臺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 整體向西推移約13公里，古臺江內海已逐漸淤填，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外，均向內侵蝕，在頂頭額汕西側最大侵蝕率約達14m╱yr。 沙丘分布主要有沙崙、臺南、鯤身及將軍溪沿岸四群，其中沙崙及臺南沙丘可能形成於大 湖期海侵（3500-4000 yr B.P.），鯤身沙丘為三百多年前濱外沙洲持續發展而成，曾文溪沿 岸沙丘則為曾文溪古流路由將軍溪出海時所形成。各處沙丘受人類開發利用所影響，規模 均不知前。 河道變遷在丘陵區以曲流頸切斷最為顯著，在曾文溪及二仁溪共有13處切斷痕跡。海岸平 原區的河道，主要受暴風雨後主流迅速淤積而發生變遷，曾文溪下游即發生過四次改道， 河道擺幅達25 km。但自河堤興建後，河道便少有大幅改道的現象。 海岸平原地區向為人口稠密地帶，地形變遷與人類生活息息相關，造成洪患威脅、土地利 用改變、沿岸聚落興衰、土地權屬爭議及行政區界劃定等方面的影響，而人類擴張聚落、 興建水庫、修築堤防、開鑿渠道、海埔地圍墾等作為，也造成天然地形變化，地形變遷研 究正可提供為土地規劃與開發利用的參考。

　　　　　The Tainan coastal plain in southern Taiwan had been formed since late Pleistocene. The coast was marked by the offshore bars and lagoons, and have prograded to the west about 13 km since last three hundred years. The large lagoon was named as "paleo Taichiang Inland Sea" in Ching dynasty historical document had been filled up and reclaimed as fish ponds and salt pans due to the rapid sedimentation. However, the west coast of offshore bars have been eroded with a maxium rate about 14 m/yr in Tingtouerh bar in this century. The coastal dunes are distributed mainly in Salun, Tainan and Kunshen. Among them, Salun and Tainan dunes were deposited in Tahu Transgression stage (3500-4000 yr B.P.) where as the Kunshen dunes developed on offshore bars in last three centuries. Besides, a series of dunes is still exsited along the former Tsengwen River. Due to the expansions of the cultivated and built areas, all the dunes have decreased in magnitude. The river channel changed significantly both in hills and coastal plains. In the hills, 13 meander neck cutoffs can be observed in Erhjen River and Tsengwen River. On the coastal plain, river channel shifted by meandering and avulted suddenly in typhoon season because of epesodic sedimentation in the river bed. There were four big channel avulsions recorded since 19 century in Tsengwen River and the range of channel avulsion from north to south is about 25 km. However, the channel was confined after the dyke had been constructed in 1934. Overall, the geomorphological changes of Tainan coastal plain were caused by long term physical processes but modified strongly by human agency in the recent time. The geomorphological changes have induced some impacts on the human beings such as the decline of port, moving of village to prevent flooding, confusion of administrative boundary, etc.