Abstract
Ofunato Bay in Northeast part of Japan has tsunami protection breakwaters at the mouth of the bay, which decrease seawater exchange rate to outside and degrade the water quality such as hypoxia and eutrophication. These are frequently due to the formation of the density stratification in summer. In order to solvet hese problems, a seawater exchanges ystem using negativep ressureh as been installed for the first time on the inner bay side rubble-mound in the world since September 21, 2004. However, it is necessary to investigate the water control effect of this system becauset his is still a stage of the demonstratione xperiment.
In this study, the field observation was performed to understand vertical water quality structures in Ofunato Bay in summer, 2003-2004. Consequently, the difference of the intrusion depth by the density current was acquired by ADCP. And, we simulated the present condition and examined the amount of the optimal exchange in bottom layer using a one-dimensionavl ertical model based on this observation.
