Research on hydrodynamic influence to Jiaojiand River estuary for taking sand from Linhai-Jiaojiang Bridge reach

With the development of social economy,the activity of taking sand in Jiaojiang River estuary is frequent with each passing day.It will change the river bed condition to take sand in estuary and the hydrodynamic condition in estuary is obviously influenced.The influence shows that low tide level will be reduced and high tide level raised,as well as tidal range and bearing tide amount enhanced and tidal current velocity increased.This kind of influence in river reach from Linhai to Haimen is obvious especially in estuary reach upstream.The hydrodynamic changes before and after taking sand are studied and the variation mechanism analyzed in the paper.