Salt wedge with vertical structure of discontinuous and continuous distribution in modaomen waterway

Abstract

The typical structure that vertical discontinuous and continuous distribution exist in the salt wedge of Modaomen waterway is firstly proved through the data from the subtitle observation on vertical salinity and velocity in Modaomen waterway of Pearl River.And the close relationship between the internal structures of salt wedge and tidal flow in estuary is also firstly proved.During the spring tide and neap tide,the saltwater is almost highly stratification,but the structures of salt wedge are different from each other.During the neap tide the salt wedge lasts a long time with vertically discontinue structure and the flow is divided into two layers.The upper layer flows seaward while the lower layer flows landward for quite a long time.The saltwater can run upstream a long way during the neap tide.During the spring tide the movement of salt wedge can be seen clearly but the structure of salt wedge during the flood is completely different from the one during the ebb.During the flood time the salt wedge has a vertically discontinue structure and the velocity of the lower high saltwater is greater than that of the upper layer.While during the ebb time the vertically discontinue structure of the salt wedge disappears and the vertical structure becomes continuous.The corresponding surface velocity is larger than bottom velocity and the vertical velocity structure is continuous.During the spring tide the changes of the salt wedge structure are significant but the saltwater runs a shorter way than that during the neap tide.