The author of this book has traveled extensively in many desert and semi-desert territories of the U.S.S.R., Morocco, Tunisia, the Egyptian region of the U.A.R., Pakistan and India where he realized the importance of water for the reclamation of vast areas of arid and semi-arid lands. During his visits the author became acquainted with the theory and practice of land irrigation in many countries of North Africa and Asia. The present book is the first attempt at generalizing the vast amount of material dealing with the hydrogeology of the irrigated lands of the arid zone of North Africa and Asia, stretching from the African coastline of the Atlantic Ocean to the central parts of Asia. Outlined in this book are the origin and distribution of saline lands in the deserts of North Africa, the Arabian Peninsula, the Iran Highlands, Middle Asia, China and Mongolia. A description is given of the surface waters in irrigated areas of the arid zone together with the sources, movement and draining, infiltration, condensation and evaporation of water in the desert and semi-desert territories. The book gives a sketch of the regime of free ground waters in irrigated areas and methods of studying it, problems of water balance and its forecasting, based on experimental research and simple theoretical calculations. Principles of the hydrogeological division of irrigated lands into districts and basic measures to prevent their salinization are also given. The book can serve as a textbook for engineer-hydrogeologists, melioration specialists and students at specialized hydrogeological and agricultural institutes and schools.