Unit 2 - Natural Environment: River Landscapes Flashcards
Define solution
Minerals that are dissolved in the water and are carried around in solution
Types of transport
Solution
Suspension
Saltation
Traction
Define suspension
Fine light material that is carried along in the water
Define saltation
Small pebbles and stones are bounced along the river bed
Define traction
Large boulders and rocks are rolled down the river bed
What is a drainage basin??
The geographical area drained by a river and its tributaries, area of water runoff. The area that covers all tributaries and the mouth
Define source?
This is were the river starts. Many sources form small streams that form together to make a big river.
Define watershed?
The boundary between to drainage basins, normally marked by a high point of land.
Define tributary
These are small streams connecting the sources to the main rivers.
Define hydraulic action?
The force of the river against the banks can cause are to be trapped in the cracks and crevices. The pressure weakens the banks and they will eventually fall away.(worn away)
Define corrasion?
Waves carrying debris such as sand shingle and pebbles and hurled against the sides of the river bank wearing it slowly away.
Corrosion(solution)
This is a chemical process, certain chemicals in the river water wear away the minerals in the river bank in tern weakening it so it can be worn away.
Define attrition?
Rocks being carried by the river smash together and break into smaller, smoother rocks and particles.
Define abrasion?
Rocks being carried along by the river wear away the bottom of the river and also the river banks.
What are the three main types of weathering?
Biological
Chemical
Physical
Define biological erosion?
This is when plants and animals were away the rocks. Etc.. Burrowing animals weaken rocks or plant roots break up rocks.
Define physical erosion?
This is caused by physical effects such as the wind, the rain the temperature (freeze-thaw)
Define chemical erosion?
This is when rocks are eroded by chemicals such as acid rain. This dissolves the minerals in the rocks, in tern weakening them and becoming more susceptible to erosion.
What are the two main methods of mass movement?
Soil creep
Slumping
Define soil creep
This is when soil and rock slowly moves down a hill due to is mass and the pull of gravity. It moves faster when the soil is saturated due to rain fall.
Define slumping?
This is when earth slides down a plain, often due to gravity and the weakness of the rock.
Define rotational slumping?
This is when earth slides down a concave plate. Like a slide it moves outwards
How many UK properties are at risk from flooding?
2.1 million
how many UK properties are at risk from flooding on the coast?
1.05 million
What flood information will people find on the Environment Agency website?
Information on the likelihood of a flood, by issuing warning codes that show people how to react, also a hotline number.
In what other ways can flooding be reduced?
adding good flood defense into the design of the building, houses should not be built in areas where it is likely to flood.
Where does flooding normally happen?
Normally an occurrence in the lower course of the river, hence why there is a flood plain.
What are human causes of flooding?
- Ploughing up and down slopes rather than around them channels the rainwater to the river faster.
- Vegetation has been removed so there is less interception and water will move to the river more quickly
- Dams may burst which will cause excess water in river channels and flooding of large areas.
- of there is a town on a flood plain, storm drains will allow water to move into the river at a greater speed and so make flooding more likely.
What normally causes flooding?
It is normally a significant rainfall event:
- A long continuous period of rainfall which saturates the ground increasing overland flow.
- A ‘cloudburst’ or heavy thunderstorm which inundates an area.
- A sudden rise in temperature which rapidly melts snow and ice - often this run off cannot be absorbed as the ground remains frozen.
How can households be helped to take precautions?
this is done in the UK through a chain of events,
- the met office predicts the likelihood of a river flooding.
- They then give the info to people via TV etc..
- tells people to be proactive and ring the flood hotline if there is anything wrong.