花蓮港東防波堤擴建前後海岸過程之研究

Coastal Processes before and after the Construction of the Eastern Breakwater of Hwalien Harbor

本文根據水利局實測斷面資料，分析花蓮海岸東防波堤擴建前後海岸線變遷、漂沙量之演變及灘距歷時變化。文中同時利用二維經驗特徵函數法預測無東防波堤存在時海灘斷面變化，並與東防波堤擴建之後實測斷面比較。另實測斷面分析結果顯示，東防波堤擴建後對灘距之變化及漂沙量的影響相當明顯，其變化係以自由街排水口為臨界點，呈現北淤南侵的現象，此情況與二維經驗特徵函數法之預測結果吻合。

Beach profile data from Hwalien Coast measured every two months for three, years were used to investigate the beach changes after the construction of the eastern breakwater at Hwalien harbor. Shoreline changes and sediment transport rate were analyzed to evaluate the effect of the eastern breakwater on the coastal processes. A 2-D empirical eigenfunction method was also applied to predict the beach profile changes with and without the eastern breakwater. The result is compared with the field data observed after the completion of the eastern breakwater. It is shown that the construction of eastern breakwater has primary influence on the coastal changes.