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A Study of Vegetation Recovery and Slopeland Sediment Yield of Landslides Caused by 921 Earthquake
|關鍵字:||崩塌地;Landslide;植生復育率;坡面泥砂產量;Vegetation Recovery Rate;Slopeland Sediment Yield||出版社:||水土保持學系||摘要:||
The 921 earthquake caused not only heavy casualties and extensive damage to building, but also a large number of landslides in Central Taiwan. Due to scattered distribution of the landslides, satellite images were applied to rapidly monitor and evaluate vegetation recovery for the large-scale landslides.
The SPOT images of the Ninety-nine Peak area located at Wu River, the Xueshankeng and Wushikeng watersheds at Daan River and the watershed between Tianlun and Techi dam along Dajia River were chosen to identify the spatial distribution of the landslides. Normalized Difference Vegetation Index (NDVI) of the images was used to calculate vegetation recovery rate (VRR) of the landslides. Universal Soil Loss Equation combined with sediment delivery ratio was used to assess the slopeland sediment yield at watershed scale.
Results show that VRR of the landslides at the Ninety-nine Peak area and in the other investigated watersheds are 36% and —10% respectively. The calculation of NDVI of SPOT image taken at the time of one and a half-year after the quake was used for calculated the soil erosion. Annual erosion depth of the landslides at the Ninety-nine Peak area, the Xueshankeng and Wushikeng watersheds, and the watershed between Tianlun and Techi dam are 4.8 cm/yr., 4.4 cm/yr., and 3.5 cm/yr. respectively. Cluster analysis for VRR of the landslides at the Ninety-nine Peak area can be grouped into three categories (good, ordinary and bad). Terrain analysis shows that the landslides whose VRR belong to bad class were located mostly at steep slope (55~100%) and northern aspect. Besides, site analysis shows that the landslides whose VRR belong to bad class were located mostly at ridge areas.
|Appears in Collections:||水土保持學系|
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