Reconstructing the Hydrological Cycle of the Ebro River Basin through Satellite Observations

The Ebro River Basin is one of the most intensively managed and climatically sensitive basins in the Mediterranean region, where increasing water demands, pronounced climate variability, and environmental constraints pose major challenges for sustainable water resources management. Addressing these challenges requires hydrological models capable of consistently representing both natural processes and anthropogenic water use. In this context, the INTERROGATION project, funded by the Italian Ministry of Universities and Research, examines the interactions between climatic and anthropogenic factors in the development and recovery of major hydrological droughts that have affected the Ebro River Basin in recent decades (1990-2023).

In this study, we present a comprehensive reconstruction of the water cycle in the Ebro River Basin, explicitly accounting for both natural processes and human water use. For this purpose, three different precipitation datasets are used as input data to the flexible conceptual hydrological model MISDc (Modello Idrologico Semistribuito in Continuo): long-term (2000-2023) daily in situ observations and two versions of a daily integrated dataset obtained by merging GPM and SM2RAIN products at low (10 km) and high (1 km) spatial resolutions.

The hydrological model is calibrated against observed river discharge and validated through a multi-variable comparison with satellite-based estimates of soil moisture, evapotranspiration, snow water equivalent, and irrigation, which were developed within the framework of the European Space Agency Digital Twin Earth (DTE) Hydrology Next project. The results of this work demonstrate the significance of employing a suitable hydrological model in conjunction with accurate satellite information for capturing the spatiotemporal evolution of the hydrological cycle within highly managed basins. These results will be the basis for developing a decision support system that will guide stakeholders toward an integrated management of water resources in the Ebro River Basin.