A decision support system for urban stormwater drainage management

n the last decades, urban pluvial floods are occurring with increasing frequency all over the world, including developed countries (eg Italy) due to factors mainly referable to Climate and Land Use Changes (coupled with urbanization and increasing population). Urbanization is typically accompanied by increases in impervious surfaces, compaction of soils, and modifications to vegetation. This results in increased surface runoff, increased runoff velocity and stream erosion, decreased time of concentration of watersheds, and decreased water quality, due to water contamination from suspended sediments, heavy metals, hydrocarbons, nutrients, and pathogens. In the context of Urban Water Management, a useful role can be represented by innovative approaches, implementing optimization techniques and new technologies for Low Impact Development (LID) type of stormwater Best Management Practices (BMPs) for urban runoff control. The main goal of these strategies should be the improvement of the resilience of the cities against the increase of the stormwater flows and the risk of flooding (urban flash floods). In this paper a Decision Support System for the identification of the best strategy for adapting to climate change and land use changes is presented. This System allows to identify the most useful BMPs, among the usual ones in the technical literature (i.e. detention ponds, infiltration trenches, pervious pavement, green roofs, etc.), In particular the System interfaces a simulation model (SWMM 5.1) with an optimization module (Harmony Search) able to identify the best combination of BMPs to adequately reduce flood peak discharges and volumes.