Germany’s Flood Risk Grows as Development Spreads into Hazard Zones

A major national study finds that flood exposure in Germany is rising due to both climate change and continued settlement growth in high-risk flood zones. Without stronger land-use planning, better protection, and lower emissions, future flood risks and costs are set to increase sharply.

When deadly floods struck the Ahr Valley in 2021, many Germans believed it was a once-in-a-generation tragedy. But new research suggests the danger is not fading. It is growing. A major study by the World Bank, the German Aerospace Center, Georgia Institute of Technology, and Mindearth finds that flood exposure across Germany has increased sharply over the past decade and is likely to rise further in the coming decades.

The research examines more than 11,000 municipalities, combining high-resolution satellite images of settlement growth with advanced flood modeling. The results show that flood risk is rising not only because of climate change, but also because new homes, roads, and buildings continue to spread into flood-prone areas.

Building in Harm’s Way

Between 2016 and early 2025, settlement areas exposed to flooding expanded significantly across the country. In many places, development in high-risk flood zones grew almost as fast as development in safer areas. In some coastal regions, growth in the most dangerous zones even outpaced growth outside them.

Northern coastal states saw especially rapid expansion in flood-exposed areas. But when measured in total square kilometers rather than percentages, large inland states such as Bavaria, Lower Saxony, Baden-Württemberg, and North Rhine-Westphalia added some of the biggest areas of new development in flood zones.

Flood exposure is particularly high along major rivers such as the Rhine, Danube, and Elbe, as well as along the North Sea and Baltic coasts and in southern regions near the Alps. Under a so-called 100-year flood scenario, many municipalities could see a large share of their built-up areas underwater. In more extreme scenarios, entire settlement areas in some municipalities are exposed.

Three Types of Flooding, One Rising Risk

The study looks at three main types of flooding: river flooding, coastal flooding, and pluvial flooding, which happens when heavy rainfall overwhelms drainage systems.

River flooding currently accounts for the largest share of severely exposed settlement areas nationwide. Coastal exposure, however, is increasing fastest. Meanwhile, pluvial flooding is becoming a growing concern across the country, especially as intense downpours become more frequent with climate change.

Unlike river and coastal flooding, pluvial floods can hit almost anywhere. Even towns far from rivers or the sea can face serious risk if rainfall exceeds what local drainage systems can handle. As more land is covered with concrete and asphalt, rainwater has fewer places to go, increasing runoff and raising flood risk further.

Protection Gaps Across the Country

Germany has more than 13,000 kilometers of dikes, mainly along coasts and large rivers. The study uses dike length as a simple measure of protection. Coastal states generally have higher levels of structural defense, reflecting a long history of managing storm surges.

But protection is uneven. Many municipalities with significant flood exposure have relatively little dike coverage, and some have none at all despite facing severe flood depths. Southern states, in particular, often show lower structural protection compared to northern coastal regions.

Researchers identified a group of underprotected municipalities that would require hundreds of kilometers of additional dikes to reach more adequate levels of protection. The cost of such upgrades would run into billions of euros. And dikes alone are not enough. They do little to prevent pluvial flooding, which requires better drainage systems and smarter urban design.

Climate Change Will Make It Worse

Looking ahead, the outlook is troubling. Even if settlement areas stop expanding today, flood exposure is projected to rise under future climate scenarios. Under optimistic global climate pathways, risk still increases steadily. Under high-emissions scenarios, the increase becomes much sharper by mid-century and beyond.

By 2080, the total area of settlement exposed to flooding could be several times larger under a high-emissions future than under a low-emissions one. Most municipalities are expected to see rising exposure, and in some of the most affected areas, flood risk could multiply significantly.

The message is clear and simple. Flood risk in Germany is shaped not only by storms and rainfall, but also by planning decisions and climate policy. Continued building in high-risk areas, combined with a warming climate, is locking in higher exposure. Reducing that risk will require stricter land-use planning, better protection systems, and strong action to limit climate change.