Erosion, transportation and deposition all occur in a river. Moving from the upper course to the lower course, the rates of erosion, transportation and deposition change.
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 tributaryA small river that joins the main river channel..
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