Identification of Critical Rainfall and Sliding Zones in a Colluvium Formation at Central Taiwan

Sung-Chi Hsu, Yi-Chun Yeh, Tai Seong Quah, Pei-Zhu Hu


The research retrieved the historical data and aerial photos of 15.85K at Nantou 89th County Road in Nantou, Taiwan. The areas of failures and failure processes are revealed by comparing the images before and after a certain rainfall event. Six different major sliding zones can be identified based on the aerial photos and failure locations. The major cause of the slope instability was the erosion initiated at gullies on down-slope sides after a heavy rainfall. Most of the upper-slope was then failed due to above reason. This research compares the rain incidents, which caused failure or non-failure of a slope, at Nantou 89th Country Road in many aspects. The accumulated rainfall for each incident is calculated and compared to obtain the suitable critical rainfall for the landslides at this location. The obtained critical rainfall is around 270mm for accumulated rainfall.


Landslide; Accumulated Rainfall; Critical rainfall


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