Coupling Water Purification and Carbon Sequestration at Various Spatial Scales From Supply and Demand Perspective

ABSTRACT Balancing ecosystem‐service supply and demand is central to understanding both the natural and social dimensions of ecosystem services and to enhancing human well‐beings. Concurrently, collaborative efforts are underway to improve multiple ecosystem services, including the promotion of carbon neutrality and water purification (WP) within basin regions. Here, we quantified the WP and carbon sequestration (CS) of the Three Gorges Reservoir Area (TGRA) and explored the driving mechanism of two ecosystem services from the perspective of supply and demand. The results reveal that CS and WP of TGRA have generally achieved a balance between supply and demand over the past 30 years. WP‐supply showed a significant decline (−6.25 × 10 2 t/year), while CS‐supply exhibited steady growth (20.27 × 10 4 tC/year). WP‐demand experienced a slight reduction (−8.42 × 10 2 t/year), whereas CS‐demand increased sharply (73.7 × 10 4 tC/year). Spatial analysis indicated that both CS and WP supply–demand reachability peaked in regions exceeding 1000 m in elevation and 25° in slope. WP exhibited strong spatial clustering, with high–high agglomerations predominantly located in the central Yangtze and southwestern areas, and low–low clusters concentrated in northern and southern zones. However, CS exhibited distinct spatial variation, featuring high–low zones in the east and low–high zones in the southwest. Climate factors significantly enhanced WP‐supply (0.41) and WP‐demand (0.54) but inhibited both CS‐supply (−0.11) and CS‐demand (−0.05). Socioeconomic factors are positively related to CS‐demand (0.94) while negatively impacting CS‐supply (−0.38). Soil factors exerted a positive influence on CS‐supply (0.35) but a negative effect on WP‐supply (−0.37). Moreover, management strategies in the TGRA should integrate spatially targeted measures for WP to address local supply–demand gaps, along with a spatially regulated regional “cap and trade” mechanism to sustain CS surplus. Supported by vegetation restoration and coordinated water–carbon governance, this approach can strengthen WP–CS synergies.