# An unusual Rain-on-Snow event preconditioning the catastrophic fate of the village La Bérarde, French Alps

Simon Filhol, Marie Dumont, Pascal Hagenmuller, François Doussot, Eckert

Nicolas, Simon Gascoin, Antoine Blanc

► To cite this version:

Simon Filhol, Marie Dumont, Pascal Hagenmuller, François Doussot, Eckert Nicolas, et al. An unusual Rain-on-Snow event preconditioning the catastrophic fate of the village La Bérarde, French Alps. EGU, EGU, Apr 2025, Vienna, Austria. 10.5194/egusphere-egu25-13270. hal-05443327

HAL Id: hal-05443327

https://hal.science/hal-05443327v1

Submitted on 6 Jan 2026

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# An unusual Rain-on-Snow event preconditioning the catastrophic fate of the village La Bérarde, French Alps, June 2024

Simon Filhol<fnref n="1" />, Marie Dumont<fnref n="1" />, Pascal Hagenmuller<fnref n="1" />, François Doussot<fnref n="1" />, Eckert Nicolas<fnref n="2" />, Simon Gascoin<fnref n="3" />, and Antoine Blanc<fnref n="4" />

On June 21st, 2024, the iconic village of La Bérarde, in the centre of the massif Les Ecrins, French Alps, was destroyed by the mountain stream "Les Etancons", that flooded the houses and deposited more than 200,000 m<fnref n="3" /> of raw material. This catastrophic event was caused by the concomitance of rapid warming with a heavy rain on top of a snowpack unusually thick in a glaciated watershed ranging from 1700 m to 4000 m a.s.l. during which a glacial lake drained simultaneously. Using observations (in-situ and remotely sensed) and the Météo-France modelling chain S2M, reanalysing meteorological and snow conditions in mountainous areas, we characterize a *posteriori* this rain-on-snow event and evaluate its contribution to the flood as well as its genuine nature within the last 65 years. Change in precipitation extremes was estimated by fitting a time dependent Generalized Extreme Value model within a Bayesian framework on available data. This analysis suggests an intensification of extreme precipitation in the studied high alpine region which is undergoing profound landscape changes with permafrost thawing and glacial retreat leading to favorable conditions for the formation of glacial lakes. This concomitance of intense meteorological events within a rapidly changing landscape is a striking reminder of how climate change is reshaping flood risk in high alpine regions.

<footnote n="1">¹Météo-France, CNRS, CNRM, Centre d'Études de la Neige, Grenoble, France</footnote>

<footnote n="2">²UMR IGE, INRAE/Univ. Grenoble Alpes, Grenoble, France</footnote>

<footnote n="3">³CESBIO, Université de Toulouse, CNES, CNRS, IRD, UT3 Paul Sabatier, Toulouse, France</footnote>

<footnote n="4">⁴ONF, RTM, Grenoble, France</footnote>