Redesigning a transboundary and spatially targeted PES scheme to sustain clean water provision across metacoupled systems in the Xin’an River Watershed, China

Watershed restoration can enhance hydrologic ecosystem services (ES) across larger regions, yet payment schemes for these services (PES) often remain confined by watershed boundaries. This limits the identification of key ES providers and beneficiaries, compromising efficacy and equity of PES interventions. Focusing on the Xin’an River Watershed, one of the largest urban headwaters in China, this study aims to develop a spatial targeting strategy for fair and cost-effective land-use measures that improve water quality; and apply ES flow-based metacoupling to incorporate payers from surrounding regions, thereby expanding the current ineffective PES scheme to include cross-regional beneficiaries of clean water. Our spatially targeted approach predicts a 24% reduction in total nitrogen export by reforesting and retiring just 8% of the most polluting croplands. The $44.5 million annual compensation required for farmers to implement these changes averages $4,022–10,248 per hectare, far exceeding their opportunity costs. In parallel, analysis based on the metacoupling framework identifies the corresponding beneficiaries of improved water quality, including users within the watershed, those in the broader metacoupled region, and a corporation that bottles and sells the watershed water nationally. This metacoupling perspective further shows that fair compensation for farmers would require water users to increase their bills by only 1.8%, with the bottler functioning as a keystone actor. This study underscores the high potential of transboundary and spatially targeted PES schemes considering metacoupled public and corporate ES beneficiaries for securing clean water across watershed boundaries in a fair, justifiable, and cost-effective manner.