Goodbye flooding

Heavy rain and heatwaves: climate change with its extreme weather conditions is putting pressure on water and sewage systems as well as on the agricultural sector. In the German-Danish NEPTUN project researchers from the universities of Kiel, Aalborg and Southern Denmark are urgently developing the solutions needed for these challenges.

Flooded road
© M. Staudt / Grafikfoto

Flensburg city centre is subject to flooding.

Anyone who lives or works at the port of Flensburg are getting their feet wet more and more often. The reason for this is the increase in heavy rainfall. Whenever the sewage system can no longer cope with the masses of water, it leads to flooding of the lower lying city centre. Since March 2020, a research project has been dealing with the question of how the effects of climate change and the resulting increase in extreme weather conditions can be better predicted and, if possible, prevented. Scientists from the Geo-Energy competence centre and the Faculty of Engineering at Kiel University are now working on this topic together with Aalborg University and the University of Southern Denmark. Regional companies and municipalities are also participating in the German-Danish Interreg project called NEPTUN, sponsored by the European Union.

"Climate change is putting severe pressure on the water and sewage systems in northern Germany," explained geoscientist Dr Agnes Sachse. Experts expect both an increase in extreme rainfall events as well as seasonal water scarcity and droughts. "These are challenges for which we must find scientific as well as practical solutions," said Sachse. Long periods of time without any significant rainfall in particular, which had already been frequently observed in the past, represent a major challenge for the supply of drinking water and for the agricultural sector. Solutions must be developed for these without delay. Researchers are carrying out studies until May 2023 to identify innovative ideas that could be helpful.

Promising approaches using radar data for early warning purposes

"My colleague, Dr Alexander Schaum, and I are working on developing an early warning system for Flensburg that enables preventive measures to be taken in the event of heavy rainfalls," reported Henry Baumann from the Institute of Electrical Engineering and Information Technology. This is supported by different cooperation partners. With the help of a computer model that describes flow paths through Flensburg, as well as radar data from which the expected precipitation amounts are calculated, it is possible to make predictions about water accumulation.

The aim is to develop a prototype that optimally controls the rainwater drainage network and can automatically empty the city’s rainwater retention basins before imminent heavy rainfall. This creates space for the new water masses if needed. "The aim is to redirect the rainwater or direct it to overflow areas in order to prevent the city centre from being flooded," said Baumann.

A similar solution could prevent flooding of the Eiderstedt marshes. "As the marshes are below sea level in many places, they can only be freely drained via sluices at low tide," explained the expert from the Faculty of Engineering. As an option, the excess water can pumped into the sea using scoop wheel pumps. "While these pumps were previously controlled on the basis of weather data and experience, we are investigating the possibility of whether the pumping activity can be automated and better coordinated with the tides so that flooding can be reduced."

Another innovation project in the Norderstedt region is focussing on water scarcity and the resulting fall in groundwater levels. In collaboration with the Norderstedt waterworks and an engineering firm in Kiel, Agnes Sachse and her colleague Dr Dirk Schäfer are investigating the cause of sinking groundwater levels and developing solutions to stabilise and increase them, together with Danish companies.

Although the innovation projects are very different, their aim is the same: "We want to find measures to adapt to climate change, which can also be transferred to other regions so that towns, municipalities and companies of both countries can use and further develop our ideas," said Sachse. "We are working on concepts for the management of water resources that have been needed for a long time and see the geological substratum as a water reservoir as well as a thermal reservoir in order to enable the town and country to withstand increasing extreme weather events, and to ensure the water supply over the long term." The innovations are to be presented at a conference in September 2022 and at the conclusion of the Interreg project.

Author: Jennifer Ruske

NEPTUN is an Interreg project that connects small and medium-sized enterprises as well as municipalities in the Danish-German region through partnerships, the exchange of knowledge and collaborating on innovations. The aim is to unleash innovation and growth potential in the water and sewage sector and find solutions for adapting to climate change. NEPTUN is financed by Interreg Deutschland-Danmark through funds provided by the European Regional Development Fund. The project runs from 2020 to 2023. (JR)

Project wbsite: neptun-vand.dk/de