Yangtze Delta Tidal Wave Propagation

There is four entry to sea of Yangtze estuary divided by third-level furcation. The tidal wave dissemination is more complex for the influence of East China Sea and the Yellow Sea tidal wave system. In this paper, the author has further analyzed on the tidal wave dissemination rule of Yangtze estuary which is based on the predecessors' studies and is combined with the analysis of actual material.Generalize south branch of Yangtze estuary and estalish generalizable model to discuss the factors which affect tidal wave dissemination. The computation indicates that the terrain of Yangtze estuary is so complex that the water depth should not be considered as constant and if not, the tidal wave dissemination is not similar as the actual one.Then, with the method of W.K.B to establish model and considering the water depth changing along the regulation, and the results of computation are similar to the actual one which can reflect the tidal wave dissemination essential feature of Yangtze estuary. The computation of ideal model indicates that the more important factors which affect tidal wave dissemination of Yangtze estuary are the river mouth cross sectional area and the friction.Establish the plane two-dimensional tide-current mathematical model with the mothod of ADI. The confirmation is good and the model can reflect the basic regulation of tidal wave dissemination in Yangtze estuary. Based on this, different hydrology conditions were carried on. According to the model results, in the longitude, tidal range,flood and ebb lasted,tidal process line,the high-low-middle tidal level and harmony constant are analysed. Through those analysis, the acknowledge was made that the seasonal change of tidal wave dissemination in Yangtze estuary is obvious and is close with the amount of runoff. The water volume of upstream is much which is equal in increasing the resistance of flood, and wear down the tidal wave energy, therefore, the amount of runoff was bigger, in its influence scope, the tidal range was smaller, flood and ebb lasted is smaller, the tidal wave distorted is more serious. The tidal wave distorts may be signed with shallow water tidal constituent. The amount change of runoff has more influence to shallow water tidal constituent, and the amount of runoff is bigger, the shallow water tidal constituent is bigger. In the horizon, range change was analysed, and for the exist of Coriolis force, north shore tidal range compared to Nanan tidal range is bigger than 5～7cm.