For several millennia water supplies have been managed by engineers without recourse to the science of hydrology. Over the last three centuries, however, hydrology has been evolving from a science to refine engineering design to an all-embracing environmental science with implications for water quality and ecology as well as for water resources, floods, and droughts. In this book the author describes the basic system of water circulation and patterns of runoff, and the major ways in which human occupation of the Earth alters both processes and patterns. The river basin or catchment area is stressed not only because of its geographical appeal but also because it is the basic experimental and data-gathering unit, and the fundamental unit for water management. A number of methodological frameworks are explored. Most of these are scientific since an acceptable replacement is still to be found for problem-solving by data collection, analysis, and prediction. Key data are still relatively scarce for the freshwater environment, however, so there is room for non-digital values - such as attitudes, preferences, policies, and laws. Having developed a holistic approach to river basins Professor Newson concludes by considering the utility of current knowledge of environmental hydrology to provide a practical response to the conservation of fresh water. This book should be of particular value to undergraduates in departments of geography, environmental science, biology, and planning although all those concerned with the sustainable management of freshwater environments - planners, agriculturalists, industrialists, conservationists, and engineers - will find answers to their questions on the basic techniques and systems in hydrology.