Rare flash floods and debris flows in southern Germany
Autor: | Ankit Agarwal, José Andrés López-Tarazón, Adrian Riemer, Ugur Ozturk, Kristin Vogel, Oliver Korup, Dadiyorto Wendi, Irene Crisologo |
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Rok vydání: | 2018 |
Předmět: |
geography
Environmental Engineering geography.geographical_feature_category 010504 meteorology & atmospheric sciences 0208 environmental biotechnology Sediment Landslide 02 engineering and technology 01 natural sciences Pollution Debris 020801 environmental engineering Debris flow Cuesta Snowmelt ddc:550 Flash flood Environmental Chemistry Institut für Geowissenschaften Physical geography Waste Management and Disposal Geology 0105 earth and related environmental sciences Riparian zone |
Zdroj: | Science of the Total Environment |
ISSN: | 0048-9697 |
Popis: | Flash floods and debris flows are iconic hazards inmountainous regions with steep relief, high rainfall intensities, rapid snowmelt events, and abundant sediments. The cuesta landscapes of southern Germany hardly come to mind when dealing with such hazards. A series of heavy rainstorms dumping up to 140mm in 2 h caused destructive flash floods and debris flows in May 2016. The most severe damage occurred in the Braunsbach municipality, which was partly buried by 42,000 m(3) of boulders, gravel, mud, and anthropogenic debris from the small catchment of Orlacher Bach (similar to 6 km(2)). We analysed this event by combining rainfall patterns, geological conditions, and geomorphic impacts to estimate an average sediment yield of 14,000 t/km(2) that mostly (similar to 95%) came from some 50 riparian landslides and channel-bed incision of similar to 2 m. This specific sediment yield ranks among the top 20% globally, while the intensity-duration curve of the rainstormis similarly in the upper percentile range of storms that had triggered landslides. Compared to similar-sized catchments in the greater region hit by the rainstorms, we find that the Orlacher Bach is above the 95th percentile in terms of steepness, storm-rainfall intensity, and topographic curvatures. The flash flood transported a sediment volume equal to as much as 20-40% of the Pleistocene sediment volume stored in the Orlacher Bach fan, andmay have had several predecessors in the Holocene. River control structures from 1903 and records of a debris flow in the 1920s in a nearby catchment indicate that the local inhabitants may have been aware of the debris-flow hazards earlier. Such recurring and destructive events elude flood-hazard appraisals in humid landscapes of gentle relief, and broaden mechanistic views of how landslides and debris flows contribute to shaping small and deeply cut tributaries in the southern Germany cuesta landscape. |
Databáze: | OpenAIRE |
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