以證據權重法探討崩塌發生之潛勢─以隘寮溪流域為例

本研究以莫拉克颱風為對象，高屏溪流域內之隘寮溪流域為研究範圍，結合衛星影像判釋所得之崩塌地和證據權重法推算個別影響崩塌之相關因子的權重，進而產生崩塌潛勢圖，作為未來崩塌風險評估應用之參考。本研究採用崩塌因子為高程、坡度、坡向、地質、水系距離、斷層距離、曲率和土地利用型態等。各項影響崩塌因子之權重分析結果，高程以1000~1500公尺最高；坡度以55%~100%度最高；坡向以南面最高；地質以廬山層和蘇礫層為主的板岩最高；河川距離以200公尺內權重最高；曲率則以>-4權重最高；斷層距離1000~2000公尺以內權重最高；土地利用以裸露地占權重最高。後續將以上數據之權重統整出每個區域的崩塌潛勢總權重(Landslide susceptibility index，LSIc)，再以八個因子進行不同組合的LSIc。組合的優劣程度是崩塌率和LSIc之間的成功率曲線(Success Rate Curves)，計算弧線下之面積(Area under curve，AUC)，AUC面積越大，能表示此因子組合對崩塌潛勢的準確率較高，最後得到以坡度、坡向、高程、地質和河川距離組合之LSIc值的成功率曲線，較能解釋崩塌地的分佈情形。組合最佳的崩塌因子權重將套疊GIS空間分析的功能，即可產生崩塌潛勢圖，並以2010年凡那比颱風和2011年0719豪雨之崩塌地驗證此崩塌感圖的準確度。

關鍵字

崩塌地；證據權重法；衛星影像；崩塌潛感圖

並列摘要

This study takes Typhoon Morakot as research object and Ailiao River region inside Gaoping River region as research scope, which combines satellite image to recognize interpreted slide land and uses weights of evidence method to calculate weights of slide’s relevant factors and furthermore generate landslide potential flows for references to slide’s risk evaluation in the future. This study adopts slide’s factors including height, slope angle, slope orientation, geology, proximity to the drainage, distance to fault, curvature, and land use type. For analysis result that affects each slide factor’s weight, it shows 1000-1500 meters is the highest for height; 55%-100% degree is the highest for slope; south side is the highest for slope orientation; Lushan Formation layer based and Su-Li layer based slate is the highest for geology; within 200 meters occupies the highest weight for proximity to the drainage; >-4 occupies the highest weight for curvature; within 1000-2000 meters occupies the highest weight for distance to fault; and bare land occupies the highest weight to land use type. Afterwards, it will generate each region’s landslide potential’s total weight as per above figures’ weight and will apply eight factors to perform LSIc(Landslide susceptibility index) with different combinations. Conditions of these combinations depend on success rate curves between landslide rate and LSIc. To calculate area under curve(AUC), bigger AUC shows these factors’ combination has more accurate rate to slide’s potential. Eventually, it will gain success rate curves which combines LSIc values in slope angle, slope orientation, height, geology, and distance from river, which explains more clearly slide land’s distribution condition. The best slide factors’ combination will overlay GIS spatial analysis’ features and generate slide potential flows, which will be testified for its landslide susceptibility map’s accuracy using the July 2010 –Typhoon Fanapi’s and the July 2011– 719 downpour event slide land.

並列關鍵字

slide land ； weights of evidence method ； satellite image ； landslide susceptibility map

參考文獻

Yueh-Chi Kuan ; Kuang-Chih Chang (2007). Conservation Practices in Reservoir Impoundment and Buffer Zones in Taiwan. Journal of Ecotechnology, Volume3, Issues 2 December 2007, 13-22.

行政院農業委員會水土保持局(2004)，七二水災崩塌地判釋與分析期末報告。

行政院農業委員會水土保持局(2007)，高屏溪等上游集水區整體調查規劃。

謝正倫、黃敏郎、蔡在宗、張維恕(2010)，運用福衛二號影像進行莫拉克颱風崩塌地判釋。中華防災學刊，第2(1)期。

雷祖強、周天穎、劉盈序(2009)，以不安定指數法與模糊推論機制於雪霸國家公園內崩塌潛勢劃分之研究。水保技術，第4(3)期，151-163頁。

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以證據權重法探討崩塌發生之潛勢─以隘寮溪流域為例

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