what are watersheds

A watershed is an area of land where all flowing surface water converges to a single point, such as a river mouth, or flows into another body of water, such as a lake or ocean. It is also referred to as a drainage basin, catchment area, catchment basin, river basin, water basin, and impluvium. The size of a watershed can vary from less than an acre to thousands of square miles depending on a number of factors, including its connectivity. Watersheds can include forests, agricultural lands, cities, and various other types of land cover. The boundaries of a watershed are determined by watershed delineation, which is a common task in environmental engineering and science. The process of finding a drainage boundary is referred to as watershed delineation. Watersheds are critical to our social, environmental, and economic well-being. They are a logical unit of focus for studying the movement of water within the hydrological cycle. Because drainage basins are coherent entities in a hydrological sense, it has become common to manage water resources on the basis of individual basins. Everyone lives in a watershed, and the U.S. Geological Survey numbers watersheds using a system of hydrological unit codes (HUCs). The Mississippi River watershed, for example, drains an area of about 1.2 million square miles from all or parts of 32 states and two Canadian provinces, accounting for about 40% of the continental U.S..