大船渡湾における自然エネルギー活用型海水交換装置の実証実験

抄録

Ofunato Bay has tsunami protection breakwaters at the mouth of the bay, which decrease a bay-water exchange rate to outside and degrade the water quality. The strong density stratification has been formed in summer. These environments have been said causes of hypoxia and eutrophication in the bay. In order to manage the bay environment, an enhancement system for bay-water exchange rate using natural energy has been implemented on the tsunami protection breakwaters since September, 2004. Enhancing mixing of surface and bottom water by flux control was a target of this system. After the implementation, continual monitoring has been done. It showed pumping discharge upward and downward by wave, tide, and oceanic water intrusion. The intensity of the discharge could be formulated as a function of approaching velocity and stratification of the bay.