Urban Drainage Flashcards
What are urban areas covered in?
Impermeable materials like concrete or tarmac many of them are designed to shed water quickly
What does the impermeable surfaces mean?
Infiltration is low so replenishment of groundwater stores is low
What is precipitation like in urban areas compared to rural areas?
Precipitation is higher and storms are more intense - increasing surface runoff
What happens to runoff?
It is channelled through manmade pipes which transport waters to rivers and streams
What does low infiltration rates, high runoff and channelling water mean?
It enters rivers quickly and gives a short lag time and high peak discharge with a. fast return to base flow
What is catchment management?
A way of managing rivers and improving drainage systems by looking at. the whole river catchment and the interactions between water and land
What are the aims of catchment management
To minimise flooding, drought, water pollution and erosion in sensitive areas to improve river catchments
What 2 methods are used to manage river catchments
Hard and Soft engineering
Explain Hard Engineering
Involves man made structures which are used to prevent flooding and ensure there’s a constant water supply. But they’re expensive and disrupt natural systems and alter wildlife habitats
Explain Soft Engineering
Uses the knowledge of the river basin and its processes work with nature. Uses land use management. and involves river restoration and conservation - normally cheaper and improves the local environment. Planning restrictions limit the construction of homes, businesses and land use management’s hard in already urbanised areas
How are decisions for what water management methods used decided
Experts in water management
What are SUDS
Sustainable Urban Drainage Systems
What are the aims of SUDS
To imitate natural drainage systems, rather than challenging water through pipes or drains
What 3 methods do they use to decrease flooding, water pollution and drought in urban areas?
1) Vegetated trenches increase interception of rainfall. They help increase infiltration and water storage decreasing runoff and channel flow which lowers flood risk. Increased infiltration. decreases. the amount of pollutants entering the river
2) Vegetated roofs intercept rainfall and increase evapotranspiration reducing flood risk
3) Containers on roofs of buildings catch and store rainwater for refuse. Helping reduce drought risk
Why are SUDS better
They’re more sustainable as they work with natural environments improving drainage and water quality. Vegetated trenches and roofs provide new habitats. and increase biodiversity
