Optimal distribution of green and grey infrastructures coupled with real time control of the sewer for combined sewer overflows control as an adaptation measure to climate change

Optimization of the spatial distribution of green infrastructures (GIs) was performed for a combined sewer system located in the Province of Quebec, Canada, using a simulation-optimization tool with the aim of reducing seasonal combined sewer overflows (CSOs). The performance of four CSOs control alternatives involving the individual and integrated implementation of GIs with storage tanks and real time control (RTC) of the sewer was evaluated for a nine-year simulation period of historical rainfall data and for 20%-increased rainfall data (representative of potential climate change impact). The integration of GIs with RTC of the sewer (with or without storage tanks) lowered the total CSO volume by 95% to 99% under historical rainfall data and by 93% to 96% under increased rainfall intensities when compared to the reference scenario. Adapting GI's number and location for optimal CSO control rather than according to space availability criteria reduced CSO frequency but had only a slight impact on CSO volume reduction.