CROSS-SHORE SEDIMENT TRANSPORT AND SEDIMENT VOLUME CHANGE DURING SYSTEMATIC MIGRATION OF MULTIPLE SANDBARS

YUHI Masatoshi, OGURA Taichi, MATSUYAMA Masayuki

doi:10.2208/kaigan.71.i_643

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多段砂州システムの周期的沖向き移動と岸沖漂砂・土砂量変動の関係に関する基礎的研究
タダンサスシステムノシュウキテキオキムキイドウトガンオキヒョウスナ・ドシャリョウヘンドウノカンケイニカンスルキソテキケンキュウ

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Abstract

The characteristics of systematic net-offshore migration of the multiple bar system on the Chirihama and neighboring beach, Japan, have been investigated using a set of annual field surveys collected over 11 years. An EOF analysis has been conducted on the periodic movements of the sandbars, and the related cross-shore sediment transport and sediment volume variation were examined. The migration cycle of bars consisting of the successive generation, migration and degeneration were well reproduced by the combination of the 1st and 2nd eigen-modes, and these two modes become dominant alternatively. The principal modes of cross-shore sediment transport are shown to be characterized by the spatial integration of space eigen-function and the temporal derivative of the time eigen-functions. Corresponding to the cyclic movement of sandbars, the direction of sediment transport at the shoreline changes alternatively between seaward and landward directions. The sediment volume over the profile varies accordingly, but on the long-term the net-offshore migration of sandbars does not contribute to the sediment volume variation.

Journal

Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering)

Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering) 71 (2), I_643-I_648, 2015

Japan Society of Civil Engineers

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