集水區崩塌地環境指標分析與崩塌潛感推估

Analysis of Environmental Factors and Landslide Susceptibility Prediction for the Watershed Landslides

穆婧(Jing Mu) ； 林昭遠(Chao-Yuan Lin)

《中華水土保持學報》 44卷2期 (2013/06) Pp. 121-130

https://doi.org/10.29417/JCSWC.201306_44(2).0003

摘要

崩塌發生受多種環境因素影響，若能選用合適之環境指標探討其成因，將有助於日後相關單位於管理、防災參考之用。本研究以莫拉克風災受創甚為嚴重之高雄旗山溪四德大橋上游集水區為研究樣區，藉由災害發生前後之衛星影像，萃取集水區崩塌區位。利用DEM、衛星影像等資料萃取環境指標，透過主成份分析篩選重要指標，構建判別分析（DA）模型，探究集水區環境指標與崩塌發生的關係，並繪製崩塌潛感推估圖。結果顯示，萃取出的三個主成份軸分別以植生、坡度和距平均高差指標為主；判別函數由海拔、坡度、NDVI、地形濕度指數、坡度粗糙度和距離平均高度離差構成，模型對崩塌地判識精度達70％以上。由崩塌潛感圖得知，研究區地形濕度指數越高且坡度粗糙度越低之區位崩塌潛勢越高。

關鍵字

崩塌地 ； 環境指標 ； 潛感分級 ； 遙感探測

並列摘要

Landslide disasters are affected by different kinds of factors. Choosing appropriate environmental indicators to investigate landslide causes and predicting potential locations would contribute to disaster management and prevention in the future. In this study, Si-de Bridge, which is located at the Qi-Shan Creek of Kaohsiung County, was used as the outlet of a watershed which suffered heavy damage during Typhoon Morakot. The landslide area was extracted from two-date SPOT-5 images with the image subtraction method. DEM satellite images were applied to calculate some environmental factors. Then, through principal component analysis (PCA), we analyzed the important factors and built a discriminant analysis (DA) model to explore the relationship between environmental indices and landslides and generated a potential landslide map. The results showed that the extracted three principal component axes were mainly vegetation index, slope and difference from mean elevation; elevation, slope, NDVI, slope roughness, topographic wetness index and deviation from mean elevation were used to build the DA model, with classification accuracy up to 70%. According to the landslide susceptibility map, the areas with higher topographic wetness index and lower slope roughness had higher landslide susceptibility.

並列關鍵字

Landslide ； environmental indices ； susceptibility classification ； remote sensing