A feasibility study on the water quality improvement by making use of underground water in Hakata Bay

Hakata Bay is an enclosed bay adjacent to Fukuoka City and the eutrophication of the bay water has been getting serious by the sewage contamination in recent years. In this study, we propose a plan to improve the water quality by making use of the underground water upwelling by plunged pipes into the bottom of the bay. The density of the underground water is smaller than sea water that the vertical circulation and the upwelling of the bottom water by the entrainment effects will be generated in the bay, which may improve the water quality of the bay. Field measurement results of the water quality and the quantity of the underground water together with the laboratory experiments and numerical simulations of the diffusion of the underground water in the bay are presented in this paper.