Spatiotemporal changes of the water conservation function in the six major river basins in Yunnan Province, Southwest China

Six major river basins in the mountainous Southwest China. Patterns and drivers of water conservation in mountainous regions with heterogeneous environments remain poorly understood. In this study, we explored spatiotemporal dynamics of water conservation in the six basins from 2000 to 2023. The InVEST model was used to simulate water yield, with trend and variability analyses characterizing temporal and spatial patterns. Correlation analysis further evaluated the roles of climate, soil, vegetation, and human activities. The results showed that the average annual water conservation was lowest in the Jinsha River basin (78.02 mm) and highest in the Irrawaddy River basin (241.24 mm). Most regions exhibited declining trends in water conservation mainly due to increasing potential evapotranspiration, while the downstream Jinsha River basin and parts of the Pearl River basin showed increasing trends due to increasing precipitation. The water conservation coefficient (WCC) was more sensitive than the water conservation volume in detecting ecosystem degradation. The Pearl River basin experienced the most significant urban expansion, while the Irrawaddy River basin showed the most severe net forest loss, both of which weakened water conservation capacity as reflected by WCC. This study provides valuable scientific guidance for region-specific ecological planning and water resource management in the southwest China. • 24-year water conservation assessment of six river basins in Southwest China. • IR basin has the highest water conservation (241.24 mm), JS basin the lowest (78.02 mm). • Climate, soil, vegetation, and human activities jointly drive variations. • Urbanization in PR and forest loss in IR reduced WCC.