Avalanche risk evaluation and protective dam optimal design using extreme value statistics

• Published in: Journal of Glaciology
• Main Authors: Favier, P., Eckert, Nicolas, Faug, Thierry, Bertrand, D., Naaim, Mohamed
• Other Authors: Erosion torrentielle neige et avalanches (UR ETGR (ETNA)), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), Laboratoire de Génie Civil et d'Ingénierie Environnementale (LGCIE), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA), FONDAP Center for Genome Regulation (CGR), Comisión Nacional de Investigación Científica y Tecnológica CONICYT, The University of Sydney, French National Research Agency (ANR), MAP3 Alcotra Interreg program, People Programme (Marie Curie Actions) of the European Unions Seventh Framework Programme under REA grant : 622899
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2016
• Subjects: avalanches; avalanche protection dam; design; EVALUATION DU RISQUE; DIGUE PARAVALANCHE; AVALANCHE; THEORIE DES VALEURS EXTREMES; DIMENSIONNEMENT; [SDE.IE]Environmental Sciences/Environmental Engineering; [SPI.GCIV.RISQ]Engineering Sciences [physics]/Civil Engineering/Risques; [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology; Journal of Glaciology
• Online Access: https://hal.science/hal-01507675; https://hal.science/hal-01507675/document; https://hal.science/hal-01507675/file/gr2016-pub00054176.pdf; https://doi.org/10.1017/jog.2016.64

[Departement_IRSTEA]Eaux [TR1_IRSTEA]RIVAGE International audience In snow avalanche long-term forecasting, existing risk-based methods remain difficult to use in a real engineering context. In this work, we expand a quasi analytical decisional model to obtain simple formulae to quantify risk and to perform the optimal design of an avalanche dam in a quick and efficient way. Specifically, the exponential runout model is replaced by the Generalized Pareto distribution (GPD), which has theoretical justifications that promote its use for modelling the different possible runout tail behaviours. Regarding the defence structure/flow interaction, a simple law based on kinetic energy dissipation is compared with a law based on the volume stored upstream of the dam, whose flexibility allows us to cope with various types of snow. We show how a detailed sensitivity study can be conducted, leading to intervals and bounds for risk estimates and optimal design values. Application to a typical case study from the French Alps, highlights potential operational difficulties and how they can be tackled. For instance, the highest sensitivity to the runout tail type and interaction law is found at abscissas of legal importance for hazard zoning (return periods of 10-1000 a), a crucial result for practical purposes.