Landscape Structural Patterns and Soil–Water Loss in the Karst Critical Zone in Southwest China: Coupling Mechanisms, Regional Specificity, and Research Challenges

Karst critical zones in Southwest China are highly vulnerable to soil–water loss because thin soils, exposed carbonate bedrock, well-developed epikarst, and strong surface–subsurface connectivity promote both surface erosion and subsurface leakage. Although soil erosion, subsurface leakage, karst rocky desertification, and ecological restoration have been widely studied, the coupling between landscape structural patterns and soil–water loss remains insufficiently synthesized. This semi-systematic critical review synthesizes evidence from karst hydrology, soil erosion, karst rocky desertification, landscape structure, and critical zone studies, with a primary focus on Southwest China. The reviewed evidence indicates that geomorphic setting, land use vegetation structure, bare-rock exposure, and epikarst development jointly regulate runoff generation, infiltration, sediment detachment, subsurface leakage, and sediment connectivity. Peak–cluster depressions commonly favor internal sediment storage and vertical leakage, whereas valley and canyon systems tend to enhance surface runoff connectivity and channelized sediment export. However, pathway dominance varies with rainfall intensity, soil moisture, soil thickness, land use, karst rocky desertification degree, and fracture–conduit connectivity. Long-term soil–water loss may further reshape landscape structure through soil thinning, vegetation degradation, bedrock exposure, and karst rocky desertification feedbacks. Current research is limited by insufficient quantification of subsurface soil loss, weak integration between landscape metrics and hydrological models, and scarce long-term monitoring data. Future studies should integrate field monitoring, tracers, remote sensing, landscape metrics, and coupled surface–subsurface models to support geomorphic-setting-specific karst rocky desertification control.