@article{Cathala2021,

title = {Modelling and characterizing glacier-bed overdeepenings as sites for potential future lakes in the deglaciating French Alps},

author = {Maeva Cathala and Florence Magnin and Andreas Linsbauer and Wilfried Haeberli},

url = {http://journals.openedition.org/geomorphologie/15255},

doi = {10.4000/geomorphologie.15255},

issn = {1266-5304},

year  = {2021},

date = {2021-04-01},

journal = {Géomorphologie : relief, processus, environnement},

volume = {27},

number = {1},

pages = {19--36},

publisher = {Groupe français de géomorphologie},

abstract = {Glacier retreat results in major landscape changes including the formation of new lakes in Glacier-Bed Overdeepenings (GBOs) that can provoke catastrophic Glacial Lake Outburst Flood (GLOF) hazards, but could also provide economic opportunities. This study aims to identify and characterize the location of potential GBOs in the French Alps as possible sites for future lakes. We first ran GlabTop (Glacier-bed Topography) and GlabTop2 models, two GIS schemes calculating glacier ice thickness and mapping potential GBOs. Their level of confidence is estimated using morphological analysis based on slope angle, crevasse fields and lateral narrowing at bedrock thresholds. 139 GBOs (>0.01km²) were predicted among which 59 have medium to very high confidence. 20 lakes are already forming at the snout of retreating glaciers, including four lakes at predicted GBOs <0,01km². The Vanoise massif hosts 43% of the predicted GBOs but the Mont Blanc massif gathers larger, deeper and more voluminous ones. Most of the predicted GBOs are below 3,500m a.s.l. as related to the elevation of the corresponding glaciers. In the Vanoise massif, many predicted GBOs have rather low confidence because of the extent of ice-cap like glaciers for which the shear stress approach used by GlabTop becomes questionable. Furthermore, 58 potential GBOs were detected by visual analysis of glacier morphologies. The study highlights the relevance of combining various methods to determine GBOs and is a first step towards the anticipation of future risks and opportunities related to the formation of new lakes in the French Alps.},

keywords = {Alpes fran{ç}aises, anticipation des al{é}as naturels, D{é}senglacement des paysages, Deglaciating landscapes, French Alps, futurs lacs potentiels, Glacier Bed Overdeepenings, hazards anticipation, Potential future lakes, surcreusements glaciaires},

pubstate = {published},

tppubtype = {article}

}

@article{Magnin2020,

title = {Estimating glacier-bed overdeepenings as possible sites of future lakes in the de-glaciating Mont Blanc massif (Western European Alps)},

author = {F. Magnin and W. Haeberli and A. Linsbauer and P. Deline and L. Ravanel},

url = {https://linkinghub.elsevier.com/retrieve/pii/S0169555X19304040},

doi = {10.1016/j.geomorph.2019.106913},

issn = {0169555X},

year  = {2020},

date = {2020-02-01},

journal = {Geomorphology},

volume = {350},

pages = {106913},

publisher = {Elsevier},

abstract = {De-glaciating high mountain areas result in new landscapes of bedrock and debris where permafrost can degrade, persist or even newly form in cases, and of new lakes in glacier bed overdeepenings (GBOs) becoming ice-free. These landscapes with new lakes in close neighborhood to over-steepened and perennially frozen slopes are prone to chain reaction processes (e.g. rock-ice avalanches into lakes triggering impact waves, dam breach or overtopping, and debris flows) with potentially far-reaching run-out distances causing valley floors devastation. The frequency, magnitude and zonation of hazards are shifting, requiring integrative approaches combining comprehensive information about landscape evolution and related processes to support stakeholders in their adaptation strategies. In this study, we intend to setup an essential baseline for such an integrative approach in the Mont Blanc massif (MBM), which is a typical high-mountain range affected by de-glaciation processes. We first (i) predict and (ii) detect potential GBOs by combining the GlabTop model with a visual analysis based on morphological indications of glacier flow through over-deepened bed parts. We then (iii) determine the level of confidence concerning the resulting information, and (iv) estimate the approximate time range under which potential lakes could form. The location of the predicted GBOs and the shape of glacier beds are evaluated against currently forming water bodies at retreating glacier snouts, and seismic and ice penetrating radar measurements on the Argentière glacier. This comparison shows that the location of predicted GBOs is quite robust whereas their morphometric characteristics (depth, volume) are highly uncertain and tend to be underestimated. In total, 48/80 of the predicted or detected GBOs have a high level of confidence. In addition to five recently formed water bodies at glacier snouts, one of the high confidence GBOs (Talèfre glacier) which is also the most voluminous one could form imminently (during coming years), if not partially or totally drained through deeply incised gorges at the rock threshold. Twelve other lakes could form within the first half of the century under a constant or accelerated scenario of continued glacier retreat. Some of them are located below high and permanently frozen rock walls prone to destabilization and high-energy mass movements, hinting at possible hot spots in terms of hazards in the coming decades, where more detailed analysis would be required.},

keywords = {De-glaciating landscapes, Glacier-bed overdeepenings, High mountains, Potential future lakes},

pubstate = {published},

tppubtype = {article}

}