Final answer:
A watershed is the land area that delivers runoff, sediment, and any dissolved substance to a stream. It is the region drained by a river or stream.
Step-by-step explanation:
A watershed is the land area that delivers runoff, sediment, and any dissolved substance to a stream. It is the region drained by a river or stream. Precipitation that falls into the watershed will eventually end up in the river if it does not evaporate or seep into the ground. The contributions of surface runoff and groundwater seepage to river discharge depend on various factors such as precipitation patterns, vegetation, topography, land use, and soil characteristics.
For example, after a heavy rainstorm, river discharge increases due to surface runoff. However, the steady normal flow of river water is mainly from groundwater that discharges into the river. Gravity pulls river water downhill toward the ocean, and along the way, the moving water can erode soil particles and dissolve minerals. Groundwater also contributes a large amount of the dissolved minerals in river water.