SHORT-TERM MORPHOLOGICAL CHANGES AND SEDIMENT DYNAMICS OF TIDAL FLAT DUE TO TYPHOON PASSAGE

Abstract

 The Maejima Tombolo Tidal Flat located in Higashitsuzu-cho, Nishio City, Aichi Prefecture has a rich natural environment in which a varaiety of organisms live. However, it has been reported that the change of wave and current conditions caused by typhoon's approach and passage gives a strong impact on the topography and its impact results in the significant morphological change in a short term. Due to the effects of global warming and others, it is considered that the intensity of typhoons and occurrence of abnormal weather will increase in the future. As a result, not only obvious mophological changes but also deterioration of water purification function may occur in tidal flats. In this research, the topographic measurement of tidal flat by UAV and surface sand sampling for spatial distribution analysis of grain sizes were conducted in typhoon season, and the investigation of topographic change, sand movement and changes of sand property in a short term due to meteorological impact. Consequently, it was inferred that active sand movement occurs all the time on the tidal flat from the position change of the top of the tidal flat cross section and the sand volume change in each small area set on the tidal flat.