river science definition

A wide, natural stream of fresh water that flows into an ocean or other large body of water and is usually fed by smaller streams, called tributaries, that enter it along its course. A river and its tributaries form a drainage basin, or watershed, that collects the runoff throughout the region and channels it along with erosional sediments toward the river. The sediments are typically deposited most heavily along the river's lower course, forming floodplains along its banks and a delta at its mouth.