A coastal dike for protecting the wetland was set back in 2004 near the mouth of the Maite River flowing into the Nakatsu tidal flat. Monitoring surveys were carried out between 2005 and 2009 after the setting back. During the observation period, Typhoon No. 5 hit the coast on August 2, 2007, resulting in the increase in tide level up to DL+4.7 m, which was a maximum since 2000. Owing to the storm surge, shoreward sand transport occurred and a high berm with a height of DL+5.02 m was formed with the recession of the foreshore by 5 m. No changes were observed in the wetland and its environment was maintained despite the storm surges, suggesting that the setting back was useful for protecting the wetland against storm surge.