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This study presents the spatial distribution of mountain permafrost based on spring water temperature in two valleys of the French Southern Alps. Spring water temperature was used as a response variable in a logistical regression model, and multiple topo-climatic factors extracted from a DEM were used as predictors. The logistical regression model was statistically significant and used to map the probability of permafrost occurrence.. The results indicate that permafrost lower limit may be located at elevations above 2600 m in favorable settings. This lower limit tends to rise as the incoming solar radiation is increasing. According to the model, the mountain permafrost covers ~2% to 10% of the study area.

The formalization of sediments cascades within a catchment is one of the main field research in geomorphology. Since the pioneering studies on geomorphic open systems, inefficient sediment exportation at catchment sinks has been widely observed. The complexity of sediment fluxes patterns is also enhanced. Well defined in concepts such as the sediment delivery problem or sedimentological anarchy, these observations are however only partially understood. After a brief synthesis of previous works led on sediment cascades, we propose in this paper to consider sediment cascades as a network. Such networks are described through graph theory and simulation tools. These methods are applied to explore how sedimentary cascades work, especially by evaluating a net contribution of the network to the volume flow. Applied to an alpine watershed, these methods show that the connectivity properties of sediments cascades can explain their structural inefficiency to export sediments.