Tidal level forecast with correlation analysis method in Zhenjiang to Wusong reach of lower Yangtze River

Base on the analysis of the factors that influence the daily average water level at the tidal stations along the Yangtze River,the correlation between the daily average water level at the tidal stations along the Yangtze River and the daily average discharge at Datong Station in upper Yangtze River was established by using the multiple linear regression equation.The Zhenjiang,Jiangyin,Xupu,Qipu,and Wusongkou tidal stations were selected for case study.The precision of the correlation equation was improved by adding the tidal range factor to the equation,considering that the daily average water level at the tidal stations along the Yangtze River was not only correlated with the daily average discharge at Datong Station in upper Yangtze River,but with the astronomical tide at Wusongkou Station.Based on the fact that there will be a decrease of the tidal range,phase delay,and tidal deformation when the tides at Wusongkou Station spread upstream,and the tidal ranges at the tidal stations along the Yangtze River are in close relation with the tidal range at Wusongkou Station and the discharge of the main stream of the Yangtze River,the correlation equation for the tidal range was established.The results show a high precision in forecasting the tidal level processes at the sections along the Yangtze River with the correlation analysis method.