Tidal level rising under adverse water level slope and high tidal level increasing along the tidal channel at Lingdingyang bay

Basing on the results of numerical calculation of Pearl River Delta, water level line of tidal channel is firstly considered as the shape of tidal wave, to analyze the propagation characteristic of tidal wave in the process of flood tide. Tidal level rises under adverse water level slope more than one hour before high tidal level, which forms the high tidal level increasing along the tidal channel. The cause of formation is found from the perspective of mass conservation. Area of cross-section decreases rapidly from bay mouth to bay head of the Lingdingyang bay, so that there is enormous gap of the flow rate of cross-section between the bay mouth and bay head.