Abstract: A large domain model has been developed to simulate the major river plumes in the China seas, which takes into account the multiple dynamic factors. The results shows that different sea area responses differently to the river plumes. In Bohai Sea, due to its semienclosed topography that restricts the water mass exchange with outer area, the sea salinity keeps low,  though the received runoffs are generally small. The Yellow Sea is also semienclosed, plus a large amount of the Changjiang River freshwater extends into the sea, the salinity there is also low in most times. The salinity in East China Sea varies seasonally along with the extension of the Changjiang River plume. In the Northern South China Sea, the Pearl River plume dominates the sea salinity variation in the east of the Qiongzhou Strait. As the offshore extension of the Pearl River is limited, the low salinity area is smaller than that in other seas. In the west of the Qiongzhou Strait, the Red River plume controls sea salinity variation.

Key words: plume extension, major rivers in China, sea salinity, numerical modeling