On the Kii Peninsula, a number of large]scale collapses of landslide dams occurred in 1889 due to a typhoon that brought rainfall of over 1000 mm between August 19 and 20. More than 33 landslide dams were formed and most of them collapsed, causing serious damage. In 2011, many large]scale collapses occurred again due to Typhoon No. 12 that lasted from August 30 to September 6, causing more than 17 river blockages and landslide dams. In this report, the authors examined the distribution characteristics of the 1889 and 2011 disasters, with the focus on the Totsukawa area in southern Nara Prefecture. It has been reported that 28 landslide dams were formed in this area in 1889 (total sediment volume:200 million m3). In 2011, 13 river blockages (mostly partial) occurred in the same area (total sediment volume:35 million m3), forming 4 landslide dams over 20 m in height.

Key wordsFheavy rainfall disasters, Kii Peninsula, landslide dam, 1889 disasters, 2011 disasters, distribution maps