FIELD OBSERVATION OF EROSION AND ACCRETION WAVES ON SHIZUOKA AND SHIMIZU COASTS IN SURUGA BAY IN JAPAN

Naoki Itabashi, Takaaki Uda

Abstract


A distinct propagation of erosion and accretion waves was discovered along the Shizuoka and Shimizu coasts facing Suruga Bay in Japan. Their propagation velocities were 270m/yr and 250m/yr. "Hagoromo-no-matsu", a scenic beach famous in Japan, where, along the shoreline, people can see Mt. Fuji in the distance, sandy beaches and pine trees, will be eroded in two years, whereas it takes 30 years for longshore sand supply to reach this beach. Countermeasures must be taken, without relying on natural sand supply from the upcoast by longshore sand transport which will take for at least 30 years. Severe beach erosion began at the time of large-scale river bed excavation conducted before 1967 in the Abe River which is the source of littoral sand, and beach erosion has a propagation mode of erosion waves. Measures combining the construction of headlands to stabilize the natural sandy beach with beach nourishment should be taken immediately.

Keywords


erosion; accretion; Shizuoka; Shimizu; Suruga Bay; field observation

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