Running water is a very potent agent of erosion in humid regions. The action of running water which include streams, rivers, and rainfall, have constantly shape the surface of the surface of earth through erosion and depositional processes.
River (or running water) is one of the most active agent of land form development. The power of a river is derived from its mass (volume) and its velocity (speed).
STAGES OF RIVER
There are three stages of a river:
- Upper course/current course/mature stage
- Middle course/valley course/mature stage
- Lower course/pain course/old stage
This is found in mountains or hilly regions. The river is flowing through a steep gradient therefore the velocity is high. The upper course is characterised by numerous small channels or streams which flow into each other as tributaries until they all eventually converge on the main channel.
The primary work of the river at this stage is erosion especially vertical erosion, otherwise called down – cutting. This leads to the formation of a v-shaped valley.
Down – cutting may proceed at such a fast rate that the river may flow through a deep narrow channel which has precipitous or almost vertical sides such a deep narrow, almost vertical, channel is called gorge.