Hydrometeorological threshold conditions for debris flow initiation in Norway

Meyer, Nele; Dyrrdal, Anita Verpe; Frauenfelder, Regula; Etzelmüller, Bernd; Nadim, Farrokh

doi:10.5194/nhess-12-3059-2012

Cited by 25 publications

(31 citation statements)

References 28 publications

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“…Therefore we analyze the temporal development of individual ID values for debris-flow events at the Spreitgraben and Riasco catchments (Figure 3), in comparison with existing ID thresholds (Table II) for debris flows and landslides (including Caine, 1980;Innes, 1983;Clarizia et al, 1996;Zimmermann et al, 1997;Crosta and Frattini, 2001;Cannon and Gartner, 2005;Guzzetti et al, 2007Guzzetti et al, , 2008McArdell and Badoux, 2007;Stricker, 2010;and Meyer et al, 2012). Immediately after a landslide event, we hypothesize that the sediment deposited on relatively steep slopes close to the angle of repose would be readily mobilized by relatively small rainfall events, causing debris flows to be triggered.…”

Section: Intensity-duration Analysismentioning

confidence: 99%

Landslides and increased debris‐flow activity: A systematic comparison of six catchments in Switzerland

Frank

Huggel

McArdell

et al. 2018

Earth Surf Processes Landf

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An increase in debris‐flow frequency is expected in steep Alpine catchments after the occurrence of a large landslide, such as a rock avalanche. Herein we describe changes in debris‐flow activity following increases in sediment availability due to landslides, or accelerated rock‐glacier movement, for five catchments in the Swiss Alps, the Spreitgraben, Schipfenbach, Bondasca, Riascio, and Dorfbach catchments. Documentation on debris‐flow activity is available from both before and after the landslide that generated the new sediment deposits. Data from nearby meteorological stations were used to explore possible changes in rainfall activity, and how the intensity and duration of rainfall events may have changed. In all cases there was a considerable increase in debris‐flows frequency for one to eight years following the landslide. The annual number of days with debris‐flow activity following the landslide was similar to that observed for the Illgraben catchment, where many such landslides occur annually. No clear change in precipitation totals preceding debris flows was apparent for the Riascio catchment, suggesting that the increase in frequency of debris flows is related to the increase in the amount of sediment that can be readily mobilized. In the two cases where rainfall data were available on an hourly basis, no systematic changes in the intensity or duration of rainfall related to debris‐flow triggering were apparent, as shown by the close‐clustering of storms on the intensity‐duration plots. Following the sediment‐generating event, an initial and sudden increase of the sediment yield was observed, followed by a decrease over time towards pre‐disturbance values. The response of the catchments appears to be related to the amount of debris‐flow activity prior to the landslide: sediment yield from catchments with frequent debris flows prior to the landslide activity did not increase as dramatically as in catchments where debris‐flow activity was less common prior to the landslide. © 2018 John Wiley & Sons, Ltd.

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Section: Intensity-duration Analysismentioning

confidence: 99%

Landslides and increased debris‐flow activity: A systematic comparison of six catchments in Switzerland

Frank

Huggel

McArdell

et al. 2018

Earth Surf Processes Landf

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“…The thresholds are defined showing critical intensities over durations of 1 to 7 days. Meyer et al (2012) provide a full description of used methodologies, including formulas. 25…”

Section: Precipitation Thresholds For Debris Flow Initiationmentioning

confidence: 99%

Impacts of extreme weather events on transport infrastructure in Norway

Frauenfelder

Solheim

Isaksen

et al. 2017

Preprint

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clearer understanding of the trends in the development of extreme weather. The studies are based on both historical data and available future scenarios (projections) from climate models. Compared to previous studies, we calculated changes in climate variables that are particularly important in relation to nature hazards. Overall, the analyses document an increase in frequency as well as intensity of both precipitation and wind. Results of projections show that the observed changes will continue throughout this century. We could also identify large regional differences, with some areas experiencing, e.g., a reduction in 30 the intensity of heavy rainfall events. However, most of the country will experience the opposite, i.e., both increased intensity and increased frequency of heavy precipitation. Our analyses show that at least 27 per cent of Norwegian roads and 31 per cent of railroads are exposed to rock fall and snow avalanches hazards. The project has also assessed relationships between different parameters that can affect the likelihood of debris flows. Variables such as terrain slope and size of watercourses are important, while local climate, which varies widely in Norway, determines threshold values for rainfall that can trigger debris 35 flows.Nat. Hazards Earth Syst. Sci. Discuss., https://doi

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“…The better performance of the rainfall threshold using hourly data from station 1 indicates that rainfall intensity is important rather than daily amount. The daily total of 20 mm was in the range of Meyer et al (2012), between 15 and 107 mm day −1 . The probability of static threshold exceedance was also similar to Meyer et al (2012), whose threshold was exceeded between 0 and 77 days in a year (8.5 % corresponds to 31 days a year).…”

Section: Weather Station Thresholdsmentioning

confidence: 99%

“…Therefore, in many threshold studies, many hazardous events are excluded from analysis. Brunetti et al (2013) automatically excluded events where the closest rain gauge was more than 5 km away or there were not sufficient rainfall data, and in Meyer et al (2012), 20 % were excluded due to insufficient information.…”

Section: Introductionmentioning

confidence: 99%

“…Finally, many of the empirical methods establish a threshold above which debris flows may occur, without considering non-event observation also above the threshold, as there are many more non-event days. Meyer et al (2012) used only debris flow events to determine the threshold, then analysed the annual frequency of days above the threshold. As rainfall is not the only factor governing debris flows, there will likely always be uncertainty in the definition of rainfall thresholds (Berti et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

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Empirical atmospheric thresholds for debris flows and flash floods in the southern French Alps

Turkington

Ettema

Westen

et al. 2014

Nat. Hazards Earth Syst. Sci.

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Abstract. Debris flows and flash floods are often preceded by intense, convective rainfall. The establishment of reliable rainfall thresholds is an important component for quantitative hazard and risk assessment, and for the development of an early warning system. Traditional empirical thresholds based on peak intensity, duration and antecedent rainfall can be difficult to verify due to the localized character of the rainfall and the absence of weather radar or sufficiently dense rain gauge networks in mountainous regions. However, convective rainfall can be strongly linked to regional atmospheric patterns and profiles. There is potential to employ this in empirical threshold analysis.This work develops a methodology to determine robust thresholds for flash floods and debris flows utilizing regional atmospheric conditions derived from ECMWF ERAInterim reanalysis data, comparing the results with raingauge-derived thresholds. The method includes selecting the appropriate atmospheric indicators, categorizing the potential thresholds, determining and testing the thresholds. The method is tested in the Ubaye Valley in the southern French Alps (548 km 2 ), which is known to have localized convection triggered debris flows and flash floods. This paper shows that instability of the atmosphere and specific humidity at 700 hPa are the most important atmospheric indicators for debris flows and flash floods in the study area. Furthermore, this paper demonstrates that atmospheric reanalysis data are an important asset, and could replace rainfall measurements in empirical exceedance thresholds for debris flows and flash floods.

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Hydrometeorological threshold conditions for debris flow initiation in Norway

Cited by 25 publications

References 28 publications

Landslides and increased debris‐flow activity: A systematic comparison of six catchments in Switzerland

Landslides and increased debris‐flow activity: A systematic comparison of six catchments in Switzerland

Impacts of extreme weather events on transport infrastructure in Norway

Empirical atmospheric thresholds for debris flows and flash floods in the southern French Alps

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