Integrated Coastal Zone Management : Application of Osaka Bay Research to Bohai Sea, China

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It has been reported from Chinese Government that red tides have often occurred in the wide ranges in the past two decades. Similar eutrophication phenomena were also observed in 1960's in Japan. Water contamination, red tide appearance, anoxic water, etc., had developed accompanied with rapidly economic growth. The surface area in Bohai Sea is about 100 times as large as that of Osaka Bay ; therefore, synthetic field surveys are not carried out. The knowledge, which has been obtained by field surveys in Osaka Bay, is transported to better understanding of hydrodynamics and ecosystem in Bohai Sea from the viewpoints of technology transfer. In addition, integrated coastal zone management system was developed for environmental conservation in Osaka Bay.Main results are shown as follows ;(1)The concept of Osaka Bay Environmental Information System(OBEIS) is shown, which is developed for synthetically management of environmental information data with various time and space sizes. Furthermo … More re, the authors criticize the concept of "environmental standard" in environmental impact assessment and provide the multi-criteria methodologies taken the fuzzy features appeared in natural phenomena into account.(2)In 1960's water pollution in coastal seas became serious problems on the back of rapidly economic growth. Area-wide Total Pollutant Load Control was put into force by the Government. An aquatic ecosystem model was applied to evaluate the processes of water pollution and quantitative impacts of such control on the water quality in Osaka Bay. The simulation, performed from 1950 to 2020, suggests that the load control should be expanded to include not only COD but nitrogen and phosphorus as well, because both nutrients cause internal production of COD.(3)Field surveys around the Kitan Strait were carried out to clarify the flow structure and nutrients fluxes to the Osaka Bay. The results showed that the stratification in this area depends on the Kuroshio Current meandering, and that nutrients intrude to Osaka Bay through the bottom layer of the strait as Kuroshio Current is detached far from Shiono-misaki point. The inflows of nutrients transported from Kii Channel to Osaka Bay are almost same order discharged from land(4)The harbor site in the head of Osaka Bay, which is highly urbanized, has been developed into an enclosed area with complicated artificial islands and breakwaters. Algal blooms frequently occur on the sea surface in this area throughout the year. During summer there is often upwelling of anoxic bottom water depending on stratification. Because of the depletion of oxygen, the upwelling anoxic water mass causes a serious water pollution problem similar to the problem caused by algal bloom.Four meetings were held with Chinese researchers in order to develop refined three dimensional baroclinic flow model based on discussion. Horizontal size is 480km x 350km, while average water depth is only 18 m. Hydrodynamic features can be clarified. Ecosystem modeling is in preparation. Less