The Growing Challenge of Flood Management in a Changing Climate: Germany's Recent Experiences

Interview by Dr. Beate Krok with Prof. Dr.-Ing. Andre Niemann

Prof. Dr. Niemann, as we approach the third year since the catastrophic floods of July 14, 2021, in North Rhine-Westphalia and the Ahr Valley, Germany has already experienced three severe flood events this year. Can you explain what's happening?

Indeed, we've seen significant flooding events this year - the Christmas floods in Northern Germany, the Pentecost floods in the Saar region, and most recently, floods in Southern Germany affecting Swabia and parts of Bavaria. This is part of a complex interplay of several components. Climate change is making an already complex climate system even more intricate.

What's causing this apparent increase in flood events?
It's a combination of factors. Our oceans are warmer than ever, and we've had 13 consecutive months of record-breaking average temperatures over land, each 1.6°C above the long-term average. The physics is clear: for every 1°C increase in temperature, the atmosphere can hold 7% more moisture. We're experiencing this physically as increased rainfall.

How does this play out in terms of specific flood events?

The specific weather patterns can vary. Sometimes it's long-lasting convective precipitation, as we observed during the Christmas flood in Northern Germany. Other times, it's a particular weather constellation that causes water absorbed from the Mediterranean to rain down steadily over a specific region, like during the Pentecost floods in the Saar region. Ultimately, it's the overall weather situation that decides. It's a complex interaction of changes in the global jet stream, ocean currents, and the constellation of weather patterns with regions.

Are some areas more at risk than others?

Absolutely. Topography plays a crucial role. Flat regions with sandy soils, like Brandenburg, have a higher capacity to absorb excess water. In contrast, mountainous and hilly areas are particularly vulnerable to intense, localized rainfall events. There are more than 30 mid-mountain regions in Germany. Unfortunately, much of our infrastructure in these exposed areas isn't adequately prepared for this new climate reality.

What short-term measures can be taken to mitigate flood impacts?
We need a three-pronged approach: land-use planning, technical flood protection, and behavior preparedness. In the short term, improved forecasting and warning systems are critical. The future of flood protection is increasingly digital, with apps and smart infrastructure like sensor empowered leeves playing a growing role in keeping communities informed and safe.

And what about long-term strategies?

Rivers need space and we will have to learn to live with the water. For long-term resilience, we're seeing creative solutions like "sponge cities" and “ sponge landscapes” that can better absorb and manage excess water. These include multifunctional urban spaces that serve daily needs while providing flood protection during extreme events. However, we face a significant challenge in implementation. There's often a lack of political will at the local level to put these plans into action.

How has public awareness changed regarding these issues?

There's been a positive shift. Media coverage of water topics in 2023 reached its highest level in 25 years. This gives us experts momentum to promote our solutions. However, awareness alone isn't enough. We need action. As I often say, every well-intentioned, planned but not implemented measure is an unrealized flood protection for society.

What's your outlook for the future?

The challenges are significant, but so are our capabilities. We have no shortage of knowledge about what's possible and necessary. Our main deficit is in implementation. Looking ahead, we need courage, creativity, and a commitment to adapting our communities to the new realities of a changing climate. Every step towards greater resilience counts. The recent experiences in various parts of Germany serve as a strong reminder of the urgency of this task.

Prof. Dr. Andre Niemann has been leading the Institute of Hydraulic Engineering and Water Management at the University of Duisburg-Essen since 2010. He completed his civil engineering studies at Leibniz University Hannover in 1996 and earned his doctorate in 2000 from the University-GH Essen. Before his academic appointment, he worked in the private sector as a consulting engineer at Dahlem Engineers. Prof. Dr. Niemann's research portfolio is extensive, his work focuses on water management, flood protection, and natural water conservation, resulting in over 40 scientific publications. In addition to his primary role, Niemann holds a guest professorship at Wuhan University in China. He is actively involved in various professional committees. Hie is a member of the board of the German Association for Water, Wastewater and Waste (DWA). Currently, Prof. Dr. Niemann supervises eight doctoral candidates, exploring topics such as river restoration, measurement technologies, and digital based integrated water management concepts. His multifaceted career demonstrates a strong commitment to advancing water management practices and education in both academic and professional spheres.

First WSA Career Navigator grant approved for Stefan Grosenick from the Aquatic Ecology working group, University of Duisburg Essen

On the road to expertise: the electrofishing licence as the key to fish ecology

The aquatic world harbours a multitude of fascinating secrets and is of enormous importance for the ecological balance of our planet. Within this complex ecosystem, fish play a central role and their study and protection is crucial for the preservation of water quality. In his quest to develop his expertise in this field and contribute to the protection of aquatic habitats, Stefan Grosenick has decided to obtain an electrofishing licence. This step not only marks a milestone in his personal and professional development, but also a significant contribution to the research and conservation of our waters.

The EU Water Framework Directive calls for an ecological assessment of flowing waters, with fish playing a prominent role as indicators of water quality. Their sensitivity to environmental changes (such as those caused by cross structures in our watercourses and obstacles to the so-called "ecological continuity" increasingly endangering spawning migrations/genetic exchange) and pollutant inputs make them crucial indicators of potential issues in our water bodies. The electrofishing licence will enable Stefan Grosenick to record fish communities and thus lay the foundation for a comprehensive ecological status assessment. This qualification not only opens up new career prospects for him, but also strengthens his expertise in the field of fish ecology. His previous studies in aquatic biology have further deepened his interest in fish and their role in aquatic ecosystems. In particular, his research work on the fish community of a revitalised lowland stream in the Ruhr area has further ignited his passion for this field.

In addition to his academic work, he is also practically active in aquatic ecology, for example through his involvement in monitoring and analysing video footage in the Baldeneysee fish lift project. This practical experience has deepened his understanding of the complexity of aquatic ecosystems and strengthened his motivation to continue working in this field.
For Stefan Grosenick, obtaining an electrofishing licence is therefore not just a formal qualification, but an important step on his path to becoming an expert in fish ecology. He is firmly convinced that this additional expertise will enable him to make an even more significant contribution to the protection of our waters and establish himself as an expert in this field.
With this in mind, we are excited about the challenges and opportunities that this step brings for Stefan Grosenick and look forward to seeing how he can put his newly acquired skills and knowledge into practice to make a lasting contribution to the conservation of our aquatic habitats.