Author(s): Esteban Sañudo; Albert Chen ; Luis Cea; Jerónimo Puertas; Barry Evans

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Keywords: Green infrastructure, Iber-SWMM, urban drainage

Abstract: Green infrastructure (GI) is considered as an alternative and sustainable solution to traditional urban drainage systems for reducing and mitigating flood impacts. The adaptation of GI on the urban drainage network has increased strongly in recent years due to its multiplies benefits, dealing at the same time with water quantity, quality and landscape design. To support the application, some urban drainage numerical models have already implemented tools for assessing the performance and optimizing the locations of GI. In this research, we adopted new functions that have recently implemented in the 1D/2D dual urban drainage model Iber-SWMM to model the effects of different green roof and green pavement configurations in urban environment. The model was applied to a settlement in the south of Spain as a case study. Green roofs are defined as subcatchments and modelled with a lumped approach. Each green roof unit is conceptualized in several layers with different properties, connected by processes such as infiltration and percolation. The exfiltrated flow generated by green roofs is conveyed directly to the nearest manhole of the sewer network. On the other hand, the precipitation on green pavement can infiltrate into the soil and either (1) be stored in the porous or further move down to groundwater, or (2) be drained via pipelines underneath the pavement. The process is modelled using a lumped transfer function for each green pavement unit. The flow entering sewer network is modelled by SWMM and the excess rainfall will become surface runoff that is simulated by Iber. Both models are connected via flow exchange at manholes and inlets. The implementation was tested in the settlement of Osuna, a high-consolidated urban area of 18000 inhabitants recurrently affected by pluvial flooding, located in the south of Spain. A complete definition of the urban drainage network (including sewers, manholes, inlets, and outfalls) and a high-resolution DTM were used to build a very detailed numerical model in Iber-SWMM. A green scenario that implements various green roof and green pavement configurations within the settlement was modelled for several design rainfalls and compared with a baseline scenario that represents the current situation. The effects of GI on the extension of flooded areas and on the outlet discharges at different control sections were evaluated. Our results show the usefulness of Iber-SWMM as a numerical tool to support the smart design of green drainage infrastructure to enhance urban resilience to pluvial floods

DOI: https://doi.org/10.3850/IAHR-39WC252171192022SS767

Year: 2022