Physical and human factors affecting flood risk Flashcards
(13 cards)
What occurs when the capacity of the river channel is exceeded?
Flooding occurs
Flooding results in water flowing over the banks and onto the surrounding area.
What is usually the cause of flooding?
Heavy or prolonged rainfall
This type of precipitation leads to increased water levels in rivers.
What is the key factor that affects flooding risk?
Lag time
This is the time taken for precipitation to reach the river from where it falls.
What happens if the lag time is shorter?
The higher the risk of flooding
A shorter lag time results in a faster increase in river discharge.
What physical factor involves prolonged periods of rainfall saturating the soil?
Precipitation
This leads to quick surface runoff and rising river levels.
Which type of rocks promote rapid overland flow of water towards river channels?
Impermeable rocks
Examples include shale and clay.
How does relief in mountain environments affect flooding risk?
Steep slopes encourage rapid water transfer
This increases the risk of flooding.
What human factor increases flooding risk by creating impermeable surfaces?
Urbanisation- impermeable surfaces
This includes tarmac roads, concrete driveways, and slate roofs.
What happens to rainwater when trees are removed (deforestation)?
Rainwater falls directly onto the ground which allows water to flow faster into river channels
This allows for rapid transfer to river channels, increasing flood risk.
What agricultural practice can lead to increased flood risk due to exposed soil?
Arable farming can lead to surface run off
Soil left unused and exposed can lead to more surface runoff.
What is the impact of overgrazing and over-cultivation on soil?
They can damage and compact the soil
This further increases the flood risk.
What are the physical factors leading to flooding?
Precipitation
Rock type
Relief
What are the human factors leading to flooding?
Urbanisation
Deforestation
Agriculture
