SuDS as a climate change adaptation strategy: Scenario-based analysis for an urban catchment in northern Italy

Abstract

Urbanization and climate change effects on precipitation are the leading cause of flood risk increase in urban settlements. Sustainable Drainage Systems (SuDS) are effective strategies to improve city resilience toward flooding but usually they are designed to meet performance standards based on historical climate settings. The reported modeling scenario-analysis strives for investigating the potential of SuDS as adaptation strategy to a projected medium-term climate change affecting Sesto Ulteriano (Milan, Northern Italy). Two drainage models, a benchmark scenario reproducing the drainage network current configuration and a designed scenario involving SuDS retrofitting, were tested under historical (observed) and expected future precipitation extremes (projected) to assess and compare hydrological and hydraulic variables essential for the definition of a Precipitation Variability Adaptation Index (PVAI), which measures the adaptation strategy performance. Results indicate that even though SuDS were confirmed as effective flood control measures, their adaptability potential is affected by changes in rainfall severity indeed. In particular, the multi-variable PVAI, a global index able to take into account the effects of different determinants for an overall assessment of SuDS potential as adaptation strategies to climate changes, decreases when rainfall frequency decreases, among the same climate scenario, or when rainfall intensity increases due to climate changes.