TY - JOUR A1 - Ozturk, Ugur A1 - Wendi, Dadiyorto A1 - Crisologo, Irene A1 - Riemer, Adrian A1 - Agarwal, Ankit A1 - Vogel, Kristin A1 - Andres Lopez-Tarazon, Jose A1 - Korup, Oliver T1 - Rare flash floods and debris flows in southern Germany JF - The science of the total environment : an international journal for scientific research into the environment and its relationship with man N2 - 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. KW - Flash flood KW - Debris flow KW - Rainfall-triggered landslide KW - Hazard KW - Germany Y1 - 2018 U6 - https://doi.org/10.1016/j.scitotenv.2018.01.172 SN - 0048-9697 SN - 1879-1026 VL - 626 SP - 941 EP - 952 PB - Elsevier CY - Amsterdam ER - TY - CHAP A1 - Bronstert, Axel A1 - Crisologo, Irene A1 - Heistermann, Maik A1 - Öztürk, Ugur A1 - Vogel, Kristin A1 - Wendi, Dadiyorto T1 - Flash-floods: more often, more severe, more damaging? BT - An analysis of hydro-geo-environmental conditions and anthropogenic impacts T2 - Climate change, hazards and adaptation options: handling the impacts of a changing climate N2 - In recent years, urban and rural flash floods in Europe and abroad have gained considerable attention because of their sudden occurrence, severe material damages and even danger to life of inhabitants. This contribution addresses questions about possibly changing environmental conditions which might have altered the occurrence frequencies of such events and their consequences. We analyze the following major fields of environmental changes. Altered high intensity rain storm conditions, as a consequence of regionalwarming; Possibly altered runoff generation conditions in response to high intensity rainfall events; Possibly altered runoff concentration conditions in response to the usage and management of the landscape, such as agricultural, forest practices or rural roads; Effects of engineering measures in the catchment, such as retention basins, check dams, culverts, or river and geomorphological engineering measures. We take the flash-flood in Braunsbach, SW-Germany, as an example, where a particularly concise flash flood event occurred at the end of May 2016. This extreme cascading natural event led to immense damage in this particular village. The event is retrospectively analyzed with regard to meteorology, hydrology, geomorphology and damage to obtain a quantitative assessment of the processes and their development. The results show that it was a very rare rainfall event with extreme intensities, which in combination with catchment properties and altered environmental conditions led to extreme runoff, extreme debris flow and immense damages. Due to the complex and interacting processes, no single flood cause can be identified, since only the interplay of those led to such an event. We have shown that environmental changes are important, but-at least for this case study-even natural weather and hydrologic conditions would still have resulted in an extreme flash flood event. KW - Flash flood KW - Climate change KW - Extreme rainfall KW - Anthropogenic impacts Y1 - 2020 SN - 978-3-030-37425-9 SN - 978-3-030-37424-2 U6 - https://doi.org/10.1007/978-3-030-37425-9_12 SN - 1610-2010 SP - 225 EP - 244 PB - Springer CY - Cham ER - TY - JOUR A1 - Bronstert, Axel A1 - Agarwal, Ankit A1 - Boessenkool, Berry A1 - Crisologo, Irene A1 - Fischer, Madlen A1 - Heistermann, Maik A1 - Koehn-Reich, Lisei A1 - Andres Lopez-Tarazon, Jose A1 - Moran, Thomas A1 - Ozturk, Ugur A1 - Reinhardt-Imjela, Christian A1 - Wendi, Dadiyorto T1 - Forensic hydro-meteorological analysis of an extreme flash flood BT - the 2016-05-29 event in Braunsbach, SW Germany JF - The science of the total environment : an international journal for scientific research into the environment and its relationship with man N2 - The flash-flood in Braunsbach in the north-eastern part of Baden-Wuerttemberg/Germany was a particularly strong and concise event which took place during the floods in southern Germany at the end of May/early June 2016. This article presents a detailed analysis of the hydro-meteorological forcing and the hydrological consequences of this event. A specific approach, the "forensic hydrological analysis" was followed in order to include and combine retrospectively a variety of data from different disciplines. Such an approach investigates the origins, mechanisms and course of such natural events if possible in a "near real time" mode, in order to follow the most recent traces of the event. The results show that it was a very rare rainfall event with extreme intensities which, in combination with catchment properties, led to extreme runoff plus severe geomorphological hazards, i.e. great debris flows, which together resulted in immense damage in this small rural town Braunsbach. It was definitely a record-breaking event and greatly exceeded existing design guidelines for extreme flood discharge for this region, i.e. by a factor of about 10. Being such a rare or even unique event, it is not reliably feasible to put it into a crisp probabilistic context. However, one can conclude that a return period clearly above 100 years can be assigned for all event components: rainfall, peak discharge and sediment transport. Due to the complex and interacting processes, no single flood cause or reason for the very high damage can be identified, since only the interplay and the cascading characteristics of those led to such an event. The roles of different human activities on the origin and/or intensification of such an extreme event are finally discussed. (C) 2018 Elsevier B.V. All rights reserved. KW - Flash flood analysis KW - Forensic disaster analysis KW - Radar rainfall data KW - Extreme discharge data KW - Extreme event Y1 - 2018 U6 - https://doi.org/10.1016/j.scitotenv.2018.02.241 SN - 0048-9697 SN - 1879-1026 VL - 630 SP - 977 EP - 991 PB - Elsevier CY - Amsterdam ER -