Flooding risk from global warming in Alpine basins: an estimate along a stream network

To provide quantitative elements to the expected rate of change of flood quantiles in Alpine basins due to global warming, a systematical assessment of a river network is undertaken in this paper through the implementation of a geomorphoclimatic approach. The model, called “FloodAlp” produces the flood frequency curve of mountainous catchments based on the stochastic interaction of precipitation and temperature. In view of a widespread application, FloodAlp was revamped here and applied to all the sections of the river network of the Chisone basin (Northwest Italy) identified through a 50 m resolution digital elevation model (DEM). We show that, based on the decrease in snow-affected contributing areas, flood frequency can increase up to 8 times compared to the current frequency, with amplifications depending on the local elevation characteristics of sub-basins.