921震災崩塌地特性分析及變遷監測之研究

Extracting Topographic Information and Monitoring Landscape Change for the Landslide Caused by the 921 Earthquake

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

《中華水土保持學報》 35卷2期 (2004/06) Pp. 141-149

摘要

本研究以多期衛星影像資料監測九九峰地區921震災前後之崩塌地現況，藉由遙測理論之植生數及變遷分析，輔以DEM資料分析崩塌地之地形特性，探討震災後崩塌地景變遷及植生復育情形。研究結果顯示，在自然復育情況下，地震後二年內（桃芝颱風前）之崩塌地面積及其地表植生已恢復為甚佳狀態，崩塌地由震災初期之829.50ha減少為187.06ha，約減少77.45%，而崩塌區位之植生復育率亦已恢復達58.93%；然受桃芝颱風災害影響崩塌地擴大為311.69ha，植生復育率減少為28.53%；在植生復育區位分析，顯示坡面不穩定、較乾燥（脊線）或陡峭區位，為不利自然植生演替之區位。

關鍵字

崩塌變遷分析 ； 常態化差異植生指標 ； 植生復育率

並列摘要

Massive landslides, caused by the catastrophic Chi-Chi earthquake, occurred at the Jou-Jou Mountain area of Wu-Chi basin. Multi-temporal satellite images and digital elevation model coupled with GIS were used to process the vegetation index analysis for identifying landslide sites and calculating vegetation recovery rate (VRR), and to extract topographic information of the areas. The result shows that within the healthy-growing plants under natural vegetation recovery condition. From September 27, 1999 through July 20, 2001, the area of landslide had decreased by 77.45%, from 829.50 ha to 187.06 ha and the VRR had risen by 58.93%;however, the area was enlarged up to 311.69 ha and the VRR reduced to 28.53% due to the stroke of Toraji typhoon in late July, 2001. In the analysis of vegetation recovery sites, it shows that unstable slopeland, drought ridgeline and steep sites are harmful to natural vegetation succession. The analyzed results can provide very useful information to the government for decision making and policy planning for the landslide area.

並列關鍵字

landslide change analysis ； Normalized Difference Vegetation Index ； vegetatoion recovery rate