Infrastructure = basic equipment/structures needed for a country/region to function properly (man-made)
○ eg/ roads, water supply, sewage
● Greenfield sites = plot of land in rural/edge of an urban area that has never been developed on before
● Land use = what the land is used for (eg/ commercial, educational, recreational, industrial, residential)
Impact of urban land use on flood risk:
● Land use is the main cause of increased flood risk → due to urban sprawl
○ New infrastructure
■ Urbanisation leads to growth of towns/cities
■ Population increases → roads, shopping centres, schools, leisure centres are built
■ The greater the area covered by buildings/roads , the greater the potential flood risk
● Infrastructure is built with impermeable surfaces , will not absorb water
○ New houses
■ Increased demand for houses → 1000s of new houses
■ Houses are being built on greenfield sites and floodplains → covered in impermeable rock
● eg/ in 2011, 7% of new dwellings were built in areas of high flood risk (England)
■ Cities have very few natural areas to store excess water
■ Water runs off quickly through gutters, drains and culverts → adds to river’s discharge
○ Disappearing gardens
■ Growth of impermeable surfaces is becoming worse in large cities
■ People pave over gardens to prevent mowing the lawn
■ Absence of garages → many households have concreted over their front gardens
● eg/ in 2013, survey revealed that 47% of UK households have 2 cars
How rural land use increases flood risk:
● Forestry
○ Felling = chopping down trees
■ Reduces interception
● Soil gets saturated quickly → runoff occurs → river discharge increases quickly
■ Roots can no longer take water from soil
○ Felling leads to exposing soil to wash into rivers , building up their beds
■ Reduces capacity of channel and river is more likely to flood
● eg/ dense forest uses up to 40% of any precipitation
Farming
○ Once crops have been harvested → soil is left bare during the winter
○ The lack of vegetation on the soil lead to less interception → soil gets oversaturated
○ When fields are ploughed up and downhill, the furrows create channels for water to flow
○ The soil gets carried away easily , raising the channel bed and leading to floods
● Disappearing fields
○ Fields intercept rainfall and soak up excess water through infiltration
○ They are disappearing due to them being sold off to property developers
■ Have been replaced by huge sheds/concrete yards (due to large-scale factory farming)
○ Pastures (land used for grazing) have been overgrazed
■ Leads to muddy runoff and an increased risk of flooding due to raise in river channel
■ Little interception and evaporation , ability of area to soak up water is reduced