Reducing sealed surfaces and promoting natural rainwater infiltration in urban areas are important steps in the fight against climate change and in preserving biodiversity and the environment. The increasing sealing of soils due to urban expansion and infrastructure development disrupts the natural water cycle. Rainwater cannot infiltrate sufficiently into fully or partially sealed soils, and instead leaves as surface water run off or is fed directly into the sewer system.

In order to determine the potential for unsealing and thus promoting natural rainwater infiltration in urban areas, the Institute of Geotechnical Engineering (Prof. Dr.-Ing. Zachert), the Department of Hydraulic Engineering and Hydraulics (Prof. Dr.-Ing. habil. Lehmann), and the Departments of Land Management and Spatial and Infrastructure Planning (Prof. Dr.-Ing. Linke) have conducted a feasibility study in collaboration with the city of Mannheim.

Content of the research project

The aim of this research project was to determine the potential of existing public transport areas and to make the selection of suitable unsealing and infiltration measures for sustainable urban development more transparent. The focus was therefore on existing areas, which are already allocated for transport use. Due to their diverse functions and their mostly high importance in the urban transport network, redesigns of existing roads pose special technical challenges. For example, additional green space is often necessary to protect the roadside area from overheating through shading and evaporative cooling, while at the same time creating infiltration areas to relieve the sewer system. However, the infiltration of road surface water is challenging, as its pollution load increases depending on traffic volume and type of use, thus requiring location-specific concepts and, if necessary, supplementary technical treatment measures.

In particular, there was high potential for redesigning existing roads with low traffic volumes and generous road cross-sections, where high added value can be achieved with low investment. At the same time, it became clear that almost all existing roads could be redesigned to be more climate-friendly and sustainable, although this would require greater financial investment in some cases.

To take into account the challenges of increasing extreme weather events, the future projections of the GERICS climate reports were used, which provide regional forecasts for the development of specific parameters (e.g. number of hot days, amount of precipitation, temperatures).

As a result, guidelines were developed to support urban decision-making processes and identify the necessary data bases and action steps, and concrete case studies and possible redesigns were presented.

Urban infrastructure areas and their potential in water-sensitive urban design (Presentation) at DAWAKO

Ruopp, Julia-Isabelle; Oberauer, Michael (2025)

Redesign of municipal roads in the context of water-sensitive urban development. in Flächenmanagement und Bodenordnung

Ruopp, Julia-Isabelle; James, Rebecca; Oberauer, Michael; Lehmann, Boris; Zachert, Hauke; Linke, Hans-Joachim (2024)

Redesign of municipal roads according to the sponge city concept (Presentation)

Ruopp, Julia-Isabelle (2024) at 27th KGIS Workshop