Heavy rain in Darmstadt: City assesses flooding and plans measures!

Heavy rain in Darmstadt: City assesses flooding and plans measures!

On July 7, 2025, heavy rain in Darmstadt caused great excitement in the Arheilgen district. The fire brigade had to process 75 locations within just two hours, which in itself shows how dramatic the situation was. Now that the situation has calmed down, the city is analyzing the data from the storm to plan future measures and to be able to better respond to similar events. As fr.de reports, the storm is classified as an “urban flash flood” that was triggered by heavy rain on sealed areas.

The rainwater that ran off from the sealed areas overloaded the Ruthsenbach and led to flooding. The flood basin along the stream was functional, the problem lay elsewhere: The Ruthsenbach did not overflow due to a backwater, but the cause was the sudden heavy rainfall. A prejudice that the city of Darmstadt was able to dispel recently was that the Seewiese flood retention basin was out of service; in fact, it is operated as a green basin and is able to temporarily store more rainwater.

Planned measures and redesigns

The city continues to implement measures to ecologically transform the basin to allow the natural flow of fish. This also includes the creation of a riparian forest on the bottom of the basin as well as care concepts to prevent bush encroachment. Furthermore, removal of woody plants and sediment from the Ruthsenbach is planned in the winter half of 2025/2026 in order to improve the water structure.

Another exciting aspect in the discussion about heavy rain events in Hesse is the heavy rain information map, which represents an important basis for municipalities. This map, as hlnug.de reports, provides an overview of the risk situation in the event of heavy rain and was last updated in 2022. The data, which is based on observations of precipitation, topography and the degree of sealing, helps municipalities to better assess their situation and to implement suitable protective measures.

The challenges of the future

With the increase in heavy rain events, municipalities are facing major challenges. A study by Prof. Theo G. Schmitt entitled “Heavy rain and urban flash floods – Agenda 2030” deals intensively with these topics and was presented at the IFAT trade fair in Munich. The study, which was carried out on behalf of the Water and Environment Responsibility Initiative of the Federal Association of German Building Materials Trade, sheds light on how lower and upper decision-makers in municipalities can adapt their risk management strategies. The main focus is on heavy rain hazard maps and municipal precautionary measures [bauing.rptu.de](https://bauing.rptu.de/ags/wir/aktuelles/neuigkeit-einzelansicht?tx_news_pi1%5Baction%5D= detail&tx_news_pi1%5Bcontroller%5D=News&tx_news_pi1%5Bnews%5D=6343&cHash=a21484fca777fbfd7b79cb9b24c1fb57) points out that more legally binding and clear regulations are required for future measures.

In summary, it can be said that the incidents in Darmstadt and the city's subsequent planning, in combination with comprehensive studies and maps of the danger situation, represent a step in the right direction in order to better meet the challenges of climate change and the associated heavy rain events.