Combat of Retrofitting Urban Drainage Networks with Nature-Based Solutions

The existing urban drainage infrastructure, which mainly consists of central solutions, has been extended in the last decades by decentralised system applications such as nature-based solutions (NBS) and is currently an area of greatest interest of the research community. To further expand the knowledge on this topic, the "Combat of retrofitting Urban Drainage Networks with NBS" is organised at the UDM 2025. The aim of the combat is to optimise the retrofitting of an existing urban drainage network with seven different types of nature-based solutions. Therefore, a calibrated combined sewer network of an Alpine municipality in Austria is provided as an SWMM5 input file, together with implementation rules (e.g., type of nature-based solution is depending on land classification). The submitted solutions will be evaluated based on seven performance indicators, including costs, biodiversity and metrics related to system performance improvements. The best teams are honoured during the closing ceremony, and the submitted solutions and the task will be published in a joint publication of all participants of the combat to support the dissemination of the case study as a benchmark network in future.