彰化地區砂丘地形之空間分佈與組成特性──以“崙＂地名為例

Spatial Distribution and Composition Characteristics of Sand Dune Landforms in the Changhua Area—A Case Study of the“Lun”Region.

臺灣地名中大多以其外顯特徵為命名依據，表自然景觀地名的「崙」，多數出現在西部平原的縣市裡，特別是彰、雲、嘉三縣，據統計又以彰化縣「崙」地名個數最多。本研究針對彰化地區表「崙」砂丘地形地名，探討其在空間分布特性，及分析其形成原因，並藉由地貌及地名的標記，恢復隨歷史的演變而被改造或破壞之原地形景觀，並記錄現今砂丘地形的土地利用情況，以提供土地規劃與開發的參考。研究結果顯示彰化平原「崙」地名共計44個，並將其分為5類，分別為方位、規模型態、與人文有關、直接命名和植物等類別。
在彰化地區砂丘粒度分析上，幾乎50%以上粒徑含量比多集中在0.062mm - 0.25mm的範圍內，屬於細沙-極細沙的質地；其次的0.25mm - 2mm屬於粗沙、中沙等級則較為少見，而在砂丘黏土方面的含量比例則是最少。而透過Pearson相關係數分析，得知風速與沙丘粒徑大小在顯著值上皆<0.01，二者呈現高度相關顯著性，風速對於砂粒的高度正相關，顯示風力越大越能使較大粒徑的砂粒移動，然在坋粒與黏粒上卻顯示負相關，因此風營力實為砂丘形成之成因之一，而對風速的負相關乃因河川作用較為強烈。透過粒徑分析，所採樣之砂丘土壤皆未有>4mm粒徑的情況，其似乎與該地的地質構造較無直接關係。
透過1926年與1996年之砂丘比較古今砂丘變遷情況，近70年的時間，突起地形演變甚劇，舊時期的砂丘要比現在來的廣大且眾多，而在自然侵蝕與人為破壞下，反觀現今，砂丘已見低矮消失，不僅數量銳減，空間上亦呈現零星分布。而砂丘的利用，多以防風定沙的樹種為主的林地，以及墓地使用為主，其餘尚有以聚落、公路建築為主的建地，和大河沙洲的草地，與沿海或河岸旁的垃圾掩埋場等土地利用型態。

Most areas in Taiwan are named after the characteristics of their natural landscapes. The area name of“Lun”mostly appears in counties and cities of the western plain, especially in Changhua, Yunlin, and Chiayi counties. According to the statistics, the area name“Lun”occurs most commonly in Changhua County. Therefore, regarding the topography of“Lun”in Changhua area, this research focuses on exploring the spatial distribution of“Lun”and examines the causes of its formation. Based on geomorphological data and name tags, this study attempts to restore the landscapes which have been modified or destroyed during historical human activities. Our results will provide reference for land planning and development in the future. The result shows there are 49 location names with“Lun”in Changhua Plain and they can be divided into 5 categories, which are based on the following criteria: position, scale, human, activity, direct naming and plantation.
On particle level, the analysis of sediments in dune areas of Changhua County shows more than 50% of the samples fall between 0.25 mm and 0.062mm in size, which is in the range of fine and very fine sand. It is followed by the grain size of 2mm-0.25mm, which is coarse and medium grade sand. Clay has the lowest ratio in grain size of samples in the dune area. Through Pearson correlation coefficient analysis of particle size and wind speed, wind speed and the particle size of sand dunes show a value of <0.01 which is a significant value, showing that the variables are highly correlated. It shows that the higher the wind speed is, the larger particle size of sand it can move. In other words, wind power is the main factor for the formation of dunes. However, the correlation of wind speed with clay content as well as with silt content is negative, which indicates that other factors such as rivers might have played a more important role.
Through the comparison of dunes between 1926 and 1996, it shows that the terrain had dramatically changed its topography over the past 70 years. Dunes in the old times were in large quantity and in wide distribution. However, due to natural erosion and human destruction, dunes are in smaller quantity and sparsely distributed nowadays. The utilization of dunes is mainly for planting woodland species and graveyards. Some dunes not only serve as settlement construction, road construction, and river shoal grassland but also as landfills next to coastal or river banks.