Highly Accurate Flood Forecasts

20/07/2021

A new early-warning system developed at RWTH Aachen University can determine the risk of flooding due to heavy rainfall and predict the expected damage right down to the house number. People affected could thus be alerted with pinpoint accuracy. After the recent flash floods in Germany and neighboring countries, the researchers are concerned that the washed-up mud may contain pollutants.

  A man and a woman examine a riverbank Copyright: © Peter Winandy Professor Holger Schüttrumpf and doctoral candidate Stefanie Wolf examine sediments on the banks of the Inde River in Eschweiler.

Researchers at RWTH Aachen University have developed a flood early warning system that is designed to predict expected damage to buildings down to the house number. The new model is currently being tested and further developed in Aachen, says Professor Holger Schüttrumpf, head of the RWTH Institute of Hydraulic Engineering and Water Resources Management.

A general flood warning for a region as issued by traditional warning apps is like a warning of a traffic jam that does not tell you exactly where it is. Such an advance warning is not very helpful – people in an affected region need to know where exactly the flood will hit and how heavy it will be. “We are now able to predict the water levels and flow velocities for each and every building.”

Using data from rainfall radars, as well as water body and geographic models, realistic simulations are used to determine which streets are affected by flooding, to what extent they are affected, and what damage to buildings can be expected. Up to now, warnings of extremely heavy rainfall have only been providing information on expected precipitation.

Integrating Flood Warnings in Navigation Systems

But the risk of flooding varies greatly depending on the topography of a region, Schüttrumpf explains. There is a difference, he says, between 200 millimeters of precipitation falling in the lowlands and basements filling up, “and 200 millimeters of precipitation coming down in low mountainous regions and transforming streams into torrents, unleashing the brute force of water.”

  A man and a woman inspecting deposits on a damaged bridge Copyright: © Peter Winandy Professor Holger Schüttrumpf and doctoral candidate Stefanie Wolf examine deposits on a damaged bridge over the River Vicht in Stolberg/Rhineland.

The research team may even seek to integrate the accurate and highly detailed warnings into existing warning apps such as NINA, KATWARN, or Google Maps. In principle, however, any opportunity to warn the population of an imminent flood should be taken: text messages, radio, television, sirens, and vehicles driving through the streets.

In a next step, the Aachen team wants to expand the early warning system to provide flood warnings via navigation systems. “In future, your navigation system will tell you: your destination is affected by floods, don’t go there.” The Aachen Institute for Hydraulic Engineering and Water Management has been dealing with the topic of flood protection for decades – more than any other university department in North Rhine-Westphalia. “We are NRW’s institute for flood protection, so to speak,” says Schüttrumpf.

International Collaboration on Climate Adaptation

In cooperation with TU Dresden and two partners in India and Thailand, RWTH is also setting up a so-called climate adaptation center in Madras, India. Over the next five to ten years, the new Center will seek to develop measures to protect people from disasters such as drought and floods. The center is funded by the German Academic Exchange Service (DAAD) and the German Federal Foreign Office.

The researchers assume that, following the recent floods in a number of German states and neighboring countries, both mud and water are contaminated with pollutants. Soil sampling should provide clarity as to which substances have found their way into gardens, playgrounds, and green spaces as a result of the floods. After all, substances from oil tanks, septic tanks, and contaminated sites have been spilled into the environment. For example, the researchers expect that heavy metals have now accumulated in sediments. “We are analyzing these samples together with colleagues from the field of ecotoxicology.” According to the researchers, the analysis of the Aachen samples can be used to derive pollution risk assessments for other flood-affected areas.