海食崖に続く堆積性弧状海岸線の形成とその変形予測

概要

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Kujukuri Beach with a 60km length located in Boso Peninsula has an arc-shaped accretive shoreline and has been formed mainly owing to the sand supply from the sea cliffs at Byobuga-ura and Taito. On south Kujukuri Beach, severe beach erosion has occurred since 1970s and erosion area has been still expanding at present. The exhaustion of sand supply by northward longshore sand transport from sea cliffs, formation of wave-shelter zone at Katakai fishing port breakwater and ground subsidence caused by the pumping-up of underground water are the major causes of the shoreline recession. A meeting point of longshore sand transport from both directions is predicted by the predominant wave direction and the coastline configuration. Then, the arc-shaped shoreline of Kujukuri Beach is reproduced given these conditions using the contour-line-change model proposed by Serizawa et al. (2002). Finally, beach erosion caused by various anthropogenic factors is reproduced. Predicted shoreline changes are in good agreement with the measured.
2009-10-25