Study on the quantitative relationship of the location of the tidal current limit and the river discharge in the Changjiang Estuary

The Changjiang Estuary is a tidal estuary with the interaction of river discharge and tidal current.The tidal variation results in the change of flow state in the river.By designing a high resolution numerical model,and based on the calculations of water flux along the river transverse sections,the Changjiang River tidal current limits were obtained in various guarantee rate river discharges in dry and flood seasons.The tidal current limit is between Taiyang island (located at the 70 km upstream of Wuhu) and Zhengjiang hydrological station in dry seasons, and is in the range of 100 km between the middle of Taiping island(located at the upstream Jiangying) and Minzhu island in flood seasons.With the multi power fitting of the calculated results,the relationship between the location of the tidal current limit and the river discharge is y=-4×10~(-10)x~3+1×10~(-5)x~2-0.193 7x+1 232.9(R~2=0.984 2)in dry season,and is y=2×10~(-13)x~3 +3×10~(-8)x~2 -0.007 4x + 359.35(R~2 = 0.996 9)in flood season.This result can provide a scientific basis for determining the tidal current limit of the Changjiang River.