The increase in water salinisation in catchments has led to increased concern in assessing major ion loadings in freshwater environments. In this study, we couple a globally fitted model on chemical weathering to the Soil and Water Assessment Tool (SWAT) for the estimation of daily geochemical loadings at the catchment scale, “SWATLitho”. The enhancements include i) a modification on the discretisation of the catchment area by integrating a layer describing lithology (QSWATLitho), and ii) the development of an extra module to compute the ionic loads derived from the chemical weathering of rocks. The model is sensitive to input data resolution, yielding the best results when including local data. Larger spatial and temporal discrepancies are found in one tributary, associated with point sources impacting the loadings; while these discrepancies are lower at headwater subbasins. Results suggest that, despite of these discrepancies, the average simulation of the daily ionic loadings is reasonable.

流域水盐化的增加导致人们对评估淡水环境中主要离子负荷的关注增加。在这项研究中，我们将全球拟合的化学风化模型与土壤和水评估工具（SWAT）结合在一起，以估算集水规模“ SWATLitho”下的每日地球化学负荷。增强功能包括：i）通过集成描述岩性的层（QSWATLitho）对集水区离散化的修改，以及ii）开发了额外的模块以计算源自岩石化学风化的离子负荷。该模型对输入数据的分辨率敏感，当包含本地数据时会产生最佳结果。在一个支流中发现了更大的时空差异，这与影响负荷的点源有关。而这些差异在源头流域较低。结果表明，尽管存在这些差异，但每日离子负载量的平均模拟还是合理的。