Fundamentals of Subsurface Hydrology

The author has made efforts to present the fundamentals of the subsurface hydrologic processes in logical order by explaining trivial details to facilitate the learning of the subject by ‘individual study’. Consequently, he has endeavored to analyze the fate of water and water borne pollutants once they infiltrate the land surface. Thus, the transport of water and solutes in the unsaturated and saturated domains beneath the land surface is the main theme of the book. These subsurface flow processes constitute the necessary elements of the ‘Fundamentals of Subsurface Hydrology’. The essential mathematical steps with requisite explanations are given throughout the book to assist ‘individual study’. Knowledge of calculus is a prerequisite for in-depth understanding of the book. Analytic solutions in Chapters 10 and 11 are developed using the Laplace transform technique. The presentation of the ‘Fundamentals of Subsurface Hydrology’ is arranged into twelve chapters. Concept of subsurface flow along with the brief history of the evolution of ideas of saturated and unsaturated flows are described in Chapter 1. Chapters 2, 3 and 4 deal primarily with the water in the porous geologic formation by comprehensively describing the (i) porous geologic matrix, (ii) elements of fluid mechanics, and (iii) water beneath the land surface. Chapters 5, 6, 7, 8, and 9 form the core of the book. They elucidate, in the same order, on (i) groundwater movement, (ii) differential equations of groundwater flow, (iii) water movement in vadose zone, (iv) pollution of subsurface water, and (v) subsurface flow equations in curvilinear coordinates. In these chapters the governing differential equations for water and solute transport in saturated and partially saturated geologic formations are derived using the principle of conservation of mass and the appropriate transport laws. Generalized form of the boundary conditions are written to complete the mathematical formulations of the transport processes in subsurface hydrology. Most of the derivations appearing in these chapters are elucidated with the help of the adequate number of mathematical steps to enable the reader to easily grasp them. Once a physical problem is formulated, it could be solved using different analytical and numerical techniques. Analytic solutions of some simple groundwater flow problems are derived in chapters 10 and 11. They comprise of (i) analytical modeling of unconfined groundwater flow, as well as (ii) hydraulics of wells, in confined and unconfined aquifers. Many of these solutions are utilized for determining the aquifer parameters. Chapter 12, the last chapter of the book, lays the theoretical foundation for the finite region approach for estimating natural groundwater recharge from precipitation and irrigation. It elucidates the principles, methods and structures for artificial groundwater recharge. Land and stream management works which store rain water, modulate runoff, and enhance groundwater recharge are adequately discussed using research data from a 850 ha integrated watershed management project in Madhya Pradesh, and field data from a 476 sq Km catchment area of Arvari river in Rajasthan, India. Improvement in groundwater quality due to recharge is demonstrated using field observations. The book is intended to serve the needs of the students, teachers, researchers, and field practitioners in the disciplines of agricultural, civil, hydrologic, and environmental engineering, water resources, soil physics, hydrogeology, and earth sciences, who are interested to learn the fate of water and solutes in the weathered zone constituting the upper mantle of the earth. The author is of the view that the book would meet its basic objective of facilitating in-depth learning of the subject by ‘individual study’.