For three days in July 2021, a weather system stalled over the Eifel mountains in Germany and Belgium dropping up to 250 mm of rain. The influx of water quickly morphed into a flash flooding event, inundating mountain valleys.

The Ahr Valley in Germany is a popular destination for wine and tourism. Villages crop up within the valley, nestled near the riverbanks. During the 2021 event, floodwaters ripped through the villages, wiping out bridges, damaging buildings, and depositing mud and debris in streets and homes. In the Ahr Valley alone, 134 people were killed.

Alpine flooding is a real concern in European countries — about 10% of Europe is made of narrow upland valleys. While flooding isn’t a new hazard, there is concern that climate change may usher in more frequent, slow-moving weather systems like the one that stalled in 2021.

 Predicting floods often depends on measuring water height with stream gauges. But for sudden and profound flooding events, gauging stations can be drowned early on, leaving nearby residents and city managers in the dark.

In a new paper, “A Seismic Approach to Flood Detection and Characterization in Upland Catchments,” published last month in Geophysical Research Letters, researchers looked at an alternative to stream measurements during floods. They turned to a seismic monitoring instrument, or seismometer, to reconstruct the signatures of the flood — not just the height of the water but the velocity, amount of sediment and debris the water was carrying, and the path of the flood through the valley.

These seismic signatures can be modeled to create a “footprint” of a flood. The researchers note that by using seismic monitoring for flooding events, downstream cities can get real-time updates on the nature of floods and information on evacuation timelines.

Read complete article at: https://www.asce.org/publications-and-news/civil-engineering-source/civil-engineering-magazine/article/2022/11/can-seismic-instruments-act-as-early-warning-systems-for-flooding