The implementation of the GEOframe system in the Po River District for the hydrological modelling and water budget quantification

As observed in the last years, flood and drought events are getting more likely to happen due to climate change and can cause significant environmental, social and economic damages.

For this reason, already in 2021, the Po River District Authority (AdbPo) undertook the implementation of the GEOframe modelling system on the whole territory of the district in accordance with the GCU-M (Gruppo di Coordinamento Unificato-Magre) to update the existing numerical modelling for water resource management and with the objective of producing a better quantification and forecast of the spatial and temporal water availability across the entire river basin and, finally, to improve the planning activity of the

Authority.

The GEOframe system was developed by a scientific international community, led by the University of Trento, and is a semi-distributed conceptual model, with high modularity and flexibility, completely open-source.

The implementation of GEOframe in the Po River District has begun in the Valle d’Aosta Region, the most upstream part of the district.

After an initial part of meteorological data collection, validation, spatial interpolation, and geomorphological analysis, a first running of the model to assess all the components of the hydrological balance (evapotranspiration, snow accumulation, water storage and discharge) was carried out.

Consequently, the calibration phase started, consisting of the research of the values of the characteristic parameters of the model which fit the discharge evolution recorded in the hydrometers of the region in the best possible way, comparing the modelled discharge trend with the measured one.

The calibration, based on KGE method, has been executed in 10 hydrometers in Valle d’Aosta across a 4 years period. The results were encouraging, with an objective function of 0.76 at the closure point of the region.

The same process is now in progress in Piemonte, one of the biggest regions of Italy, which contains more than 100 hydrometers. The resulting objective functions are in general rather high and will be presented in this work.

At the same time, thanks to the geomorphological analysis, most part of Po River District (up to Pontelagoscuro (FE)), which totally occupies more than 42,000 km², has been divided into subbasins, the hydrological reference units where the simulation process takes place, and this dataset will be open-source and shared with the scientific community.

On the other hand, the interpolation and spatialization of the meteorological data will be carried out according to the 1 km² European Environmental Agency reference grid.

In conclusion, in this initial stage of implementation of the model and calibration of its parameters, it was possible to assess the capacity of GEOframe to simulate not only the water discharge but also the other components of the water cycle, namely the evapotranspiration, the water storage and the snow accumulation. Furtheremore, implementing GEOframe in a mountainous area underlines the importance and the influence that snow and glaciers, especially in a higher temperature scenario due to climate change, can have on water availability and, therefore, a better modelling component of these elements will be implemented in the future developments of GEOframe.