Recent development dynamics of urban centres, resulting into a substantial increase in the impermeable surface, have forced the administrations to deal more frequently with problems linked to the inability of traditional urban drainage systems to manage rainwater in a sustainable and effective manner.
Several laws currently in force require compliance with the quantitative and qualitative limits to be discharged into watercourses but, in parallel with a "regulatory" approach, integrated strategies, in which sustainable technologies able to reduce the flows conveyed in the network and redevelop the territory come into play, are increasingly being developed.
It is therefore considered essential to change the planning approach or to modify the already consolidated urban contexts using sustainable drainage technologies to bring urban systems back to a configuration that is more similar to the one prior to intensive construction. A fundamental role in the implementation of this strategy is carried out by Sustainable Drainage Systems (SuDS), whose basic principle is the management of rainwater at source through the implementation of prevention, mitigation and treatment strategies.
This study, starting from a project proposal made by SMIA, IRIDRA, Studio Gioia Gibelli, Studio Idrogeotecnico and funded by PoliS-Lombardia, aims to assess the benefits deriving from the widespread application of sustainable drainage infrastructures in the Sesto Ulteriano industrial area through a comparison between a scenario that represents the current configuration of the drainage network and an ideal scenario in which different SuDS techniques have been implemented in the urban system (rain gardens, draining trenches and parking lots, floodable yards, cisterns-planters).
To this aim, therefore, the SWMM5 software was used, which allowed simulations of the behaviour of the drainage network in contexts without and with SuDS techniques after the construction of the synthetic series of precipitation and the urban drainage network model.
Although only event scale simulations have been conducted so far, the encouraging results, assessed in terms of reduction of the flow to be laminated through the implementation of SuDS, suggest that these systems can really contribute to mitigating the effects of flooding in urban areas.