Study On The Characteristics Of Tidal Current And Material Transportation In The Pearl River Estuary

The seasonal variations of runoff and wind field force have an important influence on the hydrodynamic process of the pearl river estuary.In this paper,based on EFDC(Environmental Fluid Dynamic Code)model,a three-dimensional hydrodynamic numerical model of the pearl river estuary is constructed,and the water level,velocity and tidal current ellipse are verified.This paper studies and analyzes the tidal,tidal current and material transport characteristics of the pearl river estuary and its adjacent waters,and focuses on the seasonal changes of tidal and material transport characteristics.The response of the tidal current characteristics of the pearl river estuary to the change of runoff and wind field is analyzed by model test.It is found that the annual tidal pattern of the pearl river estuary is about 1.4,the average of the summer tidal pattern is 1.53,and the average of the winter tidal pattern is 1.39,and the daily tidal component of the pearl river estuary in summer is higher than that in winter.The fluctuation tidal current velocity of the pearl river estuary changed obviously during the summer tidal period.The velocity of the flow was 1.62m/s during the summer tidal period,while that of the neap tidal period was only 1.15m/s.There is little change of ebb and flow velocity during the period of large and small tides in winter.The average ovality of M2,S2,K1 and O1 in the pearl river estuary in summer is about 0.02 higher than that in winter,while in the vicinity of guishan island and dongao island,the ovality of each tidal ellipse in winter is 0.05 ? 0.1 less than that in summer.In vertical direction,with the increase of water depth,the trend of the tidal current ellipse decreases first and then increases,and the middle water ellipse is the lowest.After the change of runoff in the pearl river estuary and the wind field conditions,characteristics and the trend of the pearl river estuary are some changes have taken place in salinity layer,the tidal current ellipse ellipticity and the salinity of the pearl river estuary stratification strength there is a significant positive correlation,offshore wind and strong runoff will enhance the salinity stratification of estuary,leading the trends rotary motion.In this paper,tracer method was used to study the material transport characteristics and seasonal variation in the pearl river estuary.Among the eight major ports,jiaomen,hengmen and hongqili have the greatest direct influence on the pearl river estuary,while jitimen,yamen gate and hutiaomen hardly participate in the material transport process in the pearl river estuary area.During the flood season,the pollutants discharged from the mouth of the mouth spread to most areas of the pearl river estuary and tend to spread to the sea in the southeast direction.In the dry season,the pollutants discharged by the mouth gate are mainly transported along the two sides of the river mouth,and the concentration of pollutants in the river mouth area is small.There are obvious seasonal changes in the material transport time of the Pearl River Estuary.During the flood season,the pollutants discharged from the mouth of the mouth spread to most areas of the pearl river estuary and tend to spread to the sea in the southeast direction.In the dry season,the pollutants discharged by the mouth gate are mainly transported along the two sides of the river mouth,and the concentration of pollutants in the river mouth area is small.The material transport time in the pearl river estuary has obvious seasonal variation,which is 15 days in the flood season and 60 days in the dry season.Moreover,the material transport characteristics of the pearl river estuary are closely related to the runoff.The correlation coefficient between the pollutant concentration and the runoff in the pearl river estuary is 0.78,and the correlation coefficient between the material transport time and the runoff is-0.70.