RELATIONSHIP BETWEEN COASTAL DUNE FORMATION AND SUBMARINE TOPOGRAPHIC CHANGES

Abstract

 At Ikobe Coast on the Pacific side of the Atsumi Peninsula, dunes began forming in front of the sea cliffs around 2010 and have since developed to a height of over 20 m. This rapid dune development is attributed to increased wind-blown sand resulting from beach expansion due to coastal protection projects. However, alongside dune growth, significant erosion has been observed on the downdrift side of the shoreline, indicating that the formation of large dunes affects longshore sediment transport. This study analyzes the relationship between dune development and changes in the beach and submarine topography using dune topography survey data, bathymetric survey data, and satellite images. The analysis reveals a negative correlation between submarine topographic changes and dune volume changes during the dune development period. Additionally, by calculating the sediment budget within the dune area under the assumption of increased wind-blown sand, it is found that sediment supply to the dunes significantly reduces the longshore sediment transport.