A new approach on design and verification of integrated sustainable urban drainage systems for stormwater management in urban areas

Stormwater runoff control is often a concern due to urbanization and extreme rainfall events. Sustainable urban drainage systems can support traditional hydraulic networks in rainwater management by providing local runoff disposal and reuse of collected stormwater. The objective of the study is based on an innovative analytical- probabilistic approach for evaluating the functioning of rainwater tanks in stormwater management with the potential for using collected water for non-potable purposes. A pilot case of a rainwater tank integrated with an infiltration system was considered within the framework of the Polisocial Award 2023 at the Off-Campus Cascina Nosedo of Politecnico di Milano (Italy). The performances of the rainwater tank in satisfying irrigation were evaluated through a new version of an analytical probabilistic approach, whose validation confirmed it is promising and offers excellent perspectives in the field of stormwater management. The probabilistic equation developed in this study relates the probability of rainwater reuse to the main parameters involved in the process (i.e., storage volume, irrigation area, rainfall depth, etc.), enabling to define the management rules of the storage for the optimization of the stormwater management. In the application, to consider an irrigation area lower than 30 m2, ensures the fully meeting of the requirements by the system in the rainiest year, and to avoid falling below the 50% (2-year return period) during the driest year.