11.10 Human causes of flooding

Question 1

How does urban land use increase flood risk

Answer 1

Due to urban sprawl associated with urbanisation, which results in more buildings and roads that are impermeable surfaces

Question 2

How do new houses increase flood risk

Answer 2

• new homes are often built on greenfield sites, increasing impermeable surfaces
• urban planning may not consider flood risk
• houses may be built in areas of high food risk
• features like tarmac roads and concrete driveways reduce water infiltration and increase runoff into drains and culverts

Question 3

Greenfield site def

Answer 3

A plot of land that has not yet been subject to urban development

Question 4

What is the effect of converting front gardens into driveways

Answer 4

increases impermeable surfaces and contributes to increased flood risk

Question 5

How does rural land use increase flood risk

Answer 5

• forestry (deforestation) reduced interception and infiltration, increasing runoff
• farming practicing like downhill ploughing and removing hedgerows increase runoff
• fields are disappearing for development. this reduces grassy areas that soak up foil

Question 6

How does forestry affect flooding

Answer 6

• reduces interception of rainfall
• tree roots no longer absorb water
• water flows quickly into rivers, increasing flood risk

Question 7

How does farming contribute to flood risk

Answer 7

• hedges removed for larger fields reduce interception
• arable farming exposes soil to erosion and runoff
• downhill ploughing encourages water flow downslope
• soil transported to rivers can raise riverbeds and increase flood risk

Question 8

Why are fields disappearing and how do they affect flooding

Answer 8

• fields sold for housing or industry reduce grasssy surfaces
• polytunnels and crops like strawberries reduce water soaking into the ground