Research on the multifunctionality of the water-energy-food system is of great significance for understanding the comprehensive efficiency of resource systems and promoting collaborative governance. Based on China’s provincial panel data from 2002 to 2023, this study constructs an evaluation index system for the multifunctionality of the water-energy-food system, adopts the entropy weight-TOPSIS method and coupling coordination degree model to measure the spatiotemporal differentiation of system multifunctionality, and reveals the evolutionary law of coupling coordination among the four major functions. The results indicate that during the study period, the national average value of the system multifunctionality index rose steadily from 0.387 to 0.486, forming an overall spatial distribution pattern characterized by high and stable index values in the eastern and central regions and locally leading levels across western China. Obvious differences exist in the spatiotemporal patterns of the four major functions. The overall coupling coordination degree among functions presented an evolutionary trend of first declining and then rising. It dropped to around 0.55 in 2003, the lowest value during the study period, and entered a steady growth stage after 2012. Most provincial-level regions achieved synchronous improvements in both multifunctionality levels and coupling coordination degrees, while the pattern of unbalanced regional development remained relatively stable.

Based on the InVEST model, the spatial-temporal distribution characteristics of water conservation in the Taizi River Basin from 2000 to 2020 were explored, and the land use change and landscape pattern evolution during the study period were quantitatively evaluated. Using Pearson correlation analysis and geographical weighted regression model, the relationship between landscape pattern and water conservation was analyzed. The results show that, at the landscape level, the amount of water conservation increases with the largest patch index, contagion index, and aggregation index; at the landscape type level, the capacity of water conservation gets higher when the cultivated land has larger area, higher patch density, and higher degree of landscape fragmentation, the forest land has higher dominance degree, and the construction land has smaller number and lower density of patches, with landscape being more fragmented. Spatially, the landscape contagion index plays a positive role in water conservation in most area of the basin, the number and density of patches in cultivated land have positive effect on water conservation in the southern central part and the northwestern part of the basin, respectively. The percentage of landscape of forest land has a positive effect on water conservation in the whole region, while the number and density of patches and percentage of landscape of construction land mainly play a negative role in water conservation.