Rivers and Flooding Flashcards
Define erosion
The wearing away of rock and soil found along the river bed and banks.
What is attrition?
Rocks being carried by the river smash together and break into smaller, smoother and rounder rocks.
What is abrasion?
Rocks carried along by the river scrape along the river and wear away.
What is solution?
Soluble particles are dissolved.
What is 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.
What is transportation?
Transportation is the movement of sediment along a river course.
What is suspension?
When fine, light material is carried along by the river.
What is traction?
When large boulders and rocks are rolled along the river bed.
What is a solution? (transportation)
When minerals are dissolved in the water. This makes a chemical change.
What is saltation?
When small pebbles and stones bounce along the river bed.
Name 5 causes of flooding.
- Heavy rainfall
- Steep land
- Built up areas
- Cutting down trees
- Lots of impermeable ground
Name 8 effects of flooding.
- Death
- Homes damaged
- People without access to drinking water
- Risks of diseases spreading
- Schools and hospitals difficult to get to.
- Bridges swept away
- Transport is difficult
- Farmland lost
Name 6 responses to flooding.
- Charities send aid
- Governments of other countries send help/money
- People are evacuated to safety
- Temporary homes set up
- Clean drinking water provided to people
- Bridges and roads repaired
What is hard engineering?
Physically changing the shape of the river or building structures to prevent flooding.
Name 4 examples of hard engineering.
- Dams
- Embankments
- Flood walls
- Straightening and deepening the river channel.
What are dams?
Dams are often built along the course of a river in order to control the amount of discharge. Water is held back by the dam and released in a controlled way. This controls flooding. Water is usually stored in a reservoir behind the dam.
What are embankments?
Embankments are mounds of earth built up at both sides of a river to increase the amount of water that the river can hold.
What are flood walls?
These are walls built along a river to protect vulnerable areas from water damage e.g. housing.
How does straightening and deepening the river channel prevent flooding?
Making rivers straight means that the water will flow more quickly through this part of the river, giving it less chance to fill up and flood. Rivers can be made deeper in order for them to hold more water.
What is soft engineering?
Working with the natural environment to prevent flooding or flood damage.
Name 3 examples of soft engineering.
- Land-use zoning
- Afforestation
- Warning systems
What is land-use zoning?
This is when more important buildings are built far away from a river to prevent damage (e.g. hospitals) whereas less important land such as football pitches are built closer to the river as they will not be faced by flooding as much.
How does afforestation prevent flooding?
Trees are planted near to the river. This increases the amount of water absorbed by the trees so less water reaches the river. This is a relatively low cost option, which looks natural.
How do warning systems prevent flooding?
People are warned by radio or TV if there is a chance of a flood. This means they have time to prepare and protect their homes from flood damage.
