Canals in Transition: Long-Term Co-Evolution of Heritage Irrigation Networks and Rural Land Use

The heritage irrigation system network (HISN) represents long-lived spatial infrastructures that have continuously shaped rural land use, settlements, and ecological spaces. Under the combined influence of irrigation modernization, rural development, and heritage conservation, understanding the long-term co-evolution of heritage irrigation networks and rural land use is important for the sustainable management of living irrigation landscapes. This study investigates the Li Canal–Gaoyou Irrigation District, a World Heritage Irrigation Structures (WHIS) site, using three temporal snapshots (1970, 2002, and 2025). The results reveal a three-stage transition from water-network adaptation to engineering-oriented restructuring and modern composite reorganization. Canal networks evolved from dense dendritic configurations toward more regular grid-like structures dominated by main canals, while rural land use and human settlements shifted toward a multifunctional system integrating production, living, and ecological functions. The relationship between the two systems showed clear stage-specific changes in both four-quadrant change types and coupling coordination states. Although adjustment states remained dominant (72.4%) in 2025, the coupling coordination degree increased overall, and antagonistic states decreased markedly. The results show clear stage-specific differences in the spatial transformation of the HISN and the spatial structure of rural human settlements between the periods 1970–2002 and 2002–2025, accompanied by pronounced spatial heterogeneity and transitions in coupling coordination states. Changes in main canal density and canal-system connectivity exhibited relatively high model-based contributions within the predefined evaluation framework across both stages, while changes in distance to urban boundary and canal–road intersection intensity showed relatively strong model associations with changes in coupling coordination degree. These findings demonstrate that the transformation of irrigation networks is closely associated with the long-term reorganization of rural land use and suggest that the sustainable management of living WHIS should integrate irrigation-network conservation with rural land-use transformation, infrastructure development, and ecological management.