卡玫基、辛樂克與莫拉克颱風於知本溪、太麻里溪及金崙溪觸發崩塌與土石流之特性分析

In this study, the Jhihben, the Jinlun, and the Taimali river watersheds in eastern Taiwan are selected as the study area to understand the characteristics of landslides and debris flows induced by the Typhoon Karmeigi and Sinlarku in 2008 and the Morakot in 2009. The landslides and debris flows inventory maps were generated by mapping the Formosat 2 images taken after the typhoons. Four parameters including the gradient of slope, the lithology, the location where landslide occurred, and the stream order of gully are used to characterize the landslides and debris flows. Landslides induced by the Karmeigi, the Sinlarku, and the Morakot are 400 ha, 216 ha, and 4239 ha, respectively. Only one debris flow occurred in the gully with a stream order 1 during the Karmeigi and the the Sinlarku. In the Morakot, 64 debris flows were recognized to occur in gullies with a stream order 1, 36 debris flows in gullies with a stream order 2. In this study, landslides mainly distributed in place with a slope in the range of 30o-40o but the landslide density has a maximum value in the place with a slope 50o-60o. In additional, the study results also show that lots of landslides are head-ward erosion related.