Question

Describe how a river erodes its channel through the following processes.

1. Abrasion
2. Solution
3. Hydraulic action

Answer 1

1. Abrasion
   1. The river uses its load (gravel,boulders) as erosive tool.
   2. The load is hurled by the river water against the banks and dragged along the bed thereby chipping off the rocks on the bank and bed.
2. Solution
   1. Running river may dissolve minerals found in the rocks in which they flow.
   2. The material is carried down the river channel in solution form.
3. Hydraulic action
   1. The force of the moving water sweep away loose materials in the river channel or water is forced into cracks on the river banks.
   2. When water is hurled against the riverbank, air in the cracks is compressed creating pressure, which widens the cracks.
   3. As water retreats, pressure in the cracks is suddenly released. The compression and widening of cracks repeatedly shatter the rocks; which are then carried away by the retreating water.