天空開闊度與局部立體模型於山崩判釋及地形變異評估：以台東縣紅葉村為例

本研究結合山崩災前高精度數值地型與災後無人機攝影測量技術產製之地表數值模型，以地形計測學常用之立體陰影圖，探討集水區內山崩判釋可行性及災後快速地貌變遷評估。本文以2016年9月15日莫蘭蒂颱風誘發臺東縣延平鄉紅葉村山崩為例，萃取災前DEM山崩微地形判釋及DSM樹冠開闊度特徵，以建立潛在山崩發生區判釋評估分析流程。另應用災後無人機拍攝影像之三維建模，配合災後地貌可研析山崩土砂運移歷程及土石流影響範圍。地形變異分析顯示紅葉村崩塌區面積約4.5公頃，平均崩滑深度5.1公尺，總崩塌量體約22.8萬立方公尺，山崩運移距離約為957公尺，轉化為土石流之總流動距離達1.23公里。由現場調查與災後三維地形之驗證，崩塌邊界及林冠陷落特徵可於災前分別透過天空開闊度立體圖及局部立體模型圖予以判釋。本研究最後提出適於潛在土砂災害識別之地形計測學指標與災害潛勢評估建議。

關鍵字

山崩；地形計測學；天空開闊度；局部立體模型；無人機

並列摘要

This study integrates pre-landslide high-resolution digital elevation model (DEM), digital surface model (DSM) produced using post-landslide drone photography, and geomorphometric analysis to explore the effectiveness of landslide interpretation and fast assessment of geomorphic change. In this study, the large-scale landslide that occurred in Hongye Village, Taitung County in Eastern Taiwan, on September 15, 2016, was investigated. We combined both the microtopography features from the DEM and canopy openness in the DSM to establish an assessment procedure for landslide hotspot extraction. Drone photography and three-dimensional modeling techniques were used to measure the sediment transportation process and conduct postdisaster influence area mapping. The results showed that the landslide area, mean sliding depth, and volume of the landslide in Hongye Village were approximately 4.5 ha, 5.1 m, and 22.8．104 m3, respectively. The runout distance of the initial landslide was 960 m and increased to 1.23 km when the landslide transformed into debris flow in the village. Field validation indicated that the landslide-prone area and subsidence features on the forest canopy could be recognized using a sky-view factor relief and local relief model. Moreover, a complete landslide susceptibility assessment approach suitable for the catchment scale is presented.

並列關鍵字

landslide ； geomorphometric analysis ； SVF relief map ； local relief model ； UAV

國際替代計量

天空開闊度與局部立體模型於山崩判釋及地形變異評估：以台東縣紅葉村為例

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