Do stormwater source control policies deliver the right hydrologic outcomes?

SummaryThe number of stormwater source control (SC) regulations adopted by local authorities is rapidly growing in many countries. We can expect that, in the near future, the hydrologic behavior of many urban and periurban catchments will reflect this diffusion. This paper discusses SC regulations through two complementary approaches: starting on three French case-studies, it analyzes how regulations are developed today and identifies a set of shortcuts in policy-making practices. Then, the hydrologic model of a periurban catchment in the Paris region is used to test the impacts that these regulations can produce if widely applied. The main finding is that inertia in policy-making, driving a singular focus on flow-rate based regulations, can produce negative impacts in the long-term. Further efforts on volume-based regulations are advocated, both in terms of research and policy-making.

► Source control regulations are changing the hydrological behavior of many urban areas. ► French regulations shows inertia in policy-making and lack of suitable tools. ► Flow-rate-and volume-based regulations are assessed on a periurban hydrological model. ► Strict flow-rate regulations can worsen receiving water conditions. ► Innovative volume regulations appear safer and should be studied and developed.