Impacts of future climatic change (2070–2099) on the potential occurrence of debris flows: a case study in the Massif des Ecrins (French Alps)

Abstract

In this paper we investigate the impacts of future climatic change on the occurrence of debris flows in the Massif des Ecrins (French Alps). Two distinct aspects are discussed: the impact of future climatic change on the evolution of the process, and changes in the spatial distribution. Three climate simulations are presented for the current period and for future periods using GCM ARPEGE CLIMAT model developed by Météo-France. Simulated data are then statistically downscaled to obtain a higher spatial resolution. In the first step, we compare occurrence probabilities in the current period and in the next century. In the second step, we estimate which zones would be affected by the process in the future at the scale of the Massif des Ecrins. For the current period, the best model was obtained between debris flows and the number of days between June 15th and October 15th with more than 20 mm calculated either from observed meteorological or simulated data. Results of the ARPEGE model considering the A2 hypothesis (IPCC 2007) showed that the most significant climatic trends for the end of the century will be a decrease in intense rainy events and an increase in temperature. These trends are expected to reduce the occurrence of hill slope debris flows in the Massif des Ecrins. From a spatial point of view, the increase in temperature should 172 Climatic Change (2009) 97:171-191 result in a shift of the 0 • C isotherm to a higher elevation which, in turn, should result in a 20% reduction of the number of slopes affected by the process.

Snow and weather climatic control on snow avalanche occurrence fluctuations over 50 yr in the French Alps

“…A possible interesting further work would be to relate these results to synoptic patterns such as annual NAO anomalies, as already pointed out in other regions (Keylock, 2003;Garcia-Sellés et al, 2010). This approach also opens the door to the possible evaluation of the future impact of climate change on avalanche activity in the French Alps by combining the regression models obtained with the results of SCM simulations forced by scenarios of climate warming, as in a study conducted by Jomelli et al (2009) for debris flows in the Ecrins massif. This may complement the results obtained by Lazar and Williams (2008) regarding the evolution of the type of releases by information regarding their numbers in terms of trend and high and low peaks, potentially very useful information for long-term avalanche hazard assessment in land use planning, which continues to be carried out within the debatable assumption of stationarity of the avalanche process.…”

The method ADAMONT v1.0 for statistical adjustment of climate projections applicable to energy balance land surface models

“…Climate projections in mountainous regions, which are motivated by a broad range of geophysical, environmental and societally relevant scientific challenges (Martin et al, 1994;Beniston, 1997;Jomelli et al, 2009;Castebrunet et al, 2014;Piazza et al, 2014;Schmucki et al, 2014;Lafaysse et al, 2014;Boulangeat et al, 2014;Thuiller et al, 2014;Castebrunet et al, 2014;Francois et al, 2015;Spandre et al, 2016) are particularly sensitive to the quality of the adjustment method. Indeed, RCM resolutions typically between 10 and 50 km are not sufficient to capture the fine-scale processes and thresholds at play.…”

Debris-flow activity in abandoned channels of the Manival torrent reconstructed with LiDAR and tree-ring data

“…1900s, 1950s, and 1990s), we do not consider our database long and complete enough to postulate for an unequivocal evidence of changes and trends in debris-flow frequency during the 20th century as a result of climate change, as put forward by other studies which were based on much larger and longer time series (e.g. Stoffel and Beniston, 2006;Jomelli et al, 2009). …”