The Seto Inland Sea, the largest enclosed sea in Japan, has unrivalled beauty of archipelago and abundant nature under temperate climate with light rain falls, and the people has been benefitted from the sea ever since the early times. We however experienced sever water pollution problems caused by rapid industrialization and the loss of seaweed bed and tidal flat due to reclamation projects particularly in the period of the high economic growth in 1960s. To resolve these issues, we have carried out water quality improvement programs including reduction of pollutant load based upon the Water Pollution Control Law and the Law concerning Special Measures for Conservation of the Environment of the Seto Inland Sea. As a result, water quality has improved as compared with Tokyo Bay and other enclosed seas.
However, there are still severe problems including the occurrence of red tide and oxygen deficient water mass in some areas in the Seto Inland Sea. Securing the bio-diversity, bio-productivity and smooth nutrient circulation are also important. Under these situations, the Law and the Basic Plan for Conservation of the Environment of the Seto Inland Sea were revised in 2015. With these law and plan, it has been made clear that our principal objective is to make the Seto Inland Sea a “Bountiful Sea” through conservation of water quality with bio-diversity and bio-productivity. Also the importance to implement environmental measures corresponding local differences in the respective region and seasonality were indicated.
In order to actualize “the Beautiful and Bountiful Seto Inland Sea”, we need to implement environmental water management as follows.
1. Environmental conservation, restoration and creation of coastal areas.
2. Conservation and management of water quality.
3. Conservation of natural and cultural landscapes.
4. Sustainable utilization of fishery resources.
Ministry of the Environment, Japan will continue to conduct corresponding programs based on scientific survey and evaluation on conservation/restoration of seaweed bed, tidal flat, smooth circulation of nutrients.
Mesoscale velocity field around Nakatsu Tidal Flat in Suo-nada ( western part of the Seto Inland Sea, Japan) and the Dispersion Characteristic of Floating Larva of Tapes Philippinarum.