A floating offshore airport has been proposed in Tokyo bay to reduce its environmental impact on the ecosystem of the bay. A new airport called Umi-Hotaru airport is proposed in the south of the Kisarazu man-made island (Trans-Tokyo bay highway: Tokyo Wan Aqua-Line) located in the center of Tokyo bay. Numerical simulations of flow and water quality covering the whole bay were conducted to assess its environmental impact on the bay. To investigate the local impact of this airport on the near field, special attention was given on the environment of Banzu tideland located on east side of the airport. Its shoreline change caused by the new airport was simulated, and the impact on the habitat of benthos was evaluated. The new airport will little impact on the environment of Banzu tideland as far as this study. The results of this study must give us the basic information on the environmental impact of the new airport on the bay, though the further detailed environmental studies will be necessary.
