Modelling the hydrological response of a complex tropical wetland system to shared socioeconomic pathway climate scenarios using SWAT +

Graphical abstract summarising the SWAT+ workflow and future seasonal and spatial hydrological responses of the CCBS under SSP scenarios. This study assessed the future hydrological response of the Bajo Sinú Wetland Complex, Colombia, under Shared Socioeconomic Pathway scenarios (SSP2-4.5 and SSP5-8.5) for the mid-future (2041–2060) and far-future (2081–2100) periods. A Soil and Water Assessment Tool Plus (SWAT+) model was configured for the basin contributing to the Bajo Sinú Wetland Complex using topographic, climate, soil and land-use data, with monthly streamflow used for calibration and validation. The calibrated model showed good performance for monthly streamflow simulation and captured 72.4% of the reference streamflows within the 95% prediction uncertainty band. Mean monthly streamflow changes were +2.0% under SSP2-4.5 and −14.9% under SSP5-8.5 in 2041–2060, and +13.1% and −0.3%, respectively, in 2081–2100. The largest changes were concentrated during the wet season, especially between June and September. Mean surface runoff changes ranged from −27.5 to +39.7 mm/yr, whereas evapotranspiration changes ranged from −13.0% to −10.7%. These findings indicate a seasonally differentiated and spatially heterogeneous future hydrological response, providing a basis for climate-adaptation planning and tropical wetland management.