INFLUENCE OF ASPECT RATIO OF A CONNECTING CHANNEL ON SEAWATER EXCHANGE IN THE BAYS OF SHIRAHAMAAND FUNAUKI IN IRIOMOTE ISLAND, OKINAWA, JAPAN

Abstract

 In this study, we investigate the sensitivities of the aspect ratio (ratio of length to depth) associated with a connecting channel on seawater exchange in Shirahama Bay and Funauki Bay in Iriomote Island, Okinawa, Japan, using a simplified tidal current model. In the case of a control experiment with moderate aspect ratio, the tidal current in the connecting channel is activated leading to the difference of salinity among the two bays. In the case of large aspect ratio, the tidal current in the connecting channel is inactivated enlarging the difference of salinity among the bays. In the case of small aspect ratio, the tidal currents in not only the connecting channel but also the channels to the oceans are inactivated causing a reduction of salinity in both the bays. It is considered that the aspect ratio of the connecting channel effectively influences on seawater exchange and seed and fruit dispersal in both the bays.