Climate Change and Hydrology: A Case Study of the Adige River Basin

Climate change has emerged as a dominant factor of hydrological variations across alpine and Mediterranean regions, escalating the fluctuation of water availability, streamflow regimes, and catastrophic events. Italy is located at the intersection of Central European and Mediterranean climatic influences, and it has seen elevated temperatures, recurring hydrological extremes, and an evident shift in seasonal hydrological balances. The Adige River Basin, Italy’s second-largest watershed and an essential socio-economic artery, faces mounting pressures on its water resources due to cryospheric decline, evolving precipitation regimes, and competing sectoral needs. The study has used the Water Evaluation and Planning (WEAP) model to evaluate both historical and future hydrological dynamics in the Adige Basin. The model was calibrated using observed streamflow data from 1948 to 2008 at three representative gauging stations: Montecastello (upper basin), Trento (middle basin), and Boara Pisani (lower basin). Calibration performance, assessed through Percent Bias (PBIAS), indicated excellent agreement between simulated and observed flows at all sites, with values within ±10%, ensuring model credibility. To assess future climate impacts, bias-corrected data from the CNRM-CM6-1 model under the SSP2-4.5 scenario (2021–2049) were integrated into the WEAP framework. Results reveal a pronounced seasonal shift in streamflow dynamics, with peak discharges occurring earlier in the year and significant reductions—up to 50–60%—in summer flows. This shift is attributed to a combination of increased air temperatures (+1.5°C to +2.5°C), reduced snow accumulation, and enhanced evapotranspiration. Although annual precipitation remains statistically comparable to historical values, it becomes markedly more erratic, with heightened interannual variability and more intense but less frequent rainfall events. These findings pose pressing challenges for water resource management, especially for hydropower generation, agriculture demand, and long-term drought resilience. The study emphasizes the urgency of adaptive strategies like dynamic reservoir operations, improved seasonal forecasting, and water-efficiency policy reforms. By linking historical validation with forward-looking climate scenarios, this analysis deepens the understanding of Alpine basin vulnerability while advancing a systems-based perspective through the Water-Energy-Food-Ecosystem (WEFE) Nexus offering a roadmap toward more resilient and integrated resource governance.