Accounting for Non-stationarity in Extreme Snow Loads: a Comparison with Building Standards in the French Alps

Roux, Erwan Le; Evin, Guillaume; Eckert, Nicolas; Blanchet, Juliette; Morin, Samuel

doi:10.5194/nhess-2020-81

Cited by 2 publications

(1 citation statement)

References 47 publications

(59 reference statements)

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“…Hopefully, this might concern few settlements as such strong increases are always located above 2000 m. However, this might impact ski resorts which should ensure that the design of avalanche protections take this change into account. Furthermore, to update structure standards for ground snow load (Biétry, 2005), we should account both for this increasing trend in annual maxima of daily snowfall, and trends in annual maxima of ground snow loads (Le Roux et al, 2020). Indeed, most known snow load destructions result from such intense and short snow events, sometimes combined with liquid precipitation.…”

Section: Implication Of the Temporal Trends In 100-year Return Levelsmentioning

confidence: 99%

Elevation-dependent trends in extreme snowfall in the French Alps from 1959 to 2019

Roux¹,

Evin²,

Eckert³

et al. 2021

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Abstract. Climate change projections indicate that extreme snowfall are expected to increase in cold areas, i.e. at high latitude and/or high elevation, and to decrease in warmer areas, i.e. at mid-latitude and low elevation. However, the magnitude of these contrasted patterns of change and their precise relations to elevation at the scale of a given mountain range remain ill-known. This study analyzes annual maxima of daily snowfall based on the SAFRAN reanalysis spanning the time period 1959–2019, and provided within 23 massifs in the French Alps every 300 m of elevation. We estimate temporal trends in 100-year return levels with non-stationary extreme value models that depend both on elevation and time. Specifically, for each massif and four elevation ranges (below 1000 m, 1000–2000 m, 2000–3000 m and above 3000 m), temporal trends are estimated with the best extreme value models selected on the basis of the Akaike information criterion. Our results show that a majority of trends are decreasing below 2000 m and increasing above 2000 m. Quantitatively, we find an increase of 100-year return levels between 1959 and 2019 equal to +23 % (+32 kg m−2) on average at 3500 m, and a decrease of −10 % (−7 kg m−2) on average at 500 m. However, for the four elevation ranges, we find both decreasing and increasing trends depending on location. In particular, we observe a spatially contrasted pattern, exemplified at 2500 m: 100-year return levels have decreased in the north of the French Alps while they have increased in the south which may result from interactions between the overall warming trend and circulation patterns. This study has implications for natural hazards management in mountain regions.

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Section: Implication Of the Temporal Trends In 100-year Return Levelsmentioning

confidence: 99%