Hydrological response and soil water soluble antimony and arsenic transport under climate change using SWAT modeling

Climate change affects hydrological processes globally, impacting the water-soluble forms of metals such as antimony (Sb) and arsenic (As) in various soils. This study developed an enhanced SWAT-based framework incorporating soil experiment data and coupled it with SSP scenarios (SSP126, SSP245, SSP370, SSP585) to project future hydrological processes, and then assessed water-soluble proportions of Sb and As distribution under climate change based on cluster analysis results of soil, precipitation, and streamflow classification. The model, incorporating measured values, accurately simulated the streamflow and sediment loads of the study area during the historical period. Under the climate scenarios, the study area exhibited trends of fluctuating precipitation and rising temperatures; compared to the reference period (2008-2014), the total streamflow generally increased across all scenarios. Experimental results revealed that Sb and As concentrations exceeded standards, with pH and soil organic matter showing significant correlations with the water-soluble proportions of these metals. Analyzing the combined results from soil, precipitation, and streamflow cluster analyses indicated that a higher percentage of water-soluble Sb and a higher percentage of water-soluble As are likely to be distributed in the subbasins along the main river in the east, potentially increasing over time. These results offer a scientific foundation for water resource management and pollutant mitigation in mining watershed areas.