Author(s)

T Hibino, K Hamabashiri & K Shimizu

Abstract

Consequence of the Kuroshio path for hydraulic phenomena around Set0 Inland Sea, Japan T. Hibino1, K. Hamabashiri1 & K. Shimizu2 1 Graduate School of Engineering, Hiroshima University, Japan. 2 Ministry of Land Infrastructure and Transport, Japan. Abstract The comprehensive water quality survey in the Seto Inland Sea has been operated by the Ministry of Land Infrastructure and Transport (MLIT), Japan. The water quality survey Program was established for the purpose of making data set available to know actual conditions of water pollution, and to generate products that would be valuable for scientific analysis of climate-related processes. The program started in May, 1981. Water qualities (salinity, water temperature, DO, pH, turbidity) were observed in February, May, August and October [l]. The observation carried out at 142 points located on 3km * 3km grid. The depths of the observed layer were upper (2m depth) and lower (2m above the bottom). We examined the physical factors affecting annual and seasonal changes in water quality of Seto Inland Sea by using the data (salinity, temperature, sea level etc.) measured by several institutions, mainly MLIT and JMA (Japan Meteorological Agency). From the present study, it is revealed that the water mass inside the Inland Sea is strongly related to the sea level along Japanese coast facing to the Pacific Ocean over the scale of 1,000km from the Inland Sea to Naha (Okinawa). High salinity water that is a part of the Kuroshio intrudes into the Inland Sea. In the recent twenty years, the Kuroshio path moved periodically. The Kuroshio was often observed to take a large meander path in the 1980s and to take a northerly path in the 1990s. Because of this shift, the salinity distribution in the Inland Sea dramatically changed

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