Rivers shape landscapes through erosion and deposition in the following ways ¹ ² ³:
- Erosion: Wearing away of the landscape by natural forces such as water or wind. Rivers erode in three ways:
1. Attrition: Rocks carried by the river collide, breaking up into smaller and smoother pieces.
2. Abrasion: Rocks carried by the river scrape along the bed and banks, loosening material.
3. Hydraulic Action: The force of the river against the banks, causing air compression in cracks and crevices, weakening the banks.
- Transportation: Material is moved further downstream. There are four types of river transportation:
1. Suspension: Smaller material that is light enough to be continuously carried along.
2. Traction: Large rocks are rolled along the riverbed at times of high energy.
3. Solution: Very small material that is dissolved and can be transported even during times of low energy.
4. Saltation: Rocks and pebbles are carried by the water and deposited along the riverbed.
- Deposition: Material is dropped by the river, usually along any part of the river but commonly in the lower course. Larger material is deposited first, followed by smaller material during low-energy times.
- Landforms: Rivers create different landforms along the river long profile, including waterfalls, rapids, v-shaped valleys, oxbow lakes, meanders, river cliffs, slip-off slopes and deltas.
