坡地超限利用與土石流災害空間關係之分析－以雲林古坑華山地區檳榔園為例

The Analysis of Spatial Relationship between Slopeland Overuse and Debris Flow- the Areca Fields in the Hwa-Shan Area of Gu-Keng, Yun-Lin

黃凱易(Kai-Yi Huang)

《中華水土保持學報》 33卷3期 (2002/09) Pp. 191-200

https://doi.org/10.29417/JCSWC.200209_33(3).0003

摘要

本研究之目的係探討雲林縣古坑鄉華山地區檳榔園與土石流之空間關係及崩塌地植生自然恢復之狀態。本研究應用地震颱風前後四期SPOT衛星影像，變遷偵測研究區崩塌及土石流的位置及範圍，並評估崩塌地植生自然恢復之狀態。結果顯示地震造成舊崩塌地擴大，並堆積大量土方，成爲此區持續發生土石流之關鍵，而與檳榔園區無直接關係，故其非土石流引發之主因。但土石流滿溢出溪床後，順勢向下流竄，淺根檳榔樹難以阻斷土石流沖刷危害，無法有效抑止災情，故陡峭地形遍植檳榔，終究是水保之負面示範。本研究比對四期植生指標影像，目前尚難顯示崩塌地植生有自然恢復的跡象。崩塌地除必要處置者外，仍應先實施非破壞性長期監測，瞭解其自然恢復狀態，不必立即採用人工處置。

關鍵字

土石流 ； 遙感探測 ； 地理資訊系統 ； 規整差植生指標

並列摘要

The major objective of the study was to determine the spatial relationship between debris flows and areca fields by identifying the locations and extents of the Ta-Jian and Erh-Jian landslide scars in the Hwa-Shan area. The second was to assess natural recovery of plants in the two scars. Image change detection and GIS techniques were applied to four-date SPOT satellite images to achieve the two goals. The study found that the areas of the two old bare lands were strikingly enlarged after Chi-Chi earthquake and there were large heaps of debris produced over the bare lands that became the major sources of debris flows. The earthquake-induced landslide was the key factor that caused debris flows to occur frequently in the study area. The study concluded that there was no direct relationship between debris flows and areca fields; however, areca fields could not effectively stop debris flows and protect people and their properties from debris flows. Up to present, there are no significant marks showing that plants in the areas are naturally recovered based on the analysis of four-date NDVI images. However, the result does not mean that reforestation should be performed immediately over the bare lands. Long-term monitoring of plant recovery in the bare lands using remote sensing technique should be done, except in urgent cases.

並列關鍵字

debris flow ； remote sensing ； geographic information system (GIS) ； normalized difference vegetation index (NDVI)