Definition - What does River Basin mean?
A river basin is the area of land over which surface run-off flows via streams, rivers, and lakes into the sea. A river basin sends all the water that falls within it to a central river, and from there to the ocean. A river basin drains all of the land around a major river. Basins are divided into watersheds, or land areas that surround a small, river or lake.
Safeopedia explains River Basin
River basins drain all of the land that surrounds a major river. The way that people treat their natural environment including the soil, water, air, plants and animals has an effect on the efficiency of river basins. When a river travels downstream, it carries with it gravel, sand and silt. In addition, bacteria and chemicals are transported. The main features of a river basin are the source, mouth, watershed, tributary and confluence.