Flood Factors

Question 1

What is the hydrological cycle?

Answer 1

Precipitation is any kind of moisture that reaches the ground and the risk of flooding depends on how fast precipitation gets into a channel (surface runoff is the easiest), but if there is a lot of runoff the discharge will increase.
Other flows are throughflow and groundwater flow

Question 2

What is flood risk increased by?

Answer 2

Bands of depression (soil can no longer hold water)
Sudden bursts of heavy rain (infiltration rate cannot cope)
Prolonged light rainfall
Sudden snow melt

Question 3

How does geology increase flood risk?

Answer 3

Type of rock can be impermeable in the mountain, clay soil

Question 4

How does relief increase flood risk?

Answer 4

Relief is the height and slope of the land and steep slopes have high surface run off before it has a chance to reach the soil
Low lying, flat lands also have no where to move the water so it just sits

Question 5

Describe the effect of infrastructure on flooding

Answer 5

When new towns and cities are built, new roads etc. Are built (impermeable surfaces)

Question 6

Describe the effect of new houses on flooding

Answer 6

Greenfield sites are being built on for houses (72% of new dwellings in England in 2011)
But there are more surfaces with impermeable and so the water cannot run off anywhere (speedy rise in a rivers discharge)

Question 7

Describe the effect of disappearing gardens on flooding

Answer 7

People are paving over gardens to save mowing or concreted over front lawns for parking

Question 8

How can rural use increase flood risk?

Answer 8

Forestry - felling means trees and roots can no longer take in water (soil becomes saturated, discharge increases)
Farming - hedges have been ripped out for land use, crops gone in the winter leave soil bare, ploughed fields leave channels for water to flow
Disappearing fields - fields are sold off for property