Additional benefits of green stormwater infrastructure

Week two of this course went over several types of green stormwater control measures. There, it was already noted that green infrastructure can do more for urban areas than just reducing stormwater flooding risks or stormwater pollution. The green nature of for example biofilters or wetlands can also make positive contribution in other aspects. These include:

• Amenity values: most people appreciate seeing greenery in their surroundings. Stormwater measures can contribute by providing simple grassed areas (e.g. swales or dry ponds) or more lush vegetation (for example in biofilters or wetlands). Wet ponds can also form a pleasant element in landscape design.
• Recreational values: beyond their appearance, larger stormwater facilities (especially wetlands) can also be used to create walking paths for people to enjoy. Detention areas (dry ponds) can be used for activities that will not be damaged by occasional flooding, such as football fields in parks.
• Biodiversity: many urban areas lack sufficient greenery to support animal life and different species of plants. Green stormwater control measures can include a mix of vegetation which can provide some habitat for insects and other animals. Although the amount of green area provided by SCMs will be modest, it still poses a clear improvement over traditional pipe-based drainage systems. In particular, SCMs like biofilters or swales that can be integrated into street designs can help create better and more connections between larger green areas such as parks.
• Health: green SCMs can increase evapotranspiration which can help mitigate the urban heat island effect. Increased temperatures pose health risks, especially to the elderly or people with pre-existing conditions: it is estimated that the heatwave that struck Europe in 2003 led to more than 70,000 deaths. SCMs can also contribute to improved air quality.

Some benefits depends on the type of SCM that is used: for example, green roofs can contribute to building insulation, while infiltration facilities can help maintain groundwater levels.

In urban planning, there is often competition between different urban functions and the space that they require. It is good to realize that stormwater measures can have these other benefits, as they can help ease the implementation of green SCMs in urban design.