Erosion is where rocks are worn down over time by the water and the particles transported by the water.
The river erodes in four main ways; attrition, corrosion, corrasion and hydraulic action.
- Abrasion (corrasion): The process of a rivers' load crashing and rubbing into a rivers' banks and bed causing pieces to break off, in an action similar to that of sandpaper.
- Solution (corrosion): The process of water dissolving a rivers' load as well as its bed and banks.
- Hydraulic action: Water and air getting into cracks in a rivers banks and bed causing erosion through increased pressure.
- Attrition: Load crashing into each other in a river. This normally happens with suspended load.
 |
River Erosion |
Erosion can be classified as either vertical erosion or lateral (horizontal) erosion. Vertical erosion is where the river bed is eroded downwards, whereas lateral erosion is where the main erosion takes place on the river banks so the river channel becomes wider.
In the upper course of the river the main erosion is vertical, then as the river flows towards the mouth this changes to being mainly lateral. This is because near the source a rivers' load is bigger and more angular and therefore less likely to be suspended in a rivers flow. Instead it will bounce and crash into the bed, causing vertical erosion. However, nearer the mouth load is smaller and smoother and therefore more likely to be suspended and therefore more likely to crash in the banks, causing horizontal erosion. Because of erosion a rivers' load tends to get smaller and smoother as you move from the source to the mouth.
Watch the following video:
No comments:
Post a Comment