By Andre Niemann

Three years ago the catastrophic floods of July 14, 2021, in North Rhine-Westphalia and the Ahr Valley, Germany finds itself grappling with an unsettling trend. Already this year, three regions in Germany have experienced severe flooding events: the Christmas floods in Northern Germany, the Pentecost floods in the Saar region, and most recently in June, floods in Southern Germany affecting Swabia and parts of Bavaria. This apparent increase in flooding events raises critical questions about their causes and frequency and the flood protection strategies applied so far.

The changing face of floods

Recent data presents a compelling view: global ocean temperatures are at record highs, and we’ve experienced 13 consecutive months of record-breaking average temperatures over land, each 1.6°C above the long-term average. This warming trend has significant implications for our weather patterns. For every 1°C increase in temperature, the atmosphere can hold 7% more moisture, leading to more intense rainfall events.

Prof. Dr. Andre Niemann has been leading the Institute of Hydraulic Engineering and Water Management at the University of Duisburg-Essen since 2010. His work focuses on digital water management, flood protection, and natural water conservation. (Photo: Frank Preuss)

This shift is manifesting in various ways, from prolonged convective precipitation, such as the Christmas floods in Lower Saxony, to specific weather patterns like the Pentecost floods in Saarland. In the latter case, a stable weather system caused an enormous amount of water absorbed from the Mediterranean to precipitate over a concentrated area. The specific weather patterns causing these floods can vary.

Complex interplay of factors

Experts explain that this perceived increase in severe flooding events is due to a complex interplay of several components. Climate change is making an already complex climate system even more intricate. The physics behind this is clear: warmer temperatures lead to more moisture in the atmosphere, which we experience physically as increased rainfall.

Crucially, it’s the overall weather situation that decides. In simplified terms, it’s the interaction of changes in the global jet stream, ocean currents, and the constellation of weather patterns with regions. As result we experience more intense weather events, necessitating increased resilience from our communities. And it is not only flooding and flash flood events. Increasing heat waves, droughts, wildfires, all of those events have a changing pattern in a changing climate. It looks like a huge challenge for societies and regions to mitigate and adapt. And it will take a long time and a large amount of money.

Vulnerable regions

Not all areas are equally affected by these changing patterns. Topography plays a crucial role in determining flood risk. Flat regions with sandy soils, like Brandenburg, have a higher capacity to absorb excess water. In contrast, mid-mountain areas are particularly vulnerable to intense, localized rainfall events that are becoming more common.

There are 30 mid-mountain regions in Germany and the infrastructure in many of these exposed areas is not adequately prepared for the new climate reality. Bridges are often not designed properly, and buildings are constructed too close to rivers. The planned reconstruction in the Ahr Valley after the 2021 catastrophic floods goes along with a reluctance to adapt to these new risks, with many choosing to rebuild in vulnerable areas despite the clear dangers.

Short-Term Measures and Long-Term Strategies

Experts emphasize that flood management requires a three-pronged approach: land use planning, technical flood protection, and behavior preparedness. While there’s no lack of knowledge in these areas, implementation often lags behind due to a lack of political will at the local level.

In the short term, improved forecasting and warning systems need to be implemented. The future of flood protection is increasingly digital, with apps and smart infrastructure playing a growing role in keeping communities informed and safe.

For long-term resilience, urban planners and landscape architects are developing creative solutions for „sponge cities“ that can better absorb and manage excess water. These include multifunctional urban spaces that serve daily needs while providing flood protection during extreme events. Sponge landscapes, sponge forests and a more flexible water sensitive land use in general will be needed also. All in all, awareness for a more water sensitive design is a key for becoming more resilient.

Public Awareness and Action

One positive trend is the increasing public awareness of water-related issues. Media coverage of water topics in 2023 reached its highest level in 25 years, providing momentum for experts to promote their solutions.

However, awareness alone is not enough. There’s a pressing need to bridge the gap between knowledge and action. Every well-intentioned, planned but not implemented measure is an unrealized flood protection for citizens.

Conclusion

As we face a future of more frequent and intense flood events, the challenge lies not in developing solutions, but in implementing them. From individual preparedness to large-scale infrastructure projects, every step towards greater resilience counts. The path forward requires courage, creativity, and a commitment to adapting our communities to the new realities of a changing climate. The recent experiences in various parts of Germany serve as a strong reminder of the urgency of this task.