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In this lesson we are going to discuss about river erosion and the processes of river erosion

Answer Text:
Action of Rivers
A river is a mass of water flowing over the land in a definite channel.
Work of a River
1. Drain excess water from the land.
2. Sculpturing land through erosion, transportation and deposition.

River Erosion
- Removal by river water of materials from the sides and bed of the river channel.

Factors Influencing River Erosion
1. River volume
- A river with a large volume has a greater kinetic energy to erode than one with a small volume.
2. Slope of land
- A river flowing on a steep channel has greater velocity and therefore more energy to
erode its channel than one flowing over gentle or flat land.
3. Rivers load
- A river with large, rough and heavy load e.g. tree trunks and boulders erodes more than one
with light, fine and smooth materials e.g. sand.
- A river carrying more load erodes more than one with less load as it has more abrasive tools.
4. Nature of bed rock
- Erosion is faster where a river flows over soft bed rock and less where it flows over hard rock.

Processes/Ways of river erosion
1. Solution/Corrosion
- River water dissolving soluble minerals and carrying them away.
2. Hydraulic Action
- Erosion by the force of river water when it thrusts itself into cracks and joints of rocks
on the sides of the channel dislodging lumps.
- Also by pushing air into the cracks, compressing it increasing pressure which widens the cracks eventually
dislodging lumps.
3. Abrasion/Corrasion
- Abrasion is scratching of the bed and banks by materials are carried away by the river.
- Corrosion is hurling of rock fragments carried by the river against rocks which weaken and eventually break them.
4. Attrition
- Hitting against one another of rock fragments carried by river water breaking one another into smaller pieces.\

Types of River Erosion
1. Vertical Erosion
- Erosion in which a river cuts back at its source.
a) Where there is a water fall.
- The river undercuts at the base of a waterfall.
- The rock above the undercut cliff collapses.
- The position of waterfall shifts upstream.
b) Where gulleying or soil creep occurs where there is a spring causing its position to shift upstream (spring sapping).