Sindhu Kalimisetty, Alberto Montanari, Serena Ceola, Irene Palazzoli, Paolo Stocchi, Paolo Filippucci, Luca Brocca, Jacopo Dari, Francesco Tornatore, Federica Bonaiuti, Stefania Camici
ABSTRACT This study presents MISDc v3.1 , a process-based, flexible and open-source hydrological model developed to simulate complex water dynamics in large and human-impacted river systems. The model is applied to the Po River basin, Italy, subjected to strong anthropogenic impact. Calibration uses hydrometeorological data from 2000–2023, while validation is performed through multi-variable comparison against observed river discharge and satellite-based measurements of soil moisture, evaporation, snow water equivalent, and irrigation volumes. Quantitative performance assessment indicates strong simulation accuracy across multiple gauge stations (modified Kling–Gupta Efficiency = 0.88–0.93). The inclusion of irrigation and reservoir operation modules markedly enhances river discharge simulations, particularly during low-flow conditions and the 2022–2023 extreme drought. Uncertainty, assessed through the BLUECAT method, fosters a better understanding of model reliability across flow regimes. Owing to its Python-based and open-access architecture, MISDc v3.1 is easily transferable to other basins, offering a robust and flexible tool for integrated water resources management.