The construction of key water projects in the Yangtze River and rising sea levels will impact the water quality of Shanghai's intake. Pollution and saltwater intrusion from economic development affect the mouth of the Yangtze River, leading to water supply shortages. The Three Gorge Water Control Project and plans to transport water from the Yangtze River to North China will worsen saltwater intrusion. The study predicts a decline in water quality at Shanghai's intake in the South Branch of the Yangtze River and Huangpu River, especially in October and the dry season from December to March.