Hydrological modeling and water budget quantification of the Po river basin through the GEOframe system

Hydrological extremes, such as floods or droughts, cause significant social and economic damages, posing risks to lives worldwide. Quantifying the spatially variability of water availability across the entire river basin is, thus, deemed important for preparedness to the intensification of such hydro-extremes.

In 2021, the Po River District Authority (AdbPo) undertook the implementation of this 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. This development is part of the research project “Data and models integrated system for the water resources management and the Po River basin district planning” which supports the use of innovative modelling tools and strengthen studies, research, monitoring and simulations of the main hydrological variables characterizing the territory of the Po River District. To reach this goal the GEOframe system has been adopted. This is an open source, hydrological modelling system developed by a technical and scientific international community, leaded by the University of Trento and already used at operational level, including the Civil Protection Agency of the Basilicata Region.

In particular, in this framework the action plan of the Po River District Authority aims to:

• deploy the GEOframe system over all the catchments in its territory (covering Valle d’Aosta, Piemonte, Lombardia, Emilia-Romagna, Veneto and Marche regions), capable to account for the major lakes and reservoirs;
• calibrate and verify the results obtained by the hydrological and hydraulic models against measured discharges and water levels across the whole area;
• interface the GEOframe system with the Deltares-DEWS system;
• analyse the water resources management impacts resulting from climate change or land use changes scenarios.

The implementation has begun on the Valle d’Aosta Region since it is in the most upstream part of the district, which makes this region a good starting point for the initial calibration of the model and the assessment of all the single components (e.g. energy balance, evapotranspiration, snow melting and river discharge components).

The activity is being carried out according to different phases:

• data collection, validation, and preliminary elaboration;
• geomorphological analysis;
• spatial interpolation of the meteorological data (mainly temperature and precipitation) through the krigings components;
• multi-site calibration of the snow melting and rainfall-runoff model parameters;
• validation of the model results against measured data.

Additionally, the calibration phase is essential to test the effectiveness of the model in simulating the components of the hydrological cycle, such us river discharge, evapotranspiration and snow water equivalent and, therefore, to determine the possible identification of drought periods in real-time forecast and long-term prediction, including climate change impacts.

In this work, the initial results achieved in the Valle d’Aosta region will be presented and a detailed analysis on the GEOframe elaboration of information is provided, with a focus on the high flexibility and modularity of the system. The results from a first comparison against river discharge and snow evolution measured in multiple points of the Valle D’Aosta are promising and encouraging.