抄録
The great bad crop of the culture laver occurred in Ariake sea on the winter in fiscal 2000. The reclamation works and the embankment of Isahaya bay are suspected as the cause. Basic data and informations about Ariake sea on physics, chemistry and biology are considerably insufficient at present. Considering this situation, we initiated the research work to investigate physical aspects of the problem, such as changes of tidal range and current due to effects of the Isahaya project. In the analysis of observed sea level, the annual variation of the tidal range at the bay head during spring tide period was investigated, however, no clear evidence was found. In the numerical simulation of flow fields, it was found that the response of the tide in Ariake sea strongly depends on the amplitude of the tidal wave in open sea. According to this property, the influence of the embankment appears differently on the tidal range. On neap and middle tide period the tidal range decreases slightly, but on spring tide period the decrement of the tidal range vanishes. This rationally explains the result of analysis of observed sea level. It was also found by the numerical simulation that there is little effect of the embankment on the current velocity in Ariake sea except Isahaya bay, but significant effects occur by tremendous number of poles and nets for the culture laver installed in the shoal in Ariake sea.
