Commissioned by the Berlin Senate Department for Mobility, Transportation, Climate Protection, and the Environment, the researchers assessed potential impacts across the entire capital city. This project was carried out in collaboration with UP Transfer GmbH at the University of Potsdam. The results can effectively support emergency responders in the future by highlighting where water is likely to accumulate most heavily. Which transportation routes remain passable on foot or by vehicle during floods? Where, in particular, do children or seniors—who are physically less able to cope with flooding—need to be evacuated? And how vulnerable are critical public infrastructure facilities? This is vital information for policymakers and administrators when making decisions.
Identifying Blind Spots
The project’s distinctive feature is the integration of topographic, statistical, and urban planning data, says project leader Annegret Thieken, Professor of Geography and Disaster Risk Research. Her team has designed an interactive dashboard that displays high-risk areas for people, vehicles, house and home. The risk assessment takes into account elevation data and potential damage to buildings, as well as demographic information—such as how many residents are registered in an apartment block and how many of them are younger than ten or older than 65. “This provides emergency responders with an important overview of the situation,” Prof. Thieken says. “Unfortunately, however, we did not have any data on the prevalence of basements in the city, even though basements pose a major danger. About a quarter of the 49 people who died in the last flood disaster in North Rhine-Westphalia in 2021 lost their lives in basements,” she recalls. “People wanted to check on their pumps or simply see if everything was okay, and then couldn’t get back outside because water was pouring in or because they had completely exhausted themselves and were overwhelmed while trying to save their belongings.” This makes it all the more important to highlight potential dangers.
An Underestimated Danger
What already exists for the densely populated city of Berlin is now to be applied to the more rural state of Brandenburg. The city of Oranienburg is the first municipality in the region to receive a visualization of the potential effects of pluvial flooding caused by rainfall. The analysis considers a statistically very rare extreme weather event with a hypothetical rainfall intensity of 100 millimeters per square meter in one hour. Measurement records already show that short-duration rainfall events of this kind are becoming more frequent as a result of global warming. Heavy downpours that lead to local flooding can occur anywhere in Germany and are not limited to areas near bodies of water.
“When people see a river, they tend to be more likely to think about the dangers of flooding than when they look at a low-lying area in the forest kilometers away,” says Sarah Lindenlaub of the Research Group for Geography and Disaster Risk Research. “But water depths as shallow as 20 centimeters are enough to cause damage to vehicles or trap people in a basement because they can no longer open their doors.” At 30 centimeters or more, it is virtually impossible for most passenger cars to be driven safely. In any case, experts advise against driving through flooded areas. After all, many of the people who died in past floods underestimated the danger—either losing control of their vehicles or getting out and being swept away by the floodwaters.
Prof. Dr. Annegret Thieken is a Professor of Geography and Disaster Risk Research and heads the research group Geography and Disaster Risk Research at the University of Potsdam.
This article was originally published in Portal - Zwei 2026 „Wasser“, the University of Potsdam magazine.