Consequence of the Kuroshio path for hydraulic phenomena around Seto Inland Sea, Japan

Abstract

The comprehensive water quality survey in the Seto LnlandSea has been operated by the Ministry of Land I.nhstructure and Transport (MLIT), Japan. The water quality survey Program was established for the purpose of making dsta set available to know aclual conditions of water pollution, and to generate produas that would be valuable for scientific analysis of climate-related processes. The program started in May, 1981. Waterqualities (salinity, water temperature, DO, pH, turbidity) were observed in February, May, August and Oclober [1]. The observation carriedout 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 dsta (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 cm.st facing to the Pacific OcearIover the scale of 1,000km horn the Inland Seato Naha (Okinawa). High salinity water that is a part of the Kuroshio intrudes into the Inland Sea. hI 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