Rivers
Water (Hydrological) Cycle
The continuous cycle of water between the sea, land and atmosphere.
There are five main processes in the hydrological cycle, these are:
1. Condensation
Water vapour changes back into water (cloud formation)
2. Evaporation
The transfer of water from the sea and the land to the air as water vapour
3. Precipitation
Any form of moisture falling from the atmosphere e.g. sleet, hail, snow, rain
4. Transpiration
Transfer of water from vegetation to the air as water vapour
5. Surface run-off
Water flowing over the surface of the earth, e.g. river
In the hydrological cycle water can be stored as snow and ice, in lakes, as ground water and in oceans and seas.
Drainage Basins
A drainage basin is an area of land drained by a river and its tributaries.
Features of a drainage basin:
1. Water shed
An area of high land which forms the edge of a river basin
2. Tributary
A small river flowing into a large river
3. Confluence
The point where two rivers meet
4. The source
Where a river starts
5. Mouth
Where a river flows into (lake or sea)
Erosion
Erosion involves the wearing away of rock and soil found along the river bed and banks. Erosion also involves the breaking down of the rock particles being carried downstream by the river.
Water (Hydrological) Cycle
The continuous cycle of water between the sea, land and atmosphere.
There are five main processes in the hydrological cycle, these are:
1. Condensation
Water vapour changes back into water (cloud formation)
2. Evaporation
The transfer of water from the sea and the land to the air as water vapour
3. Precipitation
Any form of moisture falling from the atmosphere e.g. sleet, hail, snow, rain
4. Transpiration
Transfer of water from vegetation to the air as water vapour
5. Surface run-off
Water flowing over the surface of the earth, e.g. river
In the hydrological cycle water can be stored as snow and ice, in lakes, as ground water and in oceans and seas.
Drainage Basins
A drainage basin is an area of land drained by a river and its tributaries.
Features of a drainage basin:
1. Water shed
An area of high land which forms the edge of a river basin
2. Tributary
A small river flowing into a large river
3. Confluence
The point where two rivers meet
4. The source
Where a river starts
5. Mouth
Where a river flows into (lake or sea)
Erosion
Erosion involves the wearing away of rock and soil found along the river bed and banks. Erosion also involves the breaking down of the rock particles being carried downstream by the river.
There are four main forms of river erosion:
1. Hydraulic action – the force of the river against the banks can cause air to be trapped in cracks and crevices. The pressure weakens the banks and gradually wears it away.
2. Abrasion - rocks carried along by the river wear down the river bed and banks.
3. Attrition - rocks being carried by the river smash together and break into smaller, smoother and rounder particles.
4. Solution - soluble particles are dissolved into the river.
Transport
Rivers pick up and carry material as they flow downstream. A river may transport material in four different ways:
1. Solution - minerals are dissolved in the water and carried along in solution.
2. Suspension - fine light material is carried along in the water.
3. Saltation - small pebbles and stones are bounced along the river bed.
4. Traction - large boulders and rocks are rolled along the river bed.
Deposition
When a river loses energy, it will drop or deposit some of the material it is carrying.
Deposition may take place when a river enters an area of shallow water or when the volume of water decreases - for example, after a flood or during times of drought.
Deposition is common towards the end of a river's journey, at the mouth.
No comments:
Post a Comment