Utilization of Adaptive Management Technique for Restoration of Large-Scale Tidal Flat in Tokyo Bay

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This paper proposes that the pilot field be created to apply the Adaptive Management Technique in order to promote the policy of large-scale restoration of the tidal flat/shallow sea. It will be a case study in Tokyo Bay, a major enclosed urban sea in Japan. The motif and background of the study are stated in the beginning. Creation of the symbiotic structure with marine life, of which the artificial tidal flat is a representative example, is more and more in need as a new direction of port environmental policymaking. This paper discusses that the creation of large-scale tidal flat will be especially effective in Tokyo Bay, a highly reclaimed and enclosed sea and that an innovative technical approach is necessary in view of the long-term efforts. First, an artificial tidal flat built in the past, Itsukaichi Area Artificial Tidal Flat in Hiroshima Prefecture, was analyzed to identify its technical problems. Based on what occurred in this case, the need for a new technical approach to practice the Adaptive Management Technique is discussed. Secondly, Tokyo Bay is taken up as a case study. With the ultimate goal of restoring the tidal flat/shallow sea on a large-scale, it is proposed that small pilot fields be created in the Bay and that the Adaptive Management Technique be applied. Technical and social problems will be addressed step by step in the pilot field, which will be gradually expanded. They are open experimental fields, where systematic observation will be conducted. Technically appropriate structure of the tidal flat will be assessed. The pilot field will also be a forum where consent and support of those concerned including citizens and non-specialists is sought. Furthermore, “Shiosai no Nagisa,” an artificial tidal flat with a reinforced seawall in Port of Yokohama is examined from the viewpoint of the Adaptive Management Technique. It was built by Kanto Regional Bureau of Ministry of Land, Infrastructure, Transport & Tourism in 2008.