Drainage basins

A river's water can fluctuate over time. Understanding the hydrological cycle is useful in order to understand how and why the amount of water fluctuates.

A drainage basin is the area of land around the river that is drained by the river and its tributaries.

  • Watershed - the area of high land forming the edge of a river basin.
  • Source - where a river begins.
  • Mouth - where a river meets the sea.
  • Confluence - the point at which two rivers meet.
  • Tributary - a small river or stream that joins a larger river.
  • Channel - this is where the river flows.
The river starts at the source, and flows down the channel to the mouth. Tributaries flow into the channel at confluences. The boundary of the floodplain is the watershed.