- 期刊
多時影像與空載光達資料應用於地形變遷研究～以外傘頂沙洲爲例
Change Detection of Wai-Shan-Din Sandbar by Combining Multi-Temporal Imageries and Airborne LiDAR data
摘要
本研究結合多時遙測衛星影像與三個時期的空載LiDAR資料，分析外傘頂洲地區近35年間的變化與沙洲飄移趨勢，並比對與量化往內陸移動的速率。初步結果顯示，沙洲本體北段較爲穩定，南段則呈逆時鐘方向後退中；如1973~1986年間，沙洲南段往東南方向飄移1.4公里，北段沙洲亦向東方飄移近0.6公里；1986~1990年間，沙洲南端向東偏移420公尺，北端爲240公尺；1992~1996年間之沙洲北段較爲穩定，但南端約以每年162公尺速率向陸地靠近；1997~1999年間，沙洲最南端則往北移動了近150公尺；2000~2003年間，沙洲南端約以每年50公尺的速率往嘉義移動；2004~2005年間平均移動速率增加爲每年65公尺。另以空載光達資料分析2004~2006年間之外傘頂洲地區的面積與體積變化，顯示0公尺等高線以上地區的面積與體積有減少趨勢；其中之面積由1813.10公頃減少爲1721.57公頃，體積由17.56百萬立方公尺減少爲16.24百萬立方公尺。
並列摘要
Multi-temporal satellite imageries and airborne LiDAR data are used in this study to understand the trend of change of Wai-Shan-Din Sandbar, and, thus to estimate the moving rate of the sandbar toward the inner land in recent 35 years. Results are as follows: (1) Images between 1973 to 1990 shows that the sandbar is retreating from the sea toward the land to the east side in a counter-clockwise movement with a larger amount in the southern part of 1.82 kilometers and smaller amount in the northern part of 0.84 kilometers. (2) From 1992 to 1996, the northern part of the sandbar was stable but the southern part was moving counter-clockwise with a rate of 162m per year. (3) From 1997 to 1999, the southern part of the sandbar shifting 150 meters northward. From 2000 to 2003, the annual rate is 50 meters toward the land to the east. (4) Three times of DEMs from 2004 to 2006 were obtained by airborne LiDAR. The northern part of the sandbar was subject very subtle change according to the overlay of thematic maps of zero-meter lines abstracted from Lidar DEMs. However, the southern part shows a change of around 110 to 130 meters toward the land to the east. (5) The zero-meter thematic maps and the volumes within zero-meter lines also show that the area of the sandbar decreased from 1813 to 1721 hectares, and the volume changed from 17.56 to 16.24 million m(superscript 3). It is concluded that satellite imageries give a long time of records for understanding the trend of the 2D coastal lines. However, LiDAR enhances a possibility of understanding the change patterns in 3D, including the volume of change.