fig. 5.18.C) the very last few field data points were

ignored (see Section 5.2.1). No major differences are found in storativity values. A

little higher permeability value is obtained for OW3.

Daudkandi Well Site:

A reasonably good model match was obtained for all

the observation wells by ignoring the very last few data measurements in all the

observation wells. For OW1 (Appendix. 5.3.2.A) and OW2 (Appendix. 5.3.2.B) the

198 first few data points shows lower drawdown than expected. The storativity values were all very close to each other. A little higher K value was recorded for OW3

(Appendix. 5.3.2.C) than the other two wells. A similar range of leakage was given by all the observation wells.

Burichong Well Site:

Excellent model simulation is obtained for OW2

(Appendix. 5.3.3.B) and OW3 (Appendix. 5.3.3.C) but for OW1 (Appendix. 5.3.3.A) simulation was possible only with the middle part of the field data because of its unstable nature (see Section 5.2.1). An unacceptably high simulated storativity and leakage values were also obtained for OW1 and these results are not included for further interpretation. Much different leakage values were obtained for OW2 and its storativity value is one order of magnitude lower than the simulated storativity for

OW3 but they are all within the acceptable limit.

Chandina Well Site:

The exponential distribution of drawdown caused by the pumping of a well is such that the greatest drawdown occurs at the well and the drawdown decreases with the increasing distance from the well. But the reverse is happening at Chandina OW1 (Appendix. 5.3.4.A) where the recorded drawdown is much lower than the drawdown recorded for OW2 (Appendix. 5.3.4.B) and OW3

(Appendix. 5.3.4.Cl and C2).

Reasonably good results were obtained for OW2 (recovery data only) and OW3 (both recovery and drawdown). The results obtained for OW2 suggest more vertical leakage and a less permeable situation, while OW3 suggests the opposite condition. Results obtained from OW1 are altogether ignored. Except for the recovery data of OW3 the simulation was done ignoring the very last few

199 data points.

Kotwali Well Site:

The unstable data measurement for OW3 (Appendix.

5.3.5.C) made it extremely complicated to obtain an accurate simulation. However, the results obtained are quite acceptable. The best simulation was achieved for OW2

(Appendix. 5.3.5.B) and moderate matching was possible for OW1 (Appendix.

5.3.5.A). Differences between the permeability results are quite noticeable. The storativity value for OW3 is one order of magnitude higher than the others and for the same well a high leakage is also observed. During the simulation of OW1, the initial and last few data points had to be ignored to obtain a reasonable matching.

Only the initial few data points were away from the simulated curve for OW2 but for OW3 only an average simulation was possible.

Barura Well Site:

The negative drawdown observed for OW1 (Appendix.

5.3.6.A) made it impossible to simulate the data. For OW2 (Appendix. 5.3.6.B) and

OW3 (Appendix. 5.3.6.C) simulation was done primarily on the middle portion of the data plot ignoring both the tail end portion and the first few data points. The results obtained for storativity and leakage are quite close for OW2 and OW3 but the permeability value obtained for OW3 is much higher than that obtained for

OW2.

Haziganj Well Site:

Excellent simulation results were obtained for all the

OWs by introducing some leakage for OW1 (Appendix. 5.3,7.A) and OW3

(Appendix. 5.3.7.C) but without any leakage for OW2 (Appendix. 5.3.7.B). The very

200 last few data points for OW1 were ignored during the simulation. The storativity

value obtained for OW2 is one order of magnitude lower than the other two OWs.

The drawdown data recorded for the initial 30 minutes are higher than the values

produced by the simulated curve.

Chauddagram Well Site:

Excellent matching between the field data and the

numerically obtained data plot has been obtained for all the OWs (Appendix.

5.3.8.A, 5.3.8.B, and 5.3.8.C) without requiring any leakage. Interestingly it was

noticed that higher permeability values were needed to simulate data points with

increasing distances of the OWs. The simulation has also indicated that the

storativity decreases with increasing distance. The storativity value obtained for

OW1 is very high for a confined aquifer.

Senbagh Well Site:

A very good simulation was obtained for all the OWs

(Appendix. 5.3.9.A, 5.3.9.B, and 5.3.9.C) covering the entire field data measurement

under leaky confined conditions. The permeability value obtained for OW3

(Appendix. 5.3.9.C) is slightly higher than the value obtained for the other OWs.

The calculated and simulated transmissivity values show a fair amount of closeness.

The storativity value for OW2 (Appendix. 5.3.9.B) is much lower than the other

two OWs.

Feni Well Site:

Excellent simulation is obtained for all the OWs (Fig.

5.17.A, 5.17.B, and 5.17.C) under typical non-leaky confined conditions. Both the

field and model data plots for OW2 (Fig. 5.17.B) and OW3 (Fig. 5.17.C) show

201 virtually no deviation in any part of the plot. Striking similarities were obtained for the results from both the analytical method and simulated results.

5.4 Comparison of the Results:

5.4.1 Comparison of Individual Sites:

The comparison is made considering all the results obtained from the time-drawdown solution (both straight line and type curve method), the distance-drawdown solution and the numerical solution. The comments were made on the basis of the average results obtained for each individual well site.

The results obtained from both the time drawdown and distance drawdown solutions for an individual well site are presented in a single table such as Table. 5.1 while the numerical results as well as the comparison of the average results obtained from all the methods are presented in another table such as Table. 5.12. Those results with an asterisk indicate that these values are excluded from the overall average results. It can be concluded that the aquifer condition varies from confined to leaky confined conditions. When the same well site indicates both confined and leaky confined conditions, the general condition is considered to be leaky confined. It is observed that when leaky confined conditions are found, the transmissivity values show noticeable decreases.

5.4.2 Overall Comparison:

A rapid change in aquifer condition from leaky confined to confined was noticed for different OWs of the same test site (B’Baria OW1 &

OW3 shows nonleaky-confined but B’Baria OW2 gives rise leaky-confined and

Haziganj OW2 represents nonleaky-confined but Haziganj OW1 & OW3 suggests leaky-confined condition). In such a situation the non-leaky confined condition furnished higher transmissivity and lower storativity and the opposite is

202 (a) PUMPING TEST ANALYSIS RESULTS

SITE:- FENI WELL No:- 117

SOLUTION:- NUMERICAL

POSITION VALUES OF HYDRAULIC PARAMETERS OF T (m2/d) S(-) K (m/d) L (m) PIEZOMETERS

50 ft. ( 1 5.24m.) 9 4 0 '■SC-3) 2 $ -

400 ft.( 121. 92 m.) 8 AO I-0 ( - ■ $ ) 2 -6 -

- 1 0 00 ft. ( 3 04. 80 nO $ 9 0 2 7

AVERAGE VALUES 8 9 0 1 -5 C- 3) 2 7 -

INFERRED CONDITIONS FULLY C0NFI NED

(b) COMPARISON OF HYDRAULIC PARAMETERS OBTAINED FROM DIFFERENT SOLUTIONS

METHOD VALUES OF HYDRAULIC PARAMETERS OF T (m2/d) S(-) K = T/b (m/d) L (m)

SOLUTION D ’down R EC. AVI-. I) "down RFC. AVI-. D ’down RFC. AVE. D’down REC. AVE.

TIME-DRAWDOWN 9 4 0 - 9 4 0 H 6-3) - 2 9 - 2 9 - - -

- DISTANCE-DRAWDOWN 1 170 1170 S - 7 6 - 4 ) - « ' 7 6 1 3 5 - 3 5 - - -

NUMERICAL - - - - - £ 9 0 S 9 0 ' ■ 5 6 - 3 ) - 2 7 2 7

AVERAGE VALUES 1 000 - 1000 1-2 (-3) - i ' 2 h ) 3 0 - 3 0 - - -

INFERRED f u LL Y (: 0 N F 1 N E D CONDITIONS

Table. 5.12. Aquifer test results of Feni Well; (a) Numerical results and (b) Overall comparison of results obtained by all the methods. (a) PUMPING TEST ANALYSIS RESULTS

SITE:- NABIN AGAR WELL No:- 9

SOLUTION:- NUMERICAL

POSITION VALUES OF HYDRAULIC PARAMETERS OF T (m2/d) S(-) K (m/d) L (m) PIEZOMETERS

50 ft. (15. 24m.) -430 (O II s 9

400 ft. (121.92m.) 5 2 0 9 -5 £--3) 12 [005

1 0 0 0 ft. ( 3 04.80 m.) ^loo 7-4C-4) 9 2 5 3

AVERAGE VALUES A 50 T2

INFERRED CONDITIONS LEAKY C0NFI NED

(b) COMPARISON OF HYDRAULIC PARAMETERS OBTAINED FROM DIFFERENT SOLUTIONS

METHOD VALUES OF HYDRAULIC PARAMETERS OF T (m2/d) S(-) K= T/b (m/d) L(m) SOLUTION D ’down REC. AVE. D’down RFC. AVE. D ’down RFC. AVE. D ’down REC. AVE.

TIME-DRAWDOWN A IO - 4 1 0 - 10 - lo S2S - 8 2 3

DISTANCE-DRAWDOWN 3 6 0 - 3 6 0 soC-4) - 8 -0(4; 8 - 8 AS 8 - 4 8 8

NUMERICAL - - - 10 -G - iOH> A 5 0 4 5 0 ? * H > 7264) 10 101

AVERAGE VALUES 410 - 410 1-5

INFERRED LEAKY CON F 1NED CONDITIONS

Table. 5.13. Aquifer test results of Nabinagar Well; (a) Numerical results and (b) Overall comparison of results obtained by all the methods. (a) PUMPING TEST ANALYSIS RESULTS

SITE:- B’ BARI A WELL N o:- 6

SOLUTION:- NUMERICAL

POSITION VALUES OF HYDRAULIC PARAMETERS OF T (m2/d) S(-) K (m/d) L (m) PIEZOMETERS

50 ft. ( 15* 24 m.) 950 9-7 ( - $ l6 -

1 50ft. ( 45.72 m.) 8 oo 4 6 ( - 3 ) 13 6io

400 ft. ( 121.92m.) 9 GO 2'0 (- 3) 15 -

AVERAGE VALUES 9 oo 2 - 5 ( - 3 ) 15 6to

INFERRED CONDITIONS LEAKY CONFINED

(b) COMPARISON OF HYDRAULIC PARAMETERS OBTAINED FROM DIFFERENT SOLUTIONS

METHOD VALUES OF HYDRAULIC PARAMETERS OF T (m2/d) S(-) K=T/b (m/d) L(m) SOLUTION D'down REC. AVE. D ’down REC.AVI-. D ’down REC.AVE. D'down REC. AVE.

TIME-DRAWDOWN 9 5 0 - 950 27(-3) - 2-7(-3) IG - IG GIO - GIO

DISTANCE-DRAWDOWN 9 3 0 - 930 8-8 H> - 2 8 0 24 - 24 100 2 - 1002

NUMERICAL 9 oo - 9oo 25 (-3) - 250 15 - IS GIO - Gio

AVERAGE VALUES 9 9 0 - 990 2-OC-3) - 20(-S) IS - IS 141 - 74/

INFERRED LEAKY CON FIN.E D CONDITIONS

Table. 5.14. Aquifer test results of B’Baria Well; (a) Numerical results and (b) Overall comparison of results obtained by all the methods. (a) PUMPING TEST ANALYSIS RESULTS

SITE:- DAUDKANDI WELL No:- 43

SOLUTION:- NUMERICAL

POSITION VALUES OF HYDRAULIC PARAMETERS OF T (m2/d) S(-) K (m/d) L (m) PIEZOMETERS

50ft. ( 15.24m.) 1 2 0 0 IT (-4 ) 2 g 15 2-4

150 ft. (45-72 m.) 12 10 2-2 (-4) 2 7 15S5

400 ft. (121. 92 m.) 137o 3-2 (-40 3 2

AVERAGE VALUES 12 GO 2 A (-4) 2 9 1426

INFERRED CONDITIONS LEAKY C 0 N F1 N E D

(b) COMPARISON OF HYDRAULIC PARAMETERS OBTAINED FROM DIFFERENT SOLUTIONS

METHOD VALUES OF HYDRAULIC PARAMETERS OF T (m 2/d ) S(-) K=T/b (m /d ) L (m) SOLUTION D’down RFC. Avi-:. D'down RFC. AVF. D’down RFC. AVF. D’down RFC. AVF.

TIME-DRAWDOWN IIOO 9 7 o 1035 4'4(-4) 3-1 (-3/• 8 (-3) 2 6 2 3 2 5 50f 973

DISTANCE-DRAWDOWN I O 5 0 - /050 51(H) - 5'

- NUMERICAL 1 2 6 0 - 1260 24(H) - i i t y 2 9 - 2 9 1 6 2 6 1426

AVERAGE VALUES H o 501 1140 II2 0 + o H 3 4$ 2 7 2 3 2 6 1071

INFERRED LEAKY CONFINED CONDITIONS

Table. 5.15. Aquifer test results of Daudkandi Well; (a) Numerical results and (b) Overall comparison of results obtained by all the methods. (a) PUMPING TEST ANALYSIS RESULTS

SITE:- BURICHONG WELL No:- 4 6

SOLUTION:- NUMERICAL

POSITION VALUES OF HYDRAULIC PARAMETERS OF T (m2/d) S(-) K (m/d) L (m) PIEZOMETERS * 100ft. ( 30.49m.) 3 4 0 * 9 -7 ( - 2 ^ 6 *

1 50ft. ( 45-72 m.) 4 7 - 0 4 0 (- 4) £ 625

2 50ft. ( 76.20 m. 540 4 -iC -S ) 9 2 H

AVERAGE VALUES 5 IO 2-4 6-3) g 4 5 I

INFERRED CONDITIONS LEAKY C 0 N F I NED

(b) COMPARISON OF HYDRAULIC PARAMETERS OBTAINED FROM DIFFERENT SOLUTIONS

METHOD VALUES OF HYDRAULIC PARAMETERS OF T (m2/d) S(-) K= T/b (m/d) L(m) SOLUTION D’down REC. AVE. D’down RFC. AVE. D ’down REC. AVE. D'down REC. AVE.

TIME-DRAWDOWN 5 0 5 - 505 2-3 (-3) - 2-3(-9 9 - 9 5 2 3 - 523

DISTANCE-DRAWDOWN 340 - 3 40 49{-3) - 49<3 6 - 6 J3J - 131

NUMERICAL 5 lo - 510 2-4 (-3) - 24(-? £ - 8 4S I - 4 5 1

AVERAGE VALUES 4 5 0 - 4 5 0 32(-3) - 32(-3 S - 8 3 6 8 - 368

INFERRED L EA K Y CONFJNE D CONDITIONS

Table. 5.16. Aquifer test results of Burichong Well; (a) Numerical results and (b) Overall comparison of results obtained by all the methods. (a) PUMPING TEST ANALYSIS RESULTS

SITE:- C H A N DIN A WELL No:- 5 5

SOLUTION:- NUMERICAL

POSITION VALUES OF HYDRAULIC PARAMETERS OF T (m2/d) S(-) K (m/d) L (m) PIEZOMETERS

50 ft. (15.24m.) 6 3 ? l 9-T C -if 15 5 -

1 5 0 f t . ( 4 5 . 7 2 m.) 5 6 0 9 0 C-3 ) 14 114,

400 ft. ( 1 21. 92 m.) 9-5 C -4) 3 5 \ o (*t

AVERAGE VALUES I o o o 5 -o 6- 3) 2 5 5 9 2

INFERRED CONDITIONS LEAKY CONFINED

(b) COMPARISON OF HYDRAULIC PARAMETERS OBTAINED FROM DIFFERENT SOLUTIONS

METHOD VALUES OF HYDRAULIC PARAMETERS OF T (m2/d) S(-) K=T/b (m/d) L(m) SOLUTION D'down RFC. AVF. D’down RF.C. AVI-. D’down RFC. AVF. D’down RFC. AVI-.

TIME-DRAWDOWN 1 5 8 0 1160 1370 6'3 (-4) > 3& 2 9 3 4 /7 9 3 7 /2 1/03

DISTANCE-DRAWDOWN 600 - - 4-5$ i 4 - 14 2 2 / - 2 2 /

NUMERICAL 1 ooo - 1 ooo s ° h ) - S-0{3] i 2 5 - 2 5 5 9 2 - 5 9 2

AVERAGE VALUES 10 6 0 1(60 9 9 0 3 -4(-3) 4 7 (-3 41 (-3) 2 6 2 9 2 A 7 6 9 7 /2 6 3 9

INFERRED LEAKY C O NF I NED CONDITIONS

Table. 5.17. Aquifer test results of Chandina Well; (a) Numerical results and (b) Overall comparison of results obtained by all the methods. (a) PUMPING TEST ANALYSIS RESULTS

SITE:- KOTWALI WELL No:- 59

SOLUTION:- NUMERICAL

POSITION VALUES OF HYDRAULIC PARAMETERS OF T (m2/d) S(-) K (m/d) L(m) PIEZOMETERS

50 ft. (15- 24m.-) 3 - 5 ( H ) 4 5 1 5 2 4

150 ft. ( 45.72 m.) =hBO 2-5 (-3 ) 5 2 1931

400 ft. ( 121. 92m.) 1)1-0 5 -5 (-3) 2 4 2 5 0

AVERAGE VALUES G io 2 8 C- 3) 4 0 1 2 5 2

INFERRED CONDITIONS LEAKY CONFINED

(b) COMPARISON OF HYDRAULIC PARAMETERS OBTAINED FROM DIFFERENT SOLUTIONS

METHOD VALUES OF HYDRAULIC PARAMETERS OF T (m2/d) S(-) K= T/b (m/d) L (m) SOLUTION D’down REC. AVi;. D'down RFC. av e ;. D’down RFC. AVF. D'down RFC.AVE.

TIME-DRAWDOWN 6 3 0 - 630 1*263) - 1*263) 41 - 41 7 6 8 - 76S CM DISTANCE-DRAWDOWN 410 - 4 7 0 l'Z[- 3) - 31 - 31 3 6 5 - 3 6 5

NUMERICAL 610 - 610 2S (-33 - 26 ( i 4 0 - 40 12 5 2 - 1252

AVERAGE VALUES 5 1 0 - 5?o 1*7 (r 3) - 37 - 3 7 7 9 5 - 7 9 5

INFERRED LEAKY C 0 N F 1 N E D CONDITIONS

Table. 5.18. Aquifer test results of Kotwali Well; (a) Numerical results and (b) Overall comparison of results obtained by all the methods. {a) PUMPING TEST ANALYSIS RESULTS

SITE:- BARURA WELL No:- 6 9

SOLUTION:- NUMERICAL

POSITION VALUES OF HYDRAULIC PARAMETERS OF T (m2/d) S(-) K (m/d) L (m) PIEZOMETERS

* 50 f t . (1 5- 2 4 m . ) 3 6 4 2 S-o£ ’if 8 5 * -

1 50 ft. (4 5.72m.) 1290 !■? ( - 4 ) 3 0 13 7 2

4 0 0 ft. ( 1 2 1 . 9 2 m . ) 16 3 0 2 - 0 ( - 4 ) 3 9

AVERAGE VALUES 14 6 0 1' 9 (- 4) 3 4 1574

INFERRED CONDITIONS LEAKY CONFINED

(b) COMPARISON OF HYDRAULIC PARAMETERS OBTAINED FROM DIFFERENT SOLUTIONS

METHOD VALUES OF HYDRAULIC PARAMETERS

OF T (m2/d) S(-) K=T/h (m/d) L (m)

SOLUTION D'down RFC. AVF. D'down RFC. AVF. D'down RFC. AVF. D'down RFC. AVF.

1 0 2 3 -n TIME-DRAWDOWN It IO lOGf 5 4 6 4 ) MOi) 2 2 2 7 2 3 5 8 6 6 2 6 6 0 7

DISTANCE-DRAWDOWN - - - 7 3 O 7 3 0 4 < - 4) - 17 1 7 3 7 7 3 7 7

NUMERICAL - - 146 0 1 7 6 0 1 • 9 C-4) - I-91-4 ) 3 7 - 3 7 1 5 7 7 1 5 7 7

AVERAGE VALUES 1 I / O 1 0 2 3 1090 4o(-4) 4 -3 (-4 ) 2 7 2 7 2 5 9 3 5 6 2 6 8 7 2

INFERRED L E A K Y CONFINED CONDITIONS

Table. 5.19. Aquifer test results of Barura Well; (a) Numerical results and (b) Overall comparison of results obtained by all the methods. (a) PUMPING TEST ANALYSIS RESULTS

SITE:- HAZIGANJ WELL No:- 8 2

SOLUTION:- NUMERICAL

POSITION VALUES OF HYDRAULIC PARAMETERS OF T (m2/d) S(-) K (m/d) L (m) PIEZOMETERS

5 0 ft. ( 15.24m.) 1440 3-0 ( - 4 ) Ao IS 5 9

1 5 0 f t. ( 4 5. 72 m.) IGGO I-2C-4) 4 5 -

1 0 00 ft. ( 504. 80m.) 1440 Q o C-4) 3 9 1981

AVERAGE VALUES 1510 2M /- 4 ) 41 1920

INFERRED CONDITIONS LEAKY CONFINED

(b) COMPARISON OF HYDRAULIC PARAMETERS OBTAINED FROM DIFFERENT SOLUTIONS

METHOD VALUES OF HYDRAULIC PARAMETERS OF T (m2/d) S(-) K= T/b (m/d) L(m)

SOLUTION D ’down REC.AVE. D ’down REC. a v i ;. D ’down REC. AVE. D'down REC. AVE.

TIME-DRAWDOWN 1 5 3 0 - 1530 4'5(-4) - 4-5(4) Ai - 4 2 2 2 5 0 - 22 SO

DISTANCE-DRAWDOWN 14 10 - 1410 3 ’l(-4) - 31(4) 39 - 39 1 6 3 0 - 1630

NUMERICAL I5IO - 15/0 3 4 ( - 4 ) - 3 4 ( 4 ) 4 1 - 41 1 9 2 0 - 1920

AVERAGE VALUES 1 4 8 0 - 1480 3 -7 C -4 ) - 3 -7 (4 ) 4 1 - 4 1 1930 - 1930

INFERRED LEAKY 1: 0 N F 1 N E D CONDITIONS

Table. 5.20. Aquifer test results of Haziganj Well; (a) Numerical results and (b) Overall comparison of results obtained by all the methods. (a) PUMPING TEST ANALYSIS RESULTS

SITE:- C H AUDDAGRAM WELL No:- 101

SOLUTION:- NUMERICAL

POSITION VALUES OF HYDRAULIC PARAMETERS OF T (m2/d) s(-) K (m/d) L (m) PIEZOMETERS

•* 50 f t . (15.24m.) 2 2 0 2- (, G 2 ) 3 -

150ft. (4 5.72 m.) 2 3 O 3 - 3 (- 3 ) 3 -

1 000 ft. ( 304. 80 m.) 2 g 0 8-oC-4) A -

AVERAGE VALUES 2 Ao 2-1 ( . - 3 ) 3 -

INFERRED CONDITIONS FULLY CONFINED

(b) COMPARISON OF HYDRAULIC PARAMETERS OBTAINED FROM DIFFERENT SOLUTIONS

METHOD VALUES OF HYDRAULIC PARAMETERS OF T (m2/d) S(-) K = T/b (m/d) L (m)

SOLUTION D’down REC. AVE. D'down RFC. a v e :. D ’down RFC. AVF. D ’down REC. AVE.

TIME-DRAWDOWN 2 4 0 - 2 4 0 H(-i) - I-7C-3) 3 - 3 - - -

DISTANCE-DRAWDOWN - - 9 - 9 - - -

NUMERICAL - - - 2 40 - 240 ziC-S) - 21 (-3 3 - 3

AVERAGE VALUES 3 9 0 - 2)90 MlC-3) - M(-J' 5 - 5 - - -

INFERRED 1: ULL Y c 0 N F N E D CONDITIONS

Table. 5.21. Aquifer test results of Chauddagram Well; (a) Numerical results and (b) Overall comparison of results obtained by all the methods. (a) PUMPING TEST ANALYSIS RESULTS

SITE:- S E N B A G H WELL No:- 1 3 0

SOLUTION:- NUMERICAL

POSITION VALUES OF HYDRAULIC PARAMETERS OF T (m2/d) S(-) K (m/d) L (m) PIEZOMETERS

SO f t . ( 1 5. 2 4m.) 8 5 0 m C-4) 2 0 2*5 A 7

1 5 0 f t . ( 4 5 - 72 m.) 8 OO Q 3 C -4 ) IS 945*

400 ft. (121. 92m.) IOGO I-2 ( - 3 ) rzG I! 2*2

AVERAGE VALUES 9 oo 6 5 C -4 ) 2 I M 7 3

INFERRED CONDITIONS LEAKY CONFI NED

(b) COMPARISON OF HYDRAULIC PARAMETERS OBTAINED FROM DIFFERENT SOLUTIONS

METHOD VALUES OF HYDRAULIC PARAMETERS

O F T (m2/d) S(-) K =T/b (m/d) L (m) SOLUTION D'down REC. AVE.. D'down REC. AVE. D'down RFC. AVF.. D'down RFC. AVF.

TIME-DRAWDOWN 7*70 - 7 7 0 - 7 ' H) 19 - 19 £44 - £ 4 4

DISTANCE-DRAWDOWN 6 3 0 - G'bO 6' 6 - U (:i 15 - 15 3 9 7 - 3 9 7

NUMERICAL 9 - 9 oo - 6 -5 B 21 - 2 I - M73 o O 6-5 H) 14 7 3

AVERAGE VALUES 7 7 0 7 7 0 2?(-3) - 2-7fc) IS - IS 9 0 5 - 9 0 5

INFERRED L E A K Y c 0 N F I N E D CONDITIONS

Table. 5.22. Aquifer test results of Senbagh Well; (a) Numerical results and (b) Overall comparison of results obtained by all the methods. true for leaky-confined condition. All these sequence of events are repeated by all the method of solutions.

It is observed that on many occasions the distance- drawdown solutions produced much higher leakage (lower BL) values (Nabinagar,

Burichong, Chandina, Kotwali & Senbagh test site) than the time-drawdown solution.

For some of the OWs the results obtained by the type curve method provides better harmony with the numerical results, while for others the results obtained by the straight line method exhibit closer correlation with numerically obtained results. In another situation it was found that all the results obtained by the straight line method for the OWs of a particular test site

(Nabinagar and Chauddagram) were close to the numerical results. Similarly, it was also found that for all the OWs of another site (Kotwali) the results given by the type curve method closely resemble the numerically obtained results for that particular well site. These sequence of events indicates that neither the straight line nor the type curve method is superior to the other.

In some instances both the drawdown and recovery data

(all OWs of Daudkandi well site, Chandina OW2 and Barura OW2 & OW3) and for Chandina OW2 only the recovery data were available for analysis. The results obtained by analyzing the recovery data using the time-recovery solution indicates more leakage than those obtained by the other methods.

For the B’Baria OW3, the straight line method indicated no leakage whereas the type-curve method indicated significant leakage thereby producing a great contrast in Transmissivity value. The numerical model results however match with the non-leaky confined solution.

On many occasions the numerical model results show striking similarity with the analytical results (B’Baria OW1, OW2 & OW3, Daudkandi

214 OW1 & OW3, Burichong OW3, Chandina OW3, Haziganj OW2, Chauddagram

OW2, Feni OW2 & OW3 and Senbagh OW3) which strengthens the suitability of the methods even further and provides confirmation of the results and the interpretation of the hydraulic parameters.

Transmissivity map: Finally using the overall average of all the values obtained from different types of solutions, the following transmissivity distribution map (Fig.

5.20) was prepared which will be used to calculate the ground water resource potential. On the basis of the admittedly few reliable data points, the northern part has low transmissivity values in the range from <500 to >800 m 2/d, compared with

a range from 600 to >1400 m 2/d.

215 LEG!NOS

INTERNATIONAL BOUNDARY — —

c h a n n e l s

PRIMARY SECONOART '—■—

WELL LOCATION

Contour interval 100 m2/d

12 MIL c

I 0 k I 12 H ZO KH

r

BAY OF BENGAL,f

Fig. 5.20: Distribution of transmissivity in the study area. CHAPTER 6 WELL PERFORMANCE

6.1 Step-Drawdown Tests.

6.1.1 General.

6.1.2 Standard Procedures.

6.1.3 Test Procedures Used.

6.2 Analysis of Step-Drawdown Tests.

6.2.1 Method Used.

6.2.2 Presentation of Analyses.

6.2.3 Comments on the Results.

6.3 Well Efficiency.

6.4 Specific Capacity. 6.1 Step-Drawdown Tests:

6.1.1 General:

The drawdown that occurs when a well is pumped has several components as in the expression st = (sp + sd + sb - sr + s() + s, + sw, where st = total drawdown. The two primary components which constitute more than 90% of the drawdown are s, and sw and the other components may be considered under special circumstances if identifiable but they are usually ignored.

The aquifer loss component is a function of both pumping rate and pumping period. It may be expressed as the product of the pumping rate ’Q’ and an aquifer loss factor (B) which is independent of Q (Lennox, 1966). The lower the permeability of the aquifer, the higher the aquifer loss and virtually nothing can be done to modify this part of total loss. The well loss component, on the other hand, depends primarily on the pumping rate and does not vary with time. Well

loss is associated with resistance to flow through the well screen and inside the

well. When non-laminar flow occurs due to the higher pumping rate the magnitude

of well loss also increases rapidly. Well loss may be expressed as the product of

a well loss factor ’C’ and some power of Q dependent on the nature of flow in and

around the well (Lennox, 1966). With efficient well design the well loss component

can be improved.

Jacob (1946) pioneered the step-drawdown method, which was

designed to distinguish the aquifer loss and well loss components of drawdown,

though at that time priority was given to the determination of the effective well

radius. The step-drawdown test is now widely used to determine well losses. Jacob

suggested that the well loss is approximately proportional to the square of the

discharge rate and that the relationship between the two components of drawdown

is approximately as follows:

2 1 8 st = BQ + CQ2 (6.1) where, BQ = aquifer loss and CQ 2 = well loss and later on Bruin and Hudson (1955) and Bierschenk and Wilson (1961) also limited their interpretations on this assumption for solving the well loss component

C. However Rorabaugh (1953) pointed out that with the increasing turbulent flow within the well the ’well loss’ component is best calculated when the value of n may be greater than 2 and his analysis suggested that a representative value is about 2.5. The most accurate method for the analysis of step-drawdown test data must be that of Rorabaugh because it leads under ideal conditions to the unequivocal identification of the type of flow as laminar, turbulent or transitional from one to the other. Eden and Hazel (1973) were the first clearly to suggest that a step-drawdown test can also be used to determine aquifer characteristics.

6.1.2 Standard Procedure:

The present day practice in conducting a step-drawdown test is done in two different fashions. The first procedure is the original Jacob idea in which the drawdown of a well is observed while the discharge rate from the well is increased instantly in stepwise fashion without any recovery. In the second procedure, after every step the well is allowed to recover i.e. which is equivalent to a series of short tests with full recovery after each stage from a different discharge rate. The discharge rate in either of the methods is kept constant throughout each step and the time duration of the recommended stage or step must be kept identical (Jones and Rushton, 1981). The basic assumption in all step- drawdown test analysis is that the increase in discharge rate at the beginning of each step is equivalent to a new pump in the well having a discharge rate equal to the increase in the discharge rate. The total drawdown in a step-drawdown test is equal to the sum of the drawdowns caused by the theoretical pumps responsible

219 for each discharge step in the test.

The specific drawdown-discharge rate graph (Fig. 6.6) is basic to most of the analysis done for understanding well performance and well efficiency.

Therefore the accuracy of such a plot is totally dependent on the number of data points on the graph i.e. on the number of steps in the test. It is therefore recommended that at least four steps should be used to ensure accuracy of the results. Three steps is the absolute minimum and is usually considered as insufficient. The specific drawdown-discharge rate graph will be most accurately defined if the data points are spread out. Thus it is important that the discharge rates chosen in the step-drawdown test should cover most of the total discharge range of the well and the increments of discharge should be fairly equal. The

increment in pumping rate could be a positive increment or negative increment but

a positive increment is desirable and is also simpler to organize.

The length of the steps in a test can be varied to fit local

conditions. The Eden and Hazel method can handle steps less than an hour long but

steps are usually chosen to be one hour long for ease of timing or 100 minutes or

more for ease of analysis. But a minimum step of 100 minute is recommended to

allow adequate stable data to be obtained in each step. If time should allow, then

three hour steps are recommended, because then there would be adequate data for

a constant rate test analysis of the first step (Clark, 1977).

6.1.3 Test Procedure Used:

There were about eight wells chosen in the project area to conduct

step-drawdown test (Fig. 6.1). Of these tests, four are 3-step tests and the other

four tests are 2-step tests. A brief description of testing procedure of each individual

wells are presented below:

2 20 id id

IN T£ R NA T IO N A L 6 0 U N OAA Y CHANNUi

WCtL LOCATION

Site of tests

Bvari ar

IJ Mil f

r x>

D e v id w

Buricfteag.^^

C h . m d i n a

L a ks a mi

Fig. 6.1: Location map showing the step testing wells. B’Baria (Well 6 ): Only two steps were carried out (i.e. the well was run with two different discharge rates) and after every step the well was allowed to make a full recovery. During the first step the discharge rate was 0.891 cfs while the second discharge rate was 1.34 cfs; the duration of each step was 60 minutes; and the incremental discharge was positive. However, the 2- step test is in no way capable of giving reliable results for well performance analysis.

Nabinagar (Well 9): is a three-step test and after each step the well was allowed to make a full recovery. The discharge rates chosen were 1.00 cfs for the first step,

0.67 cfs for the second step and 2.00 cfs for the third step, which suggest that neither of the conventional procedures (continuous positive increment or continuous negative increment) was adopted. The duration of each step was only 30 minutes which also provided insufficient time for obtaining good results.

Devidwar (Well 34): was a continuous two-step test, i.e. the discharge rate was

changed instantaneously during the second step with a positive increment. During

the first step the discharge rate was 0.535 cfs and increased to 1.07 cfs during the

second step, the duration of each step being 120 minutes.

Chandina (Well 55): is a three-step test. It is neither a continuous step test nor

a discontinuous step test, but rather a mixture of the two. During the first step, the

well was pumped with a discharge rate of 0.891 cfs and after 40 minutes (which

is the duration of pumping for every step) the well was allowed to make a full

recovery. During the second step the pumping rate was increased to 1.37 cfs and

after running for a period of 40 minutes the discharge rate was further increased to

1.87 cfs instantaneously without stopping for recovery. During these three steps the

incremental discharge was always positive.

2 2 2 Kotwali (Well 59): is a discontinuous 2-step test. During the first step the well was pumped with a discharge rate 0.891 cfs for a duration of 680 minutes, after that the well was allowed to make a full recovery which was then followed by pumping at the second discharge rate of 0.46 cfs for a duration of 700 minutes.

The discharge rate used indicated a negative increment of discharge.

Laksam (Well 80): is a continuous three-step test (i.e. after every step the

discharge rate was increased instantaneously without stopping the pumps for a

recovery). During the test the discharge rates chosen for different steps were 0.535

cfs for the first step, 1.07 cfs for the second step and 1.605 cfs for the third and

final step which also indicated a positive increment of the discharge rate. The

duration of all the steps was kept constant to 120 minutes.

In view of the testing method necessary for an understanding of the

performance and behaviour of the well, it may be seen that neither of the adapted

test procedures fulfilled the requirement of an ideal step-drawdown test, nor they

can be regarded as a complete test. The previous discussion of the standard

procedure indicates that 3- step test is less desirable for obtaining good results but

adequate, whereas 2- step test results are quite unacceptable. Therefore, only the

results of the four different locations where 3- step tests were conducted are

presentable and two of them (Laksam W 80 and Chandpur W 91) are better than

the others on the basis of the time duration (120 minutes) allowed and the way the

test discharge increments were chosen. Surprisingly, some of the 2- step tests also

provided some good results. In this section, the conducted tests data were analyzed

and the most important specific drawdown-discharge plots prepared.

6.2 Analysis of Step-Drawdown tests:

223 6.2.1 Method Used:

The primary purpose of present day step-drawdown test analysis has been extended from Jacob’s time. Then evaluation of the unknown factors B, C, and n was undertaken to determine and to separate the well loss component of drawdown from the aquifer loss of component. Now-a-days with the development of the technique by Eden and Hazel the aquifer transmissivity can also be determined. The following methods were used to calculate the above-mentioned parameters.

a) Jacob Method:

Jacob developed the following general arithmetic equation to evaluate the well loss factor C:

(dsj / dQi) - (dsj.! / dQj.i) C = ------(6.2) dQj.! + dQi

By plotting the test data as in Fig. 6.2 on a semi-logarithmic paper, the incremental drawdown can be separated which is then inserted into the above equation to obtain the value of C. The accuracy of this method depends on the efficient measurement of the incremental drawdown which is usually open to error.

b) Bruin & Hudson (1955) and Bierschenk & Wilson (1957) Method:

These authors are among the followers of the Jacob method which they developed one step further by dividing the original drawdown component equation by Q and rearranged it in the form of the equation of a straight line which takes the following form:

st / Q = B + CQ (6.3)

and usually describes the slope equation of a straight line with intercept. They used

224 the cumulative summation of discharge rate and drawdown of every step to calculate the summation of specific drawdown (Xsw / £Q) and produced a plot of specific-drawdown versus cumulative discharge XQ (Fig. 6 .6 ). The line of best fit is drawn which gives an intercept B and a slope C. Since this simple plot gives both the B and C factors, the well loss factor can be calculated with reasonable accuracy, so the method is popular and is widely used.

c) Rorabaugh Method:

Rorabaugh’s (1953) method is one step forward and strictly speaking is most accurate graphical method available since it calculates all the parameters B, C and n. In his modification of Jacob’s basic equation, he divided by Q and introduced logarithms to both sides of the equation in the following manner:

st = BtQ + CQ“ dividing by Q (6.4)

st / Q = Bt + CQ01 (6.5)

( st / Q - BJ = CQ01 (rearranged) ( 6 .6)

log ( st / Q - Bt) = logC + logCQ "'1 (6.7)

= logC + (n- 1) logQ ( 6.8 )

A log-log plot ( Fig. 6.13 ) of (st/Q - Bt) versus Q is prepared with several trial

values of ’Bt’ until all the plotted points lie on a straight line and that value of ’B’

is the correct value. The slope of the straight line is equal to the value (n-1), from

which n can be determined. The corresponding value of log Q = 1 cfs in the Y

axis is taken as the appropriate ’C’ value. A lower value of ’B’ would make the

points concave upwards, while a higher ’B’ value would produce a convex nature.

225 d) Eden and Hazel:

Eden and Hazel (1973) developed a graphical method of analyzing the step-drawdown test for calculating the hydraulic parameters, especially the aquifer transmissivity, based on Jacob,s original equation. The simplified version of their mathematical deductions are:

st = aQ, + b I d a log (t-0 + CQ?a (6.9)

= aQ,, + bH + CQ2, 6.10)

Where H = I dQ, log ( t - t, )

The value of H is calculated for each step which involves lengthy and tedious computation. To overcome this computation problem a computer program has been developed to handle the calculations as well as the plotting of H vs. s (Fig. 6.17)

(Holloway 1972), which produces several straight line plots, depending on the number of steps used in the step-drawdown test. The slope of these straight lines are then used to calculate the aquifer transmissivity.

6.2.2 Presentation of Analysis:

The adoption of complicated and unrealistic method in conducting

the step-drawdown tests in the study area have made it impossible to analyze all

the test data using all the available methods. Jacob’s method was usable with the

data obtained for Devidwar, Laksam and Chandpur wells, and Bruin & Hudson’s

method was found to work with all the step-drawdown test data. Rorabaugh’s

method is applicable to the test data obtained from Laksam and Chandpur wells,

but the results obtained for the parameters B, C and n are quite different from

those obtained the by Bruin & Hudson method. The Eden & Hazel technique was

applicable only with data from the Devidwar, Laksam and Chandpur Wells. A

systematic description of the results are presented below.

2 2 6 a) Jacob method:

1) Devidwar well: The time-drawdown plot (Fig. 6.2 ) was used to obtain the values of ’ds’ for each step and other parameters required for the calculations are tabulated below:

Step XQ XQ dQ duration ds Xst Xs / XQ No. gpm. cfs. cfs. minutes ft. ft. sec/ft2

1 200 0.535 0.535 120.0 20.13 20.13 37.63

2 400 1.070 0.535 120.0 11.83 31.96 29.87

The following calculations were done using the Jacob’s formula:

(ds2 / dQi) - (dst/ dQJ (11.83/0.535) - (20.13/0.535) Q ^ i = = dQ, + dQi ( 0.535 + 0.535 )

22.11 - 37.63 - 15.52 = ...... = = -14.5 secVft5 1.070 1.070

2) Laksam well:

The time drawdown plot (Fig. 6.3) was used to obtain the ds value for each step and all other parameters are tabulated below:

Step XQ XQ dQ duration ds Xst Xs / XQ No. gpm. cfs. cfs. minutes ft. ft. sec/ft2

1 200 0.535 0.535 120.0 9.920 9.92 18.54

2 400 1.070 0.535 120.0 8.000 17.92 16.76

3 600 1.605 0.535 120.0 11.49 29.41 18.33

Two well loss factors C2>1 and C32 were obtained as follows:

227 o o' OCD

CO

CO 00

CO

04

CM

40 CD £ I—U J 10 & •—«z 3: c TO ’> 40 UJ Q

CD _o o 03o

40

C 0£ TO a£ t13 Q- 40 co

CM CO th IX. in

( 133d ) Nnoanvya O V* OCD

U-I ON CO

oo <+H

■fr +

CO Uh- J ZD 2 »—t C CO

UJ in o

CD o O

in o

C 3 Fig. 6.3: Step-drawdown test; Jacob solution for Laksam well.

( 133d ) NMOanVdQ (8.00/0.535) - (9.92/0.535) - 3.59 C2tl = ------= = - 3.36 secVft5 (0.535 + 0.535) 1.07

(11.49/0.535) - (8.00/0.535) C3i2 = =6.10 sec2/ft5. 1.07

3) Chandpur Well:

The time-drawdown plot (Fig. 6.4) provides the corrected ds value and dQ values tabulated below:

Step XQ XQ dQ duration ds Xst Xs / ZQ No. gpm. cfs. cfs. minutes ft. ft. sec/ft2

1 200 0.535 0.535 120.0 8.500 8.500 15.89

2 400 1.070 0.535 120.0 4.500 12.90 12.06

3 600 1.605 0.535 120.0 5.400 18.30 11.40 from which the well loss factors and C 3)2 were calculated:

(4.40 / 0.535) - (8.50 / 0.535) - 7.67 C21 = ------= = . 7.17 secVft 5 ( 0.535 + 0.535 ) 1.07

(5.40/0.535) - (4.40/0.535) C3>2 = ------= 1.75 sec 2/ft5. 1.07

b) Bruin and Hudson Method:

All the step-drawdown test data have been analyzed using this

method and the results are presented below on an individual well basis.

230 o

uo . COo

LU 13 CD O CO CL in cc co CL Fig. 6.4: Step-drawdown test; Jacob solution for Chandpur well.

( 133d ) NnoanVdQ 1) B’Baria Well: The necessary parameters taken from the plot (Fig. 6.5) are tabulated below:

Step IQ IQ dQ duration ds I s t I s / IQ No. gpm. cfs. cfs. minutes ft. ft. sec/ft 2

1 333 0.891 0.891 60.00 11.65 11.65 13.08

2 500 1.340 0.449 60.00 2.880 14.53 10.84

The direction of slope is negative and no further use of the well data is possible.

2) Nabinagar well:

The specific drawdown vs. discharge plot in Figure 6.6 was drawn using data tabulated below:

Step IQ IQ dQ duration ds Is* I s / IQ No. gpm. cfs. cfs. minutes ft. ft. sec/ft2

1 374 1.000 1.000 30.00 20.00 20.00 20.00

2 250 0.670 -0.33 30.00 -5.84 14.16 21.13

3 740 2.000 1.330 30.00 30.34 44.50 22.25

and B and C values calculated to be

B = 19.30 sec/ft2 and C = 1.49 secVft5.

When Q = 1.00 cfs then:

BQ = 19.30 x 1.00 = 19.30 ft and CQ2 = 1.49 x (1.0)2 = 1.49 ft.

Calculated st = 20.79 ft compared with 20.00 ft measured.

When Q = 2.00 cfs then:

BQ = 19.30 x 2.00 = 38.60 ft and CQ 2 = 1.49 x (2.0)2 = 5.96 ft.

Calculated st = 44.56 ft compared with 44.5 ft measured. The differences between

232 SPo DRAWDOWN CSEC/FT2) 19: 20 21 22 18: 10 11 12 13 15 18 , i. .: pcfc rwon s dshre lt o B Bra well. Baria B’ for plot discharge vs. drawdown Specific 6.5: Fig. 00 : : Q1=0 d CQ 891CFS /Q2=1 B7 BAR IAPW 0l2 lo60 lo20 80 ICAG( F ) CFS DISCHARGE( o 3<£0CFS 2 d 00

a0 2o80 2a40 SP. DRAWDOWN (SEC/FT2) 38 CQ 36 32 28 2-6 30 20 18 22 12 16: 10 : 00 : i. .: pcfc rwon s dshre lt n yed drawdown - yield and plot discharge vs. drawdown Specific 6.6: Fig. Ql=loOOCFS*Q2=0o610CFS,Q3=2«00CFS ft2. / c e S 0 .3 9 1 = B .9 / ft f / 2 c e S 1.49 = C 0. 20. ) 0 .0 0 2 , 6 .4 (0 CQ lt o Nbngr well. Nabinagar for plot 80 ICAG( F ) CFS DISCHARGE( NAB NAB IN PLJ AGAR o0 1 lo20 d 0 2 □ 00 60 2. 22. ) 0 .6 2 2 , 0 .2 (2 2aCQ

2o80 :35 the measured and calculated drawdown at the two pumping rates are 4 and 0.13 percent, respectively.

3) Devidwar Well:

The specific drawdown vs. discharge plot in Figure 6.7 was drawn using previously determined data. The resulting straight line through the two data points is negative and no further use of the data can be made.

4) Burichong Well:

The specific drawdown vs. discharge plot in Figure 6.8 was drawn using the data tabulated below:

Step IQ IQ dQ duration ds I s t I s / XQ No. gpm. cfs. cfs. minutes ft. ft. sec/ft2

1 333 0.891 0.891 120.0 25.12 25.12 28.19

2 166 1.340 0.449 120.0 6.340 31.46 23.48

The straight line through the two data points produces a reverse alignment like that in the Devidwar well and invalidates any further use of the erroneous results.

5) Chandina Well: The specific drawdown vs. discharge plot of Figure 6.9 was drawn using the data tabulated below:

Step IQ £Q dQ duration ds I s t I s / XQ No. gpm. cfs. cfs. minutes ft. ft. sec/ft2

1 — 0.890 0.890 40.00 8.080 8.080 8.240

2 — 1.370 0.390 40.00 3.980 11.98 8.740

3 ... 1.870 0.500 40.00 5.550 17.53 9.370

235 SP. DRAWDOWN (SEC/FT2) 0 1 12 18: 20 22 38: 16: 26: 32: 36: 24 28: 30: 34 00 : : : : i. .: pcfc rwon s dshre lt o Dvda well. Devidwar for plot discharge vs. drawdown Specific 6.7: Fig. Q1=0.535CFS,Q2=1.010CFS 40 DEVIDWAR PW DEVIDWAR 0l2 l6 20 24 2a80 2a40 2o00 ln60 lo2Q 80 ICAG( F ) CFS DISCHARGE( SP. DRAWDOWN (SEC/FT2) : 0 4 : 2 4 : 8 3 : 2 3 4 3 : 6 3 : 6 2 : 8 1 0 2 : 0 3 22 : 8 2 10 4 1 12 6 1 i. .: pcfc rwon s dshre lt o Brcog well. Burichong for plot discharge vs. drawdown Specific 6.8: Fig. 00 : : : : Ql=0o891CFS,Q2=lo34CFS BUR BUR I PU)CHONG 0 8 ICAG( F ) CFS DISCHARGE( 2 0 0 o 2 d 2 0 4 o 0 8 SPa DRAWDOWN (SEC/FT2) 10 11 16: 20 21 , 2 2 2 1 13: 15 18: 19: 00 : : : i. .: pcfc rwon s dshre lt n yed drawdown - yield and plot discharge vs. drawdown Specific 6.9: Fig. Q1=0.98CFS,Q2=1.31CFS,Q3=1.81CFS 00 7.00) (0.0, .8 / ft‘ f / 2 c e S 1.28 = C lt o Cadn well. Chandina for plot CHANDINA PU CHANDINA 16, 9.00) (1.60, 80 ICAQ( F ) CFS DISCHARQE( 0 o0 0 40 2o80 2 a 4-0 2 □ 00 lo60 1 □ 20 BQ The straight line drawn passes through all three data points with a correct alignment. The following B and C values were determined:

B = 7.00 Sec/ft 2 and C = 1.28 secVft5. These allowed the drawdown components to be calculated as follows:

When Q = 1.37 cfs then:

BQ = 7.00 x 1.37 = 9.59 ft and CQ 2 = 1.28 x (1.37 )2 = 2.40 ft. Calculated st = 11.99 ft compared with 11.98 ft measured.

When Q = 1.87 cfs then:

BQ = 7.00 x 1.87 = 13.09 ft and CQ 2 = 1.28 x (1.87)2 = 4.48 ft.

Calculated st = 17.57 ft compared with 17.53 ft measured. The differences between calculated and measured drawdowns are insignificant at 0.08 and 0.23 percent.

6 ) Kotwali Well:

The specific drawdown vs. discharge plot (Fig. 6.10) was prepared using the data tabulated below:

Step m IQ dQ duration ds £ st Xs / XQ No. gpm. cfs. cfs. minutes ft. ft. sec/ft2

1 -- 0.891 0.891 680.0 21.67 21.67 24.32

2 __ 0.460 -0.451 700.0 -11.42 10.25 22.28

Although there are only two data points yet the straight line through these points shows normal alignment. The following B and C values were calculated:

B = 20.125 sec/ft2 and C = 4.80 secVft5. These allowed the drawdown components to be calculated as follows: SP. DRAWDOWN ISEC/FT2) 6 3 : 8 3 : 8 2 : 8 1 22 6 2 : 0 3 : 2 3 12 : 6 1 0 1 00 i. .0 Seii dadw v. icag po fr owl well. Kotwali for plot discharge vs. drawdown Specific 6.10: Fig. : : : Q1=0 » 891CFSsQ2=0.4 6CFS KGTWALI 0 8 ICAG( F ) CFS DISCHARGE( PI o l a I 20 0 6 o l 2 o 00 0 8 a 2 0 4 o 2 When Q = 0.891 cfs then:

BQ = 20.125 x 0.891 = 17.93 ft and CQ 2 = 4.66 x (0.891)2 = 3.70 ft.

Calculated st = 21.63 ft compared with 21.67 ft measured having a difference of

0.18 percent.

When Q = 0.46 cfs then:

BQ = 20.125 x 0.46 = 9.26 ft and CQ 2 = 4.66 x (0.46)2 = 0.99 ft.

Calculated st = 10.25 ft showsno differences in comparison with the measured s* = 10.25 ft.

7) Laksam Well: The specific drawdown vs. discharge plot (Fig. 6.11) was prepared using previously determined data. The line of best fit through the data points represents a normal alignment. The following B and C values were determined:

B = 16.80 sec/ft 2 and C = 0.96 secVft5. These allowed the drawdown component to be calculated as follows:

When Q = 1.07 cfs then:

BQ = 16.80 x 1.07 = 17.98 ft and CQ 2 = 0.96 (1.07)2 = 1.10 ft.

Calculated st = 19.08 ft compared with st = 17.92 ft measured.

When Q = 1.605 cfs then:

BQ = 16.80 x 1.605 = 26.96 ft and CQ 2 = 0.96 x (1.605)2 = 2.47 ft.

Calculated st = 29.43 ft compared with st = 29.41 ft measured. The difference between the calculated and measured drawdown at the two pumping rates are 6.5 and 0.07 percent.

8 ) Chandpur Well:

The specific drawdown vs. discharge plot (Fig. 6.12) was prepared

using the previously determined data. The best fit line through the data points

241 SP. DRAWDOWN (SEC/FT2) 38: 36 32 28 30 22 26 20 18 16: 10 12 : : C = 96 Sec2 f f / 2 c e S 6 .9 0 = C : 00 : Ql=0o535CFS,Q2=lo01CFS,Q3=lo605CFS i. .1 Seii dadw v. icag po fr asm well. Laksam for plot discharge vs. drawdown Specific 6.11: Fig. = 16. c ft2. / ec S 0 .8 6 1 = B 0. 17.20) 1 , 4 .5 (0 PU AKSAH 80 ICAG( F ) CFS DISCHARGE( 0 6 2 n60 l 1 □ 20 d 2. 18. ) 0 .6 8 1 , 0 .0 (2 0 2 00 o 0 2 40 o 80 SP. DRAWDOWN (SEC/FT2) 2 2 19: 0 2 21 13: 16: 18: 2 1 4 1 15 0 1 11 a : : : 00 Fig. 6.12: Specific drawdown vs. discharge plot and yield - drawdown = 65 Sc ft2. / Sec 16.50 = B 06, 14.60) (0.60, Ql=0o535CFS,Q2=1«01CFS,Q3=1o605CFS = .9 Sec 3.19 = C CHANDPUR PUI CHANDPUR a p l o t f o r C h a n d p u r w e l l . 2 / ft- / a 80 ICAG( F ) CFS DISCHARGE( o0 n0 o0 24 2o80 2a40 2o 00 1n60 1o20 20, 10.00) (2.05, produces a inverted alignment. The following B and C values were determined:

B = 16.50 sec/ft2 and C = 3.19 secVft5. These allowed the drawdown components to be calculated as follows:

When Q = 1.07 cfs then:

BQ = 16.50 x 1.07 = 17.66 ft and CQ 2 = 3.19 x (1.07)2 = 3.65 ft.

Calculated st = 21.31 ft compared with 12.90 ft measured. The difference between the calculated and measured drawdown at the two pumping rates are 65 and 90 percent such a great difference is primarily because of negative plotting of the data points which invalidates any further use of erroneous results. Yet various parameters were analyzer because of the availability of three data points.

When Q = 1.605 cfs then:

BQ = 16.50 x 1.605 = 26.48 ft and CQ 2 = 3.19 x (1.605)2 = 8.22 ft.

Calculated st = 34.70 ft compared with 18.30 ft measured. The difference between the calculated and measured drawdown at the two pumping rates are 65 and 90 percent respectively.

c) Rorabaugh Solution:

This method was applicable only to data from the Chandina,

Chandpur, Laksam, and Nabinagar wells because while at least three steps are

required to obtain reliable results, four or more steps are desirable. It was also

found that in tests which combined positive and negative increments of discharge

to perform the test that despite having a minimum of three steps, the Rorabaugh

method was not applicable.

1) Chandina Well: The plot of Figure 6.13 was prepared with various trial values

of ’B’ (see tabulation below) until finally all the points conformed to a

244 L0G10 :=: 3 3 Q CL cj o 1/3 (8-CD/S)) S1J/03S oo L l o O CD o D C L O C o X o L < OC CO l l J

Fig. 6.13: Step - drawdown test; Rorabaugh solution for Chandina well. Step XQ Xs/XQ (Xs/XQ-B) B=3.000 B=5.000 B=7.000 B=8.000 No. cfs. sec/ft 2 sec/ft2 sec/ft2 sec/ft2 sec/ft2 sec/ft2

1 0.980 08.240 if 05.24 03.24 01.24 00.24

2 1.370 08.740 it 05.74 03.74 01.74 0.740

3 1.870 09.370 if 06.37 04.37 02.37 01.37

straight line when B = 7.00 sec/ft2. Gratifyingly, this value coincides with the value obtained from the Bruin and Hudson method. The ’C’ value, which is obtained graphically, is equivalent to 1.25 sec 2/ft5 . The value of ’n’ was calculated from the gradient using the following relationship:

dy 1.26 - 0 .2 0 (n - l ) = ------= ------= 1.26. dx 1.00 - 0.82

n = [1+ (n-1)] = 1 + 1.26 = 2.26.

This method worked very well with this particular test though during the test a combination of discontinuous (during the first step) and continuous (during the second and third step) methods of changing the discharge rate was adopted. In the test a positive increment in discharge was always made after every step.

2) Chandpur well:

The data plot shown in Figure 6.14 was prepared using the various trial ’B’ values tabulated below until all the points fell on a straight line when

Step XQ Xs/XQ (Xs/XQ-B) B=8.000 B=10.00 B=11.03 B=11.30 No. cfs. sec/ft2 sec/ft2 sec/ft2 sec/ft2 sec/ft2 sec/ft2 ii 1 0.535 15.890 7.900 5.900 4.870 4.670 ii 2 1.070 12.056 4.060 2.060 1.030 0.756 ti 3 1.605 11.400 3.400 1.400 0.370 0 .1 0 0

246 L0G10 ---Q. _ :=: —> ——— _ —— _ — 2 CL- Q : l c c3 ■4 < . s 3 7 _ _ — .

_ — = — _ / 1 : “7 — --- _ _ --- _ / + / 9 / ■ w ------__ 1 1 ’ r < — / / \ ) s - — y * ll — — i 4 1/3 (0-(D/S)) 31J/33S ' — — f - — - - __ a / — “ — —— ~ II I — — _ —— _ —— _ A -- _ -- _ _ --- _ --- _ _ 1 \ y ------«- “ — - _— 1 1 “ — - M _ - — - _ z — - “ “ ___ — zz — — _ — — 23 —— --- ZI _ — — i _ _ --- _ ---, ------...__ ------^ 7 O in CO in CJ L C3 1 V CO a CO V* O - r L <3 O CO CO V* CO o in o 1 CO l l ll II II 1 a s. a K a

***«» 7 CO v oo I i 1 O CD V* o LU L a DC a CO co n: < CD l

Fig. 6.14: Step - drawdown test; Rorabaugh solution for Chandpur well. B = 11.03 sec/ft2. However, this straight line like that obtained from the Bruin and Hudson solution shows a reverse trend which invalidates any further determinations of C and n. It has been included to demonstrate that the methods

should not be used mechanically, since invalid data can sometimes be apparently

amenable to accepted methodology.

3) Laksam and Nabinagar Wells:

The Rorabaugh method was also attempted with the test data

obtained for Laksam and Nabinagar (Fig. 6.15) wells since they had three steps.

However, the method did not work because the plotted points never achieved a

straight line distribution so that it was not possible to obtain any results. The

alternative values of B used in the repeated trials are tabulated below and may be

seen to have been attempted for a wide range of values. The unstable condition

suggest that the wells were not properly developed for a sufficient time after the

completion of the drilling. This situation was not helped by the test procedure

adopted, which introduced a reduction of discharge for the second step.

Laksam

Step XQ Xs/XQ (Xs/XQ-B) B=4.000 B=8.000 B=16.00 U\ o

No. cfs. sec/ft2 sec/ft2 sec/ft2 sec/ft2 sec/ft2 o II Ho tt 1 0.535 18.540 14.540 10.550 2.540 2.040 ti 2 1.070 16.760 12.760 8.760 0.760 0.260 it 3 1.605 18.330 14.540 10.330 2.330 1.830

Nabinagar Step XQ Xs/XQ (Is/IQ -B) B= 15.00 B=19.00 B=19.80 B=19.96 No. cfs. sec/ft2 sec/ft2 sec/ft2 sec/ft2 sec/ft2 sec/ft2 tt 1 1.000 20.000 5.000 1.000 0 .2 0 0 0.040 tt 2 0.670 21.103 6.130 2.130 1.330 1.170 tt 3 2 .0 0 0 22.250 7.250 3.250 2.450 2.290

A O L0G10 2____

LAKSAP1 PW

k 77 "7F // _L_ HJZ

Q l=0 o535CFS /■Q2-'1p03QCFS ,Q3=1 p605CFS

-2 -2 - 1 0 L 0 G1 0 DISCHARGE ( CFS )

L 0 G1 0 1

NABINAGAR PW

t

Q1=1 d00CFS /-Q2=0 d63CFS ,Q3=2 p00CFS

1 0 LOGIO DISCHARGE ( CFS )

Fig. 6.15: Step - drawdown test; Rorabaugh solution for (a) Laksam well,and (b) Nabinagar well. d) Eden and Hazel Method:

Only three step-drawdown test data sets (Devidwar, Laksam and

Chandpur) qualified for analysis by the Eden and Hazel method. This method requires data from a continuous step-drawdown test (i.e. test data where the discharge rate has been changed instantaneously after each step) but it does not matter whether the incremental discharge is positive or negative.

An existing Fortran-77 computer program (Appendix. 6.1) was used in a modified form to suit the requirements of the data to create the sum dQ log

(T - TX) vs. drawdown plot and then best fit line was drawn through the plotted points.

1) Devidwar Well: The sum dQ log (T - TX) vs drawdown plot (Fig. 6.16) was used to draw the best fit straight line through the plotted points for each step.

The value of tan© = b is the gradient of the straight line which was calculated using the following equation:

dy 30.00 - 27.60 Tan© = b = ------= 2.86 x 105. dx (00.84 - 00.09) x 10 5 with this ’b’ value ’T’ is finally calculated as follows:

2.30 T = ...... = 6399.58 ff/d = 590 m2/d. 4 7t b

2) Laksam Well: The plot of Figure 6.17 was used to draw the best fit straight line through the plotted points for each step and ’b’ and ’T’ calculated as previous to give values of 1 x 10 '5 and 1700 m 2/d, respectively.

3) Chandpur Well: The plot of Figure 6.18 was prepared to draw the best fit straight line through the plotted points for calculating the transmissivity (T) value

250 o X t a

O o CD 00

O

O xl*

o

ID CO o CD o < oo © CO

o 00

o Fig. 6.16: Step - drawdown test; Eden and Hazel solution for Devidwar well.

( 133d ) Nnoanvua X1Q1 3 3 a 50, CO CM 0 1 a a a a a a OC MC MV CM CM CM CM CO - p o no 133d ) d 3 3 1 ( O P~ LO a 1 iMnoanvya - & * i 'T n a a a 1 CM LO o c ^ :co

Fig. 6.17: Step - drawdown test; Eden and Hazel solution for Laksam well. o CD

" CD

CD

CD

O

NT CL

O

CO

O O o o CO SUriDQLOG ( T-TX ) SUriDQLOG X105

oo o CO

o o

o CD

O

O Fig. 6.18: Step - drawdown test; Eden and Hazel solution for Chandpur well. Nf

( 1 3 3 d ) N N o a n v a a of 4140 m 2/d according to Eden and Hazel method.

6.2.3 Comments on the Results:

The various parameters obtained by analyzing different step-

drawdown test data with the available techniques and the value of transmissivity (T)

calculated for the first step (treated as a short constant discharge rate test) along

with the results of constant rate test analysis for some wells for which a step-

drawdown test has also been carried out, are presented in Table 6.1 for comparison.

During the calculation of aquifer loss factor (B), well loss factor

(C) and the indices ’n’ (for Rorabaugh solution) the drawdown data for every steps

could not be corrected other than for the Devidwar, Laksam and Chandpur wells,

because of unrealistic test procedure. Straight forward drawing of the time

drawdown data was also not possible. Therefore, uncorrected drawdown data were

used for the other wells during their analysis by the Jacob arithmetic and Bruin

& Hudson graphic solutions although very little variation in results is obtained for

both the corrected and uncorrected data.

Except the Chandina (well 55) and Kotwali (well 59) all other wells

data shows a negative C v values obtained by Jacob arithmetic solution. It

suggested an unstable well condition i.e. the well was not properly developed with

adequate pumping prior to the step-drawdown test. A positive C 3>2 values were

obtained for the ’third step’ of the same wells and other wells indicates that much

of the well development have taken place during the test itself.

The aquifer loss factor ’Bt, ranges from a maximum of 19.30 sec/ft 2

for Nabinagar (well 9) to a minimum of 7.0 sec/ft 2 for Chandina (well 55) and the

well loss factor ’C’ varies from a maximum of 1.49 sec 2/ft5 for Nabinagar well to

a minimum of 0.96 secVft 5 for Laksam (well 80). Considering all the values

obtained from Bruin & Hudson and Rorabaugh solutions, and ignoring the negative [ Q ^ PQ ^ s PQ U ' cd C h a n d p u r C a l c u l a t e d N a b i n a g a r D e v i d w a r B u r i c h o n g C h a n d i n a K o t w a l i L a k s a m Method used vo p a r a m e t e r s W . N o . 9 W . N o . 3 4 W . N o . 4 6 W . N o . 5 5 W . N o . 5 9 W . N o . 8 0 W . N o . 91 VO, i- r £ v o r T o it- VP o t to ro 10 to - N o t o T 0 0 i 1 1 1 i 1 C >—> X 4 cd O O St •S - d n i U vb o 10 o i I \ i *0 r* VO CO p v o t VP v£ cn to n i n i ft- to 00 J> 0 O O K o (S 0 o • S « 2 - O £ t S 3 ^ 5 c ii

" " !+• ii cu M-l <-h <6 5 ' O <0 t f QT r s 10 9 o 00 Or 7 Qr 00 2 » ON V) tsr vo V uD o 8 ^ 2

r O O CN o t SJ o N- N vp rO n on on =: CO w ? ? vn T o o to T * to n i Its ON n- . S N ~ CN D « CD S T rb rb b ~ cb ^ *■ *■ ^ O T v 0 0 *-h c t f O o Q) V) i H o M £ d M-, S ■ VJ 03 3 ' O 3 < 9 C V) n- 6 VJ p VJ 6 ? VI ii 'O 3 < u ll ii ii 3 ii ii r T S s ~t> 00 in VD : x O cd I-. cd CiO n i o i p 0 o VO o 1 1 1 l 1 " o U r 13 'cn a i 4 B ■i—* 9 a * s cd c >v cn -> 5 o cN o & ON NT rt- rf- o V- o i t i I i cn < *52 < 3 4 T vn CP ^r* O 4 P I s r 4 QN C

T a b l e . 6 . 1 : Comparison of step - drawdown test results. results, results produced by the instable wells and the results obtained by Jacob method. The ’B,’ an ’C’ values do not suggest any major abnormality.

The B = 7.0 sec/ft 2 (both by Rorabaugh and Bruin & Hudson method) and C = 1.25 secVft 5 (Rorabaugh method) and C = 1.28 secVft 5 (Bruin

& Hudson method) values for Chandina well shows a remarkable similarity . The index value (n = 2.26) obtained by the Rorabaugh method is an excellent example which support his theory that the index value should be slightly higher than 2. This index value (n = 2.26) also suggested that the Chandina well was properly designed and was properly developed before the test. The unstable condition of the Chandpur

(well 91) on the other hand produces a great difference in B value (11.03 secVft 5 by Rorabaugh method and 16.5 sec/ft 2 by Bruin & Hudson method) and C value

(1.15 secVft5 by Rorabaugh method and 3.19 secVft 5 by Bruin & Hudson method) and a very low index value (n = 1.2 0 ).

The drawdown values were calculated using the obtained ’B’ and

’C’ values from the Bruin & Hudson method to demonstrate the differences in the field measurements. In all cases, the calculated drawdown values were found to be higher than the measured values. The variation between the measured and calculated drawdown ranges from 0.08 (Chandina well when Q = 1.37 cfs) to 6.5 percent

(Laksam well when Q = 1.07 cfs) which is quite low and can be regarded as reasonably acceptable.

The greatest variations were seen between the transmissivity (T)

values (Table 6.1) obtained by the constant rate test analysis of the first step and

the step-drawdown test analysis of the same well using the Eden and Hazel method

for the Chandpur well. In this well the transmissivity value obtained by Eden and

Hazel method is three times higher than the values obtained from the constant rate

test analysis. In case of the Laksam well, the transmissivity values obtained by the

former method is more than twice the value obtained by the later method. A

256 different picture is seen for Devidwar well where the transmissivity values obtained by both methods are very close to each other. In theory, the transmissivity values should produce very little difference by the various methods. Once again the unrealistic step-drawdown test procedure and poor prior development of wells have considerable influence on these dissimilar transmissivity values.

The non-laminar flow condition is directly proportional to the

increasing pumping rate. Therefore, in the case of pumping with higher discharge

rates the following two conditions should be considered to ensure good results: 1 )

the calculated well losses at all test rates should not exceed the sum of the

incremental drawdown for the early stages of the tests and 2 ) the calculated

formation losses should not by themselves exceed the observed drawdown. A

failure to consider these conditions could in some instances lead to false but

superficially plausible solutions (Lennox 1966). A search for these conditions with

the present analytical results (Table 6.2) reveal that the first condition is valid with

all the test results except Burichong (well 46) but the second condition is valid only

with half of the test results.

6.3 Well Efficiency:

There are various ways of looking at the efficiency of well

performance from both a qualitative and quantitative point of view. The construction

of a Yield-Depression curve is a qualitative to semi-quantitative approach. It does

not quantify the information but provides valuable information with reasonable

accuracy about optimum discharge that should be used for a particular well under

the prevailing aquifer condition. The most commonly used quantitative approach for

presenting well efficiency is to determine a numerical parameter representing well

loss and called the ’Well efficiency factor’. It is a defined as [{BQ / (BQ + CQ2)}

x 100] and is usually expressed in percent. The well efficiency factor has been

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v P CM CP T+- CP v i> CO rt- CM cn 0 0 to VP "4 v b cS oo c h Tj

c O " t * o C* oM o tn 00 oo cO vD ON O n 9 cd _, M v p N > 00 o o +■* C in 10 vp 6o cM c CM ON c O ON 4 cn cn 1 i - ro 4 4 S t 3 4 4 4 CO S CO + t+- r4 CM o ro CM o £ to <0 CO vP o cd V0 O cn in o (I o in n II ii ►S 43 ii 11 OO CN CM cm CM c*

bO cd cd c3 C cd 3 tuo cd S cd O cd CU ’S a nd JZ *3 £ oo T3 cd PQ o c <4—> 3 lo > cd O cd cd o x : j jd PQ z Q PQ U O Table. 6.2: Verification of Lennox (1966) conditions for obtaining good results. calculated for all the eight step test wells and the Yield-Depression curve prepared for the Nabinagar, Chandina, Laksam and Chandpur wells because only they have three data points. A plot with less than 3 points would be meaningless, three points being the absolute minimum though more points are desirable because the more points allow a better interpretation.

The Yield-Depression curve is plotted on arithmetic scale which

usually presents graphic information on the performance of the well. The straighter

the line through the plotted points, the more ’efficient’ is the well over the

operating range of abstraction (Jones & Rushton, 1981). Quite frequently the line

becomes curved at higher pumping rates and the degree of curvature is direcdy

related to the relative ’inefficiency’ of the pumping well. Occasionally the change

in curvature is most abrupt and this has been called the ’Breakaway Point’ by

Ineson (1959) and indicates most clearly a rapid deterioration in performance

produced by higher pumping rates. The golden rule is that the usable discharge for

a pumping well should always be selected well below the breakaway point.

The Yield-Drawdown curves prepared for the present study (Fig.

6.19) suggest that the different discharge rates for all the wells are well below the

’breakaway’ point and all the curves suggest that the wells are quite efficient by

virtue of their comparatively straight appearance. The curves for Chandina and

Chandpur are more straight than the others.

The quantitative determination of ’well efficiency factor’ for all the

wells are presented in Table 6.3 in a systematic manner according to the position

of the wells moving from north to south. It may be seen that the efficiency value

decreases with an increasing ’well loss’ value, but for the present test data, low

’well loss’ values were calculated for all of the wells which in turn gave high

efficiency values. The lowest efficiency value (E = 75 percent) is obtained for

Chandina well with a discharge rate Q = 1.87 cfs that is in fact quite high value

259 YIELD ( CFS 10 20 30: 50: 90: 60: 10 80: 5 0 5 0 5 0 35 30 25 20 15 10 5 0 F i g . 6 .Yi 1 e 9 l : d - d r a w d o w n p l o t f o r a l l s i t e s . : : : RWON FE ) FEET DRAWDOWN( CQ

E, 15-55 19-48 SO B’ Baria - - e 2 -

E, 19-30 2 o - J 9 9 3 Nabinagar e2 3 S -6 o 4 4 -5 6 $ 7

E, 2 4 -2 6 2 2 - 3 4 SG Devidwar e 2 - — —

E i 33-41 41-59 SO Burichong -- - e 2

E, 9-59 11-99- s o Chandina e 2 13-09 17-57 7 5

21- 6 2 E i 17- 9 3 S 3 Kotwali 9-26 10-25 e 2 9 0 19-08 E, 17-99 9 4 Laksam e2 26-96 29- 4 3 9 2

E, '7-66 21-31 S 3 Chandpur

e2 26-42 34-70 76

E i 9-59 te n-99-fo 4/-59 So ko 94 Range e2 9-26 fro 32-60 10-25 h> 44-56 7 5 -to 9 2 .

Mean 2 0 - ? S 24-67 S 4 ' 5

Table. 6.3: Quantitative assessment of well efficiency factor. and should be accepted as a highly efficient well and the maximum efficiency is recorded (E = 94 percent) for the Laksam well with a relatively low discharge of

Q = 0.535 cfs.

Therefore on the basis of the information obtained from the ’Yield-

Depression’ curves and the result given by the quantitative measurement of the

’Efficiency Factor’ for all the test wells, it can be said that the wells are highly

efficient.

6.4 Specific Capacity:

Specific capacity by definition is the ratio of the pumping rate to

the drawdown for a particular duration of time i.e (Q/s)t. It is another important

measure of well performance and provides valuable clues about the productivity of

the constructed well. Depending on the unit of discharge and drawdown it has

dimensions of either m 3/d/m or ft 3/d/ft (gal/d/ft ). A rearrangement of the Theis

non-equilibrium equation ignoring the well loss fraction establishes the following:

Q/s = (4 7t T) / 2.303 log(2.25 T t/rw2S) (6.11)

relationship between the specific capacity and other hydrogeological parameters:

1 ) specific capacity is directly proportional to transmissivity.

2 ) specific capacity is inversely proportional to the logarithm of time.

3) specific capacity is inversely proportional to the square of the well radius and

4) specific capacity is inversely proportional to the logarithm of storativity.

Because of these relationships between transmissivity and specific

capacity, high specific capacities usually indicate high transmissivities and vice

versa. Though specific capacity is often affected by partial penetration, well loss and

hydraulic boundaries, in such situations it undervalues the transmissivity estimated

from specific capacity and it provides valuable information in advance about the

262 ground water potential of the investigated area.

To demonstrate the direct linear relationship between specific capacity and transmissivity a theoretical plot of specific capacity obtained using the ideal equation at 100 minutes with similar well radius versus the transmissivity has been constructed on a log-log paper (Fig. 6.20). Values of actual specific capacity

(see Table 6.4) at 100 and 1000 minutes have also been plotted on the same figure against the transmissivity obtained by the conventional methods for all the tested wells. The solid circles and crosses shown in Figure 6.20 are the measured specific capacity values for 100 and 1000 minutes, respectively. It may be seen that the higher and lower specific capacity values corresponds to the higher and lower values of transmissivity, respectively.

The theoretical data plot (specific capacity vs. transmissivity) constructed for the confined condition serves as a line of best fit through the points drawn for actual specific capacity versus transmissivity values. The appearance of the plot produced by the actual and theoretical data also provides evidence in favour of the direct linear relationship between specific capacity and transmissivity. o o o

for for all tests. Fig. Fig. 6.20: Theoretical and actual plot of specific capacity vs. transmissivity S O § 1—H ■*> s S B O S o § 8 1 « C C E f r c cd on _ /5 /0 V. co (%) 1 u

r (well) cn § «£J

Well 1 S' 'S' e

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Table. 6.4: Specific capacity data at 100 minutes and 1000 minutes for all the pumping wells. CHAPTER 7 HYDROCHEMISTRY

7.1 Collation of Existing Chemical Analytical Data.

7.2 Field Collection of Ground Water Samples.

7.3 Chemical Analysis of Ground Water Samples.

7.4 Quality of Analytical Data.

7.5 Graphical Hydrochemical Interpretation.

7.5.1 Distribution Maps.

a) Introduction.

b) TDS Distribution Map.

c) Sodium/L Cation Ratios.

7.5.2 Stiff Pattern Diagram.

7.5.3 Trilinear Diagram.

7.5.4 Chemistry Along Flow Lines.

7.5.5 Expanded Durov Classification.

7.6 Application of PHREEQE Hydrochemical Model.

7.6.1 Introduction.

7.6.2 PHREEQE Model.

7.7 Ground Water Quality.

7.7.1 Drinking Water Quality.

7.7.2 Irrigation Water Quality.

266 7.1 Collation of existing ground water samples:

The first series of chemical analysis of ground water samples was carried out by the UNDP for selected wells in the northern part of the study area

(greater Comilla district). During the four-year period (March, 1976 to June, 1979)

UNDP analyzed water samples from 20 wells. Its aim was to repeat the analysis of ground water samples from the same location several times in order to identify any major changes in the quality of the ground water.

The national organization for water management and development in

Bangladesh (BWDB) started its systematic analysis of ground water for selected locations in October, 1979. The sample locations are mainly situated in major metropolitan city areas and in important small towns. 18 BWDB wells are relevant to the present project for which they have carried out routine chemical analysis on ground water samples. For some of the wells, the analyses were done in 1979 and for others the analyses were earned out in 1990 with some of the wells being sampled on both occasions.

The Bangladesh Agricultural Development Corporation (BADC) has also analyzed ground water samples from 23 of their irrigation wells scattered all over the study area. Since their aim was to examine the concentration of certain ions, they carried out only partial analysis. Because of the lack of information on the other major constituents these analytical results were excluded from any further interpretation.

Although UNDP and BWDB have undertaken their independent analysis on ground water samples from 20 and 18 different locations, respectively; in reality they have covered 33 locations because 5 locations were duplicated.

267 7.2 Field collection of ground water samples:

After a careful evaluation of the distribution of the UNDP and

BWDB sampling locations it became evident that the southern part of the project area had a serious shortage of ground water quality information. It had complete chemical analyses for only four locations (wells 99, 122, 141 and 144) (Fig. 7.1) which are quite inadequate for the interpretation and evaluation of the hydrochemical behaviour of the ground water in the southern part.

To overcome this inadequacy a field visit was made by the author during February and March, 1988 to collect ground water samples from pre-selected locations. A total of 16 samples were collected from 15 locations most of them being from the southern part. Two water samples were collected from two different depths of well 136. Standard procedures used by the UNDP and BWDB were followed during the collection of water samples. The manner of preserving the

samples varies from constituent to constituent to obtain better analytical results.

Therefore to ensure better results the water samples were preserved in three ways:

1: The samples were filtered using no. 5 filter paper having a pore size of 2.5

micron and then acidified with concentrated HC1 having a ratio of 1 ml HC1 in 100

ml of sample. This type of preservation is needed for Mn, Fe and S i0 2.

2: Samples needing only to be filtered for good analytical results of Ca, Mg,

(TDS).

3: To avoid any alteration in N 0 3 and P 0 4 concentrations during the period

between collection and analysis, after filtering HgCl 2 is added at a recommended

ratio of 1ml HgCl 2 (solution strength 2 percent) in 1 litre of sample (pers. comm.

Dr. McArthur).

Although normally it is recommended that pH, EC, C 0 3 and H C 0 3

should be analyzed in the field because of inadequate facilities only pH was

268 77 otf [ FIG-7-1: MAP SHOWING THE L EQENQS QUALITY WELL LOCATIONS 1 N T£ R N A T l O N A L B O U N D A R Y __ __ C H A N N E L S

PRIMARY SECONDARY ------

WELL LOCATION

SUPPLE M E N TARY QUALITY STATION UNOP OUAIITY STATIONS o Owe OUAIITY STATIONS ® BAOC QUALITY STATIONS □ I U NOP • 0 WC1 QUAL ITY S T A T I O N S © IUNOP . 6AOCI OUAIITY. PIEZO WELLS UNOP QUALITY. PIEZO. WELLS G WC OUAIITY * PIEZO. WELLS © BAOC QUALITY • PUMP TEST WELLS

GWC QUALITY • AUTO-PIEZO. WELLS IBAOC • GWCIOUALITY • PIEZO. WELLS $ U N O P QUALITY'P. T.' PI EZO. WELLS

(, o <• 8 12 MILE

I 0 L g 12 14 20 KM measured in the field. All the samples were stored in air tight plastic bottles.

7.3 Chemical analysis of ground water samples:

The samples were brought to U.K. from the field and analyzed at the geochemical laboratory in the department. Analyses of TDS, pH, S i0 2, Ca, Mg,

Na, K, Fe, Mn, C 0 3, H C 03, S 0 4, Cl, N 0 3, P 0 4, F, EC were done to make a complete analysis. The analysis was made by the author assisted when necessary by the laboratory technician Mr. A. T. Osborn. Spectrophotometric, titrimetric, turbidimetric, ion selective electrodes and simple drying methods were selected to cover the whole range of analysis. Standard procedures similar to those described in the ASTM Methods Manual (1978) were followed fairly closely for all these methods in order to obtain as high an accuracy as possible for the analytical results.

The following is a list of the constituents along with the method used to analyse them:

Atomic Absorption Spectrophotometry: for Mg, Mn and Fe.

Titrimetry: for Ca, Cl, C 0 3 and HC03.

Turbidimetry: for S04.

Conductivity meter: for EC.

Flame Photometry: for Na and K.

Ion selective electrode: for F.

Spectrophotometric analysis by U.V. visible photometry: for Si02, NO, and P04.

Total dissolved solids (TDS) concentration was measured as residue on evaporation

at 80° C.

Eventually complete chemical analyses of 48 ground water samples

were considered for the present hydrochemical interpretation (Fig. 7.1). These are

the maximum number of analytical results of ground water samples available. These

270 data are summarized in Table 7.1 and the ionic-balance and comparison of TDS are presented in Table 7.1(a).

7.4 Quality of analytical data:

It is mentioned in Section 7.1 that the majority of the ground water samples were analyzed by various local and international organizations at different times during the preparation of hydrogeological reports. Although all these reports are published yet the quality of these chemical data were checked again. The criteria of ionic-balance and comparison of TDS (TDS obtained by residue on evaporation and the calculated TDS), were adopted in order to check the validity of the analytical data so that most erroneous data can be identified and excluded from any further geochemical interpretation.

The following empirical formula was used to calculate the ionic- balance {Table 7.1(a)) as percentage differences:

[(Z cation - Z anion)/(Z cation + Z anion)] x 100.

Excellent ionic-balance (error ^ + 5 percent) is obtained for 25 samples which

constitute about 41 percent of all the samples. Acceptable ionic-balance (errors +

10 percent) is obtained for another 22 samples (constitute about 36.1 percent).

Together they constitute about 77.1 percent. The hydrochemical data of 10 samples

(16.4 percent) {W18(b), W20, W27, W32(a), W75(b), W 88 (a), W89(a), W95,

W122(b) and W141) provided very high percentage differences (error between

+ 10 to +_ 15 percent) but in another 4 samples (6.5 percent) {W13(a), W13(b),

W51(b) and W54) the percentage differences (error > +_ 15 percent) obtained were

unacceptably high. These suggests that any interpretation of geochemical properties

based on these data, particularly the later wells, could be potentially erroneous and

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cs rS o O CO t 3 8 § CS o 8 O 4) 1 0 6 1 2 0 1 0 6 3 5 0 3 0 2 3 9 0 3 6 2 CO CO CO r- 7 4 CO cs ’O Os 3 r~ r- c- C Cq 00 '■4—1 oe CO *fl o

C JS o . JC. o . S ctf cd aj _ i o 2 o 2 13 SEES 3 JmUmU m Q Z a JJ 3 q :»£ z° H Well Location Date Depth Analysis pH Si02 Ca Mg Na K Fe Mn C 0 3 H C03 S 0 4 Cl N 03 P04 F EC

No. (ft) done by mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L

001 0 O CO OO V/N z d d OC CN CN CO O CN CO t x o d wo

wo ro CN ' < N/A © 2 O 2 W 2 O CO w* t x wo wo 0 3 3 O > O ) 3 r O n n 301.3 l t t U l o < (N 2 S ( p z

n 240.0 d d OCN CO t x CN O o v o - r — VO t x r^ t x wo CN p

n 0.07 200.8 no 2 CN vo o o NO CO o w O CN t x 8 o —

294.0 tL,tUtL,tuCJ^COO> d s z Z > d c O O CN O CN WO CN t x t—4 t x

n N/A N/A 201.0 o 2 2 x CN CO CO CN VO wo p d CO o 217.2 CO o s d d d .3 d VO CO CO O d CO 8 CO p o o o o o o o o n

g g g g .g g .g .g 0.79 59.0

x:x: O O' bO bO o 900 2 CN O O CO CO 00 CN xt wo xt o o p CN 00 O p P

n

205.5 Ql9xaSvi(oU 800 ^^ o ^^ S x s CN p 2 OC NO CN CO 00 oo wo OWO CO wo o Noo CN O p wo

n 194.0 Z o00 oo d wo Xt 00 oo CN CO wo o o d - od oo CN oo o d 2 CO o (N vd o 398.5 00 OC CN CN CO vo d o d Xt p 2 o Or- r VO wo CO d O CO o v

0.05 237.2 o U d d —■ £ £ o o00 oo CN O WO tw wd wd O Xt O z t x CN < N/A 36.0 303.0 W Z 5 7 S 8 O 2 d ^ U o p O Z o d CN d N/A 474.0 U o 2 00 CO vn p p Z d od O

n N/A 532.0 3 ) JL H •3 cd O O 3 3 3 t> Sample ZCation ZAnion Percent TDS TDS Parent No. (meq/1) (meq/1) (diff.) (residue) (calc.) (diff.)

1 3.282 3.214 +1.05 277 267 +1.8

2 7.526 6.408 +8.02 404 417 -1.5

4 3.533 2.910 +9.67 297 191 +21.7

6 3.159 3.172 -0.21 269 247 +4.5

9 10.205 9.216 +5.09 632 590 +3.4

13(a) 3.346 1.917 +27.15 144 187 -13.0

13(b) 2.891 1.927 +20.0 136 166 -9.9

15 2.534 2.735 -3.78 110 201 -29.3

18(a) 5.164 4.287 +9.27 281 283 -0.3

18(b) 5.387 4.294 +11.29 298 287 +1.9

20 5.461 4.100 +14.23 287 275 +2.1

22 7.375 7.552 -1.19 416 444 -3.3

23 7.860 7.117 +4.96 501 476 +2.6

27 3.235 2.552 +11.80 183 175 +2.2

32(a) 10.104 8.145 +10.73 457 470 -1.4

32(b) 5.370 5.343 +0.25 238 348 -18.8

34 9.539 8.787 +4.10 652 561 +7.5

35 4.294 5.109 +8.67 361 355 +0.8

39(a) 7.333 6.943 +2.73 437 392 +5.4

39(b) 8.098 8.396 -1.81 650 446 +18.6

43 5.686 5.016 +6.26 277 322 -7.5

50 8.868 8.023 +5.00 435 482 -5.0

51(a) 2.480 2.534 -1.07 174 177 -0.8

Table. 7.1(a): Summary of ionic-balance and comparison of TDS. Sample ECation XAnion Percent TDS TDS Fbcent No. (meq/1) (meq/1) (diff.) (residue) (calc.) (diff.)

51(b) 3.366 2.194 4-21.08 115 181 -22.3

54 3.561 2.508 +17.35 151 199 -13.7

56(a) 2.854 2.437 +7.88 136 165 -9.6

56(b) 4.032 3.643 +5.07 170 247 -18.5

60 4.008 3.333 +9.19 200 258 - 12.6

70 7.092 6.209 +6.64 373 413 -5.1

73 6.679 5.718 +7.75 402 357 +5.9

75(a) -insufficient

75(b) 6.840 5.051 +15.04 351 311 +6.0

79 2.452 2.845 -7.42 259 228 +6.4

85 6.738 6.907 -1.24 442 418 +2.8

87(a) 5.025 4.270 +8.12 179 264 -19.2

87(b) 4.355 3.710 + 8.00 204 230 -6.0

88 (a) 2.851 2.247 +11.84 175 171 +1.2

88 (b) 3.230 3.724 -7.10 519 244 +36.0

89(a) 2.815 2.149 +13.41 157 140 +5.8

89(b) 3.970 3.365 +8.25 180 202 -5.8

93(a) 7.529 6.158 +10.01 428 401 +3.2

93(b) 10.500 9.935 +2.78 553 555 -0.2

95 6.184 4.786 +12.74 312 337 -3.9

96 9.576 8.490 +6.01 641 525 +9.9

99 3.649 3.561 +1.22 169 241 -17.6

106 5.624 4.903 +6.85 338 357 -2.7

Table. 7.1(a): (continued) Sample ZCation ZAnion Percent TDS TDS Pacen No. (meqA) (meqA) (diff.) (residue) (calc.) (diff.:

107 12.719 10.583 +9.17 776 660 +8.1

112 7.973 6.836 +7.68 499 468 +3.2

113 6.442 5.675 +6.33 313 326 -2.0

114 5.605 5.205 +3.70 396 384 +1.5

120 21.643 21.480 +0.38 1180 1226 -3.5

122(a) 2.983 3.635 -9.85 198 198 -0.1

122(b) 3.642 4.687 -12.55 220 266 -9.5

123 2.239 2.108 +3.01 155 176 -6.3

128 9.910 8.117 +9.95 572 558 + 1.2

131 9.879 10.120 -1.21 652 598 +4.3

136(a) 72.887 74.355 -0.99 3964 4213 -3.0

136(b) 9.521 9.507 +0.07 584 629 -3.7

139 4.573 4.789 -2.31 331 317 +2.2

141 7.521 6.011 +11.16 315 364 -7.2

144(a) 10.691 9.869 +3.99 517 574 -5.2

144(b) 10.524 10.014 +2.48 562 566 -0.4

Table. 7.1(a): (continued) The comparison of TDS {Table 7.1(a)), on the other hand, produced a slightly different view contradicting with some of the ionic-balance interpretation.

The percentage differences were also calculated by using the same empirical formula used for ionic-balance computation but this time the Zcations and Zanions were replaced by the TDS obtained by residue on evaporation and calculated TDS, respectively. Therefore the empirical formula took the following form:

{(TDS^ - TDS^yCTDS* + TDS^J) x 100.

Excellent TDS balance (error ^ + 5 percent) was obtained for 31 samples (50.8 percent). Reasonably acceptable TDS balance (error ^ + 10 percent) is obtained for another 18 samples (29.5 percent). Both category jointly make up about 80.3 percent of all the samples. The analytical data in 3 samples (4.9 percent) (W13(a), W54 and W60) produced high percentage differences (error < ± 15 percent) but the differences (error > +_ 15 percent) were objectionally high in another 9 samples

(14.8 percent) (W4, W15, W32(b), W39(b), W51(b), W56(b), W87(a), W 88 (b) and

W99). But it is interesting to note that the ionic-balance criteria suggested good quality condition of the analytical data for most of these samples (W4, W15,

W32(b), W39(b), W51(b), W56(b), W60, W87(a), W 88 (b), and W99). Both the ionic-balance and the TDS comparison unanimously suggested that the analytical data of 3 wells {W13(a), W51(b) and W54) are potentially erroneous and are most likely to provide misleading interpretation of geochemical interpretation.

Usually the analysis of Ca, Mg, Na and K from the cationic part and

HC03, S 04, Na and K from the anionic part makes an analysis complete but unfortunately most of the previous analyses do not include the determination of K and S 0 4 so that strictly speaking those analysis can not be regarded as complete.

Interestingly it is found that the percentage of error (17.7 percent excess - ve and

82.3 percent excess + ve) in the ionic balance is fairly low (less or around 10

278 percent) in most of the samples {Table 7.1(a)). Therefore, it can be assumed that the amount of potassium and sulphate present in the ground water is fairly low. The availability of potassium and sulphate concentration might have been helpful to improve the percentage error obtained in the specified wells.

The ground water samples which were analyzed at UCL are considered to be more accurate complete chemical analysis and the percentage of error in the ionic balance is fairly low. Out of 16 samples, excellent ionic balance

(error >$ + 5 percent) is obtained for 10 samples (62.5 percent) and the ionic

balance is within acceptable range (error ^ 10 percent) for the remaining 6

samples (37.5 percent). The comparison of TDS (between the value obtained by

residue on evaporation and the calculated TDS) also produced smaller differences

between them. Excellent TDS comparison (error ^ + 5 percent) is obtained for 13

samples (81.3 percent) and the percentage difference is ^ + 6.4 percent for the

remaining 3 samples.

7.5 Graphical Interpretation:

7.5.1 Distribution Maps:

a) Introduction: A distribution map provides useful preliminary information about

the hydro-chemical behaviour of a system with some indication of prevailing water

quality trends. Very often, therefore, it is used as a guide for identifying the most

appropriate methods for further interpretation of ground water chemistry, the

active processes particularly, ion-exchange, dissolution and redox potential and

the mixing behaviour while it also provides some indication about water types.

For the present work the TDS and the sodium/Ecation ratio distribution have been

prepared for the above purposes. Figure 7.2 shows the aereal distribution of TDS

in the study area, and is used to assess potability and ground water quality. Figure

279 7.3 shows Na/E Cation ratios and is used as an index of ion-exchange, on the assumption that other processes might affect this ratio. The hydrochemical ratio map have long been favoured by French workers and can provide useful information concerning such features as ion exchange and the onset of brackish water influence

(Lloyd and Heathcote, 1985).

b) TDS distribution map: The TDS map (Fig. 7.2) is contoured at 100 mg/L intervals. It shows the distribution of TDS within the project area for all the available samples. The eastern margin shows the minimum TDS concentration which increases along flow lines (Fig. 4.5). Though the distribution map does not closely accord with the ground water flow lines because of the substantial increase in TDS concentration at wells 34 (in Devidwar) and 120 (in Sonaimuri) which dominate over most of the region and greatly upsets the general distribution pattern yet the increase of TDS concentration coincides with the increasing distance along the down gradient direction. At well 120, the TDS concentration is >1100 mg/L which is unusually high in comparison with the rest of the ground water. It should however be noted that a TDS with such a concentration is well below the EEC safety limit

(EEC standard 1975) and can be classified as a low TDS category. Apart from this, the general distribution of soluble solids is very low, and two reasons can be offered to explain this low TDS condition. Firstly, the ground water receives abundant fresh water recharge primarily by vertical deep percolation of infiltrated water (see Section 8.2.2.a) as well as by means of horizontal flow from precipitation originating at the outcrops located to the east of the area of study every year which dilutes the existing concentration of the relatively older ground water. Secondly, the ground water does not travel long enough through the aquifer to pick up enough soluble material from the aquifer matrix to markedly increase its FIG-7-2 : HYDROCHEMICAL CONTOUR LEGENDS MAP OF TOTAL DISSOLVED international boejnoart SOLIDS (mg/U CHANNELS

PRI MART SECONOART

WELL LOCATION Contour interval 100 mg/L

SUPPLEMENTARY OUALITY STATION UNOP OUALITY STATIONS GWC QUALITY STATIONS BAOC OUALITY STATIONS

(UNOP • G WO QUALITY STATIONS IUNDP. BAOCI OUALITY. PIEZO WELLS UNDP QUALITY. PIEZO. WELLS GWC OUALITY . PIEZO. WELLS

BAOC OUALITY. PUMP TEST WELLS GWC QUALITY < AUTO. PIEZO. WEILS IBAOC • G WCI OUALI TY • PIEZO. WEILS

UNOP OUAIITY.P.T.-PIEZO. WELLS

12 M IL E

I 0 I S 12 H ZO KM

C l

A Y OF B E N G A L , / , ) ' concentration. Further study of Tritium and 14C data are required to support this contention.

A smooth TDS distribution can only be prepared by ignoring TDS measurements of some of the wells where the values are considered to be anomalously high or low. Figure 7.2(a) depicts a much better regional distribution by ignoring wells 22, 23, 27, 34, 43, 96, 106, 113, 114 and 120. In this map the increase of TDS is very well defined following the major direction of flow, which is towards west, south-west and north-west.

c) Na/E Cation ratios:

The ratio index values obtained from the distribution map of the ratio of sodium/Ecations (Fig. 7.3) indicate that considerable amount of ion exchange has occurred in combination with other processes responsible for the modification of calcium and sodium ions concentration as they become predominantly affected by the ion-exchange phenomena. A contour interval value of 0.2 was used to construct the ratio map and the contoured area between 0.6 index value and the largest obtained value has been shaded to locate the area where a significant amount of ion-exchange has taken place. Four major and one minor isolated ion-exchange areas have been identified. Both the northern-most and the southern-most ion- exchanged areas demonstrate that the increasing amount of ion-exchange activities is coincident with the increasing flow distance. But the centrally located ion- exchanged areas demonstrates that the ion-exchange activities increase towards the centre of each block from all directions.

Optimum exchange condition occurs in sands with significant clay content where the permeability is still sufficiently high for the water to be developed as a resource (Lloyd and Heathcote, 1985). Even though these aquifer in

282 L f 01NQS

(N>NW(tSINTI P N A I I O N A l BOUNOARY PBIMAPY SCCONOabt

w in location

Contour interval 100 mg/L

>UPPl(MtHlAHY QUAUTY station UNOP 0 U All I V STATIONS Owe OUALITY STATIONS

Ia OC 0 UAIIIT STATIONS

iunop • o wn ouAiirr stations

iunop . iaoci o u A iu r. p h io w ius unop OUAUIY. piiio . w ins 0 w( OUALITY •PIIIO- Wtus

iaoc ouauty • pump risi wins

owe OUAUIY • auto - PIIIO. Wills IBAOC •CVCIOUAIITY • PIIIO. WIUS

UNOP OUAUTVP.l'PIIia Wtus '

II Hilt

p fip »•<& O

%

Fig. 7.2(a): Modified contour map of total dissolved solids (TDS) in mg/L. FIG-7-3 : H YD ROCHEMI C AL RATIO itQENOS DISTRIBUTION OF SODIUM I N TE RNATIONAL BOUNOARY TO TOTAL CATIONS Channels

P R I M A R Y SECONOARY

WELL I OC ATION

Contour interval

SUPPLEMENTARY OUAUIY STATION UNOP OUALITY STATIONS GWC OUALITY STATIONS

BAOC OUALITY STATIONS

IUNOP • G wo QUALITY STATIONS IUNOP. BAOCI OUALITY. PIEZO WELLS UNOP OUALITY. PIEZO. WELLS G WC OUALITY * PIEZO. WELLS

BAOC OUALITY* PUMP TEST WELLS

GWC QUALITY • AUTO-PIEZO. WELLS IIJAQC • GWCI OUALI TY • PIEZO. WELLS

UNDP QUALITY * P.T. ■ PIEZO. WEILS

C O L 8 12 MILE

L 0 A 8 '2 16 20 KM

AY OF BENGAL most cases appear to be composed of dominantly sandy and gravelly particles, up to 15% by weight of clay/silt materials are associated with the aquifer materials (see

Section 2.5). It was mentioned previously that major part of the ground water recharge takes place by direct infiltration of rain water which is solely intergranular flow in these unconsolidated deposits. As these fresh recharge water passes through the sequence some ion-exchange activity takes place which increases significantly when the recharge water comes in contact with connate water and saline water. The connate water was trapped during the deposition of sediments and the quantity of saline water is increasing by the sea water intrusion from the Bay of Bengal.

Further investigation is required to provide confirmation and better understanding.

7.5.2 Pattern Diagram:

Hydrogeological facies variation across the study area are presented in Figure. 7.4 as Stiff patterns for each well plotted on a grid map of the area.

The following comments can be made about the pattern diagram distribution:

1) With the exception of wells 9, 34, 50, 85, 107, 120, 131 and 136, the Anion group is dominated by the H C 0 3 ions. But this domination is superseded in the south by an increasing amount of chloride, which usually behaves conservatively in solution.

2) The analytical results clearly demonstrate that the ground water is dominated by sodium but the influence of calcium, magnesium and potassium ions are also observed in the following instances: a) in wells 20, 39 22 and 75 where a calcium

domination is observed; b) magnesium is important in wells 4, 70, 73, 113 and 141

and c) a limited domination of potassium ion is observed in wells 106, 112 and

114.

285 FIG-7-4: PATTERN DISTRIBUTION OF MAJOR l e g e n d s HYDROCHEMICAL CONSTITUENTS

INTERNATIONAL BOUNDARY CHANNELS

PRIMARY SECONOARY

W ill LOCATION

FIRST SAMPLE

SECOND SA M P LE

SUPPLEMENTARY QUALITY STATION UNOP OUALITY STATIONS GWC QUALITY STATIONS BAOC QUALITY STATIONS IUNOP • G W □ QUALITY STATIONS IUNOP.BAOC) QUALITY. PIEZO WELLS UNDP OUALITY. PIEZO. WELLS GWC QUALITY *PIE20- WELLS BAOC QUALITY* PUMP TEST WELLS GWC QUALITY * AUTO- PIEZO. WELLS I8A0C • GWCIQUALITT • PIEZO.WELLS UNOP QUAUTY*P.t*PIEZa WELLS

12 MILE I I I I I I E> L 0 I | 12 It 20 KM KEYi. 200 100 0 100 2Q0HO/I Co-** Co 3) The useful measure of total ionic content in terms of the pattern indicates that the width increases along the flow direction in comparison with its source which is the north-easterly located ground water divide (Fig. 7.11), although it is some time better presented by the TDS plot which is also true for the present TDS distribution.

4) The ground water towards the outcrop appears to have been an essentially

NaH C0 3 type in nature but as it moves towards the west, south-west and south hydrochemical evolution modifies the ground water into a mixed NaHCO^Cl type because of ion-exchange and mixing with connate water.

7.5.3 Trilinear Diagram:

The chemical composition of the samples has been plotted (in

%meq/l) on a trilinear diagram (Fig. 7.5) drawn by the use of fortran 77 program

(Appendix. 7.1) devised by the IGS (1978). Occasionally this plot is useful to

summarise the important chemical processes (mentioned in Section 7.5.1.a) and to

visualise the prevailing water type(s) that may have developed as a consequence of

the operation of those processes. Both the Piper-Hill (1944) (Appendix. 7.2.1) and

Back (1966) (Appendix. 7.2.2) classifications failed to elucidate processes or to give

a useful interpretation of data but they indicated that the water does not belong to

any particular group rather there are many water types.

7.5.4 Chemistry along flow lines:

A number of flow lines were selected to demonstrate the pattern of

hydrochemical change. A maximum of four flow lines were selected from Figure

4.5 and the ground water sampling locations falling along or close to each of the

flow lines (Fig. 7.6) were treated individually. The major ionic content of the

287 < Ca >

Fig. 7.5: Piper diagram showing the hydrochemical distribution of ground water samples in terms of major ion percentages. Size of symbol is proportional to TDS (mg/L). LEGENDS

international b o u n o a r y

c h a n n e l s

PRIMARY S E C O N O A R r

WELL LOCATION

SUPPLEMENTARY QUALITY STATION unop Quality STATIONS

GWC q u a l i t t stations BAOC QUALITY STATIONS

IUNOP •GWC) QUALITY STATIONS IUNOP • BAOC) O U A L I T Y * PIE20 WELLS UNOP QUALITY. Picza WELLS GWC QUALITY . PIEZO. WELLS BAOC QUAL ITY • PUMP TEST WELLS GWC OUALITY * AUTO* PIC 20. WELLS IbAOC • GWCIOUALITY • PIE20. WELLS UNDP QUALITY .P.T..PIE20. WELLS

12 M IL E

L 0 I I 12 It 20 KM

M-

B A Y OF B E N G A L 9f y{

Fig. 7.6: Map showing the selected flow lines from Figure 4.5. ground water samples falling along a particular flow line were plotted in separate trilinear diagrams as Figure 7.7 in which the flow directions are indicated by arrowheads. The total ionic concentration of each sample is expressed in terms of the size of the plotted points; the larger the size the higher is the concentration of the dissolve ions. The general rule about the ionic concentration under normal simple flow conditions is that the amount of total dissolved solids increases with increasing flow line distances. Because of the complex flow pattern this rule has not been maintained in any of the flow lines. The natural flow lines are distorted by over pumping so also the active processes. The reverse ion-exchange process may be explained by flow line 2 and 3 where both the wells 18 and 50 indicate end­ point waters and a progressive increase of unstable ions (Ca and Mg) are observed at the expense of stable ions (Na and K). The wells 23, 35 and 51 along flow line

2 can be regarded as a group so also the wells 54 and 60 along flow line 3. The sequential direction of flow in flow line 1 looks rather unlikely as a chemical evolution. The plot of wells 89, 106 and 112 can best be described as a group rather than a chemical evolution. It is not possible to resolve such fine structure in chemical processes with inadequate data. Although dissolution is not pronounced in sand dominated aquifer but occasionally it may be significant. The dominance of calcium in wells 20, 22, 39 and 75 and magnesium in wells 4, 70, 73, 113 and 141 is indicative of limited chemical dissolution of associated calcitic and dolomitic materials. Major part of the present ground water originates from the direct recharge of rain water, a solution which is oxygen rich. The inter-actions between the recharge water and the reducing aquifer matrix are responsible for redox phenomena observed in many aquifers (Lloyd and Heathcote, 1985), therefore certain amount of reduction is more likely. A detailed discussion is prevented by the absence of redox potential (EH) and other measurements.

290 o .

00

00 S

The original Durov (1948) diagram has significantly been expanded in two different stages firstly by Burdon & Mozloum (1958) and secondly by Lloyd and Heathcote (1985), into nine convenient fields to provide a better classification and understanding of the hydrochemical groupings of ground water types and some of the processes that changes ground water composition. A detailed description of the modification and the significance of each of the fields is available elsewhere

(Lloyd and Heathcote, 1985). For the present sets of hydro-chemical data, a clearer explanation of the types of water and the active chemical processes has been provided by the expanded Durov diagram.

The plotted points in the expanded Durov diagram (Fig. 7.8) fall into two fields suggesting the existence of two different types of ground water.

More than 77 percent (38 data points) of the waters are confined in the second and third fields with a majority lying in the third field. Those lying in second field show the dominance of Mg and H C 0 3 but at the same time Ca and Na are also an important part of their concentration suggestive of partial ion-exchange accomplishment. On the other hand, those falling in the third field exclusively, show the dominance of Na and H C 0 3 which normally indicates a strong ion-exchange accomplishment. Therefore the water in the second and third fields would normally be classified as ion-exchanged waters (Durov, 1948; and Lloyd and Heathcote,

1985). The second major group of water samples plotted in the ninth field indicating the dominance of Na and Cl ions. Waters having such features are usually regarded as end point waters which often suggests the existence of older waters in the aquifer. Only two water samples plotted in the eighth field suggesting

Cl ion dominance and no dominant cations which is a positive indication that the water may have experienced reverse ion-exchange processes from Na-CI waters. r > r: C aH 50% HCQ750%

• \ xcnange

SO l~ 507.

SO i" 257. Rcv/trse Ion exchange

Fig. 7.8: Classification of ground water types using the expanded Durov diagram: I, Ion exchange waters; II, Old brackish water with some reverse ion exchange. Waters in both the eighth and ninth fields jointly can be classified as Old Brackish

Water where some reverse ion-exchange processes have taken place.

The map (Fig. 7.9) of the two different types of water identified from the expanded Durov trilinear plot (Fig. 7.8) strengthens the idea that the scatter distribution of the brackish water within the major ion-exchange waters neither represents any distinct pattern nor does it indicate any link with brackish waters. Therefore, it may be concluded that the saline water entrapped in the

southern region at shallow depth is because of sea water intrusion from the Bay of

Bengal. However, this does not wholly explain the isolated locations of saline

ground waters in the northern and central parts is jointly because of connate

brackish water trapped since deposition with some possible segregation of Na, K

and Cl ions by ion-exchange processes.

7.6 Application of PHREEQE Hydrochemical Model:

7.6.1 Introduction:

The assessment of the ground water equilibrium state with respect

to soluble solids as a result of the continued action of chemical processes is made

in terms of saturation indices (SI). To perform such calculation PHREEQE the

hydrochemical model has been used and the model does this particular task by

calculating the distribution of species in the water. The saturation index (SI) of a

water is defined by the expression: SI = Log ([IAP]/[K])where,

IAP = ion activity product and

K = equilibrium constant.

A water is in equilibrium with a mineral when the Saturation Index is zero. When

this index is negative, the water is under-saturated and mineral dissolution may

occur. When the Saturation Index is positive the water is super-saturated and LEGENDS

INTE RNATIONAL 80UN0ARY CHANNELS

p r i m a r y

SECONO a Ry

WELL LOCATION Ion exchanged waters Old brackish water

SUPPLE HE N tARY QUALITY STATION UNOP QUALITY STATIONS GWC QUALITY STATIONS BAOC OUALITY STATIONS

IUNOP . G WC1 QUALITY STATIONS IUNOP . BAOCI OUALITY . Piezo WELLS UNOP OUALITY. Pino. WELLS GWC QUALITY • PIEZO. WELLS BAOC QUALITY • PUMP TEST WELLS

GWC OUALITY • AUTO. PIEZO. WELLS I b A O C • G WCI Q U A LI TY • PIEZO. WELLS

U N O P OUAl l TY- P.T.-PIEZO. WELLS

Fig. 7.9: Map showing the distribution of two water types. mineral precipitation may occur.

7.6.2 PHREEQE Model: a) Data base for species calculation:

A thermodynamic data base (See Plummer, 1985 for a detailed

description) is required to run the model. The major part of the data base is

compiled by the authors of the model and must be appended by the users analytical

data to complete the data base. In the model data base the ionic concentration is

supplied in units of mg/L. The various ions (both cation and anion) are recognized

by the model through a predefined identifying number as for example, 4 for

calcium, 5 for magnesium, 14 for chloride and so on. In the model, the ions are

treated as elements and in doing so the anions are treated as their major elemental

content. For example S04 is considered in terms of its elemental sulphur. During

simulation every element under-goes a series of reactions as intermediate stages on

its way to attain final equilibrium. These reactionary products at every stage are

individually termed as species in the PHREEQE model. All the species associated

with a particular element is grouped together as the member of a particular system.

b) Description of model results:

It would be wholly unnecessary to attach the lists of results for all

the 48 water samples for which species calculation have been completed. Therefore

a summary of the model-calculated results for a particular water sample (W 144)

are presented in Table 7.2.

The upper part of the table represents the various elemental ions

which were read and calculated by the model. Under the heading ’description of

solution’ the model summarizes certain important calculated geochemical

296 SPECIATION AND CALCULATION FOR WELL 144 SONAPUR NOAKHALI TOWN

TOTAL MOLALITIES OF ELEMENTS

ELEMENTS MOLALITY LOG MOLALITY

Ca 3.24613 ID-04 -3.4886 Mg 6.300083D-04 -3.2007 Na 8.623821D-03 -2.0643 Fe 1.433641D-05 -4.8436 Cl 1.242082D-03 -2.9058 C 8.728349D-03 -2.0591 N 4.842232D-05 -4.3150

DESCRIPTION OF SOLUTION

pH = 9.5000 PE = 0.0000 ACTIVITY H20 = 0.9997 IONIC STRENGTH = 0.0123 TEMPERATURE = 27.0000 TOTAL ALKALINITY = 1.0764D-02 ITERATIONS = 9

LOOK MIN IAP ......

PHASE LOG IAP LOG KT LOG IAP/KT (S.I.)

CALCITE -6.9992 -8.4881 1.4889 DOLOMITE -13.6368 -17.0605 3.4237 SIDERITE -11.3574 -10.5760 -0.7814

Table. 7.2: A modified form of the PHREEQE model calculated results output for well 144. parameters. In the final stage, the program determine the Saturation Indices (SI)

of those minerals (phase) for which sufficient chemical data were available to

allow their calculation.

c) State of saturation Indices:

The saturation indices (SI) of certain important minerals such as

gypsum, calcite and dolomite are summarized in Table 7.3 to provide information

on the saturation states. It should be mentioned that any interpretation on the basis

of saturation is only meaningful for sparingly dissolved mineral. Therefore to

demonstrate any possible relationship only calcite, dolomite and siderite saturation

indices were used to construct the X-Y plots.

Calcite versus Dolomite SI Plot:

A plot of calcite SI versus dolomite SI (Fig. 7.10) is effectively

linear, passing through the points of mutual equilibrium and shows 73 percent of

the water to be over-saturated with respect to both minerals. The linearity of the

plot suggests the following points: 1) the degree of saturation of the water with

respect to the minerals tends to increase with the increasing distance of the water

from the outcrops with some exceptions (see Figure 7.9 and 7.10). Some of the

wells in Figure 7.10 have been numbered to illustrate this trend; 2) the increasing

depth of water also clearly demonstrates an increase in degree of saturation with

even fewer exceptions ; 3) 28.6 percent of the strong ion-exchanged water (where

Na/Zcation ratios > 0.6) shows under-saturation while 29.6 percent of the other ion-

exchanged water (where Na/Zcation ratios < 0.6) suggest under-saturation, and 4)

50 percent of the old brackish water (wells 9,18, 34, 50 and 85) suggests under-

saturation conditions; therefore no recognisable trend is visible from the ion-

298 SATURATION INDEX (S.I.) WELL GYPSUM CALCITE DOLOMITE

" 2- 6o| - O - 621 - 1*477 ' • ^10 3 ■ 936

~ 3- 526 0 - 4 3 Q I- 2 / 6

- 2- 7 9 2 - O. 4 7 7 - 1-2 22 2- 898 - o. 7 0 6 - 1. 3 8 4 13 -O •8 3 9 - I* 7 4 3 15 o* 476 I- 0 7 O

18 - I - 402 - 2- 20 4 20 0 - 4 8 6 - 1 * 1 2 3 22 -1-923 -0-2 52 - (* 4 0 6 23 -3-0 70 I* 5 7 7 3- 3 4 5 2 7 0*6>OS 1-082

32 o- 961 2- 5 6 2 34 - o • 15o • I • 271

35 - 3-27/ 1- (9 7 2- 402

3 9 - 5-409 0. 9 7 9 I* 925 43 O- 251 0 -4 5 9

50 - I - 515 -2 -8 5 3

51 - O. 0 9 2 - o ■I 63

54 O. 7 8 9 9 3 4

56 0- 7 4 3 5 2 7 60 0 - S 67 1- 7<7 70 -2- 6(4 1- 635' 3- 666

7 3 3*335 0- 7 9 7 2 • 2 0 5 ’ 75 1- 659 3 . 9 9 g 79 -2-692 0*569 -1-450 85 - 0• 957 -1- 817-

Table. 7.3: Summary of saturation indices of certain mineral matrix. SATURATION INDEX (S.I.) WELL GYPSUM CALCITE DOLOMITE

87 - 0 . 259 2 -3 5 S 88 - 1-246 3-00 6 89 - - I - °76 - 1-643 93 -2.-94S 2 - 262 4 -3 6 5 95 - I ■ 672 3- 372

96 — 3 • 6^4 0 -5 4 9 I - 653 99 - I • 263 2- 356 106 - 2- 7 4 S — — 107 - I-59I 3- 643 1 12 -2 -9 4 2 0 - 1-9% 2- 044 1 13 — I- 194 2 - 99?

114 - 2 - S17 I - 304 2- 635 1 20 - 3 - 170 0-999 0 - 2 3 7 - 1 22 - 2-455 0 -2 6 3 0 -2 6 9 123 - 3 - 0 4 S - O - 640 - 1 • 430 128 - 2 '9 2 5 1- «6S 3 -2 3 4

13 1 -2-7-2 3 0- 933 1-954 136 - 5- 406 I - 669 3-9-02 139 -2-916 O- I-S9 o- 403 141 - I- 5 98 3- 3 9 3 144 - I- 4<39 3-424

______, Table: 7.3: continued. DOLOMITE

144

• •

123 79

Fig. 7.10: Plot showing the linear relationship between Calcite and Dolomite S.I. value. exchange point of view and saturation interpretation in terms of old brackish water.

Calcite versus Siderite SI plot:

The calcite against siderite plot (Fig. 7.11), on the other-hand, demonstrates a wide variability on the SI value reflected by their plotting position.

All the SI points are randomly scattered in all four quadrants and is probably meaningless.

7. Ground water quality:

The major part of the ground water withdrawn in urban areas is used as a potable supply whereas the major part of the rural ground water is used for both irrigation and drinking water purposes, with a little also being used for industrial purposes. Depending on the type of industry, the required quality of the usable water also varies remarkably. Therefore the following discussion will be limited to drinking and irrigation aspects of water quality.

7. .1 Drinking water quality:

The potability of a ground water is entirely dependent on the concentration of soluble solids. Some soluble materials are more injurious than others; a minute increase of some soluble materials is more harmful than a large increase of another soluble material. To maintain the quality of ground water, international agencies such as WHO (World Health Organization), EEC (European

Economic Community) and USEPA (U.S. Environmental Protection Agency) have recommended certain standard limits for most of the dissolved materials. The obtained maximum and minimum concentrations for the measured ions are compared with the three different major international standards in Table 7.4 primarily to

^09 SIDERITE

-6 -4 -3 -2 -1

5

4

3

2 • • / • • • w H 1 U • • < u ••• -1

-2

-3

-4

-5

-6

Fig. 7.11: Plot showing the random distribution of Calcite and Siderite S.I. value. U S E P A BBC S T U D V ITEM W H O 0»B-0 ( 1 9 8 8 ) Ci s t s ’) d e s v L r s MAC MRC MAC MRC MAC 0.C/ MAX. M I N . 0 * 1 1£) H /0 o a /0 Cm«/ l) HJ f) Cwg/i.) TPS l o o o - 5 o o - 1500 - 3 9 6 4 I02 6-0/ p h 6 -5 -« -5 6 - 5 - 8 5 - 100 6 - 5 -^frS-8-5 S c 02 ------7 4 - 1 1 5 - 0

c a 0 0 -3 0 0 - - - - 6S 0 7 5 A 0 0 - - - - 3 - 0 5 0 x<50 IIS -2 - - - N a 200 100 X o I 3 6 6 4 - 6 - - - - K 12 X S 6 4 1 6 - S - - F e 0 - 3 0 3 0 - 3 X 9 - 6 0-0 M n 0 1 - - 005 0 - 7 9 0 0 5 X o z 0-0 y - - - - - 460 0-0 h c o 3 - -- - - X o 5 3 2 - 0 5 9 - 0 - - 0 - 0 S o 4 400 2 5 0 250 X 4 6 - 1 c l 2 5 0 - 2 5 0 - 200 2 1 5 0 0 ‘S 10 NO 4 4 - - 50 5 1 - 9 0 - 0 O ^ 2 5 - - - - 2 X ? 3 1 3 2 0 7 2 0 F 1 -5 - 2 o - 1 -4 -2 4 0 - 5 3 4 ( 0 - 1 "0-7-1-2X 1 2 5 0 1 6 8 6 1 4 6 - - - — E c l*Sc»i x ^ o O f^SciS H s c m 1

MAC = Maximum admissible concentration GL = Guide level MRC = Minimum required concentration

Table. 7.4: Comparative tabulation of potable water quality in terms of various ions with selected international standards. indicate the range of differences and hence to visualise the status of the quality aspect of the ground water being examined. On many occasions the standards for several ions are not available. The reason for this is that for some of the ions it is unimportant to set a standard and in other cases, especially for USEPA, it was not possible to obtain the standard criteria. To assess the potable quality of the present ground water, a comparative study of more important major ionic concentrations is presented below with the EEC standard concentration.

TDS (total dissolved solids): the maximum admissible concentration (MAC) is

1500 mg/L and this limit is mainly set to retain original natural taste. The measured

TDS concentration in the study area is well below the recommended limit, except at well 136 where at a depth of 52 ft (> 15 m) the water has a TDS concentration of 3964 mg/L. The same well when it withdraws water from a depth of >1200 ft

(>365 m) provides a TDS concentration of 474 mg/L. This enormous TDS rise at shallow depth is because of the very high concentration of Na and Cl ions supplied by the sea water intrusion. The high TDS at shallow depth is not representative for the main aquifer.

pH: The MAC and minimum required concentration (MRC) levels for hydrogen ion concentrations are 9.5 and 6.0, respectively. A pH of 10.0 is recorded in a number of wells which is above the MAC limit. The majority of the remaining wells recorded a pH of 8.0 and above, indicating that the solution is increasingly basic.

Silica (Si02): The range of concentration of silica most commonly observed in natural water is from 1 to 30 mg/L. The maximum (74.1 mg/L) and minimum

305 (15.0 mg/L) silica contents from the study area indicate that they are on the very high side.

Major ions: The analytical list (Table 7.1) suggests that in most cases the calcium, magnesium, sodium, iron, sulphate, chloride and nitrate levels are well below the EEC recommended safety limits except for the following ions: calcium concentrations were found to be a little lower than the MRC limit in wells 18 and

123; magnesium concentrations less than the MRC level was noted in wells 13,

15, 22, 32, 34, 79 and 123; sodium concentrations exceeded the MAC limit in wells 2, 9, 32, 34, 39, 88, 96, 107, 120, 127, 136 and 144; iron concentrations exceeded the MAC limit in most of the wells; and chloride levels in excess of the

MAC limit are reported in wells 9, 50, 107, 120 and 136. The analytical results also revealed that where-ever an analysis of potassium and manganese is available, the MAC level has been exceeded in the case of potassium for all wells and except for wells 23, 106 and 139 the manganese level is also much higher than the MAC.

Minor ions: Of the two minor ions analyzed (Table 7.1), the fluoride level is much lower than the lower range of the MAC limit in all the analyses and phosphate concentrations in excess of the MAC limit was noted in wells 23, 35,

112 and 136.

7. .2 Irrigation Water Quality:

The ground water resource is most extensively used for irrigation purposes during the dry period (November - March). Therefore a study of the most common relevant chemical factors for irrigation water suitability has been carried out on the basis of field and laboratory measurements and calculations. The calculated indices are sodium absorption ratio (SAR) = [Na / {(Ca + Mg)/2}1/2 ] (Richard, 1954), residual sodium carbonate (RSC) = [(C03 + H C 03) - (Ca +

Mg)] (Eaton, 1950) and magnesium hazard (MH) = [{Mg / (Ca + Mg)} x 100]

(Szabolcs and Darab, 1964). All these indices were calculated in meq/1 unit.

All these indices provide a good practical guide to water suitability in terms of major ions. However, the irrigation water quality is usually represented in terms of total salt content which is normally measured as EC in irrigation uses.

The U.S. Department of Agriculture has devised a better classification for irrigation water based on a combination of parameters. In their classification (Fig. 7.12) they have considered the SAR in combination with EC which has proved very convenient and is widely used in assessing irrigation water quality.

The actual plot (Fig. 7.12) of the calculated SAR value and the measured EC values (EC values were measured only for those water samples analyzed at UCL) suggest that with the exception of wells 112, 120, 128 and 131 all the water belongs to a Low to Medium Salinity Hazard. Low sodium water as described by Wilcox (1955) can be used for irrigation on almost all soils with little danger of the development of harmful levels of exchangeable sodium. Quoting from the U.S. salinity report (1954) "low salinity water can be used for irrigation with most crops on most soils with little likelihood that a salinity problem will develop". Some leaching is required but this occurs under normal irrigation practices except in soils of extremely low permeability. Medium salinity water can be used if a moderate amount of leaching occurs. Plants with moderate salt tolerance can be grown in most instances without special practices for salinity control.

Low Sodium and High Salinity ~> hazard condition is shown in wells 112, 128

and 131.

High Sodium and High Salinity --> hazard condition is present only in well

120.

307 i. .2 Po soig h rne fcmie sdu ad aiiy aad for hazard salinity and sodium combined of range the showing Plot 7.12: Fig. Sodium hazard *o co lsiiain firgto wtr quality. water irrigation of classification CO 16 < 100 Low Electrical conductivity conductivity Electrical 123 250 Medium Salinity hazard Salinity • o 112. ?o • 1 139 35 0 • i06

23 750 u ®>28 (^S High m ') cm C3 12

0 2250 V.high Of these the only well 131 is located on the south-western border along the

Meghna estuary indicating a high salinity condition which is primarily due to salinity intrusion along the coastal belt (mentioned previously in Section 7.4.3) and not surprising being close to the Bay of Bengal. The other wells (112, 128 and 120) having higher hazards indicate isolated representation rather than part of a pattern or trend. On the basis of the above explanation of the different categories of hazards, it may be concluded that most of the waters are suitable for most crops. Nevertheless, selective cropping patterns would be more appropriate in areas having high sodium and high salinity hazard.

The bicarbonate hazard (measured in terms of residual sodium carbonate (RSC) and the magnesium hazard (MH) {empirical formula devised by

Eaton (1950)) along with the sodium absorption ratio (SAR) are summarized in

Table 7.5 which compares the agreement between different types of hazards. The result of this comparison in some cases are conflicting in nature and to elaborate this situation the status of different hazards in a couple of wells can be examined.

When the SAR index of well 36 indicates a ’Low Hazard’ and the MH indicates

a ’Harmless’ condition then the RSC provides a ’not suitable’ condition. Again

the ’not suitable’ RSC and’Harmful’ MH of well 144 is contradicted a by Low

SAR hazard. For the present sets of data, ’Low Hazard’ and ’Suitable’ conditions

for most of the wells are indicated by the SAR and RSC indices respectively rather

than the MH hazard. Perhaps these problems reflect the poor quality of some of the

analytical data. It is mentioned in Section 7.4 that better ionic-balance (error ^ +

10 percent) is obtained for 77.1 percent of the water samples therefore the

conflicting nature hazard condition due to bad or inaccurate data should be fairly

low.

309 WELL SAR RSC RSC MM M H NO. - H A3 ART) roe^x"' HfliARD HA£ART> 1 0*931 Low 0.296 SUITABLE 49 harmless 2. 3 .028 11 -4- 2 9 0 11 71 HARMFULL 4 0 • 69? II -0-820 II 88 II 6 0. 973 II 0- 706 II 31 HARMLESS $ 11 - 7«2 M EPIUM 1 - 4 0 0 MARl N AL- 46 II 1-5 2- 739 LOW 0. 600 SUITA0LE 41 II 15 I- =724 II - 0-084 II 52 HAKM FULL 18 2- 137 II - I • 0 3 0 II 59 II 20 1 • 183 II - 0 - 4 15 11 36 H ARM LESS 22 2- 651 II l* 043 II OS II 23 3- 650 II 2* 440 MARGINAL 53 HARMFULL 27 1 • 482 II 0- 392 suitable 36 HARMLESS 32 3- I2 4 If 1- 700 MAR&INAL 7? HARMFULL 34 6- 984 If -I- loo Suitable 08 HARM LESS 7* 0 35 0 H 2* 627 NOT SUITABLE 45 M 39 4- oss 11 0-263 SUITABLE 51 HARMFULL 43 3 • 321 II O. 751 II 42 HARMLESS 50 I- 686 If - 4 * 662 II 54 HARMFULL 5 1 2.404 f) 0 595 11 45 harm less 54 2- 373 II 0 - 6 9 4 If 58 HARMFULL 56 3* 456 If 1 • I04 II 4? HARMLESS 6o 3. 122 II 0 - 6 0 3 II 42 II 70 0 • 666 u 0 558 II 66 HARM FULL 73 I • on II - 2 • 292 ll 76 If 75 1* 431 II -1 * 36/ II 76 H 79 0-934 II 1. Oil II 28 HARMLESS 85 3 . 178 11 - 0 - 8 0 3 11 50 87 1 • 744 II O- 896 II 72 HAR PULL 88 11*748 M £ PI UM Z- 445 MARGINAL. 69 II 89 1- 619 LOW 0-815 Suitable 72 If 93 2 * 233 11 O - 868 fi 52 ff 95 4.028 ff 0-4*0 11 42 HARMLESS 96 3*537 11 -1 • 963 u 74 HARMFULL 99 2-339 11 0- 148 11 35 harmless 106 1* 298 If 1*403 MARGINAL 49 If 10? 3*230 U -4 * 415 S Uf TABLE 69 HARM PULL H2 1-470 11 1* 318 MARGINAL 70 Harm Full 113 1 • 132 If -0*738 su /table 76 11 114 0* 709 11 - 0-01? 11 48 HARM LESS 120 l2- 784 M6PI UM 1. II? 11 7? HARM PULL 122 0-318 4-0 W 0-327 n 64 ff 123 o- 9 5 7 U O* \93 11 38 Harm less 128 4*085 II -0 -3 4 5 11 48 II 13/ 2-. 523 If -2* 18 1 11 5o 136 5*734 II 4* 082 NOT SUITABLE 62 HARM PULL 139 1*782 II a *o?9 MARGINAL. 4? HARMLESS 141 1* 210 II 0 -0 4 g SUITABLE 80 HARMFULL I4f 8* 8 2 5 II 6-818 NOT SUITA621; 6s II

Table: 7.5: Comparative study of the irrigation water quality in terms of various types of hazards. CHAPTER 8 GROUND WATER RESOURCES

8.1 Introduction.

8.2 Assessment of Resources.

8.2.1 Introduction.

8.2.2 Ground Water Replenishment (Inputs).

a) Infiltration from Precipitation.

b) Irrigation Return Flow.

c) Influent Seepage of Surface Flow.

d) Influent Seepage of Sewage Water.

e) Leakage from Contiguous Strata.

f) Subsurface Inflow through Aquifer Boundaries.

8.2.3 Ground Water Discharge (Outputs).

a) Evapotranspiration.

b) Effluent Flow to Rivers, Canals and other Water Bodies.

c) Leakage into Contiguous Strata.

d) Subsurface Outflow through Aquifer Boundaries.

e) Artificial Withdrawal by Pumping.

8.2.4 Ground Water Budget.

8.3 Ground Water Management.

8.3.1 Introduction.

8.3.2 Development Status of Resources.

8.3.3 Perennial Yield.

8.3.4 Ground Water in Storage.

311 8.1 Introduction:

Ground water resources have long been neglected in Bangladesh despite their easy availability since surface water was considered as the only viable resource. The continued inadequacy of global potable water to meet the growing demand has now largely changed the traditional concept to include the non-potable part of ground water as resources regardless of how they became non-potable. The

scarcity of potable water has also helped to change the attitude towards water as

a whole recognising that although ground water is the only resource that is naturally

renewable, it is not of unlimited quantity. The attention directed towards water

resources during the last couple of decades has established the fact that nonpotable

waters are just as much part of the hydrologic cycle as potable water and cannot

be ignored in any ground water resources assessment.

The assessment of resources is almost entirely dependent on the

correct identification of those active components of the hydrologic cycle which

make significant contribution to water balance computations both from potable and

nonpotable sources. Using the results of ground water balance computations, Jones

(1972) defined four different states of ground water resources development, and

the state of development in turn determining the importance of the degree of

management practice. The same approach will be used to assess the state of ground

water development in Bangladesh and to recognise the status of the management

practice that may be required for the present ground water regime in the relevant

subsequent sections.

8.2 Assessment of resources:

8.2.1 Introduction:

In most ground water development programmes one of the most

important aspects of resources evaluation is to estimate how much ground

312 water is available from a ground water regime. An accurate quantitative assessment of the resources is not easy to make simply because so many parameters are involved and direct measurement of these parameters is often difficult. As a result, assessment of resources is done therefore in the form of the water balance.

The success in making a reasonably acceptable water balance depends on the proper identification and authentic calculation of the various component parts of the hydrologic cycle that control both the natural and artificial flows of ground water into and out of the basin.The variouscomponents that regulate the flow into the basin are collectively called ’recharge’ components whereas the various ways by which the ground water basin loses water are collectively called ’discharge’ components. In any water balance computation, the recharge and discharge components are related by the following expression:

Recharge = Discharge + Change in permanent ground water storage.

The following are the most important components of recharge:

-Infiltration from precipitation

-Irrigation return flow

-Influent seepage of surface waters

-Influent seepage of sewage waters

-Leakage from contiguous strata

-Subsurface inflow across aquifer boundaries.

The principal components of discharge most commonly include:

-Evapotranspiration

-Effluent flow to rivers, canals and other water bodies

-Subsurface outflow across aquifer boundaries

-Artificial withdrawal by pumping

-Leakage into contiguous strata.

313 Most of these components are governed by nature and very little can be done to affect their inherent course of action but some of them, particularly irrigation return flow and artificial withdrawal, can be controlled almost entirely to ensure their best possible utilization.

8.2.2 Ground W ater Replenishment (Inputs): a) Infiltration from precipitation:

There is no straight-forward direct and accurate method to determine the effective infiltration (Ie) component of rainfall for a large catchment. As a result, an indirect approach in the form of water balance computation (method described in Section 8.2.3.a. evapotranspiration) has become the normal practice to separate the various component of distribution for the basin rainfall over a known period.

In this computation the amount of rainfall in excess of actual evapotranspiration

(AE.) and surface runoff (SR) is considered to be the amount of rainfall that is transformed into effective infiltration (IJ.

In section 8.2.3.a. the Agnew (1982) model separates the Drainage component (1718.05 mm) which is in effect equivalent to the amount of effective infiltration (IJ. The Grindley (1969,1970) model, on the other hand, combines both the surface runoff and the effective infiltration in the form of Water Surplus

(2178.31 mm). Therefore in this section the aim is to separate the surface runoff

(SR) from the water surplus (WS). The total amount of surface runoff of a large catchment can be calculated with reasonable accuracy by analyzing and separating the river discharge hydrograph into its major components i.e. into direct runoff and base-flow. On the basis of the hydrograph analysis in Section 8.2.2.b (Effluent flow to rivers etc) the different relevant components are summarized below and expressed in cumec-days/annum.

314 Rivers Total flow Base flow Direct run-off

------______r!umec-days/ann

Northern rivers 83274 55726 27547

Southern rivers 21527 8040 13487

Total 104802 63767 41034

Total surface (direct) runoff for the entire region is 41034 cumec-days/annum

= 41034 x 60 x 60 x 24 = 3545337600 m3/annum

= 346.80 mm/annum (area = 10223 sq. km.).

Effective Infiltration (IJ = WS - SR.

= 2178.31 - 346.80 = 1831.51 mm/annum.

This amount of effective infiltration compares quite well with the amount of drainage (1718.05 mm/year) obtained by Agnew model (about 6% difference) in spite of its limitations that applies to the soil condition and surface runoff occurrences. Therefore it should not be unrealistic to consider the average

Ie (1775 mm/annum) value to compute the ground water balance.

b) Irrigation return flow:

Practically speaking it is almost impossible to provide the exact

amount of irrigation water that the producible crops require for healthy growth.

Since some percentage of irrigation water will always be lost by both evapotranspiration and deeper subsurface infiltration/percolation, the usual practice

is to provide an irrigation in excess of crop water requirements. This inevitable loss of water is called Irrigation loss and the part of irrigation loss that returns via the

vadose zone to saturated zone is called the Irrigation Return Flow.

Irrigation is provided to the crops in the study area during the dry

period (November-April) when the rainfall is insignificant or absent. Throughout this period soil moisture deficits (SMD) occur (Grindley Model, Table 8.2); more­ over, most of the time final soil moisture (FSM) remains at its wilting point

(Agnew Model, Table 8.4). As a result of the cumulative effects the actual evapotranspiration rate drops considerably and the major part of irrigation water in excess of crop water requirements attempts to turn into irrigation return flow to reduce the soil moisture deficit (SMD). Any water in excess of field capacity infiltrates down to the saturated zone to make a positive contribution and increase the amount of effective infiltration (IJ.

It must be mentioned that irrigation is not entirely sustained by the use of ground water. A significant amount of irrigation (about 25 %) is supplied from easily accessible surface water sources obtained from both running water

(rivers) and bodies of standing water (beals, haors & ponds etc). In the absence of any reliable records it is thought that about 80 percent of the ground water withdrawal is used for irrigation purposes and the remaining 20 percent is used for both municipal and industrial purposes. Because the surface water is easily available no record has ever been kept of how much surface water irrigation has been applied to the crops. Therefore it is assumed here that both the surface water and ground water irrigation is equivalent to the total ground water withdrawal (2.13 x 109 m3/year) to prepare a rough estimate of the part of irrigation return flow that becomes part of effective infiltration (IJ.

The varieties of rice (Table 8.3) produced during dry period require occasional flooding of the rice paddy lands, particularly during the early stage of crop growth. This practice allows significant amounts of water to return to the subsurface. Since there are no measurements available of how much irrigation water is lost by transpiration or turned into return flow, it was assumed that some 25 percent of the total irrigation (2 x 109 m3/year) is transformed into irrigation loss which amounts to 5 x 108 m3/year and 50 percent of this amount

316 (2.5 x 108 m3/year) reaches the saturated zone to become a part of effective infiltration (Ie). The remaining half of the irrigation loss is treated as true loss in the form of evapotranspiration and subsurface contribution to reduction of the soil moisture deficit. The evapotranspiration loss become an integral part of the total evapotranspiration loss worked out for the whole catchment (Section 8.2.3.a.).

c) Influent seepage of surface waters:

During the monsoon season, surface water levels rise very quickly due to the enormous amount of rain along with the increased flow of rivers originating outside the study area. The existing river channels and other forms of water storage can not accommodate this huge rapid inflow which overflows into the surrounding low-lying areas causing floods. During this period, huge amounts of surface water are available to infiltrate into different subsurface zones. Significant

amounts of surface water are seasonally added to ground water storage every year

until the aquifer rejects any further recharge when a major part of the surface water

surplus is wasted into the sea.

The surface water contribution to any ground water basin is

usually assessed by measuring the discharge of all the major rivers that control the

surface water hydrology of the basin, at two convenient points, one upstream of

and the other downstream of the area. The upstream measurement allows

determination how much water is entering, while the downstream measurement

quantifies how much water is leaving the basin. After allowing for evaporation, any

reduction in flow at the downstream point is indicative of influent seepage. The

difference between the incoming and outgoing flow is the amount of surface water

that has gone into ground water storage.

Out of seven perennial rivers (Section 1.8), excluding the two

bounding major rivers, discharge measurements for two points are available only for

317 the Gumti river. The upstream discharge measuring point is at Comilla Town

(BWDB station 110) and the downstream discharge measuring point is at Jibanpur

(BWDB station 114). The total amounts of flow at these two stations for the year

1979-80 (Figs. 8.1 and 8.2) and 1980-81 (Figs. 8.3 and 8.4) suggest that the amount of influent seepage to ground water during those two years was (19612-18328) =

1284 and (23196-22137) = 1059 cumec-days/annum respectively with an average of 1170 cumec-days/annum.

In the absence of basic discharge measurements for the other six rivers which are flowing inside the basin area, some generalizations have been made to estimate the influent seepage based on the following assumption. Firstly, to large extent these rivers are of similar type and their discharge capacities are not remarkably different because of relatively smaller width, cross-section and areal extension. Secondly, minimal soil variation and less textural variation of the materials making up the unsaturated zone give rise to similar infiltration characteristics. Finally, ground water flow net analysis (Section 4.4.3) suggests that the permeability does not change abruptly given the remarkably uniform hydraulic gradient. All these factors allow generalizations to be made regarding the similar range of influent seepage for the seven internal rivers. The total amount of influent seepage is estimated to be about:

= 1170 x (60 x 60 x 24) x 7 = 707616000 m3/year.

Because of high magnitudinal variations these generalizations would not be appropriate for the Meghna river, nor for the lesser Feni river from where significant amounts of inflow do take place. The above estimate thus excludes the amount of influent seepage that occurs from both these bounding rivers. The estimate, therefore, will be considerably less than the actual amount.

318 DISCHARGE (CUHECS) — Q 6 3 380(_STATION GORILLA AT DISCHARGE UPSTREAR 4 OCX.4 32Q: 34Q_ Q 4 8 1Q 6 2Q 4 20 2 360 320 280 24Q 2QQ 16Q 12Q 8Q 40 0 i. .. yrgah hwn te aelw n srae u-f component. run-off surface and baseflow the Hydrograph showing 8.1. Fig. i l i n t ii AELW NE: =6423 INDEX: BASEFLOW AELW CRCDY: 12596=8242. 19612=0859' CUREC'DAYS: BASEFLOW, CUREC'DAYS:FLOW ANNUAL TOTAL FLOUI DAILY GURTI RIVER n l r nrn ri fi r f ii I 11

'rn i n I'rr t l t r t] l i n i l i \ ii 11 i t DAYS SINCE START OF WATER YEAR WATER OF START SINCE DAYS t i i I irn |t«' Iiirn n , CRC, 1939'198Q CURECS, i

i i i

i I t i t j i t n i

i tntn i

j t i r m t

i ‘t i ] t ] n t | n u u n | j tn DISCHARGE (CUHECS) 380 LOO 360 320: 34-0 300: BSFO IDX Q6568H INDEX: hBASEFLOW i. .. yrgah hwn te aelw n srae u-f component. surface run-off and baseflow the Hydrograph showing 8.2. Fig. i i i i I I I i I I I I I I | i I I ii I i RIVER DOWNSTREAN DOWNSTREAN AELW, UE-AS 12038o2266 BASEFLOW , CUHEC-DAYS: OA ANA LW UE-AS 18328o5625 CUHEC-DAYS:FLOW ANNUAL TOTAL UT DIY LW CHC, 1919-1980 CUHECS, FLOW, DAILY GUHTI 0 2 10 0 20 8 30 360 320 280 2L0 200 160 120 80 e g r a h c s i d AS IC TR O WTR YEAR WATER OF START SINCE DAYS t TTTTI I 1 H I 1 H 1 I I I 1 I I I M T T T IT | | t l T

at

r u p n a b i j

n o i t a t s [ I [T r r T I M Ml 1 I | I I I I M 11 l M 1 M M M II

| T | T I I DISCHARGE (CUHECS) 3801 coor 3601 3

m DISCHARGE (CUHECS) 0 0 4 0 f inf n i l n r i l r i f i l f i n l r i n l r i i n f i n l f i f i l n r i i r i n l n f i l f i f i l r i f i i r i r i l f i f l l f l r l l f l f . j n a e r t s n w o d l i. .. yrgah hwn te aelw n srae u-f component. run-off surface and baseflow the Hydrograph showing 8.4. Fig. 4 8 1Q 6Q Q 2Q 8 3Q 36Q 32Q 280 24Q 2QQ 16 Q 12Q 8Q 4Q Q AELW NE: o34Q6 16394 a 4335 22139a6989 INDEX: BASEFLOW BASEFLOW , CUHEC-DAYS: CUHEC-DAYS:FLOW ANNUAL TOTAL 1980-1981 CUHECS, FLOW, DAILY GUHTI RIVER

e g r a h c s i d DAYS SINCE START OF WATER YEAR WATER OFSTART SINCE DAYS

at

r u p n a b i j

n o i t a t s d) Influent seepage of Sewage/Municipal waste water:

The generation of collected sewage/municipal waste water is minimal in the rural areas because modem sewage network facilities are not available on a sufficient scale to increase the production of sewage waste water. Because of the favourable weather conditions and the availability of surface water for most of the year the major water-related personal uses like swimming and bathing is largely done by the inhabitants in rivers, canals and ponds thereby producing no waste water. Very little waste water is also produced as a result of cooking and other household uses, and certainly none large enough to produce any significant seepage.

On the other hand, water supply and sewage/waste water collection are in operation on a limited scale in Comilla and Noakhali town areas and produce some sewage/municipal waste water. This could well result in a small amount of influent seepage which should be regarded as negligible.

e) Leakage from contiguous strata:

It was explained in the hydrogeology section (Figs. 3.1 and 3.2) that the separation of the main aquifer from aquifer 2 in some areas is not well defined because of the absence of the clay aquitard. When this is the case the main aquifer maintains hydraulic continuity via those locations so that under favourable circumstances some leakage from below might be expected. This amount is likely to be small because of the slight differences in hydraulic gradient, though at the moment there is no idea about the quantity.

The analysis of the pumping test data (Chapter 5), on the other hand, have clearly demonstrated that leaky confined conditions prevail over much of the aquifer and indicates that some leakage definitely takes place from the overlying aquiclude. The analysis of the pumping test data for almost all the leaky

323 confined condition produced a fairly high to very high leakage factor (the higher the leakage factor the lower is the amount of leakage) indicating that though leakage is occurring through the aquiclude the amount of leakage is small in comparison with the other components of recharge and has been ignored.

f) Subsurface inflow across aquifer boundaries:

Subsurface inflow takes place across the aquifer boundaries of every hydrogeological regime from the area of higher potential head to the lower potential heads, whatever small amount that may be. In the quantitative assessment of this particular component of ground water replenishment, the flow-net plays a most important role for two basic reasons. Firstly, two of the more important parameters are obtained from the flow-net. Secondly, it is from the flow-net that the peripheral extension of the aquifer boundary through which both Inflow and

Outflow occurs is identified and separated. The two parameters obtained from flow-net are the hydraulic gradient (i = dh/dl) and the length of the equipotential line which effectively represent the actual length of the inflow and outflow zones (L). The third parameter is the transmissivity (T) obtained from the analysis of the pumping test data. These three parameters are used in the most convenient form of Darcy’s Law (Q = TxixL) to make the assessment.

The greater the complexity of the flow pattern the more difficult it is to make the estimate which also reduces the degree of accuracy. Since the present flow pattern is very complicated, some degree of inaccuracy in the estimate in unavoidable. Following a standard procedure the zones of inflow have been separated from the zones of outflow (Fig. 8.5). Five different inflow zones or sections have been recognized from the flow-net constructed for the wet period

(August, 1985) and six different inflow zones or sections have been identified from the flow-net map constructed for the dry period (March 1985).

3 2 4 h—I

oo O s \Q' HH

cn

M

X) (N (N

(O) S9U02 MoyjnQ

(I) sauoz Moyui

I ------■ Fig. 8.5. Map showing the subsurface peripheral inflow and outflow zones. The conventional way of estimating the amount of inflow through the particular zone of the aquifer boundary is obtained by multiplying the actual physical length of the equipotential line that covers the maximum length of the peripheral boundary zone by the average transmissivity prevailing in that part of the area and further multiplied by the hydraulic gradient obtained by using the disposition of the adjacent pair of contours. The total inflow of the basin is obtained by totalling the amount of inflow estimated for all the zones or sections (Table

8.1). Since the total inflow for the entire basin is obtained for two different periods

(one wet and the other dry) therefore the average of the two is accepted as the ultimate total inflow (2.3 x 107 m3/year).

8.2.3 Ground water discharge: a) Evapotranspiration:

By definition, evapotranspiration is the process which accounts for the combined water losses by the processes of evaporation and transpiration. The calculation of water loss from an open water condition or from a desert condition is quite straight forward and is roughly equivalent to the evaporation loss. But in an area (like the present one) where there is extensive vegetation, which is under active cultivation and is controlled by the monsoonal climatic pattern, the total amount of water loss is significantly influenced by the process of transpiration and must be taken into consideration when calculating the true amount of water loss.

The mechanism of transpiration is well understood but difficult to quantify or present in mathematical terms. Some degree of accuracy is attainable for a very small area on an experimental basis by the use of lysimeters but that method is impractical for a large catchment area. When this is the case, calculation of evapotranspiration tends to adopt the meteorological approach that takes into account climatological factors as well as important vegetation/crop properties. This is a

3 2 6 TYPE PGtflOD N E S 2 dNE WISG PLOW TOTAL- IN PLOW (cumec [ Yeav)

w s 2 oNG-l •4-3 * lo u E 6 T 2 0 NE-2. 4-& * lo S u R P 20NE-3 3 --6 X l^ 6 2 <5" ^ 10 F E f\ , 6 R 20N€-4 3 -6 * 10 C 1 £ 0 i /\^ x Loj N E - 5 4 . 9 * 10 J>

■6 ZONE - ( 3-1 X 10 T> I R .~ 6 N 2 0 NF-2 I- 5 x 10 Y F , 6 2:0 N E -3 2-1 X 10 L I- 9 x lo P 0 E I- 5 x (0 W R 1 2.0NE- 5 4 - S X tO 6 0

D ZONE-6 5 . 9 x 10*

A VERA^e IN FLOW 2 • 3 V 1°

Table. 8.1. Subsurface Inflow of ground water along various Zones across the boundary. much simpler operation and fairly accurate, bearing in mind that water loss from a catchment does not always proceed at the same rate since it is dependent on the availability of water, degree and type of vegetation along with the climatic factors.

The value of the actual evapotranspiration over a catchment is more often obtained by first calculating the potential rate of evapotranspiration

(PEJ assuming an unrestricted availability of water and then modifying the answer by taking into consideration the other factors. Several methods are available to calculate the different components of rainfall using the water balance approach.

Some methods are more suitable for particular areas than others depending on the

geographical location and climatic condition but largely on the availability of the

data that dictates the use of certain methods. For the present example, considering

all the facts and figures, a calculation of (AEJ based on climatological factors as

well as crop properties was found to be more appropriate by the use of the

Grindley (1969) and Agnew (1982) water balance approaches.

For both approaches the key data are average monthly rainfall

and evaporation measurements recorded from standard rain gauges and widely used

U.S. class-A pan, respectively, for the year 1985-86. It is an established fact that

pan evaporation readings over-estimate the actual amount of water loss even though

a maximum possible ideal condition is maintained during the pan construction and

subsequent maintenance of the pan. To overcome this problem an adjustment factor

called the pan co-efficient has been introduced to correct the evaporation losses. The

pan co-efficient depends on several factors (a detailed description is available in

’Crop water requirements’, FAO, 1977) but the most important ones are relative

humidity, wind speed and pan setting environment (i.e. whether placed in a dry bare

soil or at the centre of a vegetated area) as well as the distance of the green crops.

Updated values of pan coefficient (FAO, 1977) for several variable conditions have

been critically examined to select that most appropriate for the present catchment

3 2 8 under the prevailing conditions. In short, the determining factors for selecting pan co-efficient are: 1) the pans are constructed within grassland or short vegetation cover; 2) the distances to green vegetation are between 10 and 100 metres from the pan; 3) during the post-monsoon and the winter season, humidity levels remain in

the medium category level, but during the pre-monsoon and the monsoon season the

humidity level remains in the high category level of the Dorenbos & Pruitt (FAO,

1977) classification chart for humidity to be used to determine the pan co-efficient

(KpJ.

Grindley (1969) water balance model:

This model allows calculation of the soil moisture budget on

a monthly basis for various types of vegetation classified according to their root

constants (the amount of soil moisture that can be extracted from a soil without

difficulty by a particular type of vegetation). Typical root constants have been

experimentally worked out for certain vegetation in the U.K. (Shaw, 1982) e.g-

permanent grassland 75 mm, potato 100 mm and woodlands 200 mm. After

personal discussions with Dr. Clive Agnew of the Department of Geography, UCL,

it was decided that the root constants for different kinds of rice and grass in the

study area would not be much different from those of British permanent grass and

similarly the root constant for woodlands should not be very different from the root

constant of woodlands in U.K. About 75 percent of the land area is covered by rice

paddy/grass vegetation, some 10 percent of the area is covered by woodlands and

the remaining 15 percent can be considered as riparian. A minor amount of other

vegetables and crops which are also cultivated in the area has been ignored because

in comparison with rice the percentage of land they cover is insignificant. The use

of the root constant is most crucial when the soil moisture deficit (SMD) is higher

than the root constant and in this situation the AEt will be much lower than the PEj (i.e. December, January and February for croplands and February to April for woodlands).

In Table. 8.2, the second column is the average monthly rainfall (P)„ the third column is the average monthly direct pan evaporation (Eq) measurement, the fourth column pan co-efficient (K^), the fifth column represents the corrected pan evaporation (E^J which is equivalent to the PEt, obtained by multiplying the pan evaporation with the corresponding pan co-efficient, the sixth column represents the rainfall in excess of the PEt, the seventh column represents the potential soil moisture deficit (PSMD) when there is no excess rainfall

(November to April), the eighth and ninth columns summarise the actual soil

moisture deficit (ASMD) and the actual evapotranspiration (AEJ, respectively, for

rice paddy crop/grass land, the tenth and eleventh columns give the ASMD and AEt,

respectively, for the woodland part of the area, the twelfth and thirteenth columns

summarise the ASMD and AEt, respectively, for the entire catchment area using the

following relationship of the proportional representation:

ASMD = 0.75 ASMD75 + 0.1 ASMD^

with the riparian areas remaining at field capacity and

AEt = 0.15 PEt + 0.75 AI^ 75 + 0*1 AE^ ^

Finally, the fourteenth column documents the amount of water surplus (effective

infiltration + surface run-off). During the months of July through October there

is no soil moisture deficit since there is enough water around during this time of

rainfall in excess of PEt; this is the true amount of water surplus. From November

through April, soil moisture deficits occur which increase with time because the

amount of rainfall is less than the PEt; accordingly there is no water surplus. In

May, the amount of rainfall in excess of PEt is +532.65 mm but there is a soil

moisture deficit from the previous month of about 118.40 mm. Therefore during

May the true amount of water surplus is 414.25 mm (532.65 - 118.40). During

3 3 0 V) 'P O' to => c n- n - in IP riD a P ip oo d T CM CO li u. 5 o O 0 (jo H cO cr\ CP cr> o 9 CM <. o cr> Q\ o T ri- 10 o CD C) CD O o

o Tt- 00 d vD !+* v0 ^r 0 10 00 01 CM CP ri­ W v0 vD ri-

X rt- CD 0 in co n ­ n- in VD v0 CM se T t- S'' o o o 0 c4 CD r<~ cO cn in m CD O 6 CD o CP C) CD 0 <0 D •~u T 'O n O oo 00 \J) Lu T o in 10 ri­ db cn OV vD 2 vi) VP ri- se in 'T n- It- vO -1 ip vP d o A A? CO in vD in 0 CD o 0 CD m ve d O O 0 IT i/d O o 6 o r*- co d sO to vD $ v0 cS 00 CD 6 CS d d cc UJ in se 00 C* T -m- o IP tn in oo o o Lu o CO 16

O' in se A in SO O' 9 2: £ O o o O' m CO in oo CD d d CD o O o n- cn d T Ci CD v0 cS CP cn c0 Cl d d CM «o> ri- ri- o CO in ip 00 IP in LU P cp d T O CO vD "T T d v0 oo a cO <3 da n- sD CO CD o d CM t o (S' cn (T> vD m 10 IP in cP o Cl LP (A d /^V s~\ 10 ip 1 T v<1 s+ / 3 lli CD tn o m- cO CO 'T O d in cn tfl O- m- o IP d T 00 Q oo o m- S' <6 n - (>> IP in d u CS vD rt~ vO sfl vS oo CP CP LU Vj& vD ip tr­ vD vD

o o O in o o o O ip in O o t oo CP CO r+- 60 CO 00 ri- ri- ri- oo a. o

in o o d o o O CO o TO o 0 ID O o ID On cP £ in rt- 0 OO 0 0 -r vi sjo “T o ob tn Lu n- 00 00 OD

rr CO cn o to ri- Q vo m d cn (Jn a \ C7D In O' CP 's A 00 0 1 'S Cu > «j cO <^ > - z _l tl Z tC a. LL 1 < h ri 01 & 0 cv i- Table. Table. 8.2. Separation of various soil moisture components using June, enough water is available with no SMD; at the same time, PEt = AEt, therefore the rainfall minus PEt is the true amount of water surplus. The water balance:

P = AEt + water surplus + dS

dS = AEt + water surplus - P

dS = 728.43 + 2178.31 - 2870.83

dS = +35.91 mm.

In theory, if the water balance can be carried out with sufficient accuracy, then the amount of water surplus plus the AEt should be equal to the amount of rainfall if there is no significant changes in storage. In this example, 35.91 mm of water is found as a positive change of storage. Several reasons could account for this, firstly, the assumed root constants could have some influence, secondly, the percentage of total land thought to have covered by a particular kind of vegetation is based on sensible guesses which could definitely have some influence of the result and thirdly, the other minor vegetation types which were ignored during this calculation also may have some influence on the result.

Agnew (1982) water balance model:

It was mentioned previously that the present study area is under active cultivation for rice. Therefore, the quantification of evapotranspiration loss in terms of rice crop production under optimum soil water and fertility conditions is another appropriate method. In this water balance model in addition to rainfall (P) and evaporation (E^), one other important parameter that is required is the crop co-efficient (K ^) of the reference crop which is rice in this instances.

The crop coefficient varies from one crop to another and for a particular crop the selection of the coefficient requires consideration of several important factors (see

Dorenbos and Pruitt, 1977). These include primarily crop characteristics, time of

3 3 2 planting/sowing, stage of crop development and the general climatic conditions, particularly humidity and wind speed. Other factors that also affect the value of the crop co-efficient include rate of crop development, length of growing season and frequency of rain or irrigation. Since rice is an important crop, special attention has been given for the correct measurement of K ^ . Dorenbos and Pruitt (1977) have tabulated the up-to-date for rice considering every possible factor that may have direct or indirect influence on the crop for different parts of the world.

The year-round cultivation in the present study area allows the production of three varieties of rice (Table. 8.3), therefore special consideration was given to the planting/sowing, growing and harvesting time for each of the varieties along with the prevailing wind speed and humidity to select the appropriate K ^ .

As a result, three different sets of crop co-efficient values were obtained for three different varieties of rice but to perform the water balance computation average

values were used.

The various steps of the water balance computation (Table.

8.4) are presented here with brief descriptions. In the table, columns 1, 2(average

monthly rainfall), 3(corrected pan evaporation) and 4(average crop co-efficient) are

self explanatory. The PEt in column5 is calculated by multiplying the E ^ by the

corresponding K ^ . The available water (AW) in column6 is worked out by adding

the current month’s rainfall (P) to the previous month’s final soil moisture (FSM).

Drainage (D) in column7 is the available soil moisture (ASM) in excess of field

capacity (FC) and that is the amount of water that goes into the sub-surface and

turns into effective infiltration (Ie). When the available water is greater than field

capacity (which is the case during the months of July, August, September and

October) then the initial soil moisture (column8) of the soil is its field capacity

(FC) and that is the maximum quantity the soil can hold as its initial soil moisture

(ISM). When the ISM is less than the FC then the ISM is obtained by subtracting

3 3 3 Q > lo d) l£> V. <0 t- i O CS| M vO z UJ CD > Z< < < a 0 o p ■X ■x a.

to 10 0 > 0 o i o i 0 z

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Ul 10 in in 2 01 o i O i o o o r*

v/1K VA z LU to o to o > o o 0 i

> P* in o A 10

•CO r+- cD n - M- O '•n cS CS o & M- 0 O o o o o D n r~ n & o z cb ^ r Co ID tn rr r+- n- n - 00 lA n- rr rt- cO rt- vD O' n- r+- r+- vD vD Ll co CD cD> n- cD cs cs T— CD CD

T rt- cO m cS tn o vD cn cO O r+- In (P cs S !+- O' O' O O' CP _u cr> O cs cn cs T LU VD ^ t CP LD T o cO vO n- cs CP vD vD vD rv n- vD vD r+- rt- n- ri1 rt-

(u» ui) V> O r+- cO c4 D o Q 0 O o O' In O' 1 S W GS o 03 D D 0 o o O' O' (O T 0 to o "T o O ^ r T n : VO O' n T 'T tn T ^ r CD cs 5 cs T CS cs *T"

UJ iE /•—' r+- CS r+- VD c>° in D T vD o z J , o cb O O LO b- 4 o o o O' 0O CP d CP O' vD CD Qd CN cs O' n- cO cD) 'S- P

in rt- 1+- cS r*- n - CO cs 0 vD 'I' cn rP o O' •O' in (T> v0 LD n O' CD T rO LD r>- T in O' <0 rO 4 CP CO VO O' CP U" vD cD O 'T in tn n- CD cC cS O' lO CP rt- in cD cs cs Csl n- CP

D' cD CD

n- CO in in o O tn in in 8- i+- <0 cn tn o o }• o o o o cs u o V

cn O cS o in CO cfi t- p "T o LO in o O' 0° 0 o ° £ T s- v v v cS i* cs T 4 O r+- cr in in oo CP 0° o vD vO VI vD Vi) r+- VP LD vD r+- co vP U) LU

cD rt- O' o 00 CD cS 0^ <£ <£. in o P U 0 LU 2 Cu h Table. 8.4. Separation of various soil moisture components using the amount of drainage (D) from the available water (AW). When there is not much water available to bring the ISM to its field capacity (FC) (which is the case during the months of November, December, January, February, March and April) then the total amount of ISM slowly decreases until it drops down to the wilting point

(WP) and in theory soil moisture can not drop below WP. Since there is very little water available in excess of WP, therefore the plants will also have very little water to transpire. As a result AEt in column9 would be much lower than the potential rate. At this stage AEt = (ISM-WP) when (ISM-PEJ

February, March and April), otherwise in all other circumstances AEt=PEt (May,

June, July, August, September and October) even if the ISM

=WP (January, February, March and April). When PEt=AEt there is no soil moisture deficit (columnll) but when AE,

Institute (SRDI), Dhaka, Bangladesh. The resultant water balance is:

P = D(IC) + SR + AEt + dS

2870.83 = 1718.05 + 0 + 784.26 + dS

dS = -368.52 mm.

Drawbacks:

This method was developed by Clive Agnew (1982) to

compute the water balance for a semi-arid part of West Africa and is particularly

applicable where the soil condition is dominantly sandy and where surface water

run-off is negligible. Therefore, strictly speaking, this method is not entirely

3 3 6 appropriate for the present conditions where the soil is predominantly loamy in texture and at the same time considerable amount of surface run-off takes place.

The method is not acceptable for computation on a daily or even weekly basis but a monthly basis calculation can be accepted with caution because it averages out most of the extreme conditions if it is not characterized by a very high flood.

Comments:

The separation of different components of rainfall by the

Grindley model (1969, 1970) is widely used for all climatic conditions with reasonable accuracy yet it depends on essential parameters which are crucial to obtain a satisfactory result. The Agnew model (1982), on the other hand, though

applicable for certain climatic and soil conditions, can be used to obtain sensible results for most conditions on a broader scale with certain reservations. It is a good

method for comparative study but can be quite useful when most of the available

methods can not be used.

b) Effluent flow to rivers, canals and other water bodies:

Apart from the major perennial rivers and canals, the study

area also has quite a large number of ponds, beals and haors (large depressed

basins where shallow water remains during most of the year in a stagnant

condition). Regardless of flow conditions, the water bodies which sustain water all

the year round or for most of the year receive a continuous supply of ground water,

especially during the dry season (winter season). The quantity of river/canal flow

that is derived from ground water resources is called the base flow, which can be

quantified by analyzing the river discharge hydrograph. Several analytical and

numerical techniques are available to separate the ground water component of

stream flow. For the present case, the method developed by the Institute of

3 3 7 Hydrology (1978), which has been written in the form of a fortran 77 program

(Appendix. 8.1 and 8.2), has been adapted to analyze the hydrograph for separating base flow.

Other than the Gumti river, the discharge measurement at a single point was available for only the Muhuri river. The Muhuri river discharge measurement is available for the year 1980-81 (Fig. 8.6) and 1982-83 (Fig. 8.7) measured at Parshuram station (BWDB station 212). The hydrograph analysis for

Gumti river (Figs. 8.1 to 8.4) shows that on an average about 67 percent (or BFI

= 0.6683) of the flow originates from ground water discharge which amounts to about 14000 cumec-days/annum. On the other hand, the ground water component of the Muhuri river discharge flow constitutes about 38 percent (or BFI = 0.3756) which is one-third of the total flow indicating that the Muhuri river is less dependent on base flow in comparison with the Gumti river. The average quantity of base flow calculated during this two year period is about 2700 cumec- days/annum.

Unfortunately, river discharge measurements are not available for the other rivers to accurately measure the base-flow component. In such a situation, the assumptions made in Section 8.2.2.C to estimate the influent seepage can be used along with the textural property of the aquifer to estimate the total base-flow. The aquifer material that constitutes the northern part is made up of relatively coarser material and via these materials the northerly located Titas,

Gumti, Buri and Dakatia rivers maintain continuity with the aquifers. Therefore it may be sensible to assume that these rivers have a similar range of base-flow.

The aquifer material, on the other hand, in the southern part is dominated by finer sandy sediments (Section 3.3.2) through which it maintains continuity with the overlying Noakhali canal, Little Feni and Muhuri rivers. In the southern part therefore similar range of base-flow may also be imagined for these rivers. The

3 3 8 DISCHARGE (CUHECS) 6L O A AN A FO CM C D Y : 6553 = 9141 260L- TOTAL ANNUAL FLOW CUMEC-DAYS:2 8 Q E - S T R E ADI M S C H A R GPA 0 E 0 3 R S U RST A n A T I O N 4 E A E L W NE: =4033 240E_ BASEFLOW INDEX: 4 8 10 6 20 4 20 2 360 320 280 240 200 160 120 80 40 0 Fig. I I I I II1 1 1 I I M I I "IT I I I I ‘I 1 I M "I II I I I II RIVER HUHURI DAILY FLOW, CUHECS, 1980-1981 A E L W CHC D Y : 2645=8301 BASEFLOW, CUHEC-DAYS: 8.6. Hydrograph showing the baseflow and surface run-off component. DATS SINCE START OF WATER TEAR ii in mi in i i « i

mi

iimih it iiii iiit | iiiii — ii i i i i » i i i i r i ii ii'T

t * i iiimfii uiiiir

Trfii1 i ii j js J- DISCHARGE (CUHECS) 6 L T T L NU L LW UE - A S 3393o9336 260L_TOTAL ANNUAL FLOW CUMEC-DAYS:2 8 0 L _ S T R E ADI M S C H A R GPA E R S U R AST M A T I O N ^ 0 0 3 240i_ 200 2201 4 8 10 6 20 4 20 2 360 320 280 240 200 160 120 80 40 0 Fig. BSF O , UE- A S 2314D8208 BASEFLOW,i CUHEC-DAYS: RIVER: nilHURI DAILY FLOW, CUMECS 1982-1983 , : A E L W NE: D3481 BASEFLOW INDEX: i I i i i 11 ii T r p r r » | r r i i i t t i 1 1 r r r i i r n i n i i r i r i i n i n r i i r r 1 r 1 i t t i i ri r | » r r p r T ii 11 i i i I i 8.7. Hydrograph showing the baseflow and surface run-off component. DAYS SINCE START OF WATER YEAR 11

111 it i i i i

" 1 i | 11 | i i 11 i"H estimated base-flow for the northern rivers (Titas, Buri, Gumti and Dakatia rivers) on the basis of the foregoing assumptions is about 14000 x 4 = 56000 cumec-days/annum, considering the Gumti river base flow as the ideal. The base­ flow for the southern rivers (Noakhali canal, Little Feni and Muhuri river) is about 2700 x 3 = 8100 cumec-days/annum, considering the Muhuri river base-flow as the ideal. It follows the total base-flow of all the rivers in the entire region is about 56000 + 8100 = 64100 cumec-days/annum, which does not take into account the base-flow loss caused by the two bounding rivers, the Meghna and the Feni.

It is true that a significant amount of base-flow of the Meghna river is derived from the presently studied main aquifer system but the major part of its base-flow comes from the aquifer system of the eastern, northern and north-eastern parts of the country. Similarly, the major part of the base-flow of the Feni river is derived from the aquifer system of the further south-eastern hilly region. The influent seepage of these two rivers have not been taken into account, therefore the exclusion of the effluent seepage of the two rivers should in fact cancel each other rather than

upsetting the results.

c) Leakage into contiguous strata:

As a consequence of the relationship between the aquifers

described in Section 8.2.2.e there could be some leakage into the contiguous strata

from the main aquifer under favourable circumstances. If so the quantity should be

small because under normal conditions, the ground water in the second aquifer

remains under greater pressure than atmospheric therefore there will always be a

tendency for the water to move upwards. The movement depends on the

potentiometric head conditions in both aquifers. When the heads are equal then the

flow of ground water will depend on the relative density of the two waters. At

present, it is not possible to make any comment on which way the flow occurs and

3 4 1 how much water is flowing from one aquifer to the other.

d) Subsurface outflow across aquifer boundaries:

Applying the same procedure which was applied to identify the different peripheral aquifer boundary zones of subsurface inflow, five different outflow zones or sections for the wet period flow-net map and six different outflow zones or sections for the dry period flow-net map have been identified

(Fig. 8.5). The Darcy formula was used to assess the quantity of outflow through each of the identified zones. The total volume of outflow (2.1 x 107) from the entire basin has been determined taking the average of the total outflows (Table

8.5).

e) Artificial withdrawal by pumping:

It has been shown previously that ground water is used both

for drinking and for irrigation purposes. The most extensive use is made for the

irrigation of croplands since the area has a high proportion of excellent cropland.

In this section the quantitative assessment of the total withdrawal of ground water

by pumping has been estimated on the assumption that the ground water is only

used for drinking and irrigation purposes and ignoring industrial and other minor

uses.

Until December, 1984 there were about 1921 deep tube wells

(DTW) and 4589 shallow tube wells (STW) on record, of which a significant

number are either out of order or are permanently abandoned (pers. comm. Pitman,

G.T.K.). There were also a significant number of purpose built shallow hand tube

wells before the installation of deep tube wells which were previously used for

drinking water purposes. But with the rapidly increasing number of power driven

shallow and deep tube wells their installation has virtually ceased a long time ago

3 4 2 TYPE PEKIOD 2oNES 2 0 NE WISE FUW TOTAL OUTFLOW (aumec /Ve<\r) \N s 2o N 6 - 1 1 ■ 5 X lo U E & T S 20NE-2 3'7 X u P R 4 •;£ X 1° 2 1 x lo? F £ 2^ME-3 A R 6 c i 2.0ME-4 3-4 X lo £ 0 3) , 6 2CNE-5 5 2 * IO

o 1> 2-0 NE-f 2-4 * u R Y 4-4 X 10 T 2oNE-Z

F P 20UE-3 3.4 x 10 , ? L 2 -i x 10 E O £ 1 r f ’ 2.0 N- 4 3 -3 X lo w 1 0 1 0) •20NE-5 4 '3 X 10

2oNE-^ 3- ? X 10

, ?• AVERAGE TOTAL. OOt PLOW 2 -i x lo

Table. 8.5. Subsurface Outflow of ground water along various Zones across the boundary. and most of the existing ones are already out of service. Therefore their influence on ground water withdrawal has altogether been ignored. To make sure that the amounts of ground water being withdrawn are not underestimated, a conservative approach has been adopted by assuming that at the time of calculation all wells

(DTW and STW) are in working condition and are able to withdraw ground water when it is required. The wells are in constant use for irrigation during the dry period, the late part of the post-monsoon period and the early part of the pre­ monsoon period (December until May). On average during this period the wells arc in operation about eight hours a day, which also automatically fulfils the drinking water requirement. During the remainder of the year (June until November), when ground water irrigation is not required, the wells are only in short time use to meet drinking water requirements. On average during this time of the year the wells are run about an hour a day. The statistics of the ground water withdrawals are summarized in the following table:

Duration Well Irrigation Other Gross Total annual With­

Type period(hrs) period(hrs) hours days drawal (m3/day)

Total (DTW) 1456 183 1.31 x 109

hour 3278 136.58 run (STW) 1456 183 0.81 x 109

A deep tube well has a capacity of 58 1/s (5000 m3/d) and a shallow tube well, on the other hand, has a capacity of 15 1/s (1300 m3/d). Therefore on the basis of the foregoing assumptions and available information, the total annual withdrawal from both the DTW and STW is about 2 x 109 m3/d. 8.2.4 Ground water Budget:

A ground water budget is the quantitative assessment of the total incoming water, total outgoing water and the changes of the ground water storage of a ground water basin over a specified period of time. Under normal conditions when all the components are known, the volume of inputs (I) should be equal to the volume of output (O) with the addition or subtraction of the changes in storage,

when expressed in mathematical terms it takes the following form:

I = O + dS where

I = Inputs O = outputs

and dS = Changes in storage.

A ground water balance is very much like the surface water balance and requires

a proper identification the different components of recharge as well as discharge

because some of the components are more important than others. This largely

depends on the climate, regional hydrogeology and the amount of ground water used

for various purposes. The present ground water regime is under the direct control

of tropical humid monsoonal climatic conditions accompanied by periodic flooding

and is under active cultivation.

Among the recharge elements, the rainfall replenishment is found

to be the largest source of recharge, followed by influent surface water seepage,

then followed by irrigation return flow and finally followed by subsurface inflow

across aquifer boundaries. The contribution towards recharge from leakage from

contiguous strata and influent sewage flow was found to be very small and

insignificant. Evapotranspiration, on the other hand, is identified as the largest form

of discharge, followed by effluent flow to rivers, canals ponds etc, then followed

by artificial withdrawal, and finally followed by subsurface outflow across aquifer

boundaries. An out flow in the form of leakage into contiguous strata is estimated

to be of negligible amount. The estimation of effective infiltration (Ie) was carried out in two different ways. The first method adapted the Grindley (1969,1970) and Agnew

(1982) form of water balance approach while the second method considered the volumetric changes obtained from ground water fluctuation contour map (Fig. 4.5 and Table 4.2). The results obtained by these two methods are grossly different and show a three-fold variation, though in theory they should be reasonably close to one another. The resulting ground water balance is therefore presented in two different budgets. The first budget (Table 8.6) includes the (IJ value obtained from

the Grindley (1970) and Agnew (1982) method which suggests a huge surplus of

ground water recharge in comparison with discharge. The second budget (Table 8.7) consider the Ie value obtained from the volumetric changes of ground water presented a huge shortage in ground water recharge suggesting an excessive ground

water mining condition, which is not the actual case.

An examination of the change in ground water level record is presented in the following table:

Incremental changes between successive years (mm) overall

Location 1980-81& 1981-82& 1982-83& 1983-84& 1984-85& incremental

1981-82 1982-83 1983-84 1984-85 1985-86 changes (mm)

W 4 +138.68 -213.36 +640.08 +096.01 -640.08 +021.33

W 58 +154.69 -106.68 +512.06 -181.36 -245.36 +133.35

W 142 +064.01 +032.01 +053.34 +096.01 -042.67 +202.69

It shows that there was a general decline of ground water level during the 1985-

86 water year by comparison with the previous 1984-85 water year (Fig. 4.1) and

this lowering has been recorded in all three observation wells (W4, W58 and

W142). But an inspection of the incremental changes of the ground water level for

3 4 6 Q cc rt- O (11 O o —O ~~ o > - \ X x x X X CO CO n- if) — 1 0 rr * 6 N CN

z 52 V/) o cn a h CL a: z p a) ? * (11 . \ z a \J 01 & -*• 111 3 vg LL a X a 3 j/5 =*

o £ o U) * 2 * o H- o > o ~~ o % X x x vD (fi X X £ vD 60 o oo 0 CN T+* CN —

kO vo X UJ H 0 CL. Z 2 CL rt- z O VL 01 a Pi 9) Z 0 p a 5 I CP 0 c UJ o O CL CL z a ^ UJ Ul 2 h CL cn a C5 G 0 CL Z CL X - h - Lil CL 3 01 al ct: dl a) a M* &^ od X 111 ^ 5 KJ Z 2 er OJ 01 O CL ct 01 > ^ * CL 3= ui c*. H ^ 0 QP a i W vA \r r- Table. 8.6. First ground water budget using the Ie value calculated UJ z -a O'* o CP,O H- OL § o ‘O P >- X- X X UJ X cO o & u o P 2 cO i : Z 3f- H/O h <£ 0 Uj o © X cl cr _i UJ V U- UJ CX v— ) OJ X <0 > V u <3 ct C cS5 a c H 3 ct U \A D ct o t V/) cd a ! > CD ^ t ^ a: o

OJ z H- CD C*U & o ay o o Jo o\ § CU o y X y >- * p kD o X UJ cT* vD ro J- it o X CO t ac —■ z a X

h 5 X Q£ cu c-j P a (/) h h Table. 8.7. Second ground water budget using the Ie value calculated all the three observation wells during the last five years provides a different picture.

With the exception of 1985-86 water year, W142 shows a continuing rise in water level therefore the incremental change is always positive. W4 and W58 represent alternative positive and negative incremental changes. When the incremental change in ground water level during the last five years is added together in the above table the overall incremental change is found to be positive which implies that no permanent lowering of ground water level has taken place. The general depletion of ground water level in the preceding year was fully recovered by the following rainfall. It also suggests that ground water withdrawal is less than the available recharge, indicating no use of permanent ground water storage, which implies that no changes in permanent ground water storage have taken place during the last five years.

S3 Ground water management:

8.3.1 Introduction:

The success of a ground water development project and the obtaining of long term benefit from it, require that skilful management should be put into practice as soon as possible. The management technique is a lot easier to effect efficiently if the water balance of the region is known or can be estimated to a reasonable degree of accuracy. During a youthful state of development management practice is unappreciated though desirable. Effective management practice becomes increasingly necessary when the mature state of ground water development prevails in a ground water regime. The management practice become absolutely essential during Old age and Rejuvenation states of development to rescue the resources from any further damage. During these stages a great deal of manipulation of resources may be required and the special circumstances when conjunctive use of surface water and ground water requires critical assessment of

3 4 9 both permanent and temporary storage and perennial yield. Only sophisticated management equipped with technological innovation can determine whether a mining yield should be put into practice because mining of ground water is prone to produce so many undesirable effects.

8.3.2 Development state of resources:

It was shown in Section 8.2.4 that the estimation of (IJ by two different methods gave a wide variability in the results (Tables 8.6 and 8.7).

Therefore two different water budgets have been prepared to demonstrate the differences in the final results. In the first, the natural inflow is found to be much higher than the combined natural and artificial outflow. The second water budget, on the other hand, demonstrates that the natural inflow is much lower that the joint natural and artificial outflow.

Using the criteria of Jones (1972), the state of development of ground water has been assessed. The first water balance computation demonstrates that the resource is at a Youthful state of development but the second water balance results suggest that the resources has passed into an Old age state of development. It can be argued that the arrival of Old age state should be indicated by the response of other parameters such as continuous decline of water table, severe deficit of moisture both in the soil and unsaturated zone which should cause destruction of shallow rooted crops/vegetation. But none of these undesirable conditions are seems to be prevailing in the study area in general, therefore, it is unlikely that the Old age state of development has been reached.

8.3.3 Perennial yield:

The modem concept of optimum ground water yield is expressed in terms of perennial yield which have shadowed the traditional safe yield concept

3 5 0 because the optimum yield does not depend on the recharge alone. The perennial yield of a ground water basin defines the rate at which water can be withdrawn perennially under specified condition of operation without producing an adverse result such as progressive depletion of the water resources, land subsidence, degradation of ground water quality, excessive pumping cost and interference with the prior water rights.

The maximum quantity of water that can be extracted from an underground reservoir depends on the perennial yield. In general, the basin recharge criterion governs perennial yield because exceeding this factor is normally responsible for inducing other undesired results. Possibly for the present ground water regime, the factors likely to produce undesired results are not present indicated by the following facts: 1) no long term decline of ground water level is visible; 2) no significant changes of ground water storage have taken place; and 3) the youthful state of development of resources prevails. The quantitative determination of perennial yield therefore has been carried out considering the recharge as the limiting factor. At this point perennial yield is defined in terms of a rate at which ground water can be withdrawn from a basin over a representative time period without producing significant changes in ground water storage and the perennial yield is estimated from the water balance computation. The volume of total recharge in excess of natural discharge is equivalent to perennial yield in this case. On the basis of the first water balance computation (Table 8.6) the amount of perennial yield is about 5.7 x 109 (= 1.9 x 1010 - 1.33 x 1010) m3/year. The total volume of present artificial withdrawal is about 37 percent of the estimated perennial yield.

A consideration of the second water balance computation (Table

8.7) shows that the available perennial yield is much lower than the natural discharge. Under this sort of prevailing condition a natural discharge of 6.6 x 109

3 5 1 m3/year plus the total artificial withdrawal of 2.13 x 109 m3/year, gives a total of

8.73 x 109 m3/year from permanent storage in the form of mining yield.

8.3.4 Ground water in storage:

The volume of ground water in storage is determined by multiplying the average saturated thickness of the aquifer by the area over which the aquifer is areally extended and further multiplied by the specific yield i.e:

Ground water in storage = b x A x S, where b = thickness of the aquifer in case of a confined aquifer or the saturated thickness of the aquifer in case of an unconfined aquifer;

A = area of the ground water basin; and

Sy = specific yield.

Since the nature of the present aquifer under study ranges from leaky confined to confined therefore the saturated thickness of the aquifer would be the total average thickness of the aquifer. The thickness of the aquifer (Section 3.3.3) ranges from

<100 ft (>30 m) to >445 ft (>135 m) with an average thickness of about 250 ft

(about 75 m). In the absence of any direct measurement a specific yield value of

20 percent has been considered acceptable on the basis of lithology and various published results (specific yield selection is justified in Section 4.5). Therefore, the volume of ground water in storage for the present basin area which is about 10,223 sq. km. is:

75 m x (10,223 x 1000000 m2) x 0.20

= 1.53345 x 10 11 = 1.5 x 10" cubic metres of ground water. CHAPTER 9 CONCLUSIONS AND RECOMMENDATIONS

9.1 Conclusions.

9.2 Recommendations.

353 9.1 Conclusions:

On the basis of the analysis of various geological and hydrogeological components

the following conclusions can be drawn about the ground water resources and the

aquifer materials:

1) In the central part of the geosynclinal basin fresh ground water occurs at a depth

of more than 2296 ft (700 m) beneath the present study area. Within this depth,

six major well-defined potential aquifers containing fresh water have been

identified. The present detailed evaluation of ground water potential is limited to the

main aquifer (no.l) which in many places maintains a hydraulic continuity with

aquifer no. 2 where the separating clay aquitard is either missing or negligibly thin.

2) The main aquifer is almost entirely covered by a clay/silt layer of variable thickness

that ranges from <10 ft (<3 m) around the Lalmai Hills to >300 ft (>90 m) around

Noakhali town. In the Lalmai Hills there is no clay/silt layer other than the covering

soil because the hill is an outcrop of the aquifer material itself. The aquifer is

mostly recharged by the indirect infiltration of surface precipitation through this

confining layer, although small amounts of recharge are derived from the outcrop

areas.

3) The aquifer itself largely consists of a continuous thick layer of sandy materials but

in some places (particularly around Lalmai Deltaic Plain area) the aquifer is

separated locally by one or more discontinuous layers of clay. In most places,

particularly in the upper part the aquifer, there is a clear gradation in grain size, the

finer material being at the top and coarsening downwards. The bottom part of the

aquifer is occasionally associated with gravels and pebbles. The aquifer maintains

a thickness of more than 200 ft (>60 m) in most places which sharply increases to

354 more than 400 ft (>120 m) towards the southernmost part where the dominant

grain size also changes to fine and medium sand.

4) With the exception of Kotwali (Comilla town), the present rate of artificial

withdrawal does not produce any undesirable effects on the resources of a regional

scale. The seasonal dry-period loss of ground water storage is restored rapidly and

regularly which is indicative of a high value of effective infiltration. Moreover, in

some places there is a steady rise of maximum water level suggesting an increased

availability of the temporary storage. The limited small-scale decline of maximum

water level around Comilla town seems to be primarily because of excessive

unplanned annual abstraction and can be regarded as a local event. Further study

is recommended to determine the exact nature and extent of the problem.

5) The ground water flow pattern is complicated because of its complex relationship

with the surface water, with all the perennial rivers maintaining a direct hydraulic

continuity with the ground water. Most of the down-stream sections show the

characteristics of gaining streams while the upstream sections show characteristics

of losing streams except the Little Feni river which shows the reverse characteristics.

6) A similar distribution of resource potential prevails over the entire study area. The

annual fluctuation is at a maximum near the places from where maximum amount

of ground water is withdrawn during the dry periods. The higher elevation of the

water table around Comilla town (which also coincides with the higher fluctuation)

to some extent could well be due to the partial blockage of ground water flow by

the north-south trending Lalmai Hills located to the west of Comilla town.

7) The analytical results of the step-drawdown test data suggest that most of the test

355 wells were not properly developed with adequate pumping prior to the test and a

significant amount of well development took place during the test exercise. The

aquifer loss factor (BJ ranges from a maximum of 19.3 sec/ft2 for Nabinagar to a

minimum of 7.0 sec/ft2 for Chandina. The well loss factor (CJ does not indicate any

major abnormality and ranges from a maximum of 1.49 secVft5 for Nabinagar to

a minimum of 0.96 secVft5 for Laksam and is supported by the minimal differences

between the measured and the calculated drawdown values. Highly efficient well

conditions are obtained for all the test wells. The fundamental relationship between

transmissivity and specific capacity has successfully been demonstrated by the test

wells.

8 ) It was concluded from the analysis of aquifer test data that the aquifer condition

ranges from non-leaky confined to leaky confined. The confined condition prevails

in a small area (around Chauddagram and Feni upazilla) located in the eastern part

while leaky confined conditions prevail over the remainder of the area. The

maximum transmissivity (>1400 m2/d equal to about 94,000 Imp.gal/day-ft) is

distributed in the central part around the Haziganj upazilla while the minimum

transmissivity (<400 m2/d equal to about 27,000 Imp.gal/day-ft) is recorded in the

eastern part. This coincides with the ideal non-leaky part of the aquifer but does

not necessarily mean that confined aquifer conditions necessarily provide lower

transmissivities. The maximum (41 m/d) and minimum (5 m/d) values for hydraulic

conductivity are obtained from the same localities having maximum and minimum

transmissivity values. In most places the amount of leakage is quite small. The

maximum (BL = 368 m) and minimum (BL = 1930 m) leakage values are obtained

around the Burichong and Haziganj upazilla, respectively. The average storativity

value ranges from 3.7 x 10-4 in Haziganj to 4.1 x 10'3 in Chandina.

356 9) The general distribution of dissolved solids is very low, although the TDS

concentration (>1100 mg/L) at well 120 is unusually high in comparison with the

rest of the ground water; yet even that concentration is well below the EEC safety

limit

10) The ground water in its initial stage appears to have been an essentially NaHC03

type in nature but as it moves in different directions hydrochemical evolution

modifies the ground water into a mixed NaHCOj/CI type because of ion exchange

and mixing with connate water.

11) The hydrochemical evolution is found to have been dominated by the ion exchange

processes though other processes particularly mixing, dissolution, and reverse ion

exchange, also play important roles in classifying the water types. The combined

action of these processes has given rise to two distinct types of water. The first type

is the ion exchanged water while the second type is the old brackish water; the

first type dominates over the second.

12) The saturation indices calculated using the hydro-chemical PHREEQE model

provides some interesting results about equilibrium status because of the rock-water

inter-action. The X-Y plot of Calcite and Dolomite revealed the following points:

a) the degree of saturation of the water tends to increase with increasing distance

from the outcrops, and b) the degree of saturation also increases with increasing

depth of water.

13) Although at present most of the ground water in its natural state does not provide

any injurious effects on heath, its long-term potability is questionable with a rising

concentration for some of the constituents in some of the wells, particularly

357 potassium, manganese, phosphate and silica. From the irrigation point of view

most waters are suitable for most crops, except in a few wells where the mixing

of ground water with connate water and sea water has initiated the deterioration of

the water quality, and will require regular monitoring.

14) Rainfall replenishment is found to be the most important recharge mechanism

followed by influent seepage, irrigation return flow and sub-surface inflow. The

highest amount of ground water is discharged by evapotranspiration followed by

effluent flow, artificial withdrawal and sub-surface outflow. The annual ground water

replenishment calculated by two different methods has produced a three-fold

variation in effective infiltration (Ie) values which raises some doubt on the quality

of the basic raw data (field measurements). The value (1775 mm) obtained by the

combined Grindley and Agnew models is the most logical amount of ground water

replenishment for an area which enjoys one of the highest rainfalls in the world

(about 2900 mm).

15) The water balance computation using the Ie value obtained from the Grindley and

Agnew methods suggest a large recharge surplus and categorises the resources at

a Youthful state of development. The volume of Perennial Yield is about 5.7 x

109 m3/year (557.57 mm) and the present amount of ground water withdrawal is

about 37 percent of the perennial yield. Available ground water in storage is

estimated to be about 1.6 x 10" cubic metres. 9.2 Recommendations:

The following recommendations are suggested on the basis of the problems

that were encountered during the collection and analysis of the relatively

scare basic data.

1) In order to encourage new research workers, some of the existing data

distribution systems as well as the data retrieval systems need to be changed

in order to improve access to the data. The data-bank section of every

organization should have a subsection to deal with the data distribution

process and make it more efficient.

2) During the analysis and preparation of geological cross-sections it was found

that most of the lithological logs could not be identified because of

inadequate description of the location. Out of several thousands of logs

available, many sites could not be located and only 367 lithological logs

with identifiable locations were available. A better representation of the

subsurface conditions could have been prepared if all the lithological logs

had been used. Any future drilling programme should be accompanied by

a more accurate description of the site locations.

3) Even when information is available another major problem is its reliability.

The question of reliability was serious during the construction and

interpretation of the water table contour maps which are directly and

indirectly essential to an understanding of the hydrogeological system. In

the water table contour map preparation, some measurements were found

which defied logical explanation. This problem could be primarily for two

reasons: 1) the measurement of water levels was not properly carried out,

359 or 2) the ground elevation was not properly determined. Therefore, special

precautions are required if beneficial results are expected from the analytical

results because an accurate interpretation of incorrect data makes for a

meaningless exercise.

4) If the contour maps can be extended towards the natural ground water

divides which are located further east in India, by including more ground

water records from the Indian part, the true flow pattern would be better

understood and delineated.

5) The conduct of the constant rate tests are quite satisfactory, though the wells

on which tests were carried out were not uniformly distributed over the area.

A more uniform distribution is needed for accurate depiction of the variation

in hydraulic properties on which further interpretations are based. Therefore,

further pumping tests in selected areas are recommended to up-date the

existing hydraulic parameter information. This is particularly so in the

southern part where lithological changes were found to be more frequent

over short distances. In the present work the hydraulic properties assigned

to the southern part of the study area have been grossly idealized and are

based on an insufficient number of pumping test analysis results

6) The step-drawdown test data are probably the worst example of how badly

some of the tests were carried out. None of the tests followed any standard

procedure. Pumping tests in general, particularly the variable rate tests, are

very costly exercises. Therefore it is recommended that more care should

be undertaken in carrying out such data collection. Also the interpretation

is very frustrating if the basic pump test data are not correct and results in

360 the miscalculation of various parameters relating to well performances.

7) Any future chemical analysis of ground water samples must include the analysis

of potassium and sulphate along with the other major ions in order to make the

analysis complete. This is essential for checking the validity of quality data

because a meaningful interpretation of existing hydrochemical evolution can

only be obtained from reliable sets of data.

8 ) The ground water is of good quality at the moment under the present rates

of withdrawal and there is no sign of any undesirable effects such as

deterioration of ground water quality. With increasing withdrawal, the

existing limited distribution of inferior quality water and saline ground

water could become more widespread and may become a serious cause for

concern. Therefore, it is recommended that sampling for chemical analysis

should be continued and more ground water wells should be brought into

the quality monitoring net-work to safeguard the ground water resources for

the greater benefit of the region.

9) The computation of the ground water balance could be more accurate if the

influent seepage and irrigation return flow components of ground water

recharge as well as the artificial withdrawal component of ground water

could be more accurately estimated. To perform any future water balance

computation it is therefore recommended that the following steps should be

considered: a) the discharge measurement at two different convenient points

across the area should be considered for all the rivers, b) the statistics about

how many hours the wells are run and how much ground water is withdrawn

seasonally and annually from a particular well should be collected as far as

361 possible. These are the basic data used to estimate the artificial ground water

withdrawal component and, c) more realistic ways should be formulated to

estimate the irrigation return flow component. The present work suggests that

some irrigation water is returning to the ground as irrigation return flow but

no attempt has yet been made to quantify such losses. In the present work

the estimation has been based on sensible guesses which may not be truly

representative. Any return flow effectively reduces the net pumpage from the

aquifer, so in the long term its magnitude should be assessed. In the future

the irrigation return flow is going to be more meaningful with the

continuous increase of ground water withdrawal.

10) It is very important that the users as well as the persons or groups

responsible for the maintenance of the wells understand the importance of

the ground water resource. They should be instructed to make a record of

the actual pumpage and their uses i.e. how much ground water is withdrawn,

how much is used for irrigation purposes and how much is used for drinking

purposes. To make sure that it has been carried out properly, an inspection

team should visit the well site periodically. Certain education programmes

should be undertaken by the responsible organizations so that both kinds of

people become encouraged spontaneously to protect the resources for the

greater benefit of the region.

11) Since considerable amounts of surface water are used continuously to irrigate

the low-lying areas adjacent to the rivers, some scheme should be undertaken

to prepare a record about how much surface water is used for irrigation

purposes. This parameter is also required for the correct interpretation of the

irrigation return flow.

362 12) Without adequate data it is impossible to undertake quantitative studies.

Considering the significant time and money spent on data gathering by a

variety of authorities in Bangladesh, it is recommended that quality control

of all types of data is initiated with joint rather than duplicate monitoring

schemes.

363 REFERENCES

Agnew, C. T., 1982: Water availability and the development of rain-feed agriculture in the south-west Niger. Trans. Instn. of British Geographers. Vol. 7, pp. 419-457.

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8 March 1985 5 August 1985 (Dry Period) (Wet Period)

BWDB New Elevation Depth of Elevation Depth Eleva Location Location of M. P. W. L. of W. L. of W. L. of W. from M. P. from M. P.

Co 35 2 9.45 3.32 6.13 3.07 6.38

Co 59 3 8.71 Not available 1.57 7.14

Co 25 4 8.18 5.45 2.73 1.78 6.40

Co 36 5 5.43 4.23 1.20 1.27 4.16

Co 63 8 6.35 7.46 -1.11 6.42 -0.07

Co 12 10 5.68 5.15 0.53 1.57 5.11

Co 46 12 6.37 Not available 1.64 4.73

Co 47 13 10.20 3.93 6.27 1.59 8.61

Co 24 14 5.44 4.15 1.29 1.40 4.04

Co 54 16 7.66 5.48 2.18 2.18 5.48

Co 56 17 4.63 5.28 -0.65 1.54 3.09

Co 37 19 6.47 5.05 1.42 1.17 5.30

Co 23 20 6.00 Not available 1.04 4.96

Co 44 21 5.87 4.26 1.61 3.04 4.26

Co 1 22 6.86 4.60 2.26 1.32 5.54

Co 34 23 6.10 5.29 0.81 1.60 4.50

Co 48 26 6.94 4.46 2.48 0.38 6.56

Co 2 25 5.62 2.96 2.66 1.50 4.12

Co 33 30 4.59 2.96 1.63 1.15 3.44

Co 53 33 6.32 3.50 2.82 1.11 5.21

Co 3 36 6.55 7.20 -0.65 1.10 5.45

370 8 March 1985 5 August 1985 (Dry Period) (Wet Period)

BWDB New Elevation Depth of Elevation Depth Elevation Location Location of M. P. W. L. of W. L. of W. L. of W. L. from M. P. from M. P.

Co 26 37 7.75 3.96 3.79 1.40 6.35

Co 5 38 7.67 Not available Not available

Co 4 41 8.14 8.70 -0.56 2.40 5.74

Co 55 42 7.42 5.50 1.92 1.65 5.77

Co 52 43 5.29 3.49 1.80 1.88 3.41

Co 21 45 6.22 5.05 1.17 1.27 4.95

Co 22 47 5.00 4.01 0.99 1.82 3.18

Co 65 49 7.07 9.47 -2.40 1.83 5.24

Co 8 50 6.46 5.01 1.45 2.03 4.43

Co 11 52 11.46 3.47 7.99 2.03 9.43

Co 45 53 8.14 5.15 2.99 2.00 6.14

Co 42 57 6.99 5.10 1.89 1.20 5.79

Co 6 58 8.68 7.98 0.70 2.22 6.46

Co 32 61 5.58 3.82 1.76 2.18 3.40

Co 49 62 10.47 Not available 2.16 8.31

Co 62 63 5.57 4.09 1.48 0.74 4.83

Co 19 64 6.09 4.27 1.82 0.89 5.20

Co 51 65 6.59 4.26 2.33 0.94 5.65

Co 60 66 6.34 4.66 1.68 2.08 4.26

Co 57 67 8.08 4.21 3.87 0.93 7.15

Co 18 68 6.84 4.85 1.99 1.11 5.73

Co 7 70 6.44 4.89 1.55 1.17 5.27

Co 50 71 12.01 12.42 -0.41 1.44 10.57

371 8 March 1985 5 August 1985 (Dry Period) (Wet Period)

BWDB New Elevation Depth of Elevation Depth Elevai Location Location of M. P. W. L. of W. L. of W. L. of W. from M. P. from M. P.

Co 58 74 7.74 5.30 2.44 1.70 6.04

Co 20 76 6.48 3.13 3.35 1.44 5.04

Co 43 77 6.53 4.26 2.27 2.20 4.33

Co 17 78 5.85 4.36 1.49 1.72 4.13

Co 13 79 12.59 15.29 -2.70 3.50 9.09

Co 38 84 9.52 8.00 1.52 3.00 6.52

Co 14 86 7.24 4.19 3.05 0.89 6.35

Co 9 89 7.24 4.15 3.09 1.20 6.04

Co 39 90 11.43 4.17 7.26 1.20 10.23

Co 16 91 4.58 4.26 0.32 1.45 3.13

Co 61 92 5.27 4.06 1.21 1.45 3.82

Co 15 94 5.23 3.17 2.06 1.17 4.06

Co 10 97 8.62 4.72 3.90 1.67 6.95

Co 64 98 5.48 3.56 1.92 2.25 3.23

No 1 99 12.18 not available Not available

Co 31 100 7.61 3.81 3.80 1.92 5.69

Co 40 102 4.58 3.25 1.33 1.27 3.31

Co 27 104 6.59 4.03 2.56 1.27 5.32

No 29 105 5.72 5.33 0.39 1.31 4.41

Co 28 106 3.26 2.69 0.57 1.72 1.54

Co 41 108 10.47 3.40 7.07 1.83 8.64

Co 29 111 5.51 2.43 3.08 0.95 4.56

No 8 112 5.50 3.25 2.25 2.44 3.06

372 8 March 1985 5 August 1985 (Dry Period) (Wet Period)

BWDB New Elevation Depth of Elevation Depth Elevation Location Location of M. P. W. L. of W. L. of W. L. of W. L. from M. P. from M. P.

No 17 110 7.63 5.44 2.19 1.04 6.59

No 18 114 5.53 Not available 1.39 4.14

No 7 115 5.06 4.03 1.03 2.20 2.86

No 2 118 9.19 2.89 6.30 1.52 7.67

No 22 120 3.45 2.60 0.85 1.17 2.28

No 23 123 6.66 4.11 2.55 2.66 4.00

No 3 124 6.85 3.73 3.12 1.24 5.61

No 30 126 3.07 4.16 -1.09 1.75 1.32

No 4 127 — Not available ------

No 28 129 4.37 4.01 0.36 1.92 2.45

No 12 131 4.19 2.94 1.25 1.19 3.00

No 9 132 6.83 4.17 2.66 1.65 5.18

No 5 133 6.58 4.21 2.37 1.65 4.93

No 6 134 4.21 3.96 0.25 2.11 2.10

No 13 138 6.89 4.72 2.17 1.07 5.82

No 21 139 7.18 2.36 4.82 1.93 5.25

No 20 140 4.75 4.51 0.24 1.52 3.23

No 10 142 5.94 3.32 2.62 0.91 5.03

No 19 143 5.98 4.44 1.54 1.14 4.84

No 16 145 6.58 not available 1.19 5.39

373 APPENDIX. 5.1.1: PUMP TEST DATA B’BARIA (WELL 6) Q = 76997 ft3/d.

Elapsed time (minutes):

1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 12.0 14.0 16.0 18.0 20.0 25.0 30.0 35.0 40.0 45.0 50.0 60.0 70.0 80.0 90.0 100.0 120.0 140.0 160.0 180.0 200.0 250.0 300.0 350.0 400.0 500.0 600.0 700.0 800.0 900.0 1000.0 1500.0 2000.0 2500.0 3000.0

Drawdown (feet):

B’Baria O.W. (r = 50 ft) 1.77 2.04 2.04 2.08 2.12 2.12 2.16 2.27 2.52 2.64 2.95 2.89 2.83 2.85 2.83 3.04 3.18 3.33 3.37 3.41 3.45 3.58 3.66 3.77 3.79 3.87 3.95 4.12 4.20 4.25 4.25 4.35 4.52 4.58 4.62 4.83 4.87 4.93 5.04 5.08 5.29 5.58 5.68 5.77 5.77

B’Baria O.W. (r = 150 ft) 0.42 0.67 0.71 0.62 0.58 0.54 0.50 0.62 0.71 0.71 0.83 0.92 1.17 1.25 1.29 1.33 1.50 1.67 1.83 1.92 1.96 2.00 2.08 2.17 2.25 2.29 2.42 2.50 2.58 2.67 2.75 2.71 3.00 3.08 3.17 3.25 3.42 3.58 3.67 3.71

B’Baria O.W. (r = 400 ft) 0.09 0.09 0.09 0.09 0.09 0.09 0.09 0.09 0.09 0.09 0.16 0.21 0.34 0.42 0.59 0.63 0.67 0.73 0.82 0.96 1.00 1.00 1.17 1.25 1.42 1.50 1.46 1.50 1.75 1.79 1.88 1.84 2.00 2.13 2.17 2.21 2.34 2.50 2.75 2.88 2.92

APPENDIX. 5.1.2: PUMP TEST DATA NABINAGAR (WELL 9) Q = 86400 ft3/d.

Elapsed time (minutes):

1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 12.0 14.0 16.0 18.0 20.0 22.0 24.0 26.0 28.0 30.0 35.0 40.0 45.0 50.0 55.0 60.0 70.0 80.0 90.0 100.0 110.0 120.0 140.0 160.0 180.0 200.0 220.0 240.0 260.0 280.0 300.0 330.0 360.0 390.0 420.0 450.0 480.0 540.0 600.0 660.0 720.0 780.0 840.0 900.0 1000.0 1100.0 1200.0 1300.0 1400.0 1500.0 1600.0 1700.0 1800.0 1900.0 2000.0 2200.0 2400.0 2600.0 2800.0 3000.0 3200.0 3400.0 3600.0 3800.0 4000.0 4100.0

Drawdown (feet):

Nabinagar O.W. (r = 50 ft) 2.29 3.67 4.37 4.87 5.08 5.33 5.50 5.83 5.96 6.17 6.33 6.50 6.75 6.83 7.17 7.29 7.46 7.50 7.58 7.75 8.08 8.23 8.42 8.54 8.75 9.08 9.25 9.42 9.50 9.62 9.87 9.92 9.92 10.12 10.29 10.42 10.63 10.75 10.87 11.08 11.12 11.25 11.46 11.62 11.71 11.87 11.92 12.00 12.08 12.17 12.20 12.30 12.37 12.40 12.47 12.47 12.58 12.62 12.62 12.62 12.71 12.71 12.71 12.79 12.92 13.00 13.04 12.04 13.06 13.06 13.08 13.12 13.21 13.42 12.42 13.42

Nabinagar O.W. (r = 400 ft) 0.04 0.04 0.04 0.13 0.17 0.21 0.25 0.34 0.48 0.54 0.67 0.76 0.92 1.00 1.09 1.17 1.25 1.42 1.59 1.75 2.00 2.09 2.17 2.34 2.59 2.84 2.84 3.00 3.17 3.34 3.59 3.42 3.50 3.42 3.88 3.89 3.92 4.34 4.42 4.54 4.75 4.84 4.88 4.96 5.04 5.17 5.25 5.40 5.67 5.75 5.86 5.84 5.75 5.92 6.00 6.00 6.09 6.00 6.09 6.09 6.17 6.21 6.34 6.34 6.34 6.40 6.40 6.04 6.46 6.54 6.59 6.75 6.71

374 Nabinagar O.W. (r = 1000 ft) 0.04 0.04 0.04 0.08 0.08 0.12 0.12 0.16 0.20 0.25 0.33 0.41 0.50 0.54 0.62 0.75 0.83 0.87 0.91 1.00 1.16 1.25 1.39 1.39 1.45 1.54 1.65 1.75 1.79 1.83 1.91 2.08 2.16 2.23 2.29 2.33 2.37 2.58 2.58 2.58 2.67 2.79 2.83 2.75 2.83 2.83 2.83 2.91 3.08 3.00 3.23 3.12 3.27 3.12 3.16 3.16 3.33 3.33 3.33

APPENDIX. 5.1.3: PUMP TEST DATA DAUDKANDI (WELL 43) Q = 172785 ft3/d

Elapsed time (minutes):

1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 12.0 14.0 16.0 18.0 20.0 25.0 30.0 35.0 40.0 45.0 50.0 55.0 60.0 70.0 80.0 90.0 100.0 110.0 120.0 140.0 160.0 180.0 200.0 220.0 240.0 260.0 280.0 300.0 340.0 380.0 420.0 460.0 500.0 540.0 600.0 660.0 720.0 780.0 840.0 900.0 1000.0 1100.0 1200.0 1300.0 1400.0 1500.0 1600.0 1700.0 1800.0

Drawdown (feet):

Daudkandi O.W. (r = 50 ft) 2.05 3.71 4.55 4.80 5.38 6.05 6.13 6.21 6.30 6.38 6.63 6.80 7.88 7.05 7.13 7.21 7.63 7.80 7.96 8.13 8.21 8.30 8.38 8.46 8.45 8.71 8.79 8.88 8.96 9.13 9.21 9.30 9.38 9.46 9.55 9.63 9.67 9.67 9.71 9.76 9.80 9.88 9.96 9.96 9.96 10.05 10.09 10.13 10.16 10.19 10.21 10.34 10.67 10.84 10.92 10.92 10.92 10.92 10.92

Daudkandi O.W. (r = 150 ft) 0.50 0.58 1.17 1.84 3.04 3.29 3.46 3.67 3.75 3.92 4.09 4.25 4.42 4.55 4.67 4.84 5.04 5.21 5.38 5.50 5.59 5.71 5.79 6.05 6.05 6.17 6.21 6.25 6.25 6.50 6.59 6.67 6.71 6.75 6.88 6.92 7.00 7.09 7.17 7.25 7.30 7.34 7.38 7.38 7.42 7.46 7.55 7.59 7.50 7.58 7.67 7.75 7.80 7.87 7.92 8.09 8.17 8.25 8.34

Daudkandi O.W. (r = 400 ft) 0.46 0.54 0.67 0.75 0.87 1.08 1.17 1.29 1.33 1.37 1.58 1.71 1.83 1.96 2.04 2.33 2.54 2.58 2.71 2.83 2.92 3.00 3.08 3.17 3.29 3.42 3.54 3.63 3.75 3.83 3.92 4.00 4.08 4.13 4.21 4.21 4.29 4.29 4.33 4.42 4.54 4.58 4.63 4.63 4.71 4.79 4.83 4.83 4.83 4.92 5.12 5.27 5.46 5.50 5.58 5.67 5.67 5.67 5.67

Calculated recovery:

Daudkandi O.W. (r = 50 ft)

Recovery time (minutes) 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 12.0 14.0 16.0 18.0 20.0 25.0 30.0 35.0 40.0 45.0 50.0 55.0 60.0 70.0 80.0 90.0 100.0 110.0 120.0 140.0 160.0 180.0 200.0 220.0 240.0 260.0 280.0 300.0 340.0 380.0 420.0 460.0 500.0 560.0 620.0 680.0 740.0 800.0 860.0 920.0 980.0

Calculated recovery (feet) 0.08 1.92 2.17 2.08 2.17 2.50 2.67 2.92 3.17 3.25 3.50 3.50 3.83 4.00 4.25 4.42 4.67 4.83 4.92 5.00 5.25 5.33 5.50 5.67 5.92 6.08 6.17 6.33 6.42 6.66 6.70 6.70 6.70 6.70 6.75 6.75 6.75 6.79 6.79 6.83 6.88 6.91 6.96 7.00 7.04 7.17 7.33 7.42 7.42 7.42 7.38 Daudkandi O.W. (r = 150 ft)

Recovery time (minutes) 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 12.0 14.0 16.0 18.0 20.0 25.0 30.0 35.0 40.0 45.0 50.0 55.0 60.0 70.0 80.0 90.0 100.0 110.0 120.0 140.0 160.0 180.0 200.0 220.0 240.0 260.0 280.0 300.0 340.0 380.0 420.0 460.0 500.0 560.0 620.0 680.0 740.0 800.0 860.0 920.0 980.0 1040.0 1100.0 1200.0 1300.0 1400.0 1500.0

Calculated recovery (feet) 0.38 0.62 0.79 1.08 1.25 1.50 1.58 1.75 1.88 2.08 2.21 2.29 2.42 2.58 2.71 2.92 3.13 3.29 3.54 3.63 3.71 3.88 4.00 4.21 4.29 4.54 4.58 4.63 4.83 5.04 5.13 5.13 5.13 5.17 5.17 5.17 5.21 5.21 5.25 5.25 5.25 5.29 5.33 5.42 5.58 5.67 5.71 5.71 5.75 5.79 5.79 5.79 5.79 5.79 5.79 5.79 5.79

Daudkandi O.W. (r = 400 ft)

Recovery time (minutes) 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 12.0 14.0 16.0 18.0 20.0 25.0 30.0 35.0 40.0 45.0 50.0 55.0 60.0 70.0 80.0 90.0 100.0 110.0 120.0 140.0 160.0 180.0 200.0 220.0 240.0 260.0 280.0 300.0 340.0 380.0 420.0 460.0 500.0 560.0 620.0 680.0 740.0 800.0 860.0 920.0 980.0 1040.0 1100.0 1200.0 1300.0 1400.0 1500.0

Calculated recovery (feet) 0.04 0.13 0.21 0.25 0.33 0.42 0.54 0.63 0.71 0.79 0.88 0.96 1.17 1.21 1.29 1.46 1.75 2.00 2.08 2.21 2.29 2.33 2.38 2.5 8 2.67 3.00 3.04 3.13 3.17 3.38 3.46 3.46 3.46 3.46 3.50 3.58 3.58 3.58 3.58 3.58 3.58 3.58 3.62 3.63 3.88 4.00 4.04 4.08 4.08 4.08 4.08 4.08 4.16 4.16 4.16 4.16 4.16

APPENDIX. 5.1.4: PUMP TEST DATA BURICHONG (WELL 46) Q = 76962 ft7d

Elapsed time (minutes):

1.0 2.0 3.0 4.0 5.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0 20.0 25.0 30.0 35.0 40.0 45.0 50.0 55.0 60.0 70.0 80.0 90.0 100.0 110.0 120.0 140.0 160.0 180.0 200.0 220.0 240.0 260.0 280.0 300.0 350.0 400.0 450.0 500.0 550.0 600.0 700.0 800.0 900.0 1000.0 1200.0 1400.0 1600.0 1800.0 2000.0 2200.0 2400.0 2700.0 3000.0

Drawdown (feet):

Burichong O.W. (r = 100 ft) 0.04 0.25 0.21 0.12 0.21 0.39 0.37 0.37 0.39 0.37 0.17 0.21 0.39 0.21 0.12 0.12 0.21 0.04 0.00 0.04 0.13 0.21 0.29 0.33 0.38 0.50 0.46 0.71 0.71 0.67 0.88 0.92 0.96 1.04 1.08 1.13 1.29 1.38 1.54 1.50 1.54 1.59 1.63 1.63 1.67 1.69 1.71 1.75 1.79 1.83 1.90 1.96 1.94 1.96 1.96

Burichong O.W. (r = 150 ft) 00.0300.4101.0601.4101.3701.6401.9502.2202.3502.4402.7002.8502.9703.2503.4503.64 03.7703.8704.0204.0804.2004.3504.5404.6204.6604.7704.9305.1005.2205.3505.5005.50 05.6205.6605.6605.6605.9106.0006.0806.1606.2506.2506.2906.2906.3706.3906.4206.44 06.5006.5406.6006.6206.6406.5806.58

376 Burichong O.W. (r = 250 ft) 0.04 0.08 0.08 0.04 0.04 0.04 0.08 0.08 0.13 0.17 0.23 0.33 0.40 0.50 0.58 0.71 0.79 0.88 0.92 1.04 1.13 1.21 1.33 1.42 1.50 1.54 1.71 1.79 2.00 2.00 2.08 2.13 2.21 2.25 2.29 2.38 2.50 2.54 2.63 2.67 2.71 2.79 2.83 2.88 2.92 3.00 3.06 3.08 3.08 3.08 3.08 3.08 3.08

APPENDIX. 5.1.5: PUMP TEST DATA CHANDINA (WELL 55) Q = 84662 ft3/d

Chandina O.W. (r = 50 ft)

Elapsed time (minutes) 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 12.0 14.0 16.0 18.0 20.0 22.0 24.0 26.0 28.0 30.0 35.0 40.0 45.0 50.0 55.0 60.0 70.0 80.0 90.0 100.0 120.0 140.0 160.0 180.0 200.0 250.0 300.0 350.0 400.0 500.0 600.0 700.0 800.0 900.0 1000.0 1100.0 1200.0 1300.0 1400.0 1500.0 1600.0 1700.0 1800.0 1900.0 2000.0 2100.0 2600.0 3000.0 3300.0 3600.0

Drawdown (feet) 0.02 0.13 0.17 0.17 0.08 0.08 0.13 0.13 0.17 0.17 0.21 0.17 0.17 0.25 0.21 0.21 0.25 0.25 0.27 0.27 0.27 0.29 0.29 0.31 0.33 0.33 0.33 0.38 0.38 0.35 0.38 0.42 0.42 0.44 0.46 0.44 0.46 0.50 0.54 0.56 0.58 0.54 0.54 0.60 0.60 0.62 0.60 0.65 0.69 0.88 0.88 0.88 0.88 0.88 0.88 0.92 0.88 0.88

Chandina O.W. (r = 400 ft)

Elapsed time (minutes) 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 12.0 14.0 16.0 18.0 20.0 22.0 24.0 26.0 28.0 30.0 35.0 40.0 45.0 50.0 55.0 60.0 70.0 80.0 90.0 100.0 120.0 140.0 160.0 180.0 200.0 250.0 300.0 350.0 400.0 500.0 600.0 700.0 800.0 900.0 1000.0 1100.0 1200.0 1300.0 1400.0 1500.0 1600.0 1700.0 1800.0 1900.0 2000.0 2100.0 2600.0 3000.0 3300.0 3600.0

Drawdown (feet) 0.04 0.09 0.13 0.17 0.25 0.25 0.29 0.42 0.42 0.42 0.42 0.54 0.54 0.59 0.63 0.63 0.67 0.71 0.75 0.79 0.94 0.84 0.92 0.96 1.00 1.04 1.13 1.13 1.17 1.29 1.29 1.38 1.42 1.42 1.50 1.54 1.67 1.67 1.75 1.75 1.75 1.84 1.88 1.88 1.88 1.92 1.92 1.96 1.96 2.00 2.00 2.0 02.09 2.09 2.09 2.09 2.17 2.25 2.25

Calculated recovery Chandina O.W. (r = 150.0 ft)

Recovery time (minutes) 6.0 7.0 8.0 9.0 10.0 12.0 14.0 16.0 18.0 22.0 24.0 26.0 28.0 30.0 35.0 40.0 45.0 50.0 55.0 60.0 70.0 80.0 90.0 100.0 120.0 140.0 160.0 180.0 200.0 250.0 300.0 350.0 400.0 500.0 600.0 700.0 800.0 900.0 1000.0 1100.0 1200.0 1300.0 1800.0 2000.0

Calculated recovery (feet) 0.06 0.08 0.15 0.17 0.17 0.25 0.31 0.28 0.46 0.52 0.50 0.63 0.69 0.71 0.83 0.92 1.00 1.11 1.15 1.25 1.40 1.52 1.56 1.67 1.51 1.90 1.982.08 2.08 2.17 2.25 2.33 2.33 2.40 2.44 2.46 2.49 2.52 2.50 2.52 2.54 2.58 2.61 2.65

377 Calculated recovery Chandina O.W. (r = 400 ft)

Recovery time (minutes) 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 12.0 14.0 16.0 18.0 24.0 26.0 28.0 30.0 35.0 40.0 45.0 50.0 55.0 60.0 70.0 80.0 90.0 100.0 120.0 140.0 160.0 180.0 200.0 250.0 300.0 350.0 400.0 500.0 600.0 700.0 800.0 900.0 1000.0 1100.0 1200.0 1300.0 1800.0 2000.0

Calculated recovery (feet) 0.08 0.13 0.17 0.17 0.25 0.29 0.33 0.37 0.42 0.42 0.50 0.50 0.54 0.57 0.59 0.71 0.71 0.79 0.79 0.83 0.82 0.82 0.96 1.00 1.04 1.08 1.13 1.21 1.25 1.29 1.33 1.38 1.42 1.46 1.50 1.54 1.58 1.61 1.67 1.63 1.71 1.71 1.71 1.71 1.72 1.76 1.76

APPENDIX. 5.1.6: PUMP TEST DATA KOTWALI (WELL 59) Q = 76982 ft*/d

Elapsed time (minutes)

1.0 2.0 3.0 4.0 5.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0 20.0 22.0 24.0 26.0 28.0 30.0 32.0 34.0 36.0 38.0 40.0 42.0 44.0 46.0 48.0 50.0 52.0 54.0 56.0 58.0 60.0 65.0 70.0 75.0 80.0 85.0 90.0 95.0 100.0 105.0 110.0 115.0 120.0 130.0 140.0 150.0 160.0 170.0 180.0 190.0 200.0 210.0 220.0 230.0 240.0 260.0 280.0 300.0 320.0 340.0 360.0 380.0 400.0 420.0 440.0 460.0 480.0 500.0 520.0 540.0 560.0 580.0 600.0 620.0 640.0 660.0 680.0 700.0 720.0 740.0 760.0 780.0 800.0 820.0 840.0 860.0 880.0 900.0 920.0 940.0 960.0 980.0 1000.0 1020.0 1040.0 1220.0 1400.0 1460.0 1520.0 1580.0 1640.0 1700.0 1900.0 2100.0 2300.0 2600.0 2900.0 2960.0

Drawdown (feet)

Kotwali O.W. (r = 50 ft) 0.34 1.17 1.75 2.34 2.63 2.75 3.29 3.76 3.76 3.92 4.09 4.25 4.39 4.50 4.42 4.67 4.73 4.88 5.00 5.09 5.09 4.88 4.84 4.96 4.96 4.88 5.04 5.00 5.00 5.11 5.13 5.13 5.23 5.23 5.34 5.27 5.25 5.38 5.34 5.50 5.59 5.59 5.67 5.67 5.67 5.71 5.84 5.77 5.75 5.90 5.84 5.84 5.86 5.92 5.92 6.06 6.06 6.17 6.17 6.25 6.25 6.34 6.39 6.39 6.39 6.42 6.54 6.67 6.77 6.59 6.59 6.54 6.50 6.50 6.54 6.59 6.59 6.59 6.71 6.88 6.84 6.84 6.84 6.88 6.84 6.96 6.90 6.75 6.75 6.79 6.79 6.79 6.79 6.86 6.86 6.86 6.86 6.94 6.94 7.09 7.54 7.59 7.59 7.42 7.42 7.36 7.36 7.36 7.36 7.36 7.36

Kotwali O.W. (r = 150 ft) 0.08 0.25 0.50 0.75 1.00 1.25 1.50 1.83 2.00 2.10 2.20 2.42 2.54 2.58 2.64 2.75 2.79 2.92 2.94 3.04 3.04 3.04 3.04 3.08 3.08 3.08 3.08 3.08 3.17 3.21 3.21 3.21 3.25 3.33 3.37 3.42 3.42 3.44 3.44 3.54 3.54 3.56 3.62 3.67 3.69 3.75 3.77 3.83 3.87 3.89 3.96 4.00 4.00 4.00 4.02 4.04 4.10 4.12 4.17 4.21 4.25 4.25 4.25 4.25 4.33 4.37 4.37 4.46 4.46 4.50 4.50 4.50 4.54 4.58 4.58 5.62 4.62 4.62 4.62 4.67 4.67 4.67 4.67 4.70 4.71 4.71 4.71 4.71 4.73 4.75 4.75 5.04 4.96 5.00 5.00 4.98 5.00 5.00 5.00 5.04 5.08 5.08 5.12 5.17

Kotwali O.W. (r = 400 ft) 0.04 0.04 0.04 0.04 0.08 0.08 0.12 0.29 0.37 0.42 0.46 0.46 0.21 0.28 0.12 0.17 0.21 0.06 0.12 0.04 0.07 0.13 0.13 0.04 0.21 0.17 0.17 0.13 0.29 0.29 0.23 0.21 0.21 0.31 0.46 0.38 0.38 0.42 0.42 0.58 0.54 0.50 0.46 0.58 0.58 0.75 0.78 0.79 0.82 0.88 1.00 1.00 1.00 1.12 1.17 1.29 1.29 1.43 1.50 1.56 1.69 1.69 1.69 1.79 1.88 1.88 1.88 1.88 2.13 2.13 1.54 1.54 1.54 1.67 1.63 1.63 1.63 1.68 2.25 2.25 2.25 2.25 2.19 2.15 2.27 2.27 2.27 1.96 1.96 1.96 2.04 2.67 2.67 2.25 2.25 2.38 2.54 2.60 2.60 2.60 2.60 2.60 2.6 2.60 APPENDIX. 5.1.7: PUMP TEST DATA BARURA (WELL 69) Q = 76982 ft3/d

Elapsed time (minutes)

1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 12.0 14.0 16.0 18.0 20.0 22.0 24.0 26.0 28.0 30.0 35.0 40.0 45.0 50.0 55.0 60.0 70.0 80.0 90.0 100.0 120.0 140.0 160.0 180.0 200.0 250.0 300.0 350.0 400.0 450.0 500.0 600.0 700.0 800.0 900.0 1000.0 1200.0 1400.0 1600.0 1800.0 2000.0 2200.0 2700.0 3000.0

Drawdown (feet)

Barura O.W. (r = 50 ft) 0.08 0.15 0.15 0.15 0.19 0.19 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.27 0.30 0.30 0.37 0.37 0.37 0.37 0.37 0.37 0.37 0.37 0.33 0.41 0.41 0.50 0.50 0.50 0.58 0.62 0.62 0.66 0.70 0.83 0.87 0.95 1.00 1.00 1.21 1.33 1.45 1.53 1.62 1.70 1.83 2.00 2.29 2.37 2.54 2.75 3.04 3.20

Barura O.W. (r = 150 ft) 0.15 0.50 1.00 1.20 1.25 1.54 1.58 1.66 1.70 1.87 2.00 2.08 2.12 2.16 2.20 2.25 2.29 2.29 2.38 2.38 2.41 2.41 2.45 2.50 2.54 2.58 2.60 2.62 2.62 2.62 2.66 2.79 2.79 2.83 2.83 2.91 2.95 3.00 3.00 3.00 3.07 3.07 3.07 3.10 3.16 3.20 3.20 3.20 3.22 3.25 3.29 3.33 3.37 3.37

Barura O.W. (r = 400 ft) 0.04 0.08 0.16 0.25 0.37 0.41 0.50 0.58 0.62 0.66 0.75 0.87 0.91 0.95 0.95 1.00 1.04 1.08 1.12 1.16 1.20 1.25 1.29 1.29 1.33 1.37 1.41 1.45 1.45 1.45 1.54 1.58 1.62 1.62 1.64 1.70 1.75 1.75 1.79 1.83 1.83 1.83 1.86 1.91 1.91 1.94 1.97 2.00 2.00 2.04 2.08 2.08 2.16 2.16

Calculated recovery Barura O.W. (r = 150 ft)

Recovery time (minutes) 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 12.0 14.0 16.0 18.0 20.0 22.0 24.0 26.0 28.0 30.0 35.0 40.0 45.0 50.0 55.0 60.0 70.0 80.0 90.0 100.0 120.0 140.0 160.0 180.0 200.0 250.0 300.0 350.0 400.0 450.0 500.0 600.0 700.0 800.0 900.0 1000.0 1200.0 1400.0 1600.0 1800.0 2000.0 2200.0 2700.0

Calculated recovery (feet) 0.71 1.00 1.21 1.37 1.50 1.62 1.71 1.75 1.83 1.87 1.96 2.04 2.04 2.17 2.21 2.295 2.29 2.33 2.33 2.37 2.46 2.50 2.62 2.58 2.62 2.62 2.67 2.71 2.77 2.75 2.79 2.859 2.87 2.87 2.87 2.92 2.96 2.96 3.04 3.12 3.17 3.04 3.08 3.12 3.08 3.10 3.12 3.12 3.12 3.12 3.17 3.17 3.21

APPENDIX. 5.1.8: PUMP TEST DATA HAZIGANJ (WELL 82) Q = 180273 ftVd

Elapsed time (minutes)

1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 12.0 14.0 16.0 18.0 20.0 25.0 30.0 35.0 40.0 45.0 50.0 55.0 60.0 70.0 80.0 90.0 100.0 110.0 120.0 140.0 160.0 180.0 200.0 220.0 240.0 260.0 280.0 300.0 340.0 380.0 420.0 460.0 500.0 560.0 620.0 680.0 740.0 800.0 860.0 920.0 980.0 1040.0 1100.0 1200.0 1300.0 1400.0 1500.0 1600.0 1700.0 1800.0 1900.0 2000.0 2100.0 2200.0 2300.0 2400.0 2500.0 2600.0 2700.0 2800.0 2900.0 3000.0

379 Drawdown (feet)

Haziganj O.W. (r = 50 ft) 2.33 3.54 4.12 4.50 4.71 4.87 5.04 5.16 5.16 5.33 5.50 5.66 5.71 5.87 5.96 6.21 6.33 6.62 6.62 6.70 6.70 6.75 6.83 6.92 7.00 7.17 7.33 7.37 7.46 7.58 7.74 7.74 7.83 7.87 7.87 7.92 7.96 8.08 8.17 8.25 8.37 8.42 8.42 8.50 8.54 8.62 8.75 8.83 8.83 8.87 8.87 8.87 8.87 8.96 8.96 8.96 8.96 8.96 9.04 9.04 9.04 9.04 9.04 9.04 9.12 9.12 9.12 9.12 9.12 9.12 9.12 9.12

Haziganj O.W. (r = 150 ft) 1.16 2.04 2.70 2.95 3.20 3.33 3.49 3.58 3.62 3.75 3.87 4.00 4.08 4.25 4.33 4.50 4.62 4.75 4.95 5.00 5.00 5.04 5.08 5.08 5.29 5.58 5.58 5.66 5.83 5.87 6.00 6.04 6.08 6.16 6.21 6.25 6.33 6.46 6.54 6.62 6.75 6.83 6.83 6.83 7.00 7.00 7.12 7.17 7.25 7.29 7.42 7.42 7.42 7.42 7.42 7.42 7.42 7.42 7.54 7.58 7.58 7.62 7.62 7.66 7.71 7.71 7.75 7.75 7.83 7.83 7.83 7.83

Haziganj O.W. (r = 1000 ft) 0.12 0.12 0.12 0.12 0.12 0.17 0.21 0.21 0.21 0.25 0.28 0.33 0.33 0.42 0.42 0.54 0.62 0.75 0.79 0.87 0.87 0.91 1.04 1.04 1.12 1.29 1.33 1.46 1.50 1.62 1.75 1.75 1.79 1.79 1.92 2.04 2.12 2.21 2.33 2.37 2.50 2.58 2.67 2.71 2.75 2.79 2.96 3.08 3.12 3.16 3.21 3.21 3.25 3.25 3.25 3.29 3.29 3.33 3.41 3.46 3.46 3.46 3.50 3.50 3.50 3.50 3.58 3.58 3.58 3.58 3.58 3.58

APPENDIX. 5.1.9: PUMP TEST DATA CHAUDDAGRAM (WELL 101) Q = 86604 ft3/d

Chauddagram O.W. (r = 50 ft)

Elapsed time (minutes) 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 12.0 14.0 16.0 18.0 20.0 25.0 30.0 35.0 40.0 45.0 50.0 55.0 60.0 70.0 80.0 90.0 100.0 110.0 120.0 130.0 140.0 150.0 160.0 170.0 180.0 190.0 200.0 220.0 240.0 260.0 280.0 300.0 330.0 360.0 390.0 420.0 450.0 480.0 510.0 540.0 570.0 600.0 700.0 750.0 800.0 850.0 900.0 950.0 1000.0 1100.0 1200.0 1300.0 1400.0 1500.0 1600.0 1700.0 1800.0 1900.0 2000.0 2100.0 2200.0 2300.0 2400.0 2500.0 2600.0 2700.0 2800.0 2900.0 3000.0 3100.0 3200.0 3300.0 3400.0 3500.0 3600.0 3700.0 3800.0 3900.0 4000.0 4100.0 4200.04290.0

Drawdown (feet) 0.12 0.17 0.17 0.21 0.25 0.33 0.42 0.46 0.54 0.67 0.79 0.96 1.16 1.33 1.50 1.79 2.29 2.67 3.00 3.33 3.58 3.83 4.09 4.50 5.04 5.25 5.50 5.83 6.13 6.33 6.54 6.77 7.04 7.17 7.25 7.32 7.54 7.77 8.00 8.25 8.54 9.00 9.25 9.42 9.58 9.81 10.09 10.29 10.46 10.5810.71 10.92 11.13 11.46 11.67 11.75 11.87 11.92 12.00 12.13 12.33 12.50 12.67 12.71 12.75 13.62 13.46 13.54 13.70 13.90 13.96 14.00 14.49 14.66 14.78 14.88 14.88 14.92 14.88 14.96 15.08 15.17 15.33 15.42 15.46 15.58 15.62 15.62 15.62 15.66 15.71 15.79 15.83

Chauddagram O.W. (r = 150 ft)

Elapsed time (minutes) 0.5 1.0 1.5 2.0 2.5 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 12.0 14.0 16.0 18.0 20.0 25.0 30.0 35.0 40.0 45.0 50.0 55.0 60.0 70.0 80.0 90.0 100.0 110.0 120.0 130.0 140.0 150.0 160.0 170.0 180.0 190.0 200.0 220.0 240.0 260.0 280.0 300.0 330.0 360.0 390.0 420.0 450.0 480.0 510.0 540.0 570.0 600.0 700.0 750.0 800.0 850.0 900.0 950.0 1000.0 1100.0 1200.0 1300.0 1400.0 1500.0 1600.0 1700.0 1800.0 1900.0 2000.0 2100.0 2200.0 2300.0 2400.0 2500.0 2600.0 2700.0 2800.0 2900.0 3000.0 3100.0 3200.0 3300.0 3400.0 3500.0 3600.0 3700.0 3800.0 3900.0 4000.0 4100.0 4200.04290.0

380 Drawdown (feet) 0.00 0.00 0.00 0.00 0.04 0.08 0.12 0.28 0.50 0.54 0.67 0.75 0.86 1.00 1.16 1.33 1.50 1.58 I.94 2.06 2.36 2.65 2.77 3.06 3.23 3.36 3.73 4.02 4.32 4.61 4.81 5.02 5.19 5.48 5.61 5.81 6.19 6.23 6.28 6.36 6.56 6.77 7.02 7.32 7.48 7.77 8.02 8.32 8.52 8.81 8.90 9.02 9.21 9.38 9.42 9.63 9.84 10.00 10.12 10.30 10.39 10.55 10.63 10.84 10.96 11.13 11.25 11.35 11.71 II.88 12.04 12.34 12.42 12.54 12.75 12.92 13.08 13.21 13.34 13.38 13.38 13.46 13.54 13.63 13.67 13.71 13.79 13.92 14.04 14.08 14.08 14.12 14.20 14.29 14.29 14.33

Chauddagram O.W. (r = 1000 ft)

Elapsed time (minutes) 25.0 30.0 35.0 40.0 45.0 50.0 55.0 60.0 70.0 80.0 90.0 100.0 110.0 120.0 130.0 140.0 150.0 160.0 170.0 180.0 190.0 200.0 220.0 240.0 260.0 280.0 300.0 330.0 360.0 390.0 420.0 450.0 480.0 510.0 540.0 570.0 600.0 650.0 700.0 750.0 800.0 850.0 900.0 950.0 1000.0 1100.0 1200.0 1300.0 1400.0 1500.0 1600.0 1700.0 1800.0 1900.0 2000.0 2100.0 2200.0 2300.0 2400.0 2500.0 2600.0 2700.0 2800.0 2900.0 3000.0 3100.0 3200.0 3300.0 3400.0 3500.0 3600.0 3700.0 3800.0 3900.0 4000.0 4100.0 4200.0 4290.0

Drawdown (feet) 0.04 0.04 0.08 0.08 0.12 0.16 0.19 0.28 0.33 0.40 0.40 0.52 0.69 0.75 0.79 0.90 0.96 1.12 1.12 1.23 1.23 1.28 1.32 1.73 1.73 1.90 2.00 2.19 2.32 2.48 2.52 2.75 2.90 2.98 3.06 3.21 3.34 3.54 3.71 3.79 3.88 4.00 4.08 4.21 4.25 4.38 4.63 4.79 4.88 4.96 5.15 5.25 5.46 5.58 5.67 5.71 5.79 5.83 6.00 6.21 6.34 6.54 6.54 6.58 6.63 6.67 6.83 6.88 6.96 7.00 7.04 7.08 7.08 7.20 7.25 7.25 7.37 7.37

APPENDIX. 5.1.10: PUMP TEST DATA FENI (WELL 117) Q = 161553 ft3/d

Feni O.W. (r = 50 ft)

Elapsed time (minutes) 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 12.0 14.0 16.0 18.0 20.0 25.0 30.0 35.0 40.0 45.0 50.0 55.0 60.0 70.0 80.0 90.0 100.0 110.0 120.0 140.0 160.0 180.0 200.0 220.0 240.0 260.0 280.0 300.0 330.0 360.0 390.0 420.0 450.0 500.0 550.0 600.0 650.0 700.0 750.0 800.0 900.0 1000.0 1100.0 1200.0 1300.0 1400.0 1500.0 1600.0 1800.0 2000.0 2200.0 2400.0 2600.0 2800.0 3000.0 3200.0 3400.0 3600.0 3800.0 4000.0 4200.0 4300.0

Drawdown (feet) 0.87 3.17 3.71 4.17 4.33 4.67 4.75 4.87 5.05 5.17 5.37 5.58 5.67 5.71 5.83 6.05 6.25 6.37 6.50 6.58 6.75 6.83 6.95 7.08 7.21 7.27 7.46 7.58 7.71 7.87 7.95 8.12 8.33 8.37 8.54 8.65 8.75 8.83 8.87 9.00 9.17 9.33 9.41 9.54 9.66 9.79 9.92 10.00 10.08 10.25 10.37 10.49 10.67 10.75 10.83 10.91 10.91 11.00 11.12 11.33 11.39 11.50 11.58 11.66 11.70 11.70 11.87 12.04 12.12 12.16 12.18 12.20

381 Feni O.W. (r = 400 ft)

Elapsed time (minutes) 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 12.0 14.0 16.0 18.0 20.0 25.0 30.0 35.0 40.0 45.0 50.0 55.0 60.0 70.0 80.0 90.0 100.0 110.0 120.0 140.0 160.0 180.0 200.0 220.0 240.0 260.0 280.0 300.0 330.0 360.0 390.0 420.0 450.0 500.0 550.0 600.0 650.0 700.0 750.0 800.0 900.0 1000.0 1100.0 1200.0 1300.0 1400.0 1500.0 1600.0 1800.0 2000.0 2200.0 2400.0 2600.0 2800.0 3000.0 3200.0 3400.0 3600.0 3800.0 4000.0 4200.0

Drawdown (feet) 0.04 0.08 0.08 0.16 0.20 0.25 0.25 0.25 0.25 0.46 0.53 0.66 0.84 0.96 1.00 1.25 1.46 1.50 1.58 1.66 1.75 1.84 1.96 2.04 2.25 2.37 2.50 2.66 2.84 2.88 3.08 3.25 3.37 3.46 3.58 3.62 3.70 3.75 4.00 4.09 4.17 4.34 4.50 4.55 4.76 4.84 4.96 5.00 5.17 5.42 5.46 5.59 5.67 5.76 5.88 5.92 6.00 6.12 6.25 6.33 6.42 6.50 6.58 6.62 6.79 6.88 7.05 7.09 7.17

Feni O.W. (r = 1000 ft)

Elapsed time (minutes) 18.0 20.0 25.0 30.0 35.0 40.0 45.0 50.0 55.0 60.0 70.0 80.0 90.0 100.0 110.0 120.0 140.0 160.0 180.0 200.0 220.0 240.0 260.0 280.0 300.0 330.0 360.0 390.0 420.0 450.0 500.0 550.0 600.0 650.0 700.0 750.0 800.0 900.0 1000.0 1100.0 1200.0 1300.0 1400.0 1500.0 1600.0 1800.0 2000.0 2200.0 2400.0 2600.0 2800.0 3000.0 3200.0 3400.0 3600.0 3800.0 4000.0 4200.0 4300.0

Drawdown (feet) 0.04 0.08 0.17 0.21 0.29 0.33 0.41 0.41 0.46 0.54 0.62 0.75 0.88 1.00 1.04 1.08 1.16 1.42 1.54 1.67 1.79 1.87 2.00 2.12 2.21 2.25 2.29 2.37 2.46 2.71 2.87 3.00 3.08 3.20 3.32 3.40 3.48 3.71 3.92 4.04 4.14 4.18 4.29 4.37 4.41 4.53 4.61 4.73 4.81 4.89 4.93 4.97 5.05 5.26 5.34 5.42 5.50 5.58 5.58

APPENDIX. 5.1.11: PUMP TEST DATA SENBAGH (WELL 117) Q = 86604 ft3/d

Senbagh O.W. (r = 50 ft)

Elapsed time (minutes) 1.0 2.0 3.0 4.0 5.0 6.0 7.0 10.0 12.0 14.0 16.0 18.0 20.0 20.0 25.0 30.0 35.0 40.0 45.0 50.0 55.0 60.0 70.0 80.0 90.0 100.0 120.0 140.0 160.0 180.0 200.0 240.0 280.0 320.0 360.0 400.0 460.0 520.0 580.0 640.0 700.0 760.0 820.0 880.0 940.0 1000.0 1100.0 1200.0 1300.0 1400.0 1500.0 1600.0 1700.0 1800.0 1900.0 2000.0 2100.0 2200.0 2300.0 2400.0 2500.0 2600.0 2700.0 2800.0 2900.0 3000.0 3100.0 3200.0 3300.0 3400.0 3500.0 3600.0 3700.0 3800.0 3900.0 4000.0 4100.0 4200.0

Drawdown (feet) 0.0 00.00 3.42 3.58 3.85 4.17 4.17 4.42 4.58 4.67 4.74 5.00 5.00 5.25 5.33 5.53 5.75 5.75 5.75 6.00 6.00 6.08 6.08 6.33 6.37 6.41 6.50 6.58 6.66 6.75 6.79 6.91 7.00 7.00 7.04 7.16 7.20 7.25 7.33 7.37 7.33 7.33 7.41 7.45 7.50 7.50 7.50 7.50 7.66 7.62 7.66 7.68 7.70 7.70 7.70 7.70 7.75 7.75 7.79 7.83 7.79 7.75 7.75 7.75 7.75 7.75 7.75 7.79 7.83 7.83 7.83 7.83 7.83 7.83 7.83 7.83 7.83 7.83

382 Senbagh O.W. (r = 150 ft)

Elapsed time (minutes) 1.0 2.0 3.0 4.0 5.0 6.0 7.0 10.0 12.0 14.0 16.0 18.0 20.0 20.0 25.0 30.0 35.0 40.0 45.0 50.0 55.0 60.0 70.0 80.0 90.0 100.0 120.0 140.0 160.0 180.0 200.0 240.0 280.0 320.0 360.0 400.0 460.0 520.0 580.0 640.0 700.0 760.0 820.0 880.0 940.0 1000.0 1100.0 1200.0 1300.0 1400.0 1500.0 1600.0 1700.0 1800.0 1900.0 2000.0 2100.0 2200.0 2300.0 2400.0 2500.0 2600.0 2700.0 2800.0 2900.0 3000.0 3100.0 3200.0 3300.0 3400.0 3500.0 3600.0 3700.0 3800.0 3900.0 4000.0 4100.0

Drawdown (feet) 0.87 0.87 0.91 1.12 1.29 1.37 1.45 1.66 1.70 1.79 1.91 2.12 2.24 2.37 2.54 2.62 2.71 2.87 3.00 3.05 3.71 3.25 3.29 3.41 3.50 3.58 3.66 3.74 3.79 3.83 3.95 4.04 4.08 4.29 4.29 4.29 4.29 4.33 4.54 4.54 4.58 4.62 4.62 4.67 4.71 4.75 4.83 4.83 4.83 4.83 4.87 4.87 4.90 4.92 4.92 4.92 4.92 4.92 4.92 4.96 4.96 5.04 5.04 4.96 4.96 4.96 5.08 5.08 5.08 5.08 5.12 5.12 5.04 5.04 5.04 5.04 5.08 5.08

Senbagh O.W.(r = 400 ft)

Elapsed time (minutes) 6.0 7.0 8.0 9.0 10.0 12.0 14.0 16.0 18.0 20.0 25.0 30.0 35.0 40.0 45.0 50.0 55.0 60.0 70.0 80.0 90.0 100.0 120.0 140.0 160.0 180.0 200.0 240.0 280.0 320.0 360.0 400.0 460.0 520.0 580.0 640.0 700.0 760.0 820.0 880.0 940.0 1000.0 1100.0 1200.0 1300.0 1400.0 1500.0 1600.0 1700.0 1800.0 1900.0 2000.0 2100.0 2200.0 2300.0 2400.0 2500.0 2600.0 2700.0 2800.0 2900.0 3000.0 3100.0 3200.0 3300.0 3400.0 3500.0 3600.0 3700.0 3800.0 3900.0 4000.0 4100.0 4200.0

Drawdown (feet) 0.04 0.04 0.12 0.16 0.21 0.33 0.33 0.33 0.42 0.50 0.58 0.71 0.79 0.87 0.95 1.00 1.08 1.12 1.21 1.29 1.33 1.37 1.50 1.54 1.62 1.71 1.71 1.83 1.88 1.92 2.00 2.08 2.17 2.17 2.21 2.29 2.33 2.33 2.38 2.38 2.38 2.38 2.42 2.46 2.62 2.712.58 2.62 2.58 2.62 2.58 2.58 2.58 2.71 2.67 2.67 2.67 2.71 2.71 2.75 2.75 2.75 2.75 2.75 2.79 2.75 2.75 2.75 2.83 3.79 2.79 2.79 2.79 2.79

383 APPENDIX. 5.2.1: RUSHTON NUMERICAL (RADIAL FLOW) MODEL.

C RUSHTON NUMERICAL TEST PUMPING MODEL C CONFINED OR WATER TABLE AQUIFER C NO VERTICAL FLOW C IN THIS VERSION THE DRAWDOWNS AT ONE SPECIFIED C OBSERVATION POINT ARE CALCULATED BY LOGARITHMIC C INTERPOLATION AND SUBSEQUENTLY PLOTTED USING C DEPT.HYDRO.RUSHPLOT. THE RADIAL DISTANCE OF THE C OBSERVATION POINT (ROBS) MUST BE READ IN THE DATA FILE, C ON THE SAME LINE AS RWELL AND RMAX, IN FREE FORMAT. C IF THE OBSERVATION POINT IS THE PUMPING WELL ITSELF C THEN SET ROBS EQUAL TO RWELL. C SPECIFY DOUBLE PRECISION IMPLICIT DOUBLE PRECISION(A-H),DOUBLE PRECISION(O-Z) DIMENSION R(100),RR(100),D(100),OLDD(100),T(100),H(100), 1RECH(100),A(100),B(100),C(100)^(100),U(100),V(100),NODE(6), 2X( 100), Y (100),RDIST(6) JDDN (6)JLINE(20), 3XPLOT(300),YPLOT(300) C READ IN TITLES AND PARAMETERS READ(5,5999)LINE 5999 FORMAT(20A4) WRITE(6,6105)LINE 6105 FORMATC RUSHTON NUMERICAL TEST PUMPING MODEL’/ 11X,20A4//) READ (5,*)PERM,SCON,SUNCON,ALPHA READ (5,*)WELLOS,BL BL2=BL*BL WRITE(6,6000)PERM, SCON, SUNCON, ALPHA, BL/WELLOS 6000 FORMAT(* PERMEABILITY’, 11X,F12.1/’ S(CONFINED)’,12X,FI2.7/ 1’ S(UNCONFINED)’, 12XJF10.5/’ ALPHA’,20X^10.5/ 2’ LEAKAGE FACTOR’, 1IX,F10.5/’ WELL LOSS’,16X,F10.2) READ (5,*) RWELL,RMAX,ROBS WRITE(6,6010)RWELL,RMAX,ROBS 6010 FORMATC R(WELL)’,16XJF12.3/’ R(MAX)’,17X,F12.1/ 1’ ROBS ’,18X,F12.3) C C SET UP RADIAL MESH DO 10 N=l,100 AN=0.16666666667*FLOAT(N-2) R(N)=RWELL* 10.0** AN IF(R(N).LT.RMAX) GO TO 10 R(N)=RMAX RR(N)=RMAX*RMAX NMAX=N NMONE=N-l GO TO 20 10 RR(N)=R(N)*R(N) 20 DELA=0.383765 DELA2=DELA*DELA C NOTE THAT ALL LEVELS MEASURED DOWNWARDS FROM DATUM

384 READ(5,*) TOP,BASE,WLEVEL,RCH WRITE(6,6020) TOP,BASE,WLEVEL,RCH 6020 FORMATC TOP OF AQUIFER’,9X ^123/’ BASE OF AQUIFER’,8XJF12.3/ 1’ STARTING WATERLEVEL’,3X,F123/’ RECHARGE’,15X,F12.3) C C SET INITIAL CONDITIONS DO 30 N=1,NMAX RECH(N)=RCH Y(N)=0.000 D(N)=WLEVEL X(N)=0.0 30 OLDD (N) = WLEVEL READ(5,*) JFIX READ(5,*) NNODES IF(JFIX.EQ. 1 )WRITE(6,6030) IF(JFIX.EQ.l) GOTO 32 WRITE(6,6031) 6030 FORMAT(22H ** FIXED BOUNDARY** ) 6031 FORMAT(22H ** FREE BOUNDARY ** ) 32 READ(5,*) (NODE(J),J=l,NNODES) WRITE(6,6040) (NODE(J),J=l,NNODES) 6040 FORMAT(’ NODES CHOSEN’,5X,613/) TSTART=0.0 READ(5,*)QPUMP,TSTOP WRITE(6,6050)QPUMP,TSTOP 6050 FORMATC/’ PUMPING RATE =’,F12.3,’ M3/DAY FOR’,F12.3,’ DAYS’/) C C CONVERT ABSTRACTION TO QABST PI=4.0* AT AN (1.0) Q AB ST=0.5 *QPUMP/(PI*DEL A) IND=0 C C INITIAL TIME AND DELT TIME=0.0 DELI=0.025*RR(1)*SCON/(PERM*CBASE-TOP)) DELT=DELI DO 35 1=1,NNODES Il=NODEa) 35 RDIST(I)=R(H) WRITE(6,6100)(NODE(J),J=1,NNODES) 6100 FORMATC’ TIME (DAYS)’,6X,’ TIME (MINS)’,15X, 1’DRAWDOWN AT NODE/DISTANCEV43X,’ PWELL ’,’ ROBS ’,619, 2’ R(MAX)’) WRITE(6,611 l)R(l),ROBS,(RDIST(J),J=1,NNODES),R(NMAX) 6111 FORMATC CUM PUMP CUM PUM P’, 19F9.2D C C CALC FOR A SPECIFIC TIME, IND=0 FOR LAST STEP ICOUNT=0 40 IF(ICOUNT.EQ.O) GO TO 42 XPLOT(ICOUNT)=SSTIME YPLOT(ICOUNT)=SOB S 42 CONTINUE

385 TIME=TIME+DELT TPLOT=TST ART+(0.1/1440.0) IF(TTME.GE.TPLOT) ICOUNT=ICOUNT+l IF(TIME.LT.TSTOP) GO TO 50 DELT=TSTOP-TIME+DELT TIME=TSTOP IND=100 50 CONTINUE C C DELAYED YIELD FACA=0.0 FACB=1.0 FACC=0.0 IF(ALPHA.EQ.0.0)GO TO 15 F=ALPHA*DELT IF(F.GT. 100.0) GO TO 45 FACA=EXP(-F) 45 FACB= 1.0-FACA FACC=FACB/( ALPHA *DELT) DO 55 N=1,NMAX X(N)=FACA* Y (N) 55 RECH(N)=ALPHA*SUNCON*X(N)+RCH 15 CONTINUE C C CALC. REPEATED 4 TIMES FOR CONVERGANCE DO 60 NUM=1,4 DO 70 N=l,NMONE C C TAKE AV. SAT. DEPTH BETWEEN N AND N+l SD=BASE-0.5*(D(N)+D(N+1)) STOR=S CON+FACB * SUN CON IF(SD.LT.(BASE-TOP)) GO TO 80 SD=BASE-TOP STOR=SCON 80 H(N)=DELA2/(SD*PERM) IF(BL.NE.O.O)RECH(N)=PERM*SD*(OLDD(N)-WLEVEL)/BL2 70 T(N)=DELT/(STOR*RR(N)) C C WELL LOSS ADJUSTMENT,CLOSEST 6 NODES DO 300 N=2,7 H(N)=H(N)*WELLOS 300 CONTINUE C C REPRESENT WATER IN WELL H(1)=0.0001*H(1) T(1)=2.0*DELT*DELA/RR(2) T(2)=2.0*T(2) H(NMAX-1 )=DLOG(R(NMAX)-DLOG(R(NMAX-1 )))*(DLOG(R(NMAX))-DLOG

1 (R(NMAX- 1)))/(SD*PERM) H(NMAX)=1.0E+10 T(NMONE)=2.0*DELT*DELA/((R(NMAX)-R(NMONE-1))*STOR*R(NMONE)) T(NMAX)=LO*DELT*DELA/((R(NMAX)-R(NMONE))s,eSTOR*R(NMAX))

386 IF (JFIX.EQ.l) T(NMAX)=1.0E-10*T(NMAX) C C GAUSSIAN ELIMINATION C COEFFICIENTS C EQUATION IS-A(N)*D(N-1)+B(N)*D(N)-C(N)*D(N+1)=E(N). B(l)=1.0/H(l)+1.0/T(l) C(l)=1.0/H(l) E(l)=OLDD(l)/T(l)+QABST DO 90 N=2,NMONE A(N)=1.0/H(N-1) B (N)=1.0/H(N -1)+1.0/H(N)+1.0/T (N) C(N)=1.0/H(N) 90 E(N)=OLDD(N)/T(N)-RR(N)*RECH(N) A(NMAX)=1.0/H(NMONE) B(NMAX)=1.0/H(NMONE)+0.5yT(NMAX) E(NMAX)=0.5*OLDD(NMAX)/T(NMAX)-0.5*RR(NMAX)*RECH(NMAX) C C ELIMINATION U(1)=B(1) V(1)=E(1) DO 100 N=2,NMAX U(N)=B (N)-(A(N)*C(N-1 ))/U(N-1) 100 V(N)=E(N)+(A(N)*V(N-1))/U(N-1) D(NMAX)=V (NM AX)/U (NM AX) DO 110 NN=l,NMONE N=NMONE-NN+1 110 D(N)=( V(N)+C(N)*D(N +1 ))/U(N)

C DELAYED YIELD DO 115 N=1,NMAX 115 Y(N)=X(N)+FACC*(D(N)-OLDD(N)) C C TEST FOR EXCESSIVE DRAWDOWNS DRA WMX=0.9*B ASE+0.1 *TOP IF(D( 1 ).LT.DRAWMX) GO TO 60 WRITE(6,580) 580 FORMAT(* EXCESSIVE DRAWDOWN’) STOP 60 CONTINUE C C OUTPUT AND THEN CHANGE PARAMETER TIMIN=TIME-TSTART STIMIN=TIMIN*1440 SSTIME=TIME* 1440 DO 120 1=1,NNODES Il=NODEa) 120 DDN(I)=D(I1) DO 46 N=2,100 IF(R(N-l).LT.ROBS.AND.R(N).GE.ROBS)THEN DOBS=(LOG(ROBS)-LOG(R(N-1 )))/(LOG(R(N))-LOG(R(N-1))) SOBS=D(N-l)+DOBS*(D(N)-D(N-l)) GO TO 43 ENDIF 46 CONTINUE 43 CONTINUE IF(TIME.LT.TPLOT) GO TO 44 WRITE(6,560) TIME,TIMIN,SSTIME,STIMIN,D(1),SOBS, 1 (DDN(J) J= 1,NNODES),D(NM AX) 560 FORMAT(’ ’,F9.6,1X,F9.6,1X,F9.3,1X,F9.3,1X,9F9.4) 44 CONTINUE DO 130 N=1,NMAX 130 OLDD(N)=D(N) EF(ALPHA.EQ.0.0) GO TO 6 DELT=TIMIN*0.21143 GO TO 7 6 DELT=TIMIN*0.25892 7 CONTINUE IF(IND.EQ.O) GO TO 40 C C END OF CALC FOR A SPECIFIC TIME DELT=DELI IND=0 TST ART=TIME C C INPUT NEW PUMPING PHASE READ(5,*)QPUMP,TSTOP QABST=0.5*QPUMP/(PI*DELA) IF(QPUMP.LT.O.O) GO TO 41 WRITE(6,6050) QPUMP,TSTOP WRITE(6,6100)(NODE(J), J= 1,NNODES) WRITE(6,6111)R(1),(RDIST(J),J=1,NNODES),R(NMAX) GO TO 40 41 XPLOT (ICOUNT)=S STIME YPLOT(ICOUNT)=SOB S WRITE(4,595)ICOUNT 595 FORMAT(I3) WRITE(4, *) (XPLOT (J), J=1 ,ICOUNT) WRITE(4, *) (YPLOT (J), J=1 ,ICOUNT) WRITE(4,600) PERM,SCON,SUNCON,RWELL,RMAX,JFIX WRITE(4,605) ALPHA,BL,WELLOS,RCH 600 FORMAT(3(1X,F10.5),2(1X,F10.3),1X,I1) 605 FORMAT(4(1X,F10.5)) STOP END

APPENDIX. 5.2.2: MODEL DATA PLOTTING PROGRAM.

C THIS PROGRAM PRODUCES A STRAIGHT LINE PLOT FOR UP TO 300 C DRAWDOWN VALUES. DRAWDOWNS UP TO A MAXIMUM OF 36 UNITS C (METRES OR FEET) CAN BE ACCOMMODATED. THE SCALE OF THE C DRAWDOWN AXIS IS ADJUSTED AUTOMATICALLY. DRAWDOWNS AT C TIMES FROM 0.1 TO 10 000 MINUTES CAN BE PLOTTED. SITE

388 C INFORMATION AND UNITS FOR DRAWEDOWN ARE PRINTED ON THE PLOT C USING THE ARRAYS NAME AND UNIT. THE GRID PRODUCED IS C COMPATABLE WITH CHARTWELL GRAPH PAPER REF 5541. THE CALL C AXISCA LINE MUST BE ALTERED IF PLOTTING DRAWDOWNS GREATER C THAN 36 UNITS. C DIMENSION X(300),Y(300),NAME(20),UNIT(20),XX(300),YY(300) READ(5,15)NAME READ(5,15)UNIT 15 FORMAT(20A4) RE AD (5,2) J 2 FORMAT(I3) READ(5,*)(X(N),N=U) READ(5,3)(Y(N),N=1J) 3 FORMAT(16F5.0) READ(3,2)I READ(3,*)(XX(N),N=1,I) READ(3,*)( YY (N),N=1,1) READ(3,*) PERM,SCON,SUNCON,RWELL,RMAXJFIX READ(3,*) ALPHA,BL,WELLOS,RCH S=Y(1) DO 99 M=2,J IF (Y(M).GT.S)THEN S=Y(M) ENDIF 99 CONTINUE IF (S.LE.0.45)S=0.45 IF (S.LE.0.9.AND.S.GT.0.45)S=0.9 IF (S.LE.3.6.AND.S.GT.0.9)S=3.6 IF (S.LE.9.0.AND.S.GT.3.6)S=9.0 IF (S.LE.18.0.AND.S.GT.9.0)S=18.0 IF (S.LE.36.0.AND.S.GT.18.0)S=36.0 IF (S.GT.36.0) GO TO 98 CALL V80 CALL UNITS(0.8) CALL PICCLE CALL DEVPAP(350.0,320.0,0) CALL WINDOW(2) CALL AXIPOS(l,30.0,20.0,312.5,1) CALL AXIPOS(l,30.0,20.0,180.0,2) CALL AXISCA(3,18,S,0.00,2) CALL AXISCA(4,0,0.1,10000.0,1) CALL GRID(3,0,0) CALL GRID(-2,1,1) CALL PENSEL(2,0.3,1) CALL GRASYM(X,Y,J,3,0) CALL GRACUR(XX,YY,I) CALL PENSEL(1,0.3,1) CALL MOVTO2(40.0,33.0) CALL CHAHOL(’K= *.’) CALL CHAFIX(PERM,-10,5) CALL MOVT02(100.0,33.0) CALL CHAHOL(’S= *.’)

389 CALL CHAFIX(SCON,-10,5) CALL MOVTO2( 165.0,33.0) CALL CHAHOL(’SY= *.’) CALL CHAFIX(SUNCON,-10,5) CALL MOVTO2(225.0,33.0) CALL CHAHOL(’Rw= *.’) CALL CHAFIX(RWELL,-10,3) CALL MOVT02(285.0,33.0) CALL CHAHOL(’Rmax= *.’) CALL CHAFIX(RMAX,-10,3) CALL MOVT02(40.0,23.0) CALL CHAHOL(*JFIX= *.’) CALL CHAINT(JFIX,-1) CALL MOVT02(90.0,23.0) CALL CHAHOL(’ALPHA= *.’) CALL CHAFIX(ALPHA,-10,5) CALL MOVTO2(149.0,23.0) CALL CHAHOL(’BL= *.’) CALL CHAFIX(BL,-10,5) CALL MOVT02(215.0,23.0) CALL CHAHOL(’WELLOS= *.’) CALL CHAFIX(WELLOS ,-7,3) CALL MOVTO2(285.0,23.0) CALL CHAHOL(’RCH= *.’) CALL CHAFIX(RCH,-10,5) CALL MOVTO2(65.0,235.0) CALL CHAHOL(’STRAIGHT LINE METHOD : TIME-DRAWDOWN PLOT*.’) CALL MOVTO2(65.0,230.0) CALL CHAARR(NAME,20,4) CALL MOVTO2(65.0,220.0) CALL CHAHOL(’FIELD DATA INDICATED BY CROSSES*.’) CALL MOVTO2(65.0,215.0) CALL CHAHOL(’RADIAL FLOW MODEL INDICATED BY CONTINUOUS 1 LINE*.’) CALL MOVTO2(165.0,10.0) CALL CHAHOL(’TIME (MINUTES)*.’) CALL MOVTO2(13.0,100.0) CALL CHAHAR(3,1) CALL CHAHOL(’DRAWDOWN ( )*.’) CALL MOVTO2(13.0,139.0) CALL CHAARR(UNIT,20,4) CALL DEVEND GO TO 96 98 CONTINUE WRITE(6,97) 97 FORMAT(’ MAX. DRAWDOWN GREATER THAN 36 UNITS. MODIFY 1 PROGRAM SO S CAN BE GREATER THAN 36 IN THE CALL AXISCA 1 STATEMENT FOR THE Y 1AXIS*.’) 96 CONTINUE STOP END

390 APPENDIX. 5.2.3: PROGRAM TO DRAW TIME DRAWDOWN TYPE CURVE PLOT.

C THIS PROGRAM PRODUCES A PLOT FOR TYPE CURVE MATCHING. THE C PROGRAM CAN ACCOMMODATE UP TO 300 DRAWDOWN VALUES. C DRAWDOWNS CAN BE PLOTTED IN THE RANGE 0.01 TO 100 UNITS C (METRES OR FEET) AND TIME IN THE RANGE 0.1 TO 100 000 MINUTES. C SITE INFORMATION AND UNITS FOR DRAWDOWN ARE PRINTED ON THE C PLOT USING THE ARRAYS NAME AND UNIT. THE GRID PRODUCED IS C COMPATABLE WITH CHARTWELL GRAPH PAPER REF 5846. DIMENSION X(300), Y(300) CHARACTERS NAME(20),UNIT(2) READ 19,NAME READ 18,UNIT 18 FORMAT(2A4) 19 FORMAT(20A4) READ 10, J 10 FORMAT(I3) READ 30, (X(N),N=1,J) 30 FORMAT( 13F6.1) READ 40, (Y(N),N=1,J) 40 FORMAT(16F5.2) CALL DEVBEG CALL DEVPAP(340.0,250.0,0) C CALL UNITS(0.5) CALL PICCLE CALL WINDOW(2) CALL AXIPOS( 1,20.0,20.0,300.0,1) CALL AXIPOS(l,20.0,20.0,180.0,2) CALL AXISCA(4,0,0.1,10000.0,1) CALL AXISCA(4,0,0.1,100.0,2) CALL GRID(-3,1,1) CALL PENSEL(2,0.3,1) CALL GRASYM(X,Y,J,3,0) CALL PENSEL(1,0.3,1) CALL MOVTO2(70.0,225.0) CALL CHAHOL(TYPE CURVE : TIME-DRAWDOWN PLOT*.’) CALL MOVTO2(70.0,215.0) CALL CHAARR(NAME,20,4) CALL MOVT02(140.0,10.0) CALL CHAHOL(’TIME (MINUTES)*.’) CALL MOVT02(10.0,75.0) CALL CHAHAR(3,1) CALL CHAHOL(’DRAWDOWN ( )*.’) CALL MOVTO2(10.0,105.0) CALL CHAARR(UNIT,2,4) CALL DEVEND STOP END APPENDIX. 5.2.4: PROGRAM TO DRAW TIME DRAWDOWN TYPE CURVE PLOT.

C THIS PROGRAM PRODUCES A STRAIGHT LINE PLOT FOR UP TO 300 C DRAWDOWN VALUES. DRAWDOWNS UP TO A MAXIMUM OF 36 UNITS C (METRES OR FEET) CAN BE ACCOMMODATED. THE SCALE OF THE C DRAWDOWN AXIS IS ADJUSTED AUTOMATICALLY. DRAWDOWNS AT C TIMES FROM 0.1 TO 10 000 MINUTES CAN BE PLOTTED. SITE C INFORMATION AND UNITS FOR DRAWDOWN ARE PRINTED ON THE PLOT C USING THE ARRAYS NAME AND UNIT. THE GRID PRODUCED IS C COMPATABLE WITH CHARTWELL GRAPH PAPER REF 5541. THE CALL C AXISCA LINE MUST BE ALTERED IF PLOTTING DRAWDOWNS GREATER C THAN 36 UNITS. DIMENSION X(300),Y(300) CHARACIER*4 NAME(20),UNIT(2) READ 15,NAME READ 14,UNIT 14 FORMAT(2A4) 15 FORMAT(20A4) READ 2, J 2 FORMAT(I3) READ 3,(X(N),N=1,J) 3 FORMAT(13F6.1) READ 5,(Y(N),N=1,J) 5 FORMAT( 16F5.2) S=Y(1) DO 99 M=2J IF (Y(M).GT.S)THEN S=Y(M) PRINT *,S ENDEF 99 CONTINUE IF (S.LE.0.45)THEN S=0.45 ELSEIF (S.LE.0.9.AND.S.GT.0.45)THEN S=0.9 ELSEIF (S.LE.3.6.AND.S.GT.0.9)THEN S=3.6 ELSEIF (S.LE.9.0.AND.S.GT.3.6)THEN S=9.0 ELSEIF (S.LE.18.0.AND.S.GT.9.0)THEN S=18.0 ELSEIF (S.LE.36.0.AND.S.GT.18.0)THEN S=36.0 ELSEIF (S.LE.54.0.AND.S.GT.36.0)THEN S=54.0 ELSE GO TO 98 ENDIF CALL DEVBEG CALL DEVPAP(350.0,320.0,0) C CALL UNITS (0.5) CALL WINDOW(2)

392 APPENDIX. 5.2.4: (CONTINUED)

CALL PICCLE CALL AXIPOS(l,30.0,20.0,312.5,1) CALL AXIPOS(l,30.0,20.0,180.0,2) CALL AXISCA(3,18,S,0.00,2) CALL AXISCA(4,0,0.1,10000.0,1) CALL GRID(3,0,0) CALL GRID(-2,1,1) CALL PENSEL(2,0.3,1) CALL GRASYM(X,Y,J,3,0) CALL PENSEL(1,0.3,1) CALL MOVTO2(65.0,240.0) CALL CHAHOL(’STRAIGHT LINE METHOD : TIME-DRAWDOWN PLOT*.’) CALL MOVTO2(65.0,230.0) CALL CHAARR(NAME,20,4) CALL MOVT02(155.0,4.0) CALL CHAHOL(’TIME (MINUTES)*.’) CALL MOVTO2(7.0,100.0) CALL CHAHAR(3,1) CALL MOVT02(7.0,75.0) CALL CHAHOL(’DRAWDOWN ( FEET )*.’) CALL DEVEND GO TO 96 98 CONTINUE PRINT 97 97 FORMATC MAX. DRAWDOWN GREATER THAN 36 UNITS. MODIFY PROGRAM SO IS CAN BE GREATER THAN 36 IN THE CALL AXISCA STATEMENT FOR Y AXIS 1* .’) 96 CONTINUE STOP END STRAIGHT LINE HETHOD : TIHE-DRAWDOWN PLOT (a) BoBARIA PIEZOd WELL AT A DISTANCE R-50o0 FT Q=16991o60 FT3/D FIELD DATA INDICATED BT CROSSES RADIAL FLOW HODEL INDICATED BT CONTINUOUS LINE

,00 1 1 1 1 1 1 1 1 i i i ’ i" r i i i ■ I i r~1 11 tt ,50 ,00 ANALTTICAL TC; ,50

h 00 ,50- ,00• M. ,50'

-

-

-

: K= 55n00000 S= o000G3 ST= olOOOO Rw= O330 Rmax=- 200000; ; JFIX= 1 ;^LPHA= oOOOOOB .= □0» 0 0 j 0 0i i- i 11 1 t-IELLOS=-- 1--j - loOOOj—a—a i i i RCH-i. j□00000-1— i—» -i- i-i-: -1 TIDE (HINUTES) L0G10

STRAIGHT LINE HETHOD : TIHE'DRAWDOWN PLOT BoBARIA PIEZOo WELL AT A DISTANCE R ~50dQ Q ^ 36993„60 FT3/D FIELD DATA INDICATED BT CROSSES RADIAL FLOW HODEL INDICATED BT CONTINUOUS LINE

□ 00 :----1 i i i i i i i » 1 1 1 1 1 7 1 I1 l I 1 I l i I i 1 1 1 1 1 1 1 1 - 1 i i i i i i ij o50 I pOO 1 o50 STNTHETIC j — 2 o00 ’ LUf- 2 □ 50 -P ^ 3 d00 Ll. ++*<4. 3 p50 S*. 2 4oOO §4o50 §5o00 cc5o50 Q 6 o00 i 6o50 loOO 3o50 o CD o 0 8o50 ; K= 51o00000 S= o00093 ST= .10000 RV- o330 Rnax= 2 0 0 0 0 0 ; ; jfix- i /^LPHA= oOOOOOB o0 0 0 0 0 IIELL0S- I d000 RCH- o 00000 ; 9o00 ■ i . .-t— j - i n j i r * » r * _ _ > —» -i i l l ■ 1 —i i i i i 1 TinE (HINUTES) 3 L0G10 Appendix 5.3.1.A:Comparison of (a) Manual and (b) Model result from B’Baria 0W1. 394 §5o00 o4o50 2 Li.[u 3 u a 00 a oc5o50 H-2o50 ~

DRAWDOWN ( FEET 1 3, 2 2 1 4, 4, 3oQ0fc 6 5, 5, 9, 8 8 6 1 1,

, , , , , 9o00 8 8 3a50 3 a 6o50 B o 4oOO 3o50 ^□50 2 loOO ,50 ,00 ,50 ,00 a 50 o o a 50 a 00 00 00 00 \J\J (a) -1 ;.. - - ■ JI- 1 JFIX- j \ : = 43a59999 K= pedx ...:oprsn f (a) of 5.3.l.B:Comparison Appendix “■ 1 1 " . . JFI = 43a00000 K= . I ' ' AIL LW OE IDCTD T OTNOS LINE CONTINUOUS BT INDICATED HODEL CROSSES BT FLOW RADIAL INDICATED FT3/D DATA Q-36993a6 FT FIELD R-150»0 DISTANCE A AT PLOT PIEZOaWELL :BoBARIA TIHE-DRAWDOWN HETHOD LINE STRAIGHT 1 I l il i l | — TT— from AIL LW OE IDCTD T OTNOS LINE CONTINUOUS BT FT3/D INDICATED 36993o6 - Q HODEL FT CROSSES BT FLOW 150a0 - R RADIAL INDICATED DATA DISTANCE PLOT A AT FIELD TIHE-DRAWDOWN :PIEZOaWELL HETHOD BoBARIA LINE STRAIGHT ' T 1 T T I ’ai 0W2. B’Baria LH= oOOOOOB ^LPHA= LH= aOOOOOB ^LPHA= ---- = o00436 S= = o004B0 S= a -- 1 - 1 « » 1 » . * ■ i ■ » «i 1 1 »r ■ ■«r \,mi 1 i—

Manual a 1 0 0 0 0 0 a (HINU 1 0 0 0 0 0 li n (b) and t ELS loOOO 1ELL0S= £

.. ELS la000 IELLOS= S. W a330 RW= s RW= 3 ) _i " r ------l l 1 1 l ll l l t ■ Model i i i i i i i i i i j ------o330 1 — i — i — iii, result NLTCL SU ANALTTICAL C= 000 : a00000 RCH= TX 200000; RT0X= ^ Rmax= 2QQQQQ; C- 000 i o00000 RCH- TTEI j STNTHETIC I 1 1 i. i 1 1 1 1 I I I 1i —I ^ i iii —i i i - i - i ! t■ r- ^ . . , . r T L0G10 L0G10 - 1-« 1 1 x , : : L J— 1 q l-60 2 - wi-20 cc2-20 §2-00 L o DRAWDOWN ( FEET l l I 1-40 2-80 2-40 1-80 3-40 2-60 3-60 3-20 3-00 ,4 .20L .ooL ,80L 160L ,4oL i20L .00 20i_ 80L 60L 20i_ ooL ooL 60L 40L 60L 80L -40 -20 o -80 -60 - o \J\J 00 -1 L (a)

pedx ...:oprsn f a Mna ad b Mdl result Model (b) and Manual (a) of 5.3.l.C:Comparison Appendix ji= i jfix= : K 51-50000 K= : — ■ ■ i i i ■ i ■ — = 4599S -00165 S= 54-59999 K= FX 1 JFIX= TAGT IEHTO : IEDADW PLOT : TIHE-DRAWDOWN HETHOD LINE STRAIGHT B AIL LW OE IDCTD T OTNOS LINE CONTINUOUS BT INDICATED HODEL CROSSES BT FLOW RADIAL INDICATED DATA FIELD 1 i l'TT i I d -AI IZ- EL T ITNER- 0- F 01916 FT3/D 0=16991-60 FT 400-0 - R DISTANCE AT WELL PIEZO- B-BARIA AILFO HDL NIAE B CNIUU LINE CONTINUOUS BT INDICATED HODEL CROSSES BT FLOW RADIAL INDICATED DATA PLOT FIELD TIHE-DRAWDOWN : HETHOD LINE STRAIGHT rm ’ai OW3. B’Baria from t AI IZ- ELA A ITNER400F 01916 FT3/D 0=16991-60 FT R-400-0 DISTANCE A AT WELL PIEZO- BARIA i i i i i i a 0 LPHA= 1 LH= -OOOOOB ^LPHA= = -00200 S= 1 « i . . i i « i 1 1 i OOOOOBL= 396 iT 1 = 000 ll -00000 .= IE (HINUtIs) TIHE « ST= ST= IE (HINUTES) TIHE ,00000 + \ T -10000 ST= 1 l l I l l l l l 1 1 -10000 «t T u i _ < _ i UELLOS= UELLOS= V ELS -1.000 JELLOS= w -330 Rw= +\ u .330 Ru= \ v 1 1 1-000 ------1 1 1 1 1 1 1 1 V .... NLTCL SU ANALTTICAL RTBX- 200000 RTBX- C= -00000 RCH= : \ 1 1 "1 — | 1 — 11 — ! \ RCH= -00000 •; -00000 RCH= DX 200000; RDaX= X TTEI ; STNTHETIC \ ■N- L0G10 N- ---- 1 1 1 | | 1 1 1 \ DRAWDOWN ( FEET ) DRAWDOWN ( FEET 12 11 10 17 15 13 1R 18 14 14 1B 15 13 11 10 17 12 18 3 2 7 1 9 R fi 4 5 9 5 3 2 4 R 7 R 1 JI= /LH- oOOOOOB /^LPHA- 1 JFIX= I pedx ...:oprsn f() aul n () oe result Model (b) and Manual (a) of 5.3.2.A:Comparison Appendix K 77o73999 K- j : : : ; : ---- JI= / 1 JFIX= j K 92o00000 K= ; —i— i—i—i-iii1— ADAD PEO WL T ITNER-5„ T0- 172785»44FT3/D - 0 FT 50„0 - R DISTANCE A AT WELL PIEZOo DAUDKANDI AIL LW OE IDCTD T OTNOS LINE CONTINUOUS BT INDICATED HODEL FLOW RADIAL IL DT IDCTD T CROSSES BT INDICATED DATA FIELD PLOT : TIHE-DRAWDOWN HETHOD LINE STRAIGHT rm adad 0 1. 0W Daudkandi from AILFO HDL NIAE B CNIUU LINE CONTINUOUS BT INDICATED 172185.,44FT3/D - Q HODEL FT CROSSES oO FLOW BT 50 - R RADIAL INDICATED DISTANCE DATA A AT FIELD WELL PIEZO„ DAUDKANDI TAGT IEHTO s IEDADW PLOT TIHE-DRAWDOWN s HETHOD LINE STRAIGHT V. LH- oOOOOOB iLPHA- = 000S= lOOR= o250 Rw= olOOOO ST= n00050 S= = o00017 S= -f" 1 i ii - i i 1 1 1 -- + \ x + + L. _1 1 l • > . 1 ++4 _L. 7 9 3 l 1 1 * * 1 1 TH (HINUT?S) TIHE 1 „= 2631 .= 5000oOOOOOI TIHE (HINUT?S) (HINUT?S) TIHE ______T olOOOO ST= i — ■ i i I. i i i i i . i ■i -- r ■■ I'mi r~TT 1 1 i r~i i p 57983I fiiil ELS lOORH oOO i oOOOOO RCH- loOOO IELLOS- ______ELS loOOO IELLOS- W o250 RW= 1 1 ■ ■ ll I l l ' l l i i _____ -- t 1 ___ - i i «— i—«ii» .1 i i , l l i . j i iI i i ' 3 I --- NLTCL SL; ANALTTICAL ; V t — ■ ■ ■|iii i i r ~ r ; RT10X= 200000; mx 200000; Rmax- C= OOO ; oOOOOO RCH= — TTEI j STNTHETIC l 1 ■ "I -- i ji_i LOGIO I- ii i _ i - 1 - 1 - 1 1 l~T .1 i ii. -i-i! — L cc5o50 L ~ 3 W §5o00 g^o50 -,

CD o50 \J\J a o d

00 50 00 0 50 00 OO O 00 i Z‘ X ! : : : : : : : : pedx ...:cmaio o () aul n () oe result Model (b) and Manual (a) of 5.3.2.B: comparison Appendix : JFix= JFix= : 8

...... 1 ' l l ' ■ 1 -- 93o00000 s= s= 93o00000 r ~ r 1 - t« ADAD PEO WL TADSAC 100 TQ 112185o4FT3/D - Q FT 150o0 - R DISTANCE A AT WELL PIEZOo DAUDKANDI RADIAL FLOW HODEL INDICATED BT CONTINUOUS LINE CONTINUOUS BT INDICATED HODEL FLOW RADIAL CROSSES BT INDICATED DATA FIELD PLOT : TIHE-DRAWDOWN HETHOD LINE STRAIGHT RADIAL FLOW HODEL INDICATED BT CONTINUOUS LINE CONTINUOUS BT INDICATED HODEL FLOW CROSSES RADIAL BT 112185o£FT3/D - INDICATED Q FT DATA 150o0 - R FIELD DISTANCE A AT WELL PLOT PIEZOo :DAUDKANDI TIHE-DRAWDOWN HETHOD LINE STRAIGHT rm adad OW2. Daudkandi from 1

1 1 I I ... 1 rn \ 1 « » 1 I 1 1 / ------iLPHA= oOOOOOB iLPHA= \ \ ■■■—■ i i = .00028 S= \ \ + "t- 1 ------I -- 00022 2 0 0 .0 V + X + _i 1 ----- • - .000006 r— i m 1

- V x 1 1 — 1 1

—i—i-i-l t _ i j»»» _ i r X 1 \ —r

X 1

1 \

1 | 1 398 -s 5200 -s 5200 - --- IE (HINUTES) TIHE ■ ‘ 11 IE (HINUTES) TIHE T olOOOO ST- ST= ST= 3150oOOOOOI . + x 1

1 -- X 1

1 olOOOO - X 0 00000 ll 1 V I 1 _l. t 1 1 1 1 1 ■ imT 1 M .

x

1 1

1 1

1 _1 IELLOS-lo000 JELLOS= loOOO x --- W o250 RW= RW= RW= x "1 \ ' 1 '"l l 1 | ._l ----- o250 1 ----- 1 II I I 1 —

.1 1 1

i i-t-i —i « 1

1 IT' I.Xi I I ANALTTICAL TCj ANALTTICAL _ RCH= oOOOOO oOOOOO RCH= RfopX= RfopX= RCH= oOOOOO j oOOOOO RCH= TTEI j STNTHETIC - ■ I 1 1 J -- LOGIO 1 1 -----

- 0 0 0 0 0 2 200000;. L 1 1

_l — 1 1 ---

I »- I 1 1

1

1-1 1 1 I.

1 : ; §5o00 g«Co50 Q L }JJ3oOO I i— 2 o~ 50 cc5o50 4o00 s L q qc §5o00 o4o50 W3o00 UJ l — 4o00 s l l — l I 2o 50 3o50 2 lo50 loOO

DRAWDOWN ( FEET ) lo50 DRAWDOWN ( FEET 8o50 8 loOO 6 9o00 Go50 loOO 5 3o50 2 lo50 loOO 8o50 8 lo50 6o50 Bo 9o00 o50 o o o o50 \J\J a o o o 0 0 0 0 0 0 0 0 0 0 50 0 0 (a) K 9o99 S- 95o39999 K- = JI- > 1: JFIX- i pedx ...:Cmaio o () aul n () oe result Model (b) and Manual (a) 5.3.2.C: Comparison of Appendix --- K= K= JFIX= JFIX= 1 • • 1 ii i i j j i III III 105o0000(

TAGT IEHTO : IEDADW PLOT : TIHE-DRAWDOWN HETHOD LINE STRAIGHT DAUDKANDI PIEZOo WELL AT A DISTANCE R - 400o0 FT Q - 112185o4FT3/0 - Q FT 400o0 - R DISTANCE A AT WELL PIEZOo DAUDKANDI RADIAL FLOW HODEL INDICATED BT CONTINUOUS LINE CONTINUOUS BT INDICATED HODEL FLOW RADIAL CROSSES BT INDICATED DATA FIELD ADAD PEO WL TADSAC 400 T - 115£FT3/D 112185o£ - Q FT 400o0 - R DISTANCE A AT WELL PIEZOo DAUDKANDI AIL LWHDL NIAE T OTNOS LINE CONTINUOUS BT INDICATED HODEL FLOW RADIAL CROSSES BT INDICATED DATA FIELD PLOT : TIHE-DRAWDOWN HETHOD LINE STRAIGHT rm adad OW3. Daudkandi from « j « » > 1 1 I M i 1 ---- iLPHA= ------^LPHA= ) S= * 1 1 T -- 1__ .00035 o00032 L ii i .000006 - oOOOOOB - 1 11 - 1 - L 1 1 1 lilt i

»« < 1 . ■ ■ 1 1 399 i < i—« « i r - i r j— .= ~ X TIHE (HINUTis) (HINUTis) TIHE _____ . X IE (HINUTIS) TIHE "1 4000oOOOOOI T olOOOO ST- ST- ST- 5800o00000l 1 » 1 » X i «i — r — i iIi I i I I ■ I ■ Il ■ t i I olOOOO N X 1 ■ » ■ « I . S i iii ______IELL0S= loOOO RCH= oOOOOO i oOOOOO RCH= IELL0S= loOOO - IELLOS- IELLOS- U o250 RU= - Rw V . V — » ■ ihi . ■ t t . « ■ ■ ■ » i ih « 1 I.,iiii , . I i ii i l l l l o250 loOQQ 1 1 t I 3 = + ■ + ANALTTICAL TC; ANALTTICAL ---- w j Xw- F?Tiax= 200000; RCH= RCH= Rmax= Rmax= TTEI j STNTHETIC 1 J 1 t i i _ i — i i i i i i — i _ i i 1 -- LOGIO 1 — — 1 oOOOOO i oOOOOO —i—Ii t i t ; 200000; 1 -

-L i 1 1 1

1

1

1 j I.

A" j ; . § L o i w u ~ 0 0 cc =,1.60 h l

DRAWDOWN ( FEET ) DRAWDOWN ( FEETlo loOO lo80 T o 60 1 Io40 2o40 2 2 2o80 2o60 2o40 2 I 2o80 2o60 3o40 3o20 3o00 2 0 0 d 1 3o60 3o00 3 3o20E 3o60t oOO oCO o □ 80 □ 60 o J V J V 0 6 0 o40 o o o 8 0 8 0 20 20 0 2 0 2 0 2 20 0 0 O O O W BURICHONG PIEZOo WELL AT A DISTANCE R - lOOoO FT Q - 16962o28FT3/D -Q FT lOOoO - R DISTANCE A AT WELL PIEZOo BURICHONG W , j F X= 1 = IX JF jj

-1 |

: x STRAIGHT LINE HETHOD : TIHE-DRAWDOWN PLOT : TIHE-DRAWDOWN HETHOD LINE STRAIGHT x : : : : : : : : : K- 8 1 - K j pedx ...:oprsn f a Mna ad b Mdl result Model (b) and Manual (a) of 5.3.3.A:Comparison Appendix

K= 19oOOOOO S- S- 19oOOOOO K= JFIX= JFIX= 1 1 1 1 1 1 1 1 1 1 1 1 1. 1 0 TAGT IE EHD TH-RWON PLOT TIHE-DRAWDOWN : HETHOD LINE STRAIGHT LINE CONTINUOUS BT INDICATED HODEL CROSSES BT FLOW RADIAL INDICATED DATA FIELD IL DT IDCTD T CROSSES BT INDICATED DATA FIELD AIL LW OE IDCTD T OTNOS LINE CONTINUOUS BT INDICATED 16962o28FT3/D - Q HODEL FT FLOW lOOoO - R RADIAL DISTANCE A AT WELL PIEZOo BURICHONG rm uihn 0 1. 0W Burichong from 1 0 0 0 3 2 ...... 1 1 1 1 / 1 l : 1 11 11 1 1l"T 1 l">‘1 ' , LH= oOOOOOB .LPHA= --- LPHA= LPHA= ...... = o0910Q 0 1 9 0 o s=. j. . + + +• ’ 1 ------0 09100 1— 1 ---- o OOOOOB + +• i 1 — — '■ 1 1 — — ' t 1 -4-- . 1

—» 1 11 1 i. 1 ■ ■ ■ r

400 ~++ = 125o0QQ00 L 0 0 Q Q 0 o 5 2 1 .= IE (HINUTES) TIHE 1+1 T oOO W a250 RW= olOOOO ST= j olOOOO = T S IE (HINUTES) TIHE 2 OOO I 121 oOOOOO . ' V ' ' ' \ 1 -t- 1 ^ t uu. uu. 1

1 1 1 * +. > > ■

1

1 iii_ ■«T ^

ELS lOORH oOO ; oOOOOO RCH= loOOO IELLOS= ELL0 lOOO O loO - 0S L L 1E ------w o250 5 2 o Rw= V V \ " 1 1 l l 1 "I 1 1

----- \ \ 1 L llllll --- \ \ 1 -- V 1 -- 1111. 1 I' 'x ‘+++ ---- ++i : i + ’+ NLTCL TC ANALTTICAL nx 200000; Rnax= na= ; 0 0 0 0 0 2 Rnnax= C oOO : oOOOOO - RCH +-f = ++*-+f — STNTHETIC STNTHETIC 1 » » » « — LOGIO 1 — i —1 1 — « j i 1 1 1 .1 1. j 1 DRAWDOWN ( FEET ) 8o50L i 0 0 a 8 DRAWDOWN ( FEET io50; laoo: SoOo: 5o50; CoOOi 3o5C: 3oOC: 2o50: 6 a6 0 5 6a00L 5o50L 0 0 o 5 , : 50 ,00 -1 « t ■ «_» t 1 1 1 « ~

pedx ...:Cmaio o (a) of Comparison 5.3.3.B: Appendix JFIX- 1 / 1 - 0 X 0 I 0 F 0 J 5 □ 6 2 ! - K j (a) M TAGT IERTO : IEDADW PLOT TIRE-DRAWDOWN : RETHOD LINE STRAIGHT (M 7 JFIX= ALPHA= «OOOOQBL= 1500a00000 LIELLOS= 1500a00000 «OOOOQBL= ALPHA= 00069 JFIX= 23a62999 K= i ir "" i UIHN PEO WL A A ITNE - 5a F Q 16962a28FT3/D - Q FT 150a0 - R DISTANCE A AT WELL PIEZOa BURICHONG IL DT IDCTD T CROSSES BT INDICATED 16962a28 - FT3/D DATA Q FT 150a0 FIELD - R DISTANCE A AT WELL PIEZOa PLOT BURICHONG TIRE-DRAWDOWN : RETHOD LINE STRAIGHT AIL LW OE IDCTD T OTNOS LINE CONTINUOUS BT INDICATED RODEL FLOW RADIAL from AIL LW OE IDCTD T OTNOS LINE CONTINUOUS BT INDICATED RODEL FLOW RADIAL IL DT IDCTD T CROSSES BT INDICATED DATA FIELD uihn OW2. Burichong - LH= oQOOOQB iLPHA= ------0 6 0 0 0 o = S 1 1 » 1 1 1 ----- * X « -- *■ V ii*i X 1 1 1 X 401 1 1 = 2050a000001 0 0 0 0 0 a 0 5 0 2 ------.= IE (RINUTfIS) TIRE IE (RINUT?S) TIRE 0 0 0 0 1 a - T S X L Manual Manual ---- 1----1 X 10000 -- X 1 -- « 1 i 1 and (b) (b) and X ELLOS 1 0 0 o 1 0 S- O L L IE W a250 5 2 a RW- . . j ■ r ■i-'i iT-i ■r i ----- Model Model 1 - - - - 1 — i —■ i ii result NLTCL TO ANALYTICAL - j RCH= 0 0 0 0 0 2 RT10X- - = x a n R C= ; 0 0 0 0 0 o RCH= j . YNTHETI j IC T E H T N SY i t 1 1 1 1 1 » 1 1 1 L0G10 L0G10 00000 0 0 0 0 0 2 i —» i i-t i "j : -lOO UJ l.O i- o80 - L LUlo20 Q 0 2 o cr2 0 0 o 2 § 0 8 o l g 0 6 lo s l

DRAWDOWN ( FEET ) 0 8 o 2 DRAWDOWN ( FEET 0 4 o 2 0 4 o 3 0 2 o 3 0 0 o 3 0 6 o 2 1 0 6 o 3 0 4 . 1 1„20 loOO loOO o80 8 lo 0 6 lo 3o00i 0 6 o 2 n40 2 o60 o20 o 0'V ' □ 40 o n40 n40 o oOO □ 60 □ 80 \J\J 20 40

-1

: pedx ...:Cmaio o () aul n () oe result Model (b) and Manual (a) 5.3.3.C: ComparisonAppendix of ■ ■ ■ ■ ■ ■ : : : : --- K 3oOO S^ ; 30oOOOOO K- j (b) 30o90500S^ 00404 0 4 0 o0 ^ S 0 0 5 0 9 o 0 3 - K FX- 1 JFIX=- x i f j 1 1"1 1 ' T1 1 1 1 1 i ii_i i * i -- 1 = i i i i i i i TAGT IE EHD TH-RWON PLOT TIHE-DRAWDOWN : HETHOD LINE STRAIGHT UIHN PEO WL A A ITNE - 250o0 F Q /D 3 T F 8 2 o 2 6 9 6 1 - Q LINE FT CONTINUOUS 0 o 0 BT 5 2 CROSSES - INDICATED BT R HODEL FLOW INDICATED DISTANCE RADIAL A DATA AT WELL FIELD PIEZOo BURICHONG UIHN PEO WL A ITNER- 5„ F - 16962028FT3/D - Q FT 250„0 -R DISTANCE A AT WELL PIEZOo PLOT BURICHONG TIHE-DRAWDOWN : HETHOD LINE STRAIGHT AIL LW OE IDCTD T OTNOS LINE CONTINUOUS BT CROSSES INDICATED BT HODEL FLOW INDICATED RADIAL DATA FIELD rm uihn 0 3. 0W Burichong from ...... 11 LH= oOOOOOB ^LPHA= / ^LPHA- oOOOOOB 4 v - i ■ —i - i » * i i i i t i i o00410 -H +- t j i « . *+ .* m j —i i i i i . _ i _ ■ . j _ i i « i i i j 402 < 11 Ti E in T 1 THE NUT?S) S ? T U iN m E TIH 1 <*4. T o RW= 0 0 0 0 o1 ST= T .10000 ST- - ■V. o50000 I1ELL0S 0 0 0 o 1 0 6 5 9 05.00000 0 0 0 0 . 5 90 i iii i i i _i« _ _ »j » ...... 1 -- e \ \ \ 1 - (HINUtIs) (HINUtIs) \ l__l \ \ - \ lilt t »« \ I t r r IELLOS=loOOO -- V, RW-

... , _t i . i i , 1 1 ------\ ’i I l t III loOOO = 20Rnx ; 0 0 0 0 0 2 nax= R o250 d 1III l " T T 1 - 250 1 —i i i i l V _i _» « « 3 ------NLTCL SU ANALTTICAL i

C= OOO ; oOOOOO RCH= RCH= oOOOOO i oOOOOO RCH= Rnax= I H H > TTEI j STNTHETIC _ i. i « _ 1 ----- ■ L0G10 L0G10 1 1 --- * i ti-ii 200000; 1— 1 I. 1—l 1 : loOO

DRAWDOWN ( FEETloOOL ) DRAWDOWN ( FEET 2»00 lo80 0 4 o l lo I lo40l 1 2»80L 2»60 2a20 lo o c|. 3o0 2»40 I 3o60t 3, 3, 2o40t 2 2 2 2o60L 3»20| 3, 3o40: □ □ □ □ □ 401 □ 80 □ 60 □ 40 □ 80L □ 60L 06 d 08 o ,

1 00 20 00 20 0 2 20 6 0 2 0 0 80: OOL Q O: OL

-1 : pedx ...:oprsn f a Mna ad b Mdl result Model (b) and Manual (a) of 5.3.4.A:Comparison Appendix : : L K 49809699" K- 1 : : : : : : : : L ; JFIX- 1 JFIX- ;

(a)

(b) K= 508oOOOOO 508oOOOOO K= Flxf f x JF.l TAGT IE EHD TH-RWON PLOT TIHE-DRAWDOWN : HETHOD LINE STRAIGHT HNIAPEO WL T ITNER- 00 T Q CROSSES FT BT 50o0 - R INDICATED DISTANCE DATA A AT FIELD WELL PIEZOo CHANDINA RADIAL FLOW HODEL INDICATED BT CONTINUOUS LINE CONTINUOUS BT INDICATED HODEL FLOW RADIAL CHANDINA PIEZOo WELL AT A DISTANCE R ' 50»0 FT Q FT ' 50»0 R DISTANCE A AT WELL PLOT PIEZOo CHANDINA TIHE'DRAWDOWN : HETHOD LINE STRAIGHT RADIAL FLOW HODEL INDICATED BT CONTINUOUS LINE CONTINUOUS BT INDICATED HODEL CROSSES BT FLOW RADIAL INDICATED DATA FIELD rm hnia W1. 0W Chandina from 1 ...... J LH= OOOt oOOOOO oOOOOOBt= ALPHA= ?S=^ tLPHA- - S d09680 0 09680 0 O OG = OOO I „= oOOOOOOOOOGB 3 0 4 ST- T o10000 ST- IE (HINUTES) TIHE IE (HINUTES) TIHE ■ • - 1 1 1 1 1 1 1 1 1 1 I 1 1 I J I 1 1 1 « 1 0 10000 ItA ±1 ELS lOO C- □00000; RCH- loOOO UELLOS= IELLOS=1„000 RW o250— W o250RW- 1

— — 1 .

1 — 1 —■ j .11 ------SU ANALTTICAL — ; ■— — ^ Rnnax= 200000; C= oOOOOORCH=: Rmax=.200000 STNTHETIC -Httf 1 ■ ■ ■ ■■ ------46o4 FT3/D 84662o04 46»4 FT 84662»04 3/D +-4- + L0G10 L0G1Q 1 ------1 — 1 —iiit* 1 *j § 0 8 o l o h ~ 0 6 o l ^ o L i w LU Q cc l - 2 3o20 2 1 o00 1 3o00 2o80 2„60 2o40 DRAWDOWN ( FEET ) 3o60 3o40 4 DRAWDOWN ( FEET 2 I 3o00L 2o80j 2o60; 2o40: 2 lo80i lo40: o o 08 06 o40 o 0 o o 06 o

,80L ,60 ,00 20 \J\J 00 0 4 20 20 0 2 0 0 \ O V O OL

K 43o50000 K= ; ; i L : - : . ■ : (a) JI- 1 JFIX- ; 45o00000 K= j pedx ...:oprsn f a Mna ad b Mdl result Model (b) and Manual (a) of 5.3.4.B:ComparisonAppendix b SRIH LN HTO : IEDADW PLOT TIHE-DRAWDOWN : HETHOD LINE STRAIGHT J K fb) JFIX= JFIX= ACRCDT CADN PEO WL A A ITNE - 5o FT3/D 150o0 - R DISTANCE A AT WELL PIEZOo CHANDINA CALCoRECoDATA 1 t- “ -1 1

- AIL LW OE IDCTD T OTNOS LINE CONTINUOUS BT INDICATED HODEL CROSSES FLOW BT RADIAL INDICATED FT " 150o0 DATA R 3/D DISTANCE FIELD A AT WELL PIEZOo CHANDINA CALCoRECoDATA STRAIGHT LINE HETHOD : TIDE"DRAWDOWN PLOT : TIDE"DRAWDOWN HETHOD LINE STRAIGHT AIL LW OE IDCTD T OTNOS LINE CONTINUOUS BT INDICATED HODEL CROSSES FLOW BT RADIAL INDICATED DATA FIELD 1 t— r—Fill 1 1

rm hnia OW2. Chandina from 1

1 y 1 v / 1 LH= oOOOOOBIiLPHA= LH= oOOOOOB iLPHA= S= S= S= 1

* 0 0 00890 ST- ST- 00890 00900 1

1

4 _ ■■■■■■ 1 » 1

1

1 404 1 I — « i i i i « — I

= 1 0 0 0 0 0 . 9 2 4 „= v ■ * s = 8o00 I .= 380o00000 TIHE (HINUTES) (HINUTES) TIHE ~ -< — - T olOOOO ST= IE (HINUTES) TIHE V ~i 1 — -- \ 1 0 0 0 0 1 = ~~r" r 1 1 — - \ 1 1 — — V j t « » 1 * i » - « * - I » > i 1 -* 1 i » I « « t « 1—1 1 —i*ii % 1 i«i

1 1 111 ELS loOOO IELLOS= \ IELLOS=- 1„000 \ 4- --- + \ RW= RW= RW= RW= k 1

1 l l l — , V 0 0 1

1 = x a n R 0 5 2 — 250 1

1 — 1 s

1 — 1 I 1 1 l ii"

111 1

1 3 ----- ANALTTICAL ANALTTICAL -- C= OOO i oOOOOO RCH= C- OOO j oOOOOO RCH- RTiax= RTiax= TTEI j STNTHETIC

'+ + * 1 ,— 1 ■

LOGIO 1 L0G10 — 1 ■

_ 200000 200000; j 1 . « — 1 1

_ 1 — 1 1

1

1 1

C T 1

1 111 ' 11 t-t; : : . § L oc 0 1 2 Q o i w L O i-loO a 80 - l l . DRAWDOWN ( FEETI ) DRAWDOWN ( FEET 2 0 4 o 3 0 2 o 3 3o 0 8 o 2 0 6 o 2 0 4 o 2 0 6 o 3 o00 2 I 1 o 08 o o o40 o60 a ,60 ,40 ,20 ,00 20 80 60 40 00 20 60 20 40 20 O -1 : - K 1909 S o00015 3 S^ 129o0099 K- : : -- : : JI= /LH= OOO = 11OOO ELS loOOO JELLOS- .= 5191oOOOOOI /^LPHA= oOOOOOB 1 JFIX= ? pedx ...1 Cmaio o () aul n () oe result Model (b) and Manual (a) of Comparison 5.3.4.C1: Appendix (a) ------JFIX= JFIX= - 4 1 1 K- > 1 I t « t ■ AILFO HDL NIAE B CNIUU LINE CONTINUOUS BT INDICATED HODEL FLOW RADIAL 84662o04FT3/D - Q FT 400o0 - R DISTANCE A AT WELL PIEZOo PLOT CHANDINA : TIHE-DRAWDOWN HETHOD LINE STRAIGHT IL DT IDCTD T CROSSES BT INDICATED DATA FIELD HNIA IZo EL T ITNER 400 T - 84662oQ4FT3/D - Q FT CROSSES BT 400o0 - R INDICATED DATA DISTANCE A AT FIELD WELL PIEZOo CHANDINA AIL LW OE IDCTD T OTNOS LINE CONTINUOUS BT INDICATED HODEL FLOW RADIAL PLOT TIHE-DRAWDOWN : HETHOD LINE STRAIGHT rm hnia W3. 0W Chandina from 1

1 0 » / 00001 1

« 1 1

1 1

1

1 - iLPHA= ) S= S= ) 1 ------0 5 9 0 0 0 1 ------oOOOOOB j 1 « iii i i i i i i i « > — 1 — t 1 « i 405 f" “H 1 .= 3400oOOOOOI TIHE (HINUTES) (HINUTES) TIHE T o10000 ST= ST= ST= IE (HINUTES) TIHE T‘ 1' » 1 ‘ * T — “ '1 1 1 1 I I I. 11 ' »1 ‘T*l T 1 1 1 1 1 1 1 1 t 1 0 W o 0 5 o2 RW- 0 0 0 0 1 i i «.r i i i «.1_ « j i » i j i « _ 1 . « t j i « i i r . « i i i * S ELS loOOO IELLOS= K RW- . .i i i 1 1 1"V 1II 1 1

.. o250 j 1 ------f 1— i—t.. i-i.i 1 j j 1 f 1 ANALTTICAL SlJ ANALTTICAL ■—■■■■■I Rmax= Rmax= C- OOO i oOOOOO RCH- mx 200000; Rmax= RCH= : ^ 3 niir ------TTEI j STNTHETIC _ , -w------1 * ------+ 4 L0G10 L0G10 1 1 oOOOOO; | | ------H- . -H- J 200000; 1—i—i -i | — 1 *

— 1 1111 | j 1 i‘ |. j glo80 L uJlo L f-loOO q qc § ^loBO ~

l l

I

co DRAWDOWN ( FEET ) DRAWDOWN ( FEET lo40 3o40 2o80 2o60 2o40 2 2 3o20 3o60

0 o60 o40 o o o80 o o ,201 ,001 ,801 : 0 ,6 i 0 ,4 ,201 .ooL 180 L ,601 ,401 ,201 i oo L ,801 ,601 ,401 ,201 ,00 o 2 20 J \ J \ 20 00 Q -1 ' ," i r1, i , i " 1 7' : - 1 : : : ------J X 1 / 9 5 lQ o 1 9 3 1 = IX JF : ; j JFIX= 1 1 JFIX= j 138 K= oj 0000' pedx ...2 Cmaio o () aul njb Mdl result Model andj(b) Manual (a) Comparison of 5.3.4.C2: Appendix (a) 1 1 1 1 1- 1 1 1 1 1 V * 1 ----- i i i 1 --- ACRCDT CADN PEO WL A A ITNE " O FT3/D oO 0 0 4 " R DISTANCE A AT WELL PLOT TIHE"DRAWDOWN PIEZOo : CHANDINA HETHOD E CALCoRECoDATA LIN STRAIGHT AIL LW OE IDCTD T OTNOS LINE CONTINUOUS BT CROSSES INDICATED BT HODEL FLOW INDICATED RADIAL DATA FIELD IL AA NIAE B CROSSES BT INDICATED DATA FT 400o0 - R 3/DFIELD DISTANCE A AT WELL PIEZOo CHANDINA PLOT CALCoRECoDATA : TIHE-DRAWDOWN HETHOD LINE STRAIGHT AIL LW OE IDCTD T OTNOS LINE CONTINUOUS BT INDICATED HODEL FLOW RADIAL rm hnia OW3. Chandina from 1 -- 1 -- ■ t t » i1 » i l — 1 1 1 1 T 1 1 1 1gli— ------oOOOOOB iLPHA= o00015 ) S= ------S- 5 1 0 o 0 0 S.- 3 LH= oOOOOOB .LPHA= 1 1 ------1 . i i ii i i .i 1 ------1—i-j_ i i 1—i-j_ -4- .... i

i 406 TH (HINUTES) TIHE 1 T olOOOO ST- . 0 0 0 0 .1 - T S IE (HINUTES) TIHE 10000 ELS loOOO IELL0S= 4100o00000I 1 6 6 0 9 5 . 5 9 3 4 "11 » 1 1 1 1 1 » 1 -"-11 T 1 i i i< 1 i 1 iT f 1 T 1 —1 1 1 1 1 1 1 % ■% V N, , N loOOO JELLOS- __ RW RW- o250 R m ax - - ax m R o250 RW- o250 — i I I I " T~T~IT I I I i 1 ■■■ 1 1 1 1 1 1 1 I i i i i A - I 1 I -1 1 i i ji i * 1 1 H—n : n +H=— NLTCL SU ANALTTICAL RCH= Rmax= C= OOO : oOOOOO RCH= TTEI j STNTHETIC ------' |* 1 1 1 1 | * 1 ' * 1' T 1 f 1 ‘“ I 1 1. ! 1 . i ------L0G10 OOO j oOOOOO l —■ I 11 1 I ■— 1— 1 -- 200000; 0 0 0 0 2 1 -- 1—I « iI Q; i . DRAWDOWN ( FEET ) DRAWDOWN ( FEET 7.50; 2.001 8.001 7.00 8.50 0 .0 8 4.501 4.oo; 2.50; 3.50; 3.001 ,ooi ,50: ,001 ,50 ,00 ,001 ,50L ,001 ,50: , ,501 ,001 ,501 ,00 ,50 ,00 00 501 oot -1 -1 pedx ...:oprsn f a Mna ad b Mdl result Model (b) and Manual (a) of 5.3.5.A:Comparison Appendix (a) ■ ii—ni r ;■

: « r K 0.90)S .00 T .00 w .5 Rmax=200000; .250 Rw= / .10000 ST- 1 JFIX=i 102.0900<) K=: .00102 S^ JFIX=1 : K= j “ (b) T 1 1 1 | | 1 1 1 | ■T 147.0000' 1 1 IL DT IDCTD T CROSSES BT INDICATED DATA FIELD PLOT : TIHE-DRAWDOWN HETHOD LINE STRAIGHT RADIAL FLOW HODEL INDICATED BT CONTINUOUS LINE CONTINUOUS BT INDICATED HODEL FLOW RADIAL FT3/D Q-76982.40 FT 50.0 - R DISTANCE A AT WELL PIEZO. KOTWALI rm owl 0W1. Kotwali from RADIAL FLOW HODEL INDICATED BT CONTINUOUS LINE CONTINUOUS BT INDICATED FT3/D HODEL CROSSES Q-76982.40 FLOW BT FT 50o0 RADIAL - INDICATED R DATA DISTANCE A FIELD PLOT AT WELL TIHE-DRAWDOWN PIEZOa : KOTWALI HETHOD LINE STRAIGHT « ■ 1« \ k

------,LPHA= .OOOOOBI iLPHA= ) .00035S= \ \ \ + 1 |11 1 1 1 T t 1 ------1 1 1 1 1 1 1 1 1 1 1 * + + \ -- + i + + + \ 1 ------oOOOOOB + + 1 ----- 1 - J l l i J 1 1 _L 1 1 1 407 1 .=5000.000001 --- - 4 < IE (HINUTES) TIHE IE (HINUTES) TIHE T . 100R= .250 RW= ST=. .10000 1250.000001 1 « « « « 1 1 -- 1 r > ^ 1

i _ i-i i _ . i l . "I 1 , W " j » i i » « 1 f 1 1 I

T 1 1 1 1 1 1 ------IELLOS= 1.000 ELS .0 C- .00000 RCH-j IELLOS-1.000 1 ------1 i. i. 1 * s v j —> ! 1 1 1l 1 — iii -- L-uu ANALTTICAL TD ANALTTICAL ------■ - H - b " “ - C= .00000RCH=: -- Rmax=200000; r 4 STNTHETIC ■fh - m - H - 4 4 - U -

M H : -M-H 1 1 1 ll l l i i ? , 1 _ J _ 1 1 i i ------L0G10 L0G10 ------—i i", i; i , " i i i— — i — r L__l _l__l_l_l! j iiii i i i i + + : ■ j

CO loOO: 5o50: 5 4o50i 4„00: 3o50: DRAWDOWN ( FEET ) DRAWDOWN ( FEET 2 lo50L 1 5n00 6o50: GoOo; 3o00; 9o00t 8o50L 0 8 8.50 RoOO loOO B„50 R o 00 fin 50 4*50 4o00 3n50 2„50 2 9 n 00 1 1n50 1

n 50

□ n

o a

„50 „00 a nOO

00: o 0 0 0 0 OOL 00 o -1 pedx ...:oprsn f a Mna ad b Mdl result Model (b) and Manual (a) of 5.3.5.B:Comparison Appendix t : : : ! ! JFIX= JFIX= ! ------v ' KOTWALI PIEZOo WELL AT A DISTANCE R - 150o0 FT Q - 16982o40 FT3/D 16982o40 -Q FT 150o0 - R DISTANCE A AT WELL PLOT PIEZOo KOTWALI : TIHE-DRAWDOWN HETHOD LINE STRAIGHT v ' (V) (b) k FX 1 JFIX- k = - 1 s= o o o i i o o n o o n o0Q025 )oooo' S= ______1 ____ rm owl 0 2. 0W Kotwali from IL DT IDCTD T CROSSES BT INDICATED DATA FIELD AIL LW OE IDCTD T OTNOS LINE CONTINUOUS BT INDICATED HODEL FLOW RADIAL AIL LW OE IDCTD T OTNOS LINE CONTINUOUS BT INDICATED HODEL CROSSES FT FLOW BT 150o0 - RADIAL R INDICATED DATA DISTANCE A PLOT AT FIELD WELL TIHE-DRAWDOWN :PIEZOo HETHOD KOTWALI LINE STRAIGHT 1 ■ ■ « 1 1 ■ 1 / ...... a + \ ------LH= oOOOOOB iLPHA= LPHA= + 1_ ------02 T o10000 ST- 00028 1— OOB= 00000ELS loOOO 5000o00000HELLOS- OOOOOBL= j \+ N\ j j i i j j. — i + 1 TIHE (HINUT&S) TIHE 1 -= G500oOOOOOI 408 T o10000 ST= IE (HINUTES) TIHE ELS loOOO IELLOS- ...... W o250 RW= + NLTCL TC- ANALTTICAL Q C- OOO j oOOOOO RCH- Rnnax= Rmax= C- oOOOOO RCH- TTEI j STNTHETIC 1924 FT3/D 16982o40 - i i j i - i j i L0G10 L0G10 200000 2000001 1 i i-i. .i „80 - loOO lo40L lo 2 1 2o40l 2 DRAWDOWN ( FEET ) 3 3o00t DRAWDOWNI ( FEET 3o20: 2 2 I I 3nG0; JFIX- 1 1 JFIX- 3nG0; 3o00: 2„80: 2o60! ° ^ ° ° o40; i lo loOO! 3 2o40; 0 9 9 9 6 4 o 6 9 = K /0| uCQ o oOO □ 60 d 08 o o oOG; 08 06 o 20 0 2 L 0 6 0 2 0 0 0 2 0 2 OL O: O: -1

: : ■ ■ L L : : : : ■ j K= K= j : i ------i i pedx ...:oprsn f a Mna ad b Mdl result Model (b) and Manual (a) of 5.3.5.C:Comparison Appendix

(a) (b) ...... FX 1 JFIX- i A -i 1

1 -1 1 «1 - j 1 iji * r « 1 . . 1 » 1 . ..1 . 1 » « - r « * 1 1 i 1 j i j -1 « «11 1 1 1 1 - 1 0 8 6 1 < i ■i ----- STRAIGHT LINE HETHOD : TIHE-DRAWDOWN PLOT : TIHE-DRAWDOWN HETHOD LINE STRAIGHT KOTWALI PIEZOo WELL AT ADISTANCE R - 400o0 FT Q-36982,,40 FT FT3/D 400o0 - R ADISTANCE AT WELL PIEZOo KOTWALI RADIAL FLOW HODEL INDICATED BT CONTINUOUS LINE CONTINUOUS BT INDICATED HODEL CROSSES FLOW BT RADIAL INDICATED DATA FIELD OWL PEO WL T DSAC " Qo F Q1924 FT3/D Q'16982o40 FT 4Q0o0 " R ADISTANCE PLOT AT WELL TIHE'DRAWDOWN : PIEZOo HETHOD KOTWALI LINE STRAIGHT AIL LW OE IDCTD T OTNOS LINE CONTINUOUS BT INDICATED HODEL CROSSES FLOW BT RADIAL INDICATED DATA FIELD rm owl 0 3. 0W Kotwali from 1 O ---- 6 1—III! O S=- OOO 1

1

1 a 1 ;1 LH= oOOOOOB iLPHA= LPHA=

= o00502 S= 1 i — ■ i + 0 00^16 ST- ST- 00^16 OOOJ 10oOO ELS lOO C= oOOOOO RCH= loOOO HELLOS^ 1000oOOOOO oOOOOOBJ- + + + 1 ■■ 4 ‘t . * + +* 1

t t i 409 1 ------= . IE (HINUTES) TIHE - + ’ ’+ 4- + + + T o00 W o250 RW- o10000 ST= IE (HINUTES) TIHE 6 6 1 ------II 0 1 0 ----- OQ L QOQQQ 10000 1 — 1 —■ T + 1

1

1 , & ELS loOOO IELLOS- RW— RW— \ \ _l . ii 1 0 .« -w- a - A.l.Al -J 1 250 *

A T ------NLTCL TC; ANALTTICAL i ™ N : + RCH= oOOOOO i oOOOOO RCH= nX 200000; RnaX- Rmax= * * STNTHETIC -L- m T i 1 ------L0G10 L0G10 1 — 200000 1

1

1 j j 1

r 2 2 DRAWDOWN ( FEET ) t 0 6 o 2 2 DRAWDOWN ( FEET 2 3, 3, 2 o O loO 3, 3, 2 2oC0L 0 8 o l 0 6 o l 3 3o00fc 3o COt 3o

o , oOO o80 o60 oCO □ o 80 0 ,8 0 ,6 .CO ,20 ,00 ,80 ,60 ,co r L 20 ,00 0 20 6 q o|

-1

------pedx ...:oprsn f a Mna ad b Mdl result Model (b) and Manual (a) of 5.3.6.A:Comparison Appendix • - : J X= 1 / 1 = IX JF : j ■ W BARURA PIEZOo WELL AT A DISTANCE R - 50o0 FT Q - 36982040 FT3/D 36982040 - Q FT 50o0 -R DISTANCE A AT WELL PIEZOo BARURA W - • jfix= = x i f j ; K= 280o0000< ; ■ \ , (b)

STRAIGHT LINE HETHOD : TIHE-DRAWDOWN PLOT : TIHE-DRAWDOWN HETHOD LINE STRAIGHT 62o50000 0 0 0 5 o 2 6 - K i , 1 1 IT T I H1 I T IT 1 1 --- AIL LW OE IDCTD T OTNOS LINE CONTINUOUS BT CROSSES INDICATED BT HODEL FLOW INDICATED RADIAL DATA FIELD AUA IZo EL T DSAC R T - 36982o40 FT3/D 0 4 o 2 8 9 6 3 - Q FT 0 o 0 5 CROSSES - BT R INDICATED DISTANCE PLOT DATA A TIHE-DRAWDOWN AT WELLFIELD : HETHOD PIEZOo E BARURA LIN STRAIGHT AIL LW OE IDCTD T OTNOS LINE CONTINUOUS BT INDICATED HODEL FLOW RADIAL rm aua W1. 0W Barura from 1 — 1 i r ii tt I 0 LH- oOOOOOB kLPHA- 1 S 008000 S=) l ---- LPHA- LPHA- "T11 | l I I I l t | | ""'T1111' ^ 46000 0 0 6 o4 S^ l I lPi I I I l I 1

+ ~ ~ + ~ T ~ + ~ ~ ~ ~ r T 1

o OOOOOB 1

1 1

* 1

’ l i T XjLIJ 1 i 410 1

------■ -t-t- = OOO I oOOOOO .= » oOO I oOOOOO-»= S T - - T S IE HINUTES) (H TIHE T 010000ST= I (HINUTES) E TIH I J—-L 1 -1—L_ 1 I 1 1

H . \ 1H1.I 1 0 i rr 1 1—1—1,1, 1 1 ■ 'i“ rrr> r 0 0 0 0 1 1

1 r t ELS loOOO IELLOS- ELS loOOO IELL0S- Rw= W o250 5 2 o RW— 1 J . 1 I 200000; 0 0 0 0 0 2 ' - x a n R 0 5 2 o + 1 1 ----- L +• 1 11 11 + + 4- NLTCL SU ANALYTICAL ------\ " ; 4" C- OOO : oOOOOO RCH- C= OOO j oOOOOO RCH= Rnax='200000: \ TTEI ; STNTHETIC *\ +* + + - : 4- 1 . -1 1. 1

----- + + \ 0 10 L0G 1 1 1 1 1 1 L0G10 , ------L. ,— _ i. i. _ , — 1 I 1 ri—r i ||. . . I* 1 6P FI3 JF-I "60P 3 3o40L DRAWDOWN ( FEET ) DRAWDOWN ( .FEETloOG; 3o20: 3 ZuQO: 2o4C: 2 Z a 1 lo 60: o40; i In loOO 2„60 2o40i 2 2 0 4 lo lo 3»20L 3o00i 2o80L I I o 80: o a o80 o oOO n o60; o40L o 8 0 06 00: 00: 0 2 2 20 0 2 0 2 0 0 C; OL OL : -1 (a) \ ! j JFIX= 1 1 JFIX= oOOOOOj 9 9 K- ; - L : i- i i » i i - ■ i - r t . pedx ...:Cmaio o () aul n () oe result Model (b) and Manual (a) 5.3.6.B: Comparison of Appendix \ \ = ... L (b) - 3100S o00059 S= 53o15000 K- Cf.^ AIL LW OE IDCTD T OTNOS LINE CONTINUOUS BT INDICATED CROSSES HODEL FLOW BT RADIAL INDICATED FT3/D DATA 76982»40 - Q FT FIELD 150o0 -R DISTANCE A AT WELL PLOT PIEZOo BARURA : TIHE-DRAWDOWN HETHOD LINE STRAIGHT TAGT IE EHD TIHE-DRAWDOWN PLOT : HETHOD LINE STRAIGHT AUA IZo EL T DSAC R 5o F Q 68o0 FT3/D 76982o40 - Q LINE CONTINUOUS FT BT INDICATED CROSSES HODEL FLOW 150o0 BT RADIAL INDICATED - DATA R FIELD DISTANCE A AT WELL BARURA PIEZOo rm aua W2. 0W Barura from ...... t i a t -H= oOOOOOBd-PHA= LPHA= \ o00017 - S \ + 1 —l l 1— 1 1 1 OOO ,■ 13o895IlLO^OO BCH= oOOOOOB .,=■ I o lELLOS^UOQO 1153 84985 X t , X X \ l » ■ i"l i l " i »■ l » l 1 l l l 1 1 4 > ------OOO ELS loOOO oOOOOOI 0 IELL0S= 0 5 4 -- X T olOOOO ST= IE (HINUTES) TIHE T o00 RW— o250 o10000 ST= IE (HINUTES) TIHE X ------, u X i ------o250 t ------—i —r i~r ~ i r i— i— i— NLTCL SL ANALTTICAL C= oOOOOO j RCH= TTEI j STNTHETIC —i—i i i— — i i— i L0G10 L0G10 200000 00000 0 0 0 0 0 2 . i i i ; 0 8 , 1 § L i w ID h- § 60 , i p - 0 ,8 ~ o cc l . 20 ,2 3 0 0 , 2 0 ,4 1 0 0 , 1

DRAWDOWN ( FEET ) 0 ,0 3 0 ,8 2 0 ,6 2 0 ,4 2 DRAWDOWN2 ( FEET 60 ,6 3 0 ,4 3 2 2,001 1,601 1,401 1,201 1,001 2,601 2,601 2,401 1,801 1,801 3o20| 3o20| 3,001 2,801 3 O Kn : JF IX - 1 1 - IX JF J : Kn Oa OUt 60 ,6 0 ,4 0 ,2 J \ J \ a o 20 ,2 ,401 ,401 ,20L □ ,801 ,801 ,60L o 20 00 0 2 K 125, = oQQ02Q S= 0 0 0 0 ,0 5 2 1 K= ; n ^ 1 _

J X- / i - IX JF 9 9 9 5 ,1 ; 0 9 K- ; pedx ...:Cmaio o () aul n () oe result Model (b) and Manual (a) 5.3.6.C: ComparisonAppendix of L ------

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(a) (K) ' AIAJ IZo EL T DSAC R OOO T - 180213o6FT3/D - Q FT lOOOoO - R DISTANCE A AT WELL PIEZOo HAJIGANJ ' v TAGT IE EHD TIHE-DRAWDOWN PLOT : HETHOD LINE STRAIGHT 1 _ j i_

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— 1 .. 1 » — \ \ 1111 1 » .\ 1 lHli*$ax= ______NLTCL SL; ANALTTICAL : \ c OOO : oOOOOO RcW CoOO i O OO RC^oOO TTEI j STNTHETIC ■ —i—i—ii— ii LOGIO LOGIO ___ 0 0 0 0 0 2 0 0 0 0 0 2 i _ _ i __ , __ 11 ] . ] DRAWDOWN ( FEET ) DRAWDOWN ( FEET 14! 15! n ! K= 9olQQQQ 9olQQQQ s\o\ K= ! n 16! 1 -1 ■ pedx ...:oprsn f a Mna ad b Mdl result Model (b) and Manual (a) of 5.3.8.A:Comparison Appendix ; ‘ : JI = 1 = JFIX : i k= k= i ______FX 1 JFIX= HUDGA IZo ELA ITNER5o T -60o4 FT3/D Q-86604o64 FT R-50o0 DISTANCE A AT WELL PIEZOo CHOUDDAGRAH PLOT : TIHE-DRAWDOWN HETHOD LINE STRAIGHT W , v ill A.I-i-l. l - i - I . A l l i 1 ■ • « « « i « « « » 1 O 0 TAGT IE EHD TIHE'DRAWDOWN PLOT : HETHOD LINE STRAIGHT RADIAL FLOW HODEL INDICATED BT CONTINUOUS LINE CONTINUOUS BT INDICATED HODEL FLOW RADIAL CROSSES BT INDICATED DATA FIELD AIL LW OE IDCTD T OTNOS LINE CONTINUOUS BT INDICATED CROSSES HODEL FLOW BT RADIAL INDICATED DATA FIELD HUD GA PEO WL A A ITNE “00 T ~60o4 FT3/D Q~86604o64 FT R“50o0 DISTANCE A AT WELL CHOUDDAGRAH PIEZOo rm hudga OW1. Chauddagram from O 8 O = o20 T . 0 0 0 0 .1 ST- o02000 S=- OOO I - LH- OOO OOO ILO- loOOO IIELLOS- oOOOOO oOOOOOB iLPHA- = o02550 S= 1 *TH (HINUTES) TIHE * T olOOOO ST= IE (HINUTES) TIHE % - - V RW— o250 V \ 1

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1 l I V 1

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1

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lo 5 0 STNTHETIC j — 2 o00 ^ K U , •—2 d 50 LU W 3.00 u_ 3o50 z £o00 + o £ o 5 0 § 5 . 0 0 < _ __ cr5o50 q 6 0 OO ' 6o50 ToOO To50 8 0 OO 8 .5 0 K= 8£o00000 S= 00 0 1 2 0 s r = .1 0 0 0 0 RW= . 2 5 0 Rnax= 20000.I JFIX- 1 /iLPHA- oOOOOOB 9o00 r.= - 3100.000001-*■ i ■ i ■ ■ ■ .TIELL0S= . .. loOOO . .... i RCH- . oOOOOO.... j 1 TIHE (HINUT§S) 3 LOGIO Appendix 5.3.9.C:Comparison of (a) Manual and (b) Model result from Senbagh 0W3. APPENDIX. 6.1: PROGRAM TO ANALYZE STEP DRAWDOWN TESTS (EDEN AND HAZEL METHOD).

C THIS PROGRAM RECALCULATES AND PLOTS TIME/DRAWDOWN DATA c FOR THE EDEN AND HAZEL(1973) ANALYSIS OF STEP TESTS. THIS C PROGRAM IS WRITTEN SPECIFICALLY FOR THE DATA FOR SAUDIA C ARABIA FROM LEWIS CLARK’S PAPER(1977). SOME FORMAT AND WRITE C STATEMENTS MUST BE MODIFIED FOR TESTS WHICH DO NOT HAVE 7 C STEPS. SIMILIARLY SOME OF THE PLOTTING ROUTINES WILL NEED TO C BE ALTERED, INCLUDING THOSE WHICH SCALE THE AXES. 1= NUMBER C OF STEPS. J = NUMBER OF DRAWDOWN MEASUREMENTS. I AND J TO C BE GIVEN ON THE FIRST DATA CARD IN 12,13 FORMAT. MAXIMUM C CAPACITY OF PROGRAM IS 10 STEPS AND 300 MEASUREMENTS DQ( ) IS C AN ARRAY CONTAINING THE STEP DISCHARGE INCREMENTS. DTLME( ) IS C AN ARRAY CONTAINING THE TIMES AT WHICH EACH STEP STARTS. C TIME( ) IS AN ARRAY CONTAINING THE TIMES AT WHICH DRAWDOWNS, C CONTAINED IN THE ARRAY Y, ARE MEASURED. DQLOGT( , ) IS AN C ARRAY CONTAINING THE RECALCULATED TIME DATA. ARRAY X IS AN C ARRAY CONTAINING THE RECALCULATED TIME DATA SUMMED OVER C THE STEPS. IF PLOTTING IS NOT REQUIRED REMOVE RELEVENT LINES. C REMEMBER THE VALUE FOR ’VEND’ IN THE CALL AXISCA ROUTINE FOR C THE X AXIS WILL DEPEND ON THE MAXIMUM VALUE CALCULATED BY C THE PROGRAM FOR ARRAY X. (SO RUN THE PROGRAM WITHOUT THE C PLOTTING ROUTINES TO DETERMINE THIS VALUE). THE VALUE FOR C ’VEND’ FOR THE Y AXIS WILL ALSO DEPEND ON THE MAXIMUM C DRAWDOWN. C C DIMENSION DQ( 10),DTIME( 10),TIME(300),X(300),Y(300) DIMENSION V(300,10),DQLOGT(300,10) DATA DQLOGT/3000*0.0/ READ 1, I,J 1 FORMAT(I2,I3) READ 2,(DQ(K),K=1,I) READ 2,(DTIME(K),K= 1,1) 2 FORMAT(3F10.1) READ 4,(TIME(N),N=1,J) READ 3,(Y(N),N=1,J) 4 FORMATQ3F6.1) 3 FORMAT(16F5.2)

DO 12 K=1,I DO 11 N=1,J V (N,K)=TIME(N)-DTIME(K) IF(V(N,K).LE. 1.0) THEN GO TO 11 ELSE DQLOGT(N,K)=DQ(K)*ALOG10(V(N,K)) ENDIF 11 CONTINUE 12 CONTINUE DO 13 N=1,J

422 APPENDIX. 6.1: (CONTINUED).

XST=0.0 DO 14 K=1,I XST=XST+DQLOGT(N,K) 14 CONTINUE X(N)=XST 13 CONTINUE PRINT 20,(DQ(K),K=1,1) 20 FORMAT(’0\15X,’DQ(1)=’,F10.1,1X,’DQ(2)=’,F10.1, 11X,’DQ(3)=\F10.1) PRINT 21 21 FORMAT(’0\6X,*TIME’,5X,*DQLOGT(N,1)’,1X,’DQLOGT(N,2)’

l,lX ,,DQLOGT(N,3)MX,’X(N)’,8X,’Y(N)’) DO 50 N=1,J PRINT 23,TIME(N),DQLOGT(N,l),DQLOGT(N,2),DQLOGT(N,3),X(N),Y(N) 23 FORMAT(F10.1,7F12.1,F12.0,F12.3) 50 CONTINUE CALL DEVBEG C CALL UNITS(0.5) CALL PICCLE CALL DEVPAP(320.0,270.0,0) CALL AXIPOS(l, 15.0,15.0,280.0,1) CALL AXIPOS(l, 15.0,15.0,230.0,2) CALL AXISCA(3,50,0.0,500000.0,1) CALL AXISCA(3,5,0.0,5.0,2) CALL GRID(3,0,0) CALL GRID(-2,1,1) CALL GRASYM(X,Y,J,2,0) CALL MOVTO2(35.0,260.0) CALL CHAHOL(’EDEN & HAZEL STEP TEST ANALYSIS*.’)

CALL MOVTO2(35.0,250.0) CALL CHAHOL(’DRAWDOWN AGAINST SUMDQLOG(T-TX)*.’)

CALL DEVEND STOP END

423 APPENDIX. 7.1: PROGRAM TO PLOT TRELINEAR DIAGRAM.

C THIS PROGRAM WRITES OUT THE DATE(IDATE), TIME(ITIME), SAMPLE C NUMBER(ISPLE), TEMPERATURE (TEMP), FIELD PH(PHF), LABORATORY C PH(PHL), AND THE CONCENTRATIONS OF CA(X(I)),MG(X(2)), C NA(X(3)), K(X(4)), FIELD HC03((HC03F),X(5)), LABORATORY C HC03((HC03L),X(6)), S04(X(7),CL(X(8)),N03(X(9)) IN MG/L C SUPPLIED BY THE USER WITH A FORMAT SIMILAR TO THAT USED BY C THE INSTITUTE OF GEOLOGICAL SCIENCES. THIS PROGRAM ALSO C CALCULATES AND WRITES OUT MILLI-EQUIVALENTS PER LITRE(F(I)) C FOR EACH IONIC SPECIES, SUMS OF EQUIVALENTS PER LITRE OF C CATIONS(SUMC) AND ANIONS(SUMA) AND PERCENTAGE C MILLIEQUrVALENTS PER LITRE(PF (I)). WHERE DATA IS NOT AVAILABLE C THE PROGRAM WRITES OUT 0.0. CFEPM IS A TABLE OF EQUIVALENT C WEIGHTS FOR CA,MG,NA,K,HC03(TWICE),S04,CL,N03 THE MAXIMUM C CAPACITY OF THIS PROGRAM IS 200 SAMPLES C DIMENSION X(9),CFEPM(9),F(9),IDATE(200),ITIME(200), 1ISPLE(200),TEMP(200),PHF(200),PHL(200),SUMC(200),SUMA(200) 2,PFCA(200),PFMG(200),PFNAK(200),PFHC03(200),PFS04(200) 3,PFCLNO(200),TDS(200) DATA CFEPM/0.0499,0.0822,0.0435,0.0256,0.0164,0.0164,0.0208 1,0.0282,0.0161/ READ 1,N 1 FORMAT(I3) PRINT 10 10 FORMAT(’0’,2X,’DATE’,2X,’TIME’,IX,’SAMPLE’,IX,’TEMP’,2X,’PHF’,IX, l ’PHL’,3X,’ION CONCENTRATION 1ST IN MG/L 2ND IN EPM 3RD IN% EPM ’,8 2X,’SUM‘CATION’,IX,’SUM ANION’) PRINT 11 11 FORMAT(’ ’,13X,’NUMBER’,17X,’CA’,4X,’MG’,4X,’NA’,6X,’K’,5X,’HC03F’ 1,2X,’HC03L’,2X,’S04’,3X,’CL’,5X,’N03’,5X,’EPM’,8X,’EPM’) DO 400 J=1,N READ 2,IDATE(J),ITIME(J),ISPLE(J) 2 F0RMAT(I6,1X,I4,1X,I6) READ 3,TEMP(J),PHF(J),PHL(J) 3 FORM AT(51 X,F4.1,1 X,2F5.2) READ 4,X 4 FORMAT(6X,F7.1,F7.2,F8.1 ,F7.2,F6.1 ,F 6 .1 ,F7.1 ,F8 .1 ,F7.2) IF(X(5).EQ.0.0)THEN X(5)=X(6) ENDIF TDS(J)=X(1)+X(2)+X(3)+X(4)+X(5)+X(7)+X(8)+X(9) DO 20 1=1,9 F(I)=X(I)*CFEPM(I) 20 CONTINUE SUMC(J)=F(1)+F(2)+F(3)+F(4) SUMA(J)=F(5)+F(7)+F(8)+F(9) PFCA(J)=F(1)/SUMC(J) PFMG(J)=F(2)/SUMC(J) PFNAK(J)=(F(3)+F(4))/SUMC(J) PFHC03 (J)=F(5)/SUMA (J) PFS04(J)=F(7)/SUMA(J)

424 PFCLNO(J)=(F(8)+F(9))/SUMA(J) PRINT * PRINT 12, EDATE(J),ITIME(J),ISPLE(J),TEMP(J),PHF(J),PHL(J),X 12 FORMAT(’ ’,I6,2X,I4,1X,I6,1 X,F4.1 ,F5.2,F5.2,1X,F5.1,1 X,F5.2 1,2X,F5.1,2X,F5.2,2X,F5.1,2X,F5.1, 1X,F5.1,2X,F5.1,2X,F4.1) PRINT 13, F,SUMC(J),SUMA(J) 13 FORMAT(’ ’,36X,F5.3,1X,F5.3,1X,F6.3,2X,F5.3,2X,F5.3,1X,F5.3 1,2X,F5.3,1X,F6.3,1X,F5.3,3X,F6.3,5X,F6.3) PRINT 14,PFCA(J),PFMG(J),PFNAK(J),PFHC03(J),PFS04(J),PFCLN0(J) 14 FORMATC \36X,F5.3,1X,F5.3,5X,F5.3,9XJF5.3,5X,F5.3,5X,F5.3) 400 CONTINUE PAUSE CALL T4010 CALL PICCLE CALL DEVPAP(184., 140., 1) CALL WINDOW(2) CALL SHIFT2(90.0,120.0) CALL ROTAT2(-120.0) CALL SHEAR2(2,1.0/SQRT(3.0)) CALL SCALE2(1.0,SQRT(3.0)/2.0) C DRAW PIPER DIAGRAM CALL MOVTO2(0.,0.) CALL LINT02(50.,0.) CALL LINT02(50.,50.) CALL LINT02(0.,50.) CALL LINT02(0.,0.) DO 72 L=l,5 A=L*10. CALL MOVTO2(A,0.) CALL LINTO2(A,50.) CALL MOVTO2(0.,A) CALL LINTO2(50.,A) 72 CONTINUE CALL MOVTO2(60.,0.) CALL LENT02(110.,0.) CALL LINT02(60.,50.) CALL LINT02(60.,0.) DO 73 L=l,5 A=L*10. CALL MOVTO2(60.+A,0.) CALL LENT02(60.+A,50.-A) CALL LINTO2(60.,50.-A) CALL LINT02(110.-A,0) 73 CONTINUE CALL MOVTO2(0.,60.) CALL LENT02(0.,110.) CALL LINTO2(50.,60.) CALL LINT02(0.,60.) DO 74 L=l,5 A=L*10. CALL MOVTO2(0. ,60.+A) CALL LINTO2(50.-A,60.+A) CALL LINT02(50.-A,60.)

APPENDIX. 7.1: (continued).

425 CALL LINT02(00.,110.-A) 74 CONTINUE CALL CHAMOD C PLOTTING ROUTINE DO 30 J=1,N CALL MOVTO2(50.0*PFHCO3(J), 110.0-50.0*(PFS04(J)+PFHC03(J))) CALL DOT(0.5) CALL M0VT02(110.0-50.0*(PFMG(J)+PFNAK(J)),50.0*PFNAK(J)) CALL DOT(0.5) 30 CONTINUE DO 33 J=1,N CALL MOVT02(50.0*PFHC03(J),50.0*PFNAK(J)) CALL DOT(TDS(J)/500.0) 33 CONTINUE CALL DEVEND STOP END

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427 and and cation facies. ion ion percentages, (b): Back’s (1961, 1966) classification diagram for anion

428 APPENDIX. 8.1: PROGRAM TO DRAW RIVER DISCHARGE HYDROGRAPH.

C THIS PROGRAM WORKS OUT TOTAL DISCHARGE FOR WATER YEAR C SUPPLIED FOR RIVER ITCHEN AND PLOTS ANNUAL HYDROGRAPH. C REMOVE GRAPHIC SUBROUTINE CALLS IF TOTAL DISCHARGE ONLY IS C REQUIRED. EDIT THE CALL CHAHOL LINE FOR YEARS OTHER THAN C THOSE GIVEN. C DIMENSION Y(370),X(370) YSUM=0.0 READ 10,(Y(I),I=1,366) 10 FORMAT( 13F6.2) DO 20 J=l,366 Y SUM=Y SUM+Y (J) IF(Y (J).GT.400.0)THEN Y(J)=400.0 ENDIF 20 X(J)=J PRINT 1, YSUM 1 FORMAT(F8.2) CALL DEVBEG CALL PICCLE C CALL V80 C CALL UNITS(0.5) CALL DEVPAP(268.0,350.0,0) C CALL WINDOW(2) CALL AXIPOSQ,40.0,40.0,160.0,1) CALL AXIPOS(l,40.0,40.0,230.0,2) CALL AXISCA(3,19,0.0,380.0,1) CALL AXISCA(3,20,0.0,400.0,2) CALL PENSEL(1,0.3,3) CALL GRID(3,0,0) CALL GRID(-2,1,1) CALL MOVT02(40.0,20.0) CALL CHAHOL(’UPSTREAM DISCHARGE COMILLA STATION *.’) CALL MOVT02(40.0,12.0) CALL CHAHOL(’RIVER GUMTI DAILY FLOW, CUMECS, 1979-1980*.’) CALL MOVT02(40.0,5.0) CALL CHAHOL(’TOTAL ANNUAL FLOW, CUMEC-DAYS: *.’) CALL MOVT02(90.0,30.0) CALL CHAHOL(’DAYS SINCE START OF WATER YEAR*.’) CALL MOVTO2(25.0,160.0) CALL CHAHAR(3,1) CALL CHAHOL(’DISCHARGE (CUMECS)*.’) CALL MOVT02(160.0,5.0) CALL CHAHAR(3,0) CALL CHAFIX(YSUM, 14,4) CALL GRAPOL(X,Y,365) CALL DEVEND STOP END

429 APPENDIX. 8.2: PROGRAM TO SEPARATE BASE-FLOW FROM HYDROGRAPH

C THE METHODS OF I.H.Q978). THE INDEX IS CALCULATED ON A 365 DAY C WATER YEAR BASIS, USING AVERAGE DAILY FLOW DATA, FROM THE C YEARLY COMPUTED SEPARATED BASE-FLOW (BF) AND THE TOTAL C YEARLY FLOW(QSUM). Q(365,4) IS AN ARRAY WHICH CONTAINS THE DAY C NUMBER(Q(365,1), THE CORRESPONDING FLOW(Q(365,2)), THE VALUES OF C THE 5 DAY MENIMA(Q(365,3) AND THE VALUES OF THE TRIAD TURNING C POINTS(Q(365,4). NP(73) IS AN ARRAY CONTAINING THE DAY NUMBERS C OF 5 DAY MINIMA, NT(73) IS AN ARRAY CONTAINING THE DAY NUMBERS C OF TRIAD TURNING POINTS. IN THIS VERSION THE ANNUAL HYDROGRAPH C IS PLOTTED AND THE BASEFLOW IS SEPARATED BY JOINING THE C TURNING POINTS WITH STRAIGHT LINES. C DIMENSION Q(365,4), NP(73), NT(73),BNT(73) DIMENSION Ql(365), Q2(365), Q4(365) DATA Q /l460*0.0/ QSUM=0.0 READ 51,(Q(I,2),I=1,365) 51 FORMAT(13F6.2) C SUM ANNUAL TOTAL FLOW DO 91 1=1,365 Q ( U ) = I 91 QSUM = QSUM + Q(I,2) C FIND MINIMUM Q IN PENTAD IN = 0 DO 100 1=1,361,5 D= 10**6 IN = IN+1 DO 110 J=l,5 IF ( Q(I+J-1,2).GE.D) THEN GOTO 110 ENDIF D=Q(I+J-1,2) JJ=J 110 CONTINUE NP(IN) = I+JJ-1 Q(I+JJ-1,3)=D 100 CONTINUE C FIND TURNING POINTS AND SUM BASEFLOW

L=NP(1) NT(1) = L Q(L,4)=Q(L,2) NTP = 1 BF = Q(L,4)*L DO 200 1=2,72 LA=NP(I-1) LB=NP(I) LC=NP(I+1) D=0.9*Q(LB,3) APPENDIX. 8.2 (CONTINUED).

IF(D.LE.Q(LA,3).AND.D.LE.Q(LC,3)) THEN Q(LB ,4)=Q(LB ,2) NTP=NTP+1 NT(NTP)=LB LD=NT(NTP-1) BF = BF+ 0.5*(LB-LD)*(Q(LB,4) + Q(LD,4)) ENDIF 200 CONTINUE C ADD IN EFFECT OF LAST PENTAD NT(NTP+1) = LC Q(LC,4) = Q(LC,2) IF(NT(NTP).NE.NP(72))THEN LD=NT(NTP) BF=BF+0.5 * (LC-LD) * (Q(LC,4) + Q(LD,4)) ELSE BF = BF + 0.5*(LC-LB)*(Q(LC,4) + Q(LB,4)) ENDIF BF = BF+(365-LC)*Q(LC,4) DO 300 K=1,(NTP+1) BNT(K)=FLOAT(NT(K)) N=NT(K) Q4(K)=Q(N,4) 300 CONTINUE DO 400 L= 1,365 Q1(L)=Q(L,1) Q2(L)=Q(L,2) 400 CONTINUE C RESULTS 7 BH = BF/QSUM PRINT 500, BFI , BF , QSUM 500 FORMATC ’/BFI = \F14.4/’ BF = \F14.4/’ QSUM = \F14.4) PRINT 503,((Q(I,J),J= 1,4),I= 1,365) 503 FORMAT(’ ’,1F14.4,3F14.4) CALL DEVBEG CALL PICCLE C CALL UNITS(0.5) C CALL V80 CALL DEVPAP(268.0,350.0,0) C CALL WINDOW(2) CALL AXIPOS(l,40.0,40.0,160.0,1) CALL AXIPOSO,40.0,50.0,230.0,2) CALL AXISCA(3,19,0.0,380.0,1) CALL AXISCA(3,20,0.0,400.0,2) CALL PENSEL(1,0.3,3) CALL GRID(3,0,0) CALL GRID(-2,1,1) CALL MOVT02(40.0,30.0) CALL CHAHOL(’UPSTREAM DISCHARGE AT COMILLA STATION *.’) CALL MOVT02(40.0,22.0)

4 3 1 APPENDIX. 8.2: (CONTINUED)

CALL CHAHOL(’RIVER GUMTT DAILY FLOW, CUMECS, 1980-1981 *.’) CALL MOVT02(90.0,40.0) CALL CHAHOL(’DAYS SINCE START OF WATER YEAR *.’) CALL MOVTO2(40.0,15.0) CALL CHAHOL(’TOTAL ANNUAL FLOW CUMEC-DAYS: *.’) CALL MOVT02(150.0,15.0) CALL CHAFIX(QSUM, 14,4) CALL MOVT02(40.0,8.0) CALL CHAHOL(’BASEFLOW, CUMEC-DAYS:*.’) CALL MOVT02(150.0,8.0) CALL CHAFIX(BF, 14,4) CALL MOVTO2(40.0,1.0) CALL CHAHOL(’BASEFLOW INDEX:*.’) CALL MOVT02(150.0,1.0) CALL CHAFIX(BFI, 14,4) CALL MOVTO2(25.0,160.0) CALL CHAHAR(3,1) CALL CHAHOL(’DISCHARGE (CUMECS)*.’) CALL PENSEL(1,0.3,3) CALL GRAPOL(Ql,Q2,365) CALL GRAPOL(BNT,Q4,(NTP+1)) CALL DEVEND STOP END

4 3 2