长江口平面盐度锋对径流量变化的响应特征

Response Characteristics of Horizontal Salinity Front to Runoff in the Yangtze River Estuary

摘要:

基于1950年―2018年大通站月均径流量数据，应用MIKE21软件建立长江口平面二维水动力及盐度输运模型，探究三峡工程建成后径流量变化对长江口4支平面盐度锋位置与强度的影响。结果表明：在长江口口门处，全年平均盐度整体增加，南槽处增加最明显；除北港外，各支盐度锋都具有双锋面结构；锋面位置与径流量成线性关系，第一锋面位置变化较第二锋面明显；各锋面强度与径流量成二次函数关系，二次项系数在第一锋面处为正，第二锋面处为负。

Abstract:

Based on the monthly average discharge calculated from measured runoff from 1950 to 2018 at the Datong Station in the Yangtze River Estuary， the two-dimensional hydrodynamic and salinity transport model was established by MIKE21 to investigate the effect of runoff change on the position and intensity of horizontal salinity fronts in the four branches of the Yangtze River Estuary after the Three Gorges Project was completed. The numerical results show that： the annual average salinity increases in the mouth of the Yangtze River Estuary and the increase is the most obvious in the South Passage. Except the North Channel， all salinity fronts have a double frontal structure. There is a linear relationship between the position of the salinity front and the runoff， and the change of position at the first front is more obvious than that at the second front. The relationship between the intensity of each front and the runoff is a quadratic function. The coefficient of the quadratic term is positive at the first front and negative at the second front.