Study on Differences in Saltwater Intrusion Risk at Water Sourcesin the Yangtze Estuary

Against the backdrop of global climate change, extreme droughts and severe saltwater intrusion events in the Yangtze River Basin have become increasingly frequent, posing a serious threat to estuarine water supply security. Clarifying the saltwater intrusion response patterns of the Weijiaohe and Liuhe water sources, which are located in different branches under complex hydrodynamic conditions, is of great social significance for safeguarding freshwater resource security. Using the UFDECOM-i model, this study developed a three-dimensional numerical model of saltwater intrusion in the Yangtze Estuary by coupling multiple dynamic drivers, including discharge, tides, and wind. By simulating saltwater transport under scenarios where the discharge at Datong Station varied from 10,000 to 30,000 m³/s, the study revealed the spatiotemporal evolution characteristics and risk disparities of saltwater intrusion in the two water sources. Results indicate that under multi-year average wind conditions, the two sources exhibit distinct spatial responses: the Weijiaohe water source, dominated by saltwater spillover from the North Branch, faces a higher intrusion risk. This study clarifies the differential response mechanisms of various water sources to discharge variations, providing a scientific basis for the safety guarantee of water sources in the Yangtze Estuary.