Unveiling long-term changes in river flow regimes across Northern Italy

This thesis investigates long-term changes in river discharge across 22 Piedmont catchments in northwestern Italy and tests their consistency with trends in precipitation, temperature, and potential evapotranspiration (PET). Daily flows were aggregated to annual, seasonal, and monthly scales. Trends were assessed with the Mann–Kendall test and Sen’s slope. Summer low flows decline in a coherent and spatially robust way, most clearly in July and August minima. This marks stronger drought stress. High-flow indicators do not rise uni- formly; annual and seasonal maxima are mixed or not significant, so flood change appears less systematic in Piedmont than in nearby Mediterranean basins. Temperature and PET increase strongly at all time scales, with the steepest slopes in summer. Precipitation is weak and spatially variable, with modest summer declines and no consistent autumn rise. Taken together, these signals identify warming-driven atmospheric demand as the main cli- matic control on discharge change, with physiography amplifying outcomes. Alpine head- waters show earlier snowmelt and smaller spring to summer contributions. Lowland rivers combine alpine inflows with higher evaporative losses and local demand. Foothill tributaries sit between these end members. By applying one nonparametric framework to both hydrological and climatic variables, the study shows that climate forcing is already reshaping Piedmont flow regimes. The added value lies in month by month resolution, which fixes the timing of change and singles out July and August as the critical period of intensification. The results point to the need for stronger drought resilience while keeping flood preparedness proportionate.