About the Book :

The book on numerical groundwater hydrology is written for undergraduate and graduate students of civil engineering, environmental engineering, agriculture engineering, earth sciences and those who are pursuing a degree or diploma in water resources development, water resources management, hydrogeology, hydrology, environmental science and engineering. Teachers, researchers, planners, administrators and managers dealing with water will find it a useful reading material.

The book introduces the subject of groundwater followed by its exploration in second chapter. Chapter 3 looks to various practical applications of Darcy law whereas various governing equations are discussed in chapter 4. Chapters 5 and 6 consider various aspects of steady and time variant well hydraulics. Analytical and analog methods of solution are considered in chapter seven, whereas sea water intrusion is focused in chapter eight. Finite difference and finite element groundwater modeling is discussed in greater detail in chapter nine. Inverse modeling involving genetic algorithm, simulated annealing and conventional methods of numerical optimizations are dealt in chapter ten. Chapter eleven aims to look at the important aspects of groundwater quality modeling in greater detail. Various modeling techniques along with numerical dispersion are discussed in this chapter. Chapter twelve examines the important aspects of artificial recharge of groundwater.

Except chapter one and twelve, all chapters are provided with several numerical examples. The book aims to provide enough confidence and theoretical background for a groundwater modeler to use the available soft wares with confidence after going through chapters nine, ten and eleven.

About the Author

Prof. Ashok Kumar Rastogi obtained Ph.D. Degree in Civil Engineering from the University of Birmingham, UK in 1983. He has special interest in ground water systems planning and management, aquifer remediation, pollutants movement in the subsurface, sea water intrusion, its hydrodynamics and inverse modeling for aquifer systems. He has supervised several M.Tech. and Ph.D theses and undertaken sponsored and consultancy research projects in these areas. In 1987, he was in USA to work on systems modeling and optimization. He has reviewed a number of research papers for ASCE, Institution of Engineers, Hydrology Journals, and projects for DST, IARI and other organisations. He has been external examiner to Ph.D. and M.Tech. theses from various leading institutions. Participated in many National/International conferences, chaired sessions and delivered keynote addresses in the area of water resources engineering. He has published several papers in refereed research journals, offered courses in the areas of Ground Water Hydraulics, Fluid Mechanics, Environmental Impact Assessment of Water Resources Projects, Subsurface Hydrology, Water Wave Mechanics and Geophysics to graduate and post graduate students at IIT Bombay . He was a visiting professor at the Univ. of Auckland , New Zealand and at the University of Incheon , South Korea . He is Fellow/ Member of several professional organizations, and presently working as Professor, Department of Civil Engineering at I I T Bombay. He was also Associate Dean Planning at IIT Bombay for over three years. He has widely traveled around the world in pursuit of his academic engagements.

Contents

1. Introduction to Groundwater Hydrology 1 General Water Balance 3 Regional Groundwater Balance 4 Distribution of Subsurface Water 4 Different Types of Aquifers 6 Occurrence of Groundwater in Hydrogeologic Formations 9 Structure and Types of Wells 13 Components of Groundwater Studies 13 Questions 18

2. Geophysical Methods in Groundwater Exploration 19 Introduction 19 Electrical Resistivity Method 21 Analytical Derivation for Resistivity in Vertical Electrical Sounding 26 Seismic Refraction Method 33 Determination of Aquifer Thickness 44 Determination of the Top of the Sloping Aquifer 53Estimation of Sloping Aquifer Thickness 66 Problems 73 Questions 76

3. Application of Darcy's Law and Aquifer Characteristics 79 Darcy's Law 79 Determination of In Situ Hydraulic Conductivity 113 Flow through a Fractured Medium 133 Problems 140 Questions 144

4. Governing Equation of Groundwater Flow in Aquifers 145 Derivation of General Differential Equations for Groundwater Flow 145 Regional Groundwater Problems 152 Governing Equations for Transient Flow Conditions 155 Consideration of Various Recharge and Discharge Terms 172 Applicable to the Equation Governing Groundwater Flow in Porous Media Problems 177 Questions 179 Appendix I 180

5. Steady State Well Hydraulics 183 Analysis of Steady Radial Flow Towards a Well in a Confined Aquifer 183 Dupuit Forcheimmer (DF) Theory of Free Surface Flow 223 for Steady Flow in Unconfined Aquifers Analysis of Steady Radial Flow in Laterally Stratified Phreatic Aquifers 239 Problems 256 Questions 260

6. Analysis of Unsteady Radial Flow to Wells 263 Analytical Solution of Unsteady Radial Flow to a Well 264 Flow Through a Leaky Confined Aquifer 315 Application of Image Well Theory to Simulate 318 Hydrogeological Boundaries Further Application of Pumping Test Analysis 357 Interference between Wells 370 Partial Penetration of Wells 377 Collector Wells (French Well or Ranney Well) 382Delayed Yield 384 Problems 390 Questions 394 7. Methods of Solution 39

7 Analytical Solutions 397 Steady Flow in Homogeneous Isotropic Confined Aquifer 398 of Variable Thickness Flow Net Analysis 432 Flow Net Construction 434 Physical Models 440 Electrical Analog Model 447 Problems 480 Questions 486

8. Sea Water Intrusion in Coastal Aquifers 489

Ghyben-Herzberg Theory 489 Shape of Interface in Circular Oceanic Islands 521 To Locate the Actual Interface for a Confined Aquifer 523 Modeling Equations in Sea Water Intrusion 535 Prevention and Control of Sea Water Intrusion 541 Case Study Involving Sea Water Intrusion Modeling 544 Problems 555 Questions 557

9. Models for Groundwater Analysis 559 Introduction 559 Major Applications of Groundwater Models 560 Numerical Modeling of Groundwater Systems 562 (Finite Differences) Numerical Examples 569 Time Variant Groundwater Flow Modeling 593 Groundwater Modeling by the Finite Element Method (FEM) 624 Galerkin's Finite Element Formulation 631 Case Study (FEM & FD) 653 Problems 670 Questions 678

10. Inverse Modeling in Groundwater Flow 681 ` The Importance of Inverse Modeling 681 Direct Method of Parameter Estimation 691 Indirect Method of Parameter Estimation 696 Genetic Algorithm (GA) 715 Case Study 1 723 Inverse Problem by Simulated Annealing Method 732 Case Study 2 753 Problems 748 Questions 749

11. Pollution of Groundwater 751 Introduction 751 Hydrodynamic Dispersion of Pollutants in Groundwater Environment 770 Advection – Dispersion Equation for Modeling of 777 Contaminant Transport in Porous Media Direct Measurement of Average Linear Velocity 794 Experimental Determination of a 797 Models for the Prediction of the Quality of the 813 Groundwater Environment (Finite Difference and Finite Element) Solute Transport Modeling by the Finite Element Method 841 Case Study 860Modified Method of Characteristics (MMOC) 871 Particle Tracking Method 880 Random Walk Transport Model 897 Protection of Groundwater Environment 904 Problems 907 Questions 909

12. Artificial Recharge of Aquifers 913

Introduction 913

Current Trends in Artificial Recharge 915

Case Study 1 932

Case Study 2 939

Case Study 3 944

Closure 948

Questions 949

Appendix 951

References and Selected Bibliography 957

Index 977