Climate-driven historical changes in streamflow extremes and consequences for reservoir inflows over the Upper Po river basin (Italy)

Over the past few decades, extreme hydrological events, particularly floods and droughts, have increased across the European Alps.Changes in the frequency and duration of wet and dry extremes may complicate reservoir management by intensifying tradeoffs among water supply, flood control, and ecosystem needs. Prolonged droughts can limit the ability to maintain minimum release requirements, while increased precipitation may raise storage levels and flood risks.In this study, we present a preliminary assessment of changes in the frequency and duration of wet and dry extreme events in two anthropized, snow-dominated catchments of the upper Po River basin, with a specific focus on variations in reservoir inflows. The aim is to improve understanding of upstream streamflow variability and to support future reservoir and watershed management.We use the GEOframe hydrological modeling system to simulate the complete hydrological cycle including snow water equivalent, soil moisture, and river discharge at ~1km2 - daily resolution. We exploit the potential of recently developed meteorological datasets for rainfall and air temperature covering the study area over the past 30 years. Model simulations are calibrated using historical streamflow observations and validated through both in situ data and independent validation based on MODIS MOD10A2 satellite observations of snow-covered areas.This modeling effort provides insights into historical hydrological changes in hydrological extreme events, particularly those affecting inflow discharges to the analyzed reservoirs, and establishes a foundation for future analyses of projected hydrological changes and reservoir operation over a changing environment.This work is supported by the project WATER4ALL JTC2022” - WaterMA-WaDiT - “Water Management and Adapation based on Watershed Digital Twins” CUP: E63C23001680007