崩塌地對生態環境影響之評估－以九份二山崩塌地爲例

Eco-environment Impact Assessment for the earthquake-induced landslide-A Case Study at the Chiufenershan Landslide

林文賜(Wen-Tzu Lin) ； 馮梓琁(Zi-Xuan Feng) ； 周文杰(Wen-Chieh Chou) ； 林昭遠(Chao-Yuan Lin) ； 黃碧慧(Pi-Hui Huang)

《明道學術論壇》 3卷2期 (2007/12) Pp. 27-48

https://doi.org/10.6953/MJ.200712.0027

摘要

研究以多期SPOT衛星影像資料監測九份二山之921地震前後崩塌地變遷資訊。藉由遙測理論之影像相減法、類神經網路之自組特徵映射分類法，判釋不同時期之崩塌區位，輔以地形特性分析、景觀生態指標及坡面泥砂產量推估模式，探討崩塌地對生態環境之衝擊，以供崩塌地植生復育及災害防治之參考。分析結果顯示，九份二山地震初期(1999/9/27)之崩塌面積爲217.38ha，六年後(2006/3/11)崩塌面積減少爲97.15ha，約有55.31%的崩塌區位復原。地震初期生態指標之嵌塊體數量大量減少，但平均嵌塊體大小指數變大，且空間分佈上嵌塊體雖較地震前聚集，但其間之鄰近距離越來越遠，顯示整體呈現破碎化之生態空間結構，於六年後已有回復之趨勢。而地震前之坡面沖刷深度爲0.401cm、地震初期增加爲1.710cm、地震後六年減少爲1.144cm。研究結果顯示，九份二山在921 地震後，雖地形地貌受到巨大改變，但長期以來植生持續入侵崩塌地，使得崩塌區位有逐年復原之趨勢。

關鍵字

崩塌地 ； 自組特徵映射分類法 ； 景觀生態指標 ； 坡面泥砂產量

並列摘要

Massive landslides, caused by the catastrophic Chi-Chi earthquake on September 21, 1999, occurred at the Chiufanershan area in Nantou County. In this study, multi-temporal SPOT satellite images were chosen for landslide change analysis. First, image subtraction algorithm coupled with unsupervised Self-Organizing Map were used for landslide sites identification. Then, terrain analysis, ecological patch indices and hillslope sediment estimation were used to assess the eco-environmental impacts as the references of vegetation recovery and disaster prevention in the landslide area. The analyzed results indicate that landslide areas have decreased from 217.38 ha on September 27, 1999 to 97.15 ha on March 11, 2006, about 55.31% of area restored, indicating that the sites of landslide have been gradually restored. In accordance with ecological patch indices analysis, the restoration trend at landslides became obvious. From Semtember 27, 1999 through March 11, 2006, number of patch (NP) hugely decreased, mean patch size (MPS) was decreasing and ecological patch structure became fragile. Additionally, the annual erosion depth at landslides on April 1, 1999, September 27, 1999 and March 11, 2006 were 0.401cm, 1.710cm and 1.144cm, respectively. The analyzed results indicate that the landslides have been recovered over six years of vegetation succession. Nature itself has quite robust vegetation restoration ability in the landslide area.

並列關鍵字

Landslide ； Self-Organizing Map SOM ； Ecological patch indices ； Hillslope sediment yield