Response of water retention to multi-scenario land use change in a subtropical karst desertification area

Water retention is a key ecosystem service in subtropical karst rocky desertification regions, where fragile geological conditions and intensive human activities exacerbate hydrological vulnerability and influence multiple ecosystem functions. Understanding how alternative land use policies may affect water retention is therefore important for sustainable land management and ecological restoration. The coupling between land use and water conservation in mining-impacted subtropical karst regions remains poorly quantified, and multi-scenario frameworks for post-mining restoration are particularly lacking. In this study, land use dynamics in Shaoguan City, south China, were examined based on multi-temporal data from 1994 to 2017. Future land use patterns for 2040 were simulated under four scenarios—Natural Development (NDS), Cropland Development (CDS), Conservation Priority (CPS), and Comprehensive Protection and Development (CPDS)—using the PLUS model, and water retention was estimated using the InVEST model as an ecosystem-service indicator of hydrological response. The results showed that historical land use change was dominated by the expansion of construction land and cropland, accompanied by a decline in forestland and other ecological land types, resulting in a decrease in water retention from 9.54 × 10 9 m 3 in 1994 to 9.31 × 10 9 m 3 in 2017. Multi-scenario simulations for 2040 indicated marked differences in both land use patterns and water retention outcomes. The CDS was characterized by extensive cropland expansion (+55.48%) and substantial forestland loss (−12.15%), and was associated with the lowest projected water retention (8.44 × 10 9 m 3 ). The NDS indicated continued urban and agricultural expansion, with moderate reductions in water retention (9.09 × 10 9 m 3 ). The CPDS achieved a relative balance between development and conservation, preserving moderate water retention (9.17 × 10 9 m 3 ) with limited forestland change. In the CPS scenario, expansion of construction land was more constrained, and forestland loss was alleviated, resulting in the highest projected water retention among the four scenarios (9.27 × 10 9 m 3 ), with the smallest decline relative to 2017. Among the simulated scenarios, the CPS scenario was projected to maintain the highest water retention. These findings suggest that land use configuration may influence water retention in karst rocky desertification regions. This study provides scenario-based insights that can inform land use planning and the enhancement of hydrological ecosystem services in subtropical karst landscapes.