However, these are transported at different rates. A stream is in dynamic equilibrium and can be thought of as using various mechanisms to adjust itself when the balance of one or more variables is changed.
Streams have a lot of energy at their headwaters.
Velocity of a stream has the most relationship to its competency and capacity. A change in the form of a channel affecting its velocity will change both its competency and capacity. A headcut may move up a stream until it is checked by bedrock, at which point a waterfall will occur. This leaves friction to be applied primarily to the bed and banks. An entrenched stream loses its access to the floodplain.