The Problems and Solutions
The problem with traditional drainage systems
In the natural environment the majority of rainfall soaks into the permeable ground (known as infiltration). Here it is able to be taken up by plants, an extremely small amount of it becomes surface runoff and enters our rivers and lakes.
However, in the urban environment, due to the large amount of impermeable surfaces (roads, car parks, roofs and pavements) the majority of urban rainfall becomes surface runoff, taking harmful pollutants with it down traditional drainage systems and into nearby rivers which flow out to the marine environment. On top of releasing many harmful pollutants into aquatic environment, urban surface runoff is a primary contributor to flooding.
SuDS are the Solution
To manage urban surface runoff we need to implement nature based techniques that mimic the natural environment. SuDS (Sustainable Urban Drainage Systems) store surface water close to the source. Therefore, they act as buffers which decrease flow rates to rivers as well as removing the pollutants thus improving water quality. Some SuDS are able to store water to be used in the future during times of low rainfall to water plants or flush toilets.
Illustrations by Thames 21 demonstrating how SuDS improve a cities drainage.
The Bristol Drain Campaign aims to raise awareness to the problems caused by urban surface runoff in Bristol and encourage developers to implement sustainable drainage systems within their designs.
Above: Bristol Harbourside, head to the case study page to find out about this shining example of SuDS and green infrastructure.