Describe the hydrologic cycle.
Condensation, precipitation, runoff, infiltration of substrate, transportation. The velocity of runoff is the biggest factor in determining how much erosion occurs.
What factors determine stream velocity?
The incline of the stream bed. After a time, the erosion caused by the stream will cause this to even out into a smooth plane. The shape of the channel also can cause friction, as well as the bottom surface of the channel.
What is a stream's competence?
This refers to the maximum size of sediment that the stream can transport.