Predição das vazões futuras na bacia do Rio Capibaribe no período de 2030 a 2060 utilizando modelos climáticos globais e o SWAT+

Abstract

Climate change represents one of the greatest threats to water resources, as it alters the hydrological cycle and increases uncertainty in the occurrence of extreme events, such as prolonged droughts, intense rainfall over short periods, rising air temperatures, and increased evapotranspiration. These changes pose significant challenges to water resources management, especially in semi-arid regions, which are characterized by high climatic variability. Therefore, this study aimed to estimate river discharge under future climate scenarios for the Capibaribe River Basin through hydrological modeling using meteorological data for the period from 2030 to 2060. The adopted methodology involved the use of the SWAT+ model and outputs from global climate models. The model was calibrated and validated based on historical monthly streamflow series, and model performance was evaluated using the following statistical metrics: Pearson correlation coefficient (r), coefficient of determination (R2), Nash–Sutcliffe efficiency (NSE), percent bias (PBIAS), root mean square error (RMSE), and the Kling–Gupta efficiency (KGE). In addition, a parameter sensitivity analysis was conducted to identify the parameters with the greatest influence on hydrological behavior. Future projections of precipitation and temperature were obtained from the global climate models ACCESS-CM2, HadGEM3- GC31-LL, and MIROC6, considering the SSP2-4.5 (intermediate) and SSP5-8.5 (pessimistic) climate scenarios for the prospective period from 2030 to 2060. Initial uncalibrated results showed an overestimation of streamflow, with negative NSE values. After calibration and validation, the model showed satisfactory performance in the contributing areas of Toritama and Vitória de Santo Antão, whereas unsatisfactory performance was observed in Limoeiro and Paudalho. Climate projections indicated a gradual increase in temperature across the entire basin, with more pronounced increases under the SSP5-8.5 scenario, reaching monthly peaks close to 35 °C. Future precipitation scenarios showed an overestimation by the models compared to observed data. Estimated future streamflows indicate a significant reduction in discharge under the pessimistic scenario. Under the intermediate scenario, high discharge peaks were projected at the Toritama gauging station, while low flow values (below 2.5 m3 s−1) were projected at the Vitória de Santo Antão station.