Distributed Hydrological datasets of the Po River Basin: geomorphology, catchments, and hydrological daily budgets for the 1991-2020 time period

In recent years, Italy has observed more frequent and intense drought events, with a particularly severe drought in 2022, leading to significant environmental, social, and economic damage. Also at a global scale, extreme events, floods and droughts, have been reported to be more likely due to climate change and environmental modifications. For this reason, already in 2021, the Po River Basin District Authority (ADBPO) started the implementation of the GEOframe modelling system on the entire territory of the District to update the existing numerical modelling for water resource management, and then to improve the planning activity of the Authority itself, producing a better quantification and forecast of spatial and temporal water availability. The GEOframe system is an open-source, semi-distributed conceptual modelling framework characterized by high modularity and structural flexibility, collaboratively developed under the leadership of the University of Trento. After a starting phase of data collection, validation, spatial interpolation of precipitation and temperatures (for the reference period 1991-2020), and geomorphological analysis, all the components of the hydrological balance (evapotranspiration, snow accumulation, water storage and discharge) have been simulated. Subsequently, a zonal calibration was carried out station by station over a four-hydrological-year window, using the Kling–Gupta Efficiency (KGE) as objective function: the characteristic model parameters were sought that best reproduce the discharge recorded at the hydrometric stations of each zone, proceeding from the headwaters downstream so that each calibrated zone provides the upstream boundary condition for the next. Calibration has been completed for Valle d’Aosta (12 stations, mean KGE 0.785) and Piemonte (49 stations, mean KGE 0.823), and is in progress for Lombardia and Emilia-Romagna; validation against independent periods is ongoing. The resulting product is a distributed dataset covering the reference period 1991-2020: the geomorphological decomposition of the District into subbasins and Hydrological Response Units, and, for each of them, daily time series of all the terms of the water budget (precipitation partitioning, snow water equivalent and melt, canopy interception and throughfall, evapotranspiration, root-zone and groundwater storage, surface and subsurface runoff, and discharge). Particular attention has been paid to the snow contribution, which has a major impact in alpine regions, dominating local and regional hydrology, strongly influencing vegetation growth and water availability and utilization (Sturm et al. 2017; Viviroli et al. 2007; Wu et al. 2015), as in the Po River Basin, which is bounded by the Alps along its entire course. The dataset is intended to support water-budget assessment, drought characterisation and water-resource planning at district scale.