Rising temperatures and more frequent climate extremes are amplifying regional water risks. Water conservation ecosystem services (WCES) buffer droughts and floods, yet most ecosystem service flow studies overlook these services. In this study, we employ the metacoupling model as a framework to trace the multi-scale material pathways of WCES. Results reveal significant spatial heterogeneity and temporal variability in WCES flows from 2000 to 2020 in the hilly area of South China. Notably, regions with insufficient local supply increased by approximately 8.40 %. Among the three types of coupling, intracoupling flows accounted for 30 flow paths, primarily concentrated in the Dongting Lake and Poyang Lake Basins. The Poyang Lake Basin demonstrated stronger internal coupling with a higher peak flow (9.59 × 10¹⁰ m³ in 2010), while the Dongting Lake Basin exhibited greater temporal fluctuations. Pericoupling flows comprised four pathways; the Poyang–Yangtze flow was 4.80 times greater than Dongting’s in 2000, but the ratio declined to 1.99 by 2020. Telecoupling flows, though limited to two long-distance pathways, highlight the role of Poyang Lake—the largest freshwater lake in China—in supplying the Taihu Basin, a densely populated and economically vital region. The Poyang–Taihu telecoupling index (TCI) consistently exceeded 1, indicating that WCES from Poyang Lake alone was sufficient to meet Taihu’s water demand. The proposed framework enables more precise quantification of freshwater pathways and their spatial distribution, supports cross-regional water resource management, and provides actionable insights for optimizing watershed resource allocation and ecosystem-service governance.
Wang et al. (Fri,) studied this question.