Spatial heterogeneity in indirect flooding-mitigation benefits of the Three Gorges Project across China

Assessing flood mitigation strategies is crucial on a global scale, where Large-scale Hydraulic Projects (LHPs) are essential in enhancing socio-economic resilience and mitigating flood impacts. However, the failure to recognize the spatial distribution patterns of these direct and indirect benefits can lead to a substantial underestimation of the positive effects that LHPs can have on various socio-economic activities and regions susceptible to flooding. This study develops a Spatial Footprint Impact Assessment framework (SFIA), which is applied to the Three Gorges Project (TGP), evaluating the spatial heterogeneity of indirect flood-retention benefits induced by the TGP across 31 provinces in China. Our findings demonstrate that while Hubei and Hunan gain the largest direct reductions in GDP and welfare losses, more distant provinces benefit indirectly through stabilized supply chains supported by the TGP. Quantitatively, the TGP’s flood-retention capacity helped reduce China’s flood-induced GDP losses by 28–37 billion Chinese Yuan. By introducing the concept of “hydraulic project’s footprints,” this study demonstrates that overlooking such indirect benefits substantially underestimates the value of LHPs. Our findings can offer detailed, region-specific insights into formulating flood management strategies and provide a transferable framework for assessing other large-scale hydraulic projects worldwide.