General Introduction And Hydrologic Definitions
Hydrologic techniques, capably applied, are essential for the sound development and management of water resources. The population of our country is increasing rapidly but water use outpaces the growth in population and thus creates demands for water that frequently impinge on the available supply. The mounting demands, the increasing areas of conflict, and the rising rate of flood damage impel a need for refined methods of analysis of water problems. Consider the planning for a water supply for a town or an irrigation project: How much water is available in the river? How does this supply compare with the demand? Is reservoir storage needed? If so, how much? Riverflow varies and therefore reservoirs are built to store water to tide over from times of excess to times of deficiency. The problem is to design the storage reservoir so that the demands for water can be supplied despite variations in riverflow. Reservoirs that are built too small cannot do the job expected of them.
Hydrologic Definitions, Manual of Hydrology; Part I., General Surface-Water Techniques