RIASSUNTO
In recent years, the environmental relevance of coastal areas has increased. Therefore, development of environmentally friendly breakwaters is strongly expected. We selected three cases as the breakwater arrangements; one with no breakwater, one with conventional breakwater often seen near the mouths of Japanese bays, and finally a new breakwater procuring enhancement of water exchange. We studied the effects of these breakwaters on wave suppression with a hydraulic model and on water quality by numerical simulation. In addition, we numerically simulated the effect of the combination of a breakwater and a Density Current Generator (DCG) to prevent water stratification. As a result, comparing the conventional breakwater with the new one expected to enhance water exchange, we found that both were similarly effective in suppressing waves, and that the latter weakens a degree of strong thermal stratification more than the conventional one. Moreover, when a DCG was installed, there was less temperature stratification than even that with no breakwater. Therefore, it is suggested show that water quality in the bay can be further improved by installing a DCG.