Hazard assessment in Switzerland - Codes of Practice for mass movements

Abstract. The objectives of the present investigation are (i) to study the effects of climate change on precipitation extremes and (ii) to assess the uncertainty in the climate projections. The investigation is performed on the Lech catchment, located in the Northern Limestone Alps. In order to estimate the uncertainty in the climate projections, two statistical downscaling models as well as a number of global and regional climate models were considered. The downscaling models applied are the Expanded Downscaling (XDS) technique and the Long Ashton Research Station Weather Generator (LARS-WG). The XDS model, which is driven by analyzed or simulated large-scale synoptic fields, has been calibrated using ECMWF-interim reanalysis data and local station data. LARS-WG is controlled through stochastic parameters representing local precipitation variability, which are calibrated from station data only. Changes in precipitation mean and variability as simulated by climate models were then used to perturb the parameters of LARS-WG in order to generate climate change scenarios. In our study we use climate simulations based on the A1B emission scenario. The results show that both downscaling models perform well in reproducing observed precipitation extremes. In general, the results demonstrate that the projections are highly variable. The choice of both the GCM and the downscaling method are found to be essential sources of uncertainty. For spring and autumn, a slight tendency toward an increase in the intensity of future precipitation extremes is obtained, as a number of simulations show statistically significant increases in the intensity of 90th and 99th percentiles of precipitation on wet days as well as the 5- and 20-yr return values.

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“…Chiarle et al, 2007;Szymczak et al, 2010), landslides (e.g. Raetzo et al, 2002;Crosta et al, 2004), hail (e.g. Vinet, 2001) and avalanches (e.g.…”

Section: Introductionmentioning

confidence: 99%

Simulating future precipitation extremes in a complex Alpine catchment

Dobler

Bürger

Stötter

2013

Nat. Hazards Earth Syst. Sci.

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“…However, the distinction between both classes is important as in the stability analysis they showed a different susceptibility. Finally, the MF matrix has been prepared considering the degrees of hazard of the Swiss Federal Guidelines (Raetzo et al 2002) and it is shown in Fig. 10.…”

Section: Resultsmentioning

confidence: 99%

“…This topic has been widely discussed in countries such as Switzerland, Italy as well as Australia, among others, where custom methodologies have been developed (AGS 2007;Kranitz and Bensi 2009;Raetzo and Loup 2009) and implemented elsewhere (e.g. Cardinali et al 2002Cardinali et al , 2006Raetzo et al 2002;Sterlacchini et al 2007;Posch-Trözmüller 2010;Strozzi et al 2013).…”

Section: Landslide Hazard Mappingmentioning

confidence: 99%

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Preparing first-time slope failures hazard maps: from pixel-based to slope unit-based

2019

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In this work, we present a novel quantitative geographical information system-based procedure to obtain the magnitude (area) and frequency of medium to large first-time shallow slope failures. The procedure has been set up at the Barcedana Valley, in the Tremp Basin (Eastern Pyrenees). First, pixel-based susceptibility classes were defined using a slope stability index obtained with the physically based model SINMAP. The frequency calculated from the number of firsttime failures recorded during the last 60 years was then assigned to each susceptibility class. We devised a procedure to estimate the size of potential failures by means of the aggregation of pixels within the boundaries of morphological slope units, optimized for the purpose. Finally, the landslide hazard was prepared using the magnitude-frequency matrix. Results show that a proper pixel clustering has been carried which avoids the generation of small groups of pixels with different susceptibility degrees within the same slope unit. For a given hill slope, the area of the cluster of pixels depends on the size of the slope unit, which is not unique as it depends on the criterion used to delineate them. Therefore, the latter is a key factor in the final results. In this study, we validated our results with the size distribution of the observed landslides. The methodology presented in this work can be applied using any susceptibility assessment method with a pixel-based output.

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“…According to the guidelines from Raetzo et al (2002), flow velocities and heights can be translated into different intensity levels. Three scenarios were defined: the dimensions of the 2010 event were taken for the small scenario (450,000 m 3 ); the medium and large scenarios involved avalanche volumes of 1 and 3 million m 3 , respectively .…”

Section: Risk Knowledge (Glof Modeling)mentioning

confidence: 99%