Germany: Building Back in Flood-Prone Areas After a Flood

Kuhlicke says the right decision for some property owners in the region might be to move to higher ground. He cites the US town of Valmeyer, which relocated entirely out of the Mississippi Valley up into the nearby hills after a devastating flood in 1993.  

“Now it’s a prospering community close to the borders of St. Louis,” he says. “So if people are really convinced that moving out of the floodplain is a smart decision, these people should be supported.”  

In the case of the Ahr Valley, he would like to see more regulation, including incentives for flood-resilient buildings. Instead, he says decisions about how to rebuild, or whether to relocate, are largely left up to the residents and communities themselves: “That means that the political signal is rather: We want to keep the communities in the valley.”  

Floodproofing Homes
Kuhlicke stresses that while there was nothing that could have prevented the July flash floods because the volume of rainfall was just too great, there are ways people can adapt their homes to limit damage.  

For example, by dry floodproofing homes — reinforcing doors, windows, and other openings to prevent water entering the building. Or wet floodproofing — allowing the water to enter the building in the event of a flood and using water-friendly building materials that won’t get water-logged and destroyed.   

Rebuilt homes should also be “designed in a way that’s not impacting climate change negatively by contributing CO2 emissions,” he says. “One can only hope that they have really some good engineers there and architects that help people to rebuild in a way that is more resilient and more sustainable.” 

But it’s not only the houses that need to change. Sebastian says it will also be crucial to implement measures to keep more water in the landscape in future, including building retention basins upstream and in side valleys, to reduce the impact of any future flooding. 

A Chance to Rebuild Differently
Sebastian also sees the town’s reconstruction as an opportunity for change. A group of researchers has put forward a proposal for how the region can generate 100% of its energy supply from renewables by 2027, for example, by using wind power and installing solar panels directly onto roofs being repaired.  

He says one of the main lessons drawn from the flood is that homes in Dernau won’t be fitted with fossil oil heating in future — currently used by about a quarter of homes in Germany. Many oil heating systems leaked in the flood, effectively contaminating houses and upping the overall damage and cost. Instead, Sebastian wants to build a modern village heating network powered by renewable energy.  

“But this requires state support,” he says. “If the Ahr Valley is to become a model region with a sustainable energy infrastructure, we’re going to need more funding, and fast, otherwise people here will simply get their own fossil fuel heating systems back again.” 

Building Resilient Homes — Is There a Trade-Off?
Climate change is expected to make extreme weather events more powerful and more frequent across the globe in the future. Building resilient homes will clearly be important, as will switching to more sustainable forms of energy. But what about the materials used in the reconstruction process?

The construction sector, including the manufacture of building materials such as concrete and steel, accounted for almost 40% of global energy-related emissions in 2019.  

“There is absolutely a trade-off, and there is a choice to be made about construction materials,” says Elizabeth Hausler, the CEO of Build Change, an NGO that builds disaster-resistant houses for people who face risks from hurricanes, floods and earthquakes.  

“In hurricane-prone areas, for example, there is a strong preference toward heavy, sturdy concrete blocks,” she adds. Concrete is seen as a reliable, climate-resilient material, but the cement used to produce it is responsible for 8% of global CO2 emissions alone. 

Hausler stresses the main priority should be preventing houses being lost in the first place, “so that we don’t have an increased carbon footprint from rebuilding.”   

In the village of Dernau, the streets are largely empty. A brown water line is still visible on the upper levels of many buildings, showing just how high the river came. Still, Mayor Alfred Sebastian says he expects 90% of the town’s 2,000 residents to return and rebuild their homes — a process that will likely take years to complete.  

“This used to be a paradise,” he says. “And now after the flood it’s more like a desert. I hope that in 10 years’ time we will be back better than ever and that we never have such a catastrophic flood again. But, of course, nobody can guarantee that.”   

The interviews in this article were conducted for DW’s environment podcast On the Green Fence. You can listen here. 

Natalie Muller is journalist and producer at Deutsche Welle. Neil King is a DW reporter. This article is published courtesy of Deutsche Welle (DW).