Rare flash floods and debris flows in southern Germany

Öztürk, Uğur; Wendi, Dadiyorto; Crisologo, Irene; Riemer, Adrian; Agarwal, Ankit; Vogel, Kristin; López‐Tarazón, José A.; Korup, Oliver

doi:10.1016/j.scitotenv.2018.01.172

Cited by 55 publications

(28 citation statements)

References 30 publications

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“…An integrated spatiotemporal analysis of rainfall evolution, together with soil storages in the basin, is necessary to study the relevance of antecedent conditions and precipitation type, intensity, and location in the generation of flash flood events. Event 1 increased the overall soil moisture with an associated decrease in infiltration rates, similar to the results reported by Marchi et al (2010), Penna et al (2011 and Zehe et al (2010); additionally, low infiltration increased the runoff rates, ultimately affecting the susceptibility of the basin to flash flood occurrence (Wagner et al, 1999;Penna et al, 2011;Tramblay et al, 2012). Due to geomorphological characteristics (see Table 5), water tends to reach the channels in hills of orders 1 and 2 more quickly, and, at the same time, the sediment production and transport in these hills tend to be larger.…”

Section: Discussionsupporting

confidence: 84%

“…These features are typical of Andean mountainous basins. Geomorphologically, this kind of watershed tends to be prone to the occurrence of flash floods (Lehmann and Or, 2012;Penna et al, 2011;Martín-Vide and Llasat, 2018;Longoni et al, 2016;Ozturk et al, 2018;Khosravi et al, 2018;Marchi et al, 2016;Bisht et al, 2018).…”

Section: Catchment Descriptionmentioning

confidence: 99%

“…This study addresses two broad hydrological issues. The first issue consists in exploring the relationship between rainfall spatiotemporal structure (Llasat et al, 2016;Fragoso et al, 2012), soil moisture and runoff generation (Penna et al, 2011;Tramblay et al, 2012;Garambois et al, 2013) during the successive rainfall events and the second one in proposing a simplified hydrological modeling scheme, including landslide and hydraulic submodels, to assess the potential occurrence of flash flood events.…”

Section: Introductionmentioning

confidence: 99%

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Reconstructing the 2015 Salgar flash flood using radar retrievals and a conceptual modeling framework in an ungauged basin

Velásquez

Hoyos

Vélez

et al. 2020

Hydrol. Earth Syst. Sci.

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Abstract. On 18 May 2015, a severe rainfall event triggered a flash flood in the municipality of Salgar, located in the northwestern Colombian Andes. This work aims to reconstruct the main hydrological features of the flash flood to better understand the processes modulating the occurrence of the event. Radar quantitative precipitation estimates (QPEs), satellite information, and post-event field visits are used to reconstruct the Salgar flash flood, in an ungauged basin, addressing the relationship among rainfall spatiotemporal structure, soil moisture, and runoff generation during successive rainfall events by using a conceptual modeling framework including landslide and hydraulic submodels. The hydrological model includes virtual tracers to explore the role of runoff and subsurface flow and the relative importance of convective and stratiform precipitation in flash flood generation. Despite potential shortcomings due to the lack of data, the modeling results allow an assessment of the impact of the interactions between runoff, subsurface flow, and convective–stratiform rainfall on the short-term hydrological mechanisms leading to the flash flood event. The overall methodology reproduces the magnitude and timing of the La Liboriana flash flood peak discharge considerably well, as well as the areas of landslide occurrence and flood spots, with limitations due to the spatial resolution of the available digital elevation model. Simulation results indicate that the flash flood and regional landslide features were strongly influenced by the antecedent rainfall, which was associated with a northeasterly stratiform event. The latter recharged the gravitational and capillary storages within the model, moistening the entire basin before the occurrence of the flash flood event and impacting the subsurface–runoff partitioning during the flash flood event. Evidence suggests that the spatial structure of the rainfall is at least as important as the geomorphological features of the basin in regulating the occurrence of flash flood events.

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Section: Discussionsupporting

confidence: 84%

Section: Catchment Descriptionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Reconstructing the 2015 Salgar flash flood using radar retrievals and a conceptual modeling framework in an ungauged basin

Velásquez

Hoyos

Vélez

et al. 2020

Hydrol. Earth Syst. Sci.

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“…Not only do mountain headwater streams generate sediment-laden flows with aftermaths within and along fans [8,9], but also streams and gullies of first-order catchments (up to 10 km 2 ) in moderate relief can be responsible for local damage to infrastructure. Ozturk et al [10] analysed extraordinary flash flood events (140 mm per 2 h) in a small catchment (6 km 2 ) that resulted in damage to infrastructure and a high amount of suspended sediments (t/km 2 ) due to intense hillslope-channel coupling. In addition, Terti et al [11] pointed to a short response time of small catchments to flash floods, thereby increasing the probability of trapping people during outdoor activities.…”

Section: Introductionmentioning

confidence: 99%

Hydrogeomorphic Impacts of Floods in a First-Order Catchment: Integrated Approach Based on Dendrogeomorphic Palaeostage Indicators, 2D Hydraulic Modelling and Sedimentological Parameters

Tichavský

Ruman

Galia

2020

Water

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Floods represent frequent hazards in both low- and first-order catchments; however, to date, the investigation of peak flow discharges in the latter catchments has been omitted due to the absence of gauging stations. The quantification of flood parameters in a first-order catchment (1.8 km2) was realised in the moderate relief of NE Czechia, where the last flash flood event in 2014 caused considerable damage to the infrastructure. We used an integrated approach that included the dendrogeomorphic reconstruction of past flood activity, hydraulic modelling of the 2014 flash flood parameters using a two-dimensional IBER model, and evaluation of the channel stability using sedimentological parameters. Based on 115 flood scars, we identified 13 flood events during the period of 1955 to 2018, with the strongest signals recorded in 2014, 2009 and 1977. The modelled peak flow discharge of the last 2014 flood was equal to 4.5 m3·s−1 (RMSE = 0.32 m) using 26 scars as palaeostage indicators. The excess critical unit stream power was observed at only 24.2% of the reaches, representing predominantly bedrock and fine sediments. Despite local damage during the last flood, our results suggest relatively stable geomorphic conditions and gradual development of stream channels under discharges similar to that in 2014.

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“…Hence, it comes as no surprise that a task force was formed shortly after the event, to assess the risk and adjust mitigation efforts accordingly. Fifth, evaluations by independent technical experts suggest that the task force above initially did not pay sufficient attention to the potential risks associated with morphological changes and the transport of sediment and large woody debris ("large wood" hereafter) in the risk assessment and planning of mitigation measures [34,[40][41][42][43]. Consequently, the municipalities' mitigation efforts were slow to take into consideration these aspects of the fluvial geomorphology.…”

Section: Collaborative Governance After the 2016 Flash Flood In Braunmentioning

confidence: 99%

Impact of Scientific Scrutiny after the 2016 Braunsbach Flash Flood on Flood-Risk Management in the State of Baden-Württemberg, Germany

Witting

Brandenstein

Zarfl

et al. 2020

Water

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This paper presents interdisciplinary research focusing on the municipality of Braunsbach in the German state of Baden-Württemberg, where, in May 2016, a flash flood attracted media attention and scientific scrutiny that highlighted the fact that certain aspects of flood risk were overlooked during earlier assessments conducted by the municipality, such as sediment transport. Using a network analysis and a focus-group discussion, we traced the flow of knowledge through the reported interactions between governmental, private, and academic actors in the two and a half years after the event. From our analysis, we learned that the extreme event attracted scientists to the formal and informal assessment of the hazard and the associated damages. Most importantly, we found conditions under which scientific scrutiny is not detached from but becomes integrated in a governance setting. While it is through this process that sediment transport has become an integral part of flood-risk management in Baden-Württemberg, with an evident impact on the measures already implemented, the impact of morphological changes, as well as large wood and sediment transport, have not been factored into the risk assessment as of yet. These variations in scientific impact on the assessment can be explained by decision biases that can occur when decision makers are under pressure to tackle vulnerabilities and thus lack the time to deliberate in a way that uses all the available evidence.

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Rare flash floods and debris flows in southern Germany

Cited by 55 publications

References 30 publications

Reconstructing the 2015 Salgar flash flood using radar retrievals and a conceptual modeling framework in an ungauged basin

Reconstructing the 2015 Salgar flash flood using radar retrievals and a conceptual modeling framework in an ungauged basin

Hydrogeomorphic Impacts of Floods in a First-Order Catchment: Integrated Approach Based on Dendrogeomorphic Palaeostage Indicators, 2D Hydraulic Modelling and Sedimentological Parameters

Impact of Scientific Scrutiny after the 2016 Braunsbach Flash Flood on Flood-Risk Management in the State of Baden-Württemberg, Germany

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