以GIS分析土砂災害集水區之生態環境脆弱度-以知本溪及太麻里溪集水區為例

Using GIS to Analyze the Eco-environmental Vulnerability of Debris Disaster Watershed Areas-An Illustration of Zhiben River and Taimali River Watersheds

陳桂嘉(Kuei-Chia Chen)

指導教授 ： 陳朝圳

國立屏東科技大學/農學院/森林系所/碩士(2010年)

https://doi.org/10.6346/NPUST.2010.00030

摘要

台東縣位處於台灣地震、颱風侵襲較頻繁的地區，因為地理位置特殊，容易受到天災的干擾而引起土砂災害的發生。知本溪集水區與太麻里溪集水區為台東縣較嚴重的土砂災害集水區，崩塌地是該集水區內最嚴重的土砂災害類型。本研究目的在於建立土砂災害集水區的生態環境脆弱程度。研究方法係整合GIS與RS技術，建立的生態環境資料，利用因素分析法，求解崩塌地影響因子之權重，以模糊集合建立各影響因子之隸屬函數，利用環境脆弱度指標，評估集水區生態脆弱區域，並建構以自然環境潛在因子，及保全對象危害度因子為基礎的評估模式，評估崩塌地的復育需求。結果顯示，兩個集水區之生態環境，除了受到環境區位因子的干擾外，人為開發亦為崩塌地發生的重要影響因子，引起崩塌地發生的因素中，必須考慮人為開發程度對環境脆弱度的影響。在脆弱度分析方面，本研究將脆弱度強度共分為6個等級，兩個集水區均有75%以上的崩塌地位置被歸屬為脆弱至極脆弱狀態，顯現崩塌地確實是處於高危險且高脆弱之地區；其中又以太麻里溪集水區最為嚴重，整個區域內被歸類於極脆弱等級之崩塌地高達41.35%，顯示此集水區處於極不穩定且脆弱狀態，尤其是台東縣嘉蘭村是境內最為脆弱的村里。依據本研究所建立的崩塌地復育需求評估模式，將復育優先處理需求得分分為4個等級，知本溪集水區約有29.41%的崩塌地屬於立即處理等級，太麻里溪集水區則為27.97%。而比對兩個集水區崩塌地整體的復育處理需求，知本溪集水區平均得分值為0.46，太麻里溪集水區為0.52，顯示太麻里溪集水區崩塌地有較高的復育處理需求。研究結果有助未來集水區進行治理及崩塌地植生復育之參考。

關鍵字

生態環境脆弱度 ； 地理資訊系統 ； 崩塌地 ； 復育評估 ； 集水區

並列摘要

Due to the geographical location, earthquakes and typhoon frequently hit, that is easy to cause the sediment disasters in Taitung County. Among the watersheds in Taitung, the river watersheds of Zhiben and Taimali are more serious natural disaster areas, in which landslide is the most serious type of sediment disasters in those watersheds. The purpose of this study was to build an eco-environmental vulnerability for the landslide disaster watershed. First, we integrated GIS and RS techniques to build the eco-environmental data base. Second, we used the factor analysis to get the weights of landslide causing impact factors. Third, we used fuzzy set to build the membership function of the impact factors. Fourth, we used environmental vulnerability index (EVI) to assess the eco-environmental vulnerable area of watershed. Finally, we created the assessment model of vegetation recovery that was based on the natural potential environmental factors and the protected object factors.
The results indicated that not only landslide occurred was base on the watershed environment at factors, the impact of human activity was also an important factor in these two watersheds. In this study, the vulnerability was divided into six levels, such as safe, light, moderate, heavy, heavier, and extreme levels. In Zhiben and Taimali river watersheds, there were more than 75% of the landslides occurred between heavier to extreme levels, indicating that the landslides were located in high-risk and high-vulnerability areas. Especially, Taimali river watershed was the gravest, and there was 41.35% of landslide belonging extreme level. The most vulnerable area was Granville village, Taitung County in the Taimali river watershed.
According to the landslide vegetation recovery assessment model, the First Score (FS) was divided into four levels, including postponement, reinforcement, precedence, and immediateness. The landslides at immediateness level in Zhiben and Taimali river watersheds are 29.41% and 29.41%, respectively. Comparing with the requirement of vegetation recovery of landslide in these two watersheds, the average value of Zhiben’s FS was 0.46, and those of Taimali’s FS was 0.52. Therefore, landslide of Taimali river watershed is necessary to give the precedence action. This research can give the guideline of vegetation recovery in future.

並列關鍵字

Eco-environmental vulnerability ； GIS ； Landslide ； Vegetation recovery assessment ； Watershed

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