Rivers - floods Flashcards
Name 3 types of soft engineering with regards to river management schemes.
- Afforestation
- Demountable Flood Barriers
- Managed Flooding
What is afforestation?
A form of soft engineering river management where trees are planted to soak up rainwater in order to reduce flood risk.
What are demountable flood barriers?
A form of soft engineering river management where temporary flood barriers are put in place when the warning is raised.
What is managed flooding?
A form of soft engineering river management where the land is allowed to flood naturally and settlements are therefore protected.
Name 3 types of hard engineering river management schemes
- Straightening channel
- Artificial levees
- Deepening of widening rivers
What is “straightening channel” with regards to river management?
A form of hard engineering river management where channels are straightened to increase velocity and remove flood water.
What are “artificial levees” with regards to river management?
A form of hard engineering river management where the river is heightened so that flood water is contained.
How does deepening or widening rivers help in river management?
They are a form of hard engineering which results in increased capacity for a flood.
Name 3 physical causes of flooding
- Prolonged and heavy rainfall
- Geology
- Relief
How does prolonged and heavy rainfall cause flooding?
Long periods of rain causes soil to become saturated leading runoff.
How does relief cause flooding?
Steep-sided valleys channel water to flow quickly into rivers causing greater discharge.
How does geology lead to flooding?
Impermeable rocks causes surface runoff to increase river discharge.
Describe a human cause of flooding
Land use: Tarmac and concrete are impermeable. This prevents infiltration & causes surface runoff.
How are natural levees formed?
Closer to the river’s banks, the heavier materials build up to form natural levees.
How are floodplains formed and what are the consequences?
When a river floods, fine silt/alluvium is deposited on the valley floor.
Nutrient rich soil makes it ideal for farming.
Flat land for building houses.
