Probabilistic assessment of water network influence zones and ecosystem responses following the middle route of the South-to-North Water Diversion Project

Large-scale inter-basin water transfer (IBWT) projects fundamentally reshape regional hydrological networks, triggering profound eco-hydrological consequences. This study quantitatively assesses the structural transformation of water networks and their ecohydrological consequences in central and southern Hebei Province, a major recipient area of the Middle Route of China’s South-to-North Water Diversion (SNWD) project. By integrating multi-source remote sensing data, environmental variables, and machine learning techniques, we developed a probabilistic framework to delineate hydrological influence zones and their associated seasonal dynamics before and after the project’s implementation. Utilizing water network density and connectivity indices derived from high-resolution surface water datasets, we quantified changes in network structure across 175 water distribution units. Our findings indicate a 23% increase in water network density and a 26.7% improvement in connectivity, reflecting a substantial enhancement of hydrological integration post-2015. Land use classification models (overall accuracy: 91.7%) identified water network density and soil moisture as primary determinants of ecosystem distribution, with forests and grasslands exhibiting heightened sensitivity to seasonal hydrological variations. The newly constructed artificial water conveyance pathways significantly expanded the spatial extent of ecological influence zones, particularly during the wet season. Probabilistic modeling further revealed distinct environmental preferences among land cover types, and calibrated ecological influence zones closely aligned with existing irrigation district boundaries. These findings underscore the importance of dynamic, data-driven approaches for assessing the ecological consequences of engineered hydrological changes. The proposed framework offers a scalable methodology for evaluating the ecological consequences of IBWT projects, thereby supporting the development of more responsive and ecologically attuned water resource management strategies.