Change of Tidal Current in Recent Years and Variation Properties of Residual Current in the Head of Ariake Sea

It has been suspected that the construction of the Isahaya sea-dike causes deterioration of aquatic environment in the Ariake Sea. Many studies on the aquatic environment have ever been conducted, but the causes have not been made clear yet. In this study, we examine the change of the tidal current due to the sea-dike by using the field observation data before and after constructing the sea-dike. As a result of the present study, it is clarified that the tidal current direction is changed and the M2 tidal current is weakened in the head of the Ariake Sea by the sea-dike. In addition, it is concluded that properties of residual current might be affected by the sea-dike.