How Do Different Policy Instruments Influence Water–Energy–Food Coupling Coordination? Evidence from the Yellow River Basin

Understanding the interactions between the Water–Energy–Food (WEF) coupling coordination and policy instruments is a pivotal pathway toward achieving ecological conservation and sustainable development in basins. Nonetheless, the association between policy instruments and WEF coupling remains inadequately documented. This study develops an integrated evaluation framework for WEF coupling coordination and policy instruments, and employs a two-way fixed-effects model to examine the effects of policy instruments on WEF coupling coordination across nine YRB provinces during 2010–2022. The results show that all three categories of policy instruments significantly improve the WEF coupling coordination degree. Heterogeneity analysis reveals that, in non-arid regions, command-and-control and guidance-based instruments have significant positive effects, whereas the effect of economic incentive instruments is not statistically significant. Technological innovation partially mediates the effects of command-and-control and economic incentive instruments, but not that of guidance-based instruments, whereas capital intensity partially mediates the effects of all three policy instruments on the WEF coupling coordination degree. Government fiscal pressure weakens the positive effects of command-and-control and economic incentive instruments, while its moderating effect on guidance-based instruments is not statistically significant. This study offers valuable insights for supporting the coupling coordination development of WEF in other river basins worldwide.