摘要:近十年來高精度空載雷射掃瞄(Light Detection And Ranging,LiDAR)(亦稱空載光達)技術業已發展至成熟階段,且已實際應用於地形測製與地質相關災害之判釋與研究,配合國內航空照片與自主福衛二號衛星的影像之高解析能力,使得利用高精度的數值高程模型(Digital Elevation Model,DEM)配合衛星影像與航空照片成為進行山崩與土石流等坡地環境地質因子分析與活動地形構造判釋之有效方法。
莫拉克風災造成南部、中部與東部地區嚴重之山崩、土石流與淹水災害,災區以往之調查數據對於巨大變異之國土現況,已無法應付所需。為能快速、精確的取得災區相關資訊,本計畫將運用LiDAR技術,取得受災區域高精度的數值高程模型,配合衛星影像與航空照片等,進行山崩與土石流等坡地環境地質因子判釋與地形變異、地質特性分析,並對具有保全對象之重點地區進行現地調查,因100年度相關LiDAR航拍計畫作業不及,於100年度計畫期間內無法取得數值地形與同步正射影像資料,並完成分析及判釋工作,因此需待LiDAR資料測製完成後,再將100度部分工作項目,進行第2階段之資料成果的精進作業。
本研究團隊結合成功大學、台灣大學、中央大學、台北科技大學及屏東科技大學、長榮大學專精於地質災害調查研究之教授與研究人員,以3年(99至101年度)為期,分析空載雷射掃瞄技術所產製之高精度數值地形與同步正射航照,完成之莫拉克受災地區災後之相關判釋、調查、分析與評估等工作,以精確完整的評估災區之地質敏感地區、地質災害潛勢區域及地質災害可能影響區域分布,並適切討論相關地質災害之成因、影響範圍、影響程度與未來可能之發展等,以供後續國土規劃、國土分級管理、國土保育等目的使用。
本計畫於99年度已完成南部地區共計1,049幅1:5,000圖幅範圍之地質敏感地區判釋圈繪與101幅1:5,000圖幅範圍之重點區域的地質敏感特性評估工作,於100年度已完成中部地區共計1,100幅1:5,000圖幅範圍之地質敏感地區判釋圈繪與100幅1:5,000圖幅範圍之重點區域的地質敏感特性評估工作。台灣大學負責的部分為台東縣的知本及太麻里流域,圈繪的圖幅總共有97幅,重點區域的地質敏感特性評估工作的圖幅有14幅。
Abstract: The techniques of LiDAR are well developed in last ten years and it has been successfully applied in geodetic survey to produce a high resolution Digital Elevation Model (DEM). Combining with the high resolution satellites images such as the Formosat-2 images and aerial photos, and DEM became a powerful tool to study active geomorphology and geohazards on a regional scale.
The accumulated rainfall during typhoon MORAKOT in 2009 reach to 3,500 mm and induced severe landslides, debris flows, and flooding hazards in south-central and eastern Taiwan. In the severe damaged area, previous survey results in topography and geohazards become insufficient due to violent changes in topography. Therefore, in order to obtain better topographic and geological information in severe damaged area, Central Geological Survey (CGS), MOEA initiates a 3-year project for generate high resolution DEM by LiDAR. One of the main purposes of the project is to recognize active geomorphologic structures and geohazards from LiDAR generated DEM.
This project started from 2010 and will be ended in 2012. According to the damage situation influence by Typhoon Morakot, this project will spent three years to study active geomorphologic structures by using high resolution DEM. Landslides, debris flows, dip slopes, headward erosions, lateral erosions will also be recognized from DEM, aerial photos and satellite images. The study method includes geohazards interpretation, geomorphology analysis, geohazards susceptibility analysis, field investigation and database construction.
Our research team which consists of faculty and researchers from National Cheng Kung University, National Taiwan University, National Central University, National Taipei University of Technology, Chang Jung Christian University, National Pingtung University of Science and Technology will spent three years to study active geomorphologic structures by using high resolution DEM. Landslides, debris flows, dip slopes will also be recognized from DEM, aerial photos and satellite images. In addition, in areas where villages or important construction located will be surveyed by field investigation. All the above mentioned result will be used to evaluate the geohazards susceptibility in the severe damage area to prevent secondary hazards to occur in near future.
The geospatial database and several thematic maps of geohazards will be established in this year. The geospatial database includes location, attributes and susceptibility of geohazards. And a total of 1,100 geohazards maps(1:5,000 scale), 1,100 geomorphology analysis maps(1:5,000 scale), 1,100 geohazards susceptibility analysis maps(1:5,000 scale) and 100 field survey maps (1:5,000 scale) will be generated. National Taiwan University, responsible for part of Taitung County the Chihpen & Taimali basin areas, will complete 97 maps14 maps of key areas and sensitive geological features.