What is the term for the branching channel of a river found at its mouth?

The term for the branching channel of a river found at its mouth is a "distributary." Distributaries occur when a river splits into several smaller channels as it approaches its end point, usually flowing into a larger body of water such as an ocean or sea. This branching pattern helps to distribute water and sediment over a wider area, which can lead to the formation of fertile land in deltas.

Understanding distributaries is crucial for grasping how river systems operate, especially in deltas, where sediment deposition creates new land and shapes the local ecosystem. In contrast, tributaries would refer to smaller rivers or streams that flow into a larger river, while estuaries are areas where freshwater from rivers meets and mixes with saltwater from the ocean. A delta describes the landform created by sediment deposition at the mouth of a river, often characterized by its distributaries.