Geomorphologic causes of sediment disasters in August 2000 in south Bhutan are studied in the Padzekha Chhu (River) watershed. A flood originated from the burst of a natural dam, which had been formed by a debris flow, caused the sedimentation disaster in downstream. Most slope failures of Aug. 2000 occurred on the slopes formed by deep-seated landslides and sagging in the upper watershed. Geomorphologic mapping of deformed slopes by slope movement is essential for various development projects planned nearby the Main Central Thrust and the Main Boundary Thrust in the Bhutan Himalaya.
