3.2.3.5 Urban Drainage

Factors influencing amount/distribution of precipitation

Urban Heat island effect, Air pollution, Tall buildings

How does the UHI influence the amount/distribution of precipitation

Increases air temperature and causes greater convection to result in intense rainfall

How does air pollution influence the amount/distribution of precipitation

Condensation nuclei encourage cloud formation

How do tall buildings influence the amount/distribution of precipitation

Create turbulence and encourage uplift

Type of urban surfaces

Impermeable, semi- permeable (gardens), drainage infrastructure

Features of the urban water cycle

Rapid transfers, Little evapotranspiration, Water extracted fast to create a steep falling limb, Lower soil moisture levels and slow recharge

Issues with catchment managment

Flood risk, Water pollution, Land use, Climate change

how is water pollution an issue

Sewage overflows, oils and litter worsen water quality

How is land use an issue

Housing, transport, industry limit space

SUDS

Management techniques which mimic natural drainage to reduce runoff

Advantages of SUDS

Control runoff, improve water quality, enhance biodiversity, cheap, adapt to climate change

Example of SUDS

Permeable pavement, Greenroofs, Retention ponds

Permable pavements

Allow water to infiltrate to reduce runoff and recharge soil

Greenroofs

Vegetation increases interception and evapotranspiration

Retention ponds

Permanent bodies increase storage and biodiversityDisa

Disadvantages of SUDS

Require space, maintaince needed