Factors affecting the speed of a river: The main factor affecting the speed of a river are the gradient and roughness of the channel and the wetled perimeter gradient.
1) Gradient: It refers to the drop in elevation of the river channel as the river flows down the hill. If the gradient is steep, the rivers flow quickly, whereas if the gradient is gentle the river flows slowly. In the upper course, the river flows rapidly through a steep gradients. On the other hand, the middle and the lower course, the river flows gently through a greater gradient.
2) Roughness: As water flows through a river channel; it encounters obstacles such as rocks, boulders, numerous river bed and underwater vegetation obstacles cause friction between the river and the channel. Rougher channels will reduce the speed of the river due to the higher friction.
3) Wetled perimeter: When the wetled perimeter is large, more water comes in contact with the channel causing more friction. When the friction is high the flow of the river becomes slow on the other hand when the wetled perimeter is small, less water flow along the channel causing less friction. When the friction is less, flow of water is fast.
