This book attempts to describe runoff, infiltration and subsurface flow of water by adopting a holistic approach rather than restricting itself to a particular section of the hydrological cycle. It includes reports on recent studies which have led to a better understanding of a variety of problems prevailing in semi-arid and arid zones. Emphasis has been put on studies which incorporate the use of advanced applied techniques developed for dealing with these water problems. This has been done with the hope of providing guidance in solving special problems of water supply and safe reuse of wastes, liable to arise during future development in these zones. Audience: This volume is of value for experts from academia, consultancies and water resources planning and management institutes interested in hydrological problems in semi-arid and arid regions.