Rapidly changing floods are a major and expanding global threat. Existing systems make it difficult to determine their onset and development. Existing seismic sensors to detect earthquakes could provide a solution to this issue. Researchers led by the University of Gottingen demonstrate that a seismometer can detect a flood up to 1.5 kilometers away, such as the devastating one that struck Germany in July 2021. This could serve as a warning signal to save lives and reduce damage. In addition, they discovered that the ability to monitor the flood’s “seismic footprint” provides information on its magnitude, velocity, and trajectory in real time, which might be used for future flood defense. The results were published in Geophysical Research Letters.
The researchers revealed that seismic stations can detect signals emitted from the surface of our planet, such as explosions, landslides, storms, and flooding. For this study, scientists converted an existing earthquake seismometer station near the town of Ahrweiler into a tool for flood detection and monitoring. Using seismological data from the time of the disaster, they reconstructed how it spread and killed people up until the power went out and stopped the data stream.
For one hour, Germany’s Rech, Dernau, Walporzheim, and Ahrweiler were traversed by the flood for one hour as the seismometer literally depicted the river’s path along the steep, winding valley. By merging mathematical models, the researchers were able to predict the speed at which the flood flowed as well as extract information on the growing water level and the amount of debris washed away by the flood, including gravel, automobiles, and oil tanks. Since the three water level stations in the valley were destroyed early on, this data was the only way to know how the flood got worse in a systematic way.
When the seismic data is analyzed, this method gives vital information for optimizing flood behavior models for warning and rescue efforts. Dr. Michael Dietze of the University of Gottingen‘s Faculty of Geosciences and Geography explains, “If the data stream from that station had been accessible and analyzed as our research demonstrates, vital real-time information on the scale and velocity of the flood would have been available.” Dietze adds: “As 10% of Europe’s surface area is susceptible to rapid flooding from rivers restricted in valleys, we may wish to consider novel flood early warning methods. Current water level monitoring stations are insufficient to appropriately prepare for future disasters. ”
Dietze and his colleagues are already working on a plan to identify other flood-prone regions and equip them with low-cost “watch tower” seismometer pairs—a project that would cost a fraction of one percent of the damage caused by future floods. Dietze writes, “The terrible July flood that hit the Ahrtal in Germany in 2021 showed residents, lawmakers, emergency services, and scientists that they need to figure out how to improve flood warning systems that are already in place.”
