Multiple benefits of blue-green infrastructure and the reduction of environmental risks: case study of ecosystem services provided by a SUDS pond

This paper gives an account of multiple benefits provided by Granton SUDS pond and discusses their relevance to the alleviation of environmental, economic and social risks. The pond was established in 2005 and is situated in a park, close to a supermarket and a college. It has an area of approximately 2600 m2 and a hydrographic survey carried out as part of this research provided an estimate for the pond’s volume of 1904 m3 for the normal operating conditions. However, during flooded conditions (also observed during this research) the pond’s volume increases to circa 2545 m3. The pond has considerable biodiversity value and an important amenity function. The locality is enjoyed daily by many visitors and is particularly popular with joggers, dog walkers and families. Modelling of the pond’s catchment was undertaken using the hydrodynamic model CityCAT coupled with the hydrological model SHETRAN. Changes in water discharge from the pond were simulated using the time series of precipitation and air temperature data obtained from the Scottish Environment Protection Agency (SEPA). The discharge is higher in winter, which determines shorter retention times. That has implications for the observed dynamics of the hydrobiological community, with higher risk of cyanobacterial development in the summer. However, according to the ICP MS analysis of water chemistry, the observed planktonic community and the biological water quality estimated by macroinvertebrate sampling, are all broadly similar to those in other ponds. CityCAT results show that the presence of the pond delays and reduces the peak discharge after extreme precipitation events, with reductions being greater for smaller events. This study contributes to accumulating evidence of interlinkages among hydrology, ecology, biogeochemistry and biological water quality at the SUDS ponds sites, thus underlying the need for a comprehensive simultaneous consideration of their subsystems. These aspects are indispensable for reducing the risk of negative environmental effects and vital for planning future urban developments and nature-based solutions, as well as for the management of existing SUDS assets