The development of environmentally sound groundwater resources has recently become a high priority throughout the world. Many countries are currently developing comprehensive regulations for the management of groundwater resources. Within this framework an assessment of renewable groundwater resources is one of the most important factors.This book is based on the author's many years of experience in the assessment of surface and subsurface water resources, field experiments and computer oriented work, in both developed and developing countries. An environmental approach is followed. Groundwater resources are seen as a part of the aquatic ecosystem in which not only geology but the whole lithosphere, vegetation, surface resources and atmosphere play an equally important role.Both simple and advanced models are presented, which can also be applied to complicated geological structures where standard groundwater models fail to operate. Conceptual and stochastic models are presented in a form which the reader can use as a guide for further model development - an approach much in demand in regions where many different features and a variety of data are available. Experimental work leading to the identification of groundwater resources is also broadly discussed.The book will prove valuable to students at university level, researchers, institutes, departments, and consultancies involved in water resources.