This study focused on the geomorphological evolution of a dense landslide in the Ailiao River watershed.The landslide formed during Typhoon Morakot in 2009 and demonstrated slow recovery. An analysis of the data tracking the evolution of this landslide identified 13 subwatersheds within the landslide area; further analyses of these
13 subwatersheds revealed that the landslide had substantially changed the morphology of the Ailiao River. Four subwatersheds within the Ailiao River upstream watershed had landslide ratios of >10.0%, and the new, old, and recovered landslide ratios of the four subwatersheds had oscillated in the years since 2009. The landslide ratio in the neighborhood of the river was >3.0% and was characterized by numerous small bank-erosion landslides. The maximum sinuous width of the river was approximately 350 m, and the sinuosity index was 1.5 times larger than it had been prior to Typhoon Morakot in 2009.
Key Words: Ailiao River watershed, dense landslide, geomorphological evolution, subwatershed