Spatiotemporal impacts of climate change and human activities on blue and green water resources in northwest river basins of China

Exploring the spatiotemporal impacts of climate change and human activities on freshwater resources through the concepts of blue and green water can effectively improve the sustainability of basin water resource management. However, previous relevant studies have not considered the specific impacts of different climate models and land use changes on the future simultaneously. To mitigate this issue, this study proposes a hydrological modeling framework by integrating geographic detectors, Future Land Use Simulation (FLUS) models, and the Soil and Water Assessment Tool (SWAT) model. This framework was capable of identifying the major driving factors of land use changes, predicting future land use patterns, and assessing the spatiotemporal characteristics of water resources under different future climate scenarios and land use distributions. Applying the framework to the Wei River Basin (WRB) in northwest China, it identified the primary drivers of land use change in the WRB and quantitatively analyzed the spatiotemporal changes of blue and green water resources in the WRB under four scenarios. The results show that: 1) FLUS model and SWAT model can effectively simulate land use change and runoff process with high simulation accuracy; 2) Precipitation, temperature and GDP are the main drivers of land use change; 3) The amount of blue and green water in the middle and lower reaches of the basin is significantly higher than that in the tributaries and upper reaches. Blue water and green water flow are more affected by climate than land use, while green water storage is more sensitive to land use change. This study can provide effective information for basin land planning and rational allocation of water resources.