Catchment management and SUDS

cathcmnet management aims

• Catchment management aims to reduce urban drainage issues, it’s a way of managing rivers and improving drainage systems by looking at a whole river catchment, and the interactions between water and land. 

• It aims to minimise issues such as flooding, drought, water pollution and erosion, and to improve river ecosystems 

name the two main methods of managing river catchments

• hard engineering

• soft engineering

hard engineering definition

Man-made structures such as dams, floodwalls and reservoirs, which are often used to prevent flooding and ensure a constant water supply. 

issues with hard engineering

However, hard engineering schemes are often expensive, can disrupt natural systems, and alter wildlife habitats. E.g. dams can prevent salmon migrating upstream. 

examples of hard engineering with pos and neg

River Straightening  + Moves water quickly out of the straightened area  -moves the problem downstream

Artificial levees  + increases the capaciy of the river  -look unattractive, high cost

Diversion spillways (flood relief channels)  +Reduce the threats of flooding by creating new wetlands  -can threaten areas not used to flooding

River channelisation(lining straightened channels with concrete)  +Improves rate of flow and reduces buildup of silt  -looks unsightly and damages local ecosystems

soft engineering defintiion and aims

Uses knowledge of the river basin and its processes to try and work with nature. It involves using land management (e.g. planting trees) to decrease flood risk and water pollution. It can also involve river restoration and conservation. It is generally cheaper than hard engineering, and it can improve the local environment. 

issues with soft engineering

However, Planning restrictions can limit the building of new homes, and land use management is difficult in areas that are already urbanised. 

examples of soft engineering with pos and neg

Afforestation  +increases interception, lengthens lag time  -difficult with limited space, take a long time to grow

Floodplain zoning                                                          +stops important areas from flooding                                   -cities are already built around rivers

Riverbank conservation  +The removal of hard engineering and preservation of the riverbank

Suds aims/definition

Sustainable urban drainage systems (SUDS) aim to imitate natural drainage systems, rather than channeling water through drains and pipes. 

benefits of SUDS over other methods

SUDS are more sustainable than traditional urban drainage methods as they work with the natural environment to improve drainage systems and water quality. Some methods also provide new wildlife habitats and increase biodiversity

methods of SUDS with details

• Vegetated trenches: increase interception of rainfall, and retention basins store water. They help to increase infiltration and water storage, this decreases runoff and channel flow, which lowers the flood risk. Increased infiltration rates also decrease the number of pollutants entering water courses. 

• Vegetated roofs: Intercept rainfall and increase evapotranspiration, reducing flood risk, also provides habitats. 

• Containers on the roofs of buildings: Catch and store rainwater for reuse, reducing drought risk. 

• Permeable roads and pavements 

• Swales: Wide, shallow drainage channels that are normally dry.