Quantitative Assessment of Hydrological Alterations Induced by the Panzhihua Irrigation Project and an Adaptive Ecological Restoration Strategy in the Dry-Hot Valley of the Jinsha River

Large-scale irrigation infrastructure in arid and semi-arid river valleys frequently induces hydrological regime shifts that compromise river connectivity, degrade aquatic habitats, and threaten endemic biodiversity, thereby necessitating rigorous quantitative impact assessment and site-specific adaptive management frameworks to reconcile water-resource development with ecosystem resilience. The Panzhihua Irrigation Project in the ecologically fragile dry-hot valley of the Jinsha River exemplifies these challenges. In this study, the ecological impact of the Panzhihua irrigation project on the dry and hot valley of Jinsha River is analysed with the help of Indicators of Hydrologic Alteration (IHA), Lindeman-Merenda-Gold (LMG) variance partitioning and complementary multi-source monitoring methods, and the impact of water diversion is relatively small, only 8.6%.The discharge of downstream rivers has increased by 3.2% to 32%, and the runoff of receiving rivers has increased by 0.1% to 11%.From the local point of view, the connectivity between rivers has declined, vegetation has been damaged, and the habitat of endemic fish has been lost. The main driving factors are fish passage (16.5%), water intake (38.2%) and hydrological change (25.7%). It is necessary to implement adaptive management, design fishways, build ecological flow regulation projects and set up buffer zones for native vegetation, which is conducive to the restoration of fragile ecosystems.