Numerical simulation on the behavior of discharge from Chikugo River in Ariake Sea by using a 3-D flow model with wind shear stress acting on the water surface

项目负责人发现，在雨季，伊沙亚湾整个区域都形成了盐度分层，伊沙亚湾深水区的盐度在某些情况下下降到普通海水的一半左右，在某些情况下恢复。本项目的假设是，盐度分层可能是由于流入有明海的河流的排放，其出现和消失可能是由伊沙亚湾的当地风造成的。结果表明：1）伊沙亚湾整个区域的盐度分层主要是由筑后河的排放造成的。2)东北偏北风将有明海近水面的低密度水团输送到伊沙亚湾; 3）西南偏南风倾向于抑制有明海低密度水团向伊沙亚湾的流入，反之则促进其从伊沙亚湾向有明海的流出。

The project leader found that the salinity stratification is formed over the whole region of Isahaya Bay in the rainy season and that the salinity in the deep region of Isahaya Bay decreases to about half value of ordinary sea water in some cases and it recovers in some cases. This project was made under the hypothesis that the salinity stratification might be due to the discharge from the rivers running into Ariake Sea and its appearance and disappearance might be generated by local wind in Isahaya Bay. The obtained results are as follows: 1)The salinity stratification over the whole region of Isahaya Bay is mainly due to the discharge from Chikugo River. 2)The north-northeasterly wind transports the water mass of low density near the water surface from Ariake Sea to Isahaya Bay.3)The south-southwesterly wind tends to suppress the inflow of the water mass of low density from Ariake Sea to Isahaya Bay and to promote conversely its outflow from Isahaya Bay toAriake Sea.