Contemporary Urban Enviroments - Section 5 Urban Drainage Flashcards
What is catchment management?
A way of managing rivers and improving drainage systems by looking at the whole river catchment
Aims to minimise flooding, drought, water pollution and erosion and improve river ecosystems.
What is the hard engineering method to manage river catchments?
Involves man made structures eg) dams, floodwalls, reservoirs to prevent flooding and ensure water supply
Expensive
Can disrupt natural ecosystems - silt can get trapped behind dams reducing downstream areas of sediment and increasing erosion
What is the soft engineering method to manage river catchments?
Involves land use management eg) preventing building on flood plain
Can involve river restoration and conservation
Cheaper
Use of knowledge of river basin and processes to work with nature
What are some examples of hard engineering in managing river catchments?
River straightening - cutting through meanders to create straight channel. Increases gradient and speed of flow which may increase flood risk downstream
Natural levées can be made higher, increasing capacity
What are some examples of soft engineering in managing river catchments?
Afforestation - increase interception and reduce through flow and surface runoff
Riverbank conservation - planting vegetation reduces lateral erosion, bank collapse. Because roots stabilise the banks binding lose sediment together
What are SUDS?
A relatively new approach to managing rainfall using natural processes to reduce / control flooding.
They aim to imitate natural drainage systems rather than channelling water through pipes and drains.
More sustainable than traditional methods as they work with natural environment to improve water quality and drainage
What are some things that SUDS help to do?
Slow down surface runoff and reduce flood risk
Prevent water pollution
Create green spaces in urban areas
Provide habitats for wildlife in urban areas
What are some SUD strategies
Vegetated trenches (swales)
Vegetated roofs
Permeable paving
Water butts
What is the water butt strategy?
Roof water is collected
Use in gardens
Supplies water to residents
What is the permeable paving strategy?
Permeable block paving used on roads and paths
Rain falling on these surfaces is filtered and stored in the stone below and filtered into grass channels
Reduces surface runoff and flood risk
What is the vegetated roofs strategy?
A layer of vegetation on the roofs
Retains rainwater
Promotes evapotranspiration
Prevents large volumes of water pouring into Downpipes during sudden downpours
What is the vegetated trenches (swales) strategy?
Fill up during heavy rainfall and sore water
Protect other areas downstream
Water storage in local landscape provides and attractive place for wildlife and recreation
