SEAWATER EXCHANGE PROCESSES THROUGH THE BAYS OF SHIRAHAMA AND FUNAUKI IN IRIOMOTE ISLAND, OKINAWA, JAPAN

Abstract

 In order to investigate seawater exchange processes in Shirahama Bay and Funauki Bay, Okinawa, Japan, which are mutually connected by a channel at the inner parts of the bays, observational, numerical, and theoretical studies are conducted in this study. In-situ observations and numerical simulations indicate that periodic currents in the connecting channel are dominate in response to flood tidal and ebb tide, and the stagnation of river-origin and low-salinity water is often observed at the 10-cm surface layer in Funauki Bay. Continuum theory of momentum and mass transfer suggest that periodic currents and steady-state flows among the bays and ocean depend mainly on the differences of depth and length among the two bays. As a result of the geographical features, it is concluded that river-origin water likely stagnates in Funauki Bay over the long periods of time, compared to Shirahama Bay.