Extreme weather events, which now occur regularly as a result of climate change, pose major challenges for cities and municipalities. In Dresden, the Institute of Hydraulic Engineering and Technical Hydromechanics (IWD) is developing an "Urban Digital Heavy Rain Twin" for the Saxon state capital. In future, users will be able to use the app to simulate heavy rainfall events, obtain information on hazard situations and prepare protective measures on this basis. The prototype based on free and open software is now available.

As part of the Smart City Dresden model project, researchers at IWD have been working on the technological and methodological creation of the so-called heavy rain twin since May 2024: a virtual model of the city in which geographical data (the topography of Dresden) and urban information (such as street and building types) are brought together. Following the integration of specialist information from hydrology and hydrodynamics, runoff simulations can be carried out in the digital twin, enabling the state capital of Dresden to make dual use of the data.

"The aim of the project is to create a capabilities system that can be used both as an early warning system for heavy rainfall events and as a planning tool for adapting to climate change," explains developer Lars Backhaus.

© Virtual City Systems

The prototype offers fully automated generation of 2D simulation models, which can be supplemented by precipitation forecasts from the German Weather Service. The simulation results provide detailed information on water depths and flow velocities in flooded areas and can be intersected with urban infrastructure elements such as roads and buildings in order to precisely analyze potential hazards.

Basic map and area data can be visualized and accessed via a 3D web app available for desktop and mobile devices. Users can start heavy rain simulations in manually selected urban areas and track the results in real time. The flood risk can be assessed for the entire urban area down to individual buildings in order to ultimately calculate the potential impact and damage. This can support the responsible authorities and private individuals in making flood prevention decisions.

© Virtual City Systems

According to Backhaus, a special capability of the system is that the simulation models can be generated quickly and easily on the basis of the municipal and state-wide database linked in the Urban Digital Twin. This makes it possible to create both classic 2D hydrodynamic-numerical simulations for urban areas and 3D simulations of structures such as bridges derived from them. This allows the city to obtain precise data on the risk of flooding and thus react more quickly in the event of a disaster.

The platform is to be made publicly accessible in the second quarter of 2025. The complete development of the Urban Digital Heavy Rain Twin is planned for the end of 2026. Further development beyond this is planned.

About the Smart City Dresden model project and the "Environmental monitoring/digital heavy rain twin" measure

In the "Smart City Dresden model project" (2022-2026), which is funded by the German government, innovative measures are being tested in model districts of Dresden in order to make the city sustainable, community-oriented and liveable.

The project management of the state capital (Eigenbetrieb IT-Dienstleistungen) is working together with TU Dresden in several areas. The WISSENSARCHITEKTUR - Laboratory of Knowledge Architecture is responsible for scientific management. A Business Information Systems research team is investigating the value generation of the city's open data portal. The measure "Environmental Monitoring/Digital Heavy Rain Twin" is being developed under the leadership of the Environmental Office of the City of Dresden (Dr. Katja Maerker) and continues the BMU-funded project WAWUR (Wild Runoff Water in Urban Areas).

Contact

Lars Backhaus M.Sc. (Media Computer Science)
Institute of Hydraulic Engineering and Technical Hydromechanics (IWD)
Phone: +49 351 463-32262
E-mail: