USA Water is an irreplaceable natural resource without which humans can neither live nor be active.
Fresh water is a fundamental resource, integral to all environmental and societal processes.
It is a critical component of ecological, physical, and aquatic systems. Fresh water is a renewable resource, which is continuously cycled by the constant flow of solar radiation, which evaporates water from the ocean and land and redistributes it around the globe. Scientists, studying specific issues such as desertification, waste management, and flood control, have established methods for managing water resources based on watersheds as a basic mapping unit in dealing with these spatial problems. These requirements have caused a continuously growing demand for drainage basin mapping. The development of increased computer technology, GIS algorithms and appropriate models have also lead to an increased demand for drainage basin data.