¹Department of Civil Engineering, Graduate School of Engineering Kyoto University, Uji, JAPAN

kokim@rcde.dpri.kyoto-u.ac.jp

　

²Disaster Prevention Research Institute Kyoto University, Uji, JAPAN

　

Features of the Ariake Sea are that difference of tidal height between ebb and full tide is very large and tidal current is very fast. In recent years, Ariake Sea has encountered serious environmental problems, such as seaweed damage by anomalously multiplied planktons. In this study, characteristics of the tide and tidal current in Ariake Sea was investigated by numerical experiment.

　

A parallelized three-dimensional primitive σ-coordinate model was set to calculate and predict the Ariake Sea tide at parallel linux system. The calculated results were compared with the existing charts, previous model results, coastal tidal observations and limited moored current observations. Also the influence of the Isahaya Bay sea-dyke on the changes in tide and currents in Ariake Sea was examined.

　

This study is the beginning of establishing the comprehensive model for mesoscale air-sea circulation by coupling the third-generation ocean wave model, the three-dimensional ocean circulation model and mesoscale atmospheric model. Seawater circulation is the basis of predictions of pollutant diffusion, sediment transport from the rivers, sea bottom changes as well as seawater exchange. Dominant external forces for water circulation are winds, waves and tides, which generate wind-driven and wave-driven currents with three-dimensional structure.

　

　

Kyushu University Kasuga. Fukuoka, JAPAN

kyozuka@esst.kyushu-u.ac.jp

　

As a countermeasure of the global warming, the promotion of the utilization of natural energy is urgent. There are several kinds of energy resources in ocean such as wave, thermal difference, tidal level and tidal current. Tidal motion is characteristic in two points, one is its regularity governed by celestial motions of the earth, moon and sun. The other is the dependency on the geometry of the sea. As the tidal energy is strongly concentrated at a narrow channel, the utilization of tidal energy is effectively possible.

　

A feasibility study on tidal current power generation in Kanmon Straits is presented in this report. Kanmon Strait is between Honshu and Kyushu in Japan, and the narrowest breadth is about 600 m. The maximum velocity of the current in a tidal period is about 2.5m/s. A numerical model called MEC ocean model is applied to obtain the distributions of the tidal current velocity and the tidal energy in the straits both in horizontal and vertical planes. Finally, the electric power by a propeller type generator with a 10 m diameter is calculated as a number of the average houses consumed in a year.

　

　

¹Division of Construction, Environment & System Engineering Kwandong University, Yangyang, Kangwondo, KOREA

yoonyy@mail.kwandong.ac.kr

kkhkim@mail.kwandong.ac.kr

　

²Department of Civil and Environmental Engineering Myongji University, Yongin, Kyonggido, KOREA

bmyoon@mju.ac.kr, ckpyun@mju.ac.kr

　

The study for evaluating the purification capacity of the tidal flat in Young-Jong Do, where reclamation has been accelerated for new airport and harbor, was carried out owing to recognize its function and value. According to the results obtained during two tidal period at the station (depth: high tide 8 m, low tide 2.5 m) located in the strategic point of water mass movement, the almost maximum values of water quality items were obtained at low tide and the values obtained during ebb tide are higher than them during flow tide, which indicate that pollutants escape from the tidal flat to sea, instead of its removal at the tidal flat.

　

This results show that the pollutant inputs from adjacent costal area exceed the purification capacity of tidal flat and its inherent characteristics get more and more discolored, even though we could not conclude its disappearance.