臺灣西南部嘉南平原的海岸變遷研究
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Date
1998-05-??
Authors
張瑞津
石再添
陳翰霖
Journal Title
Journal ISSN
Volume Title
Publisher
地理學系
Department of Geography, NTNU
Department of Geography, NTNU
Abstract
嘉南海岸平原形成於晚更新世，海岸線的變遷與海水進退相對應，近三百多年來整體呈現向西推移的趨勢，古笨港、魍港（蚊港）及倒風內海已逐漸淤填，並被大量圍墾開發為魚塭或鹽田。濱外沙洲西側海岸除河口地區外，均向內侵蝕，在海汕洲及王爺港汕西側最大侵蝕率約達 12mn/yr。 外傘頂洲整體向東南方陸地漂移， 沙洲北段漂移速率甚至達58mn/yr。 沙丘主要分布於新港、鹿草一線以西，其中北港地區因濁水溪供沙充足，較嘉義沿海發達。 北港以西的海岸沙丘，大致分布在 7mn 以下，呈四列南北帶狀分布，隱示不同時期的海岸線位置， 應形成於大湖期海侵（ 3500-4000yr B.P. ）之後。 比較 1904-1926及 1990 年各時期之沙丘，其規模大致逐漸減小，係受人類開發利用影響所致。海岸平原地區向為人口稠密地帶，地形變遷常造成洪患威脅、丘沙漂移、土地利用改變、沿岸聚落興衰、土地權屬爭議及行政區劃定等之衝擊。相反的，人類擴張聚落、興建水庫、修築堤防、開鑿渠道、圍墾海埔地、取直河道等作為，也造成天然地形之改變，地形變遷與人類生活息息相關，其研究正可提供為土地規劃與開發利用的參考。
Chianan Coastal Plain had been built since late Pleistocene. It wasmarked by the lagoons and offshore bars. The coast has been changed coincidentlywith transgression and regression. Since last three hundred years, it hasprograded westward due to rapid sedimentation. Lagoons of Benkang, Wangkang andTaofeng have been filled up and reclaimed as fish ponds or salt pans. However,the west coast of offshore bars, Haishan and Wangyeh, have been eroded with amaximum rate of 12m/yr in average. In addition, the offshore bar migratedlandwardly, such as the northern section of Waishanting bar moved toward theland with a rate of 58 m/yr during 1904-1990. Responding to the abundant sandsupply from Choshui River, the sand dunes distributed in Peikang coastal plainare wider than those in Chiayi. They scattered on the coast plain below 7m andcould be built after Tahu transgress (3500-4000 yr B. P.). They lie in fourbands approximately, which might indicate four different stages of coastline.Most of the sand dunes decreased in altitude caused by humans modification in1990 comparing with 1904 and 1926, which become cemetery field in landuse.Overall, bi-directional relationship existed between human and landform in thecoastal plain since last three hundred years. The coastal changes produced someimpact on human beings including the decline of small sea ports, changes oflanduse and threat of flood. In contrast, the human activities influenced thegeomorphological change such as reclamation of tidal flat, construction of dikeand reservoir, etc.
Chianan Coastal Plain had been built since late Pleistocene. It wasmarked by the lagoons and offshore bars. The coast has been changed coincidentlywith transgression and regression. Since last three hundred years, it hasprograded westward due to rapid sedimentation. Lagoons of Benkang, Wangkang andTaofeng have been filled up and reclaimed as fish ponds or salt pans. However,the west coast of offshore bars, Haishan and Wangyeh, have been eroded with amaximum rate of 12m/yr in average. In addition, the offshore bar migratedlandwardly, such as the northern section of Waishanting bar moved toward theland with a rate of 58 m/yr during 1904-1990. Responding to the abundant sandsupply from Choshui River, the sand dunes distributed in Peikang coastal plainare wider than those in Chiayi. They scattered on the coast plain below 7m andcould be built after Tahu transgress (3500-4000 yr B. P.). They lie in fourbands approximately, which might indicate four different stages of coastline.Most of the sand dunes decreased in altitude caused by humans modification in1990 comparing with 1904 and 1926, which become cemetery field in landuse.Overall, bi-directional relationship existed between human and landform in thecoastal plain since last three hundred years. The coastal changes produced someimpact on human beings including the decline of small sea ports, changes oflanduse and threat of flood. In contrast, the human activities influenced thegeomorphological change such as reclamation of tidal flat, construction of dikeand reservoir, etc.