臺灣北部福隆海域海灘類型和裂流分布之短期變動研究

The Short-term Change on the Beach Type and Rip Current of the Fulong Beach in the North Coast of Taiwan

林雪美(Hsueh-Mei Lin) ； 黃翊翔(I-Hsing Hwang) ； 沈淑敏(Su-Ming Shen)

《地理學報》 61期 (2011/04) Pp. 57-80

https://doi.org/10.6161/jgs.2011.61.03

摘要

過去有關海灘模式研究的理論基礎和分類，主要來自Wright and Short(1984)於澳洲海灘進行的研究，其探討海灘營力機制對水下沙洲和裂流變化的影響。福隆海域南端有雙溪注入，不僅同時受到波浪、潮汐等海灘營力的影響，其海灘類型和裂流分布勢必也會受到河口逕流的影響。此外，福隆為北部海岸遊憩人數最多的海灘，探討其海灘安全性更是刻不容緩。本研究即以Wright and Short的理論為基礎，透過監視器的固定影像，來探討福隆海域短期內海灘類型和裂流分布的時空變動，並討論造成其變動之河海營力，作為海灘安全性評估參考之依據。就海灘類型變動而論。福隆海域沙灘冬季海灘類型較夏季偏消散，為波浪營力的不同所致；北部鹽寮海灘段的海灘類型和當日平均示性波高的相關係數可達0.90以上，反映出海灘類型在波高影響下的立即反應；東南部河口附近海灘則深受河口逕流流路切穿的影響，無法利用Wright and Short的理論進行分類，乃以河口逕流出海的角度最為型態判斷的依據。結果發現波浪營力增大時，河口逕流會往河口左側沿岸偏移。就裂流分布變動而論。裂流數的多寡以TBR型海灘為分界，平均示性波高大約介於1.0m-1.1m之間，當偏向消散或反射形態之時，裂流數皆呈現減少的趨勢；若比較冬、夏季的裂流分布，冬季的裂流數遠較夏季為多，且其位置的偏移量也較夏季為大，此反映出冬季中等波浪能量與營力變化較大，夏季波浪營力趨於穩靜的事實；若比較各海灘段裂流位置偏移的空間差異，東南部河口左側沙洲附近之裂流擺移量遠較北部的鹽寮沙灘為大，單日移動量最高可達到75m以上，且相較於北部裂流往東南偏移為主的情形，其皆是往西北偏移的現象，推測是由於波浪和逕流共同作用的結果。

關鍵字

海灘模式 ； 裂流 ； 時空間變動

並列摘要

Past classification methods of beaches were largely based on the discussion of Wright and Short (1984) of the influences of morphodynamics on sand bars and rip currents. The Fulong Beach is not only influenced by waves and tides, but also by runoff from the Shuangsi river. In addition, the location of the Fulong beach on the north coast of Taiwan makes it the closest one to the Taipei metropolitan area, and often attracts large numbers of tourists. As a result, safety evaluation in this beach region is particularly important. To discuss short-term changes of the beach type and rip current at the Fulong beach, the researchers classified the Fulong beach using video camera images and digitized rip channel locations. The results reveal the most suitable location and time for public recreation on the beach.

並列關鍵字

beach state ； rip current ； time and spatial change

參考文獻

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