MONITORING MOUNTAIN CRYOSPHERE DYNAMICS BY TIME LAPSE STEREO PHOTOGRAMMETRY

In situ glacier point mass balance data are crucial to assess climate change in different regions of the world. Unfortunately, these data are rare because huge efforts are required to conduct in situ measurements on glaciers. Here, we propose a new approach from remote sensing observations. The method has been tested on the Argentière and Mer de Glace glaciers (France). It should be possible to apply this method to high-spatial-resolution satellite images and on numerous glaciers in the world.

Among mountainous permafrost landforms, rock glaciers are composed of boulders, fine frozen materials, water and ice in various proportions. Displacement rates of active rock glaciers can reach several m/yr, contributing to emerging risks linked to gravitational hazards. Thanks to passive seismic monitoring, resonance effects related to seasonal freeze–thawing processes of the shallower layers have been monitored and modeled. This method is an accurate tool for studying rock glaciers at depth.

This study aims to assess the occurrence of rock glacier destabilization in the French Alps, a process that causes a landslide-like behaviour of permafrost debris slopes. A significant number of the landforms in the region were found to be experiencing destabilization. Multivariate analysis suggested a link between destabilization occurrence and permafrost thaw induced by climate warming. These results call for a regional characterization of permafrost hazards in the context of climate change.

Parameter estimation of distributed hydrological models is usually conducted with a single method. However, the main methods can be combined to consider differently the model parameters according to their characteristics. The strategy presented in the paper takes advantage of three different methods to provide four different spatial patterns. This tailor-made method then proves to be more robust and more relevant for prediction in ungauged basins while significantly reducing the number of degree.