Wanderlust World Wanderlust World The downstream portion of a river is the section that flows away from its source toward its mouth. It is the lower part of the river system, where the water is nearest to the sea, ocean, or lake into which the river empties.
This segment is also commonly referred to as the lower course or lower reaches of the river.
In the downstream area, the river typically becomes wider, deeper, and slower-moving. Sediment deposition increases, often forming deltas or floodplains near the mouth.