LANDSLIDES AND PRECIPITATION CHARACTERISTICS DURING THE TYPHOON LIONROCK IN IWATE PREFECTURE, JAPAN

Abstract

In August 2016, the typhoon Lionrock made landfall on Japan's northeastern coast and caused
floods and landslides. Lionrock b rought heavy precipitation to Japan, which Shimotokusari station (33201)
recorded 24-hour rainfall amount over 200 mm and the peak rainfall intensity was approximately 65 mm/hr.
The total cost of damage within the Iwate pre fecture is over 700 million dolla rs, moreover, 20 lives were lost
and 4 people missing. Therefore, the objective of this paper is to present the results of the post-disaster
investigation, including, the back-analysis of landslides and precipitation due to the typhoon Lionrock. The
rainfall and landslides relat ionship is significantly important for rainfall intensity -duration threshold. For this
typhoon, the empirical rain fall intensity-duration threshold has been derived as I = 20.24D-0.33. The slope
failure could be broadly categorized into the debris flo w, surfic ial erosion, and soil slide, mo reover, occurred
on slopes ranging from 19 to 58 degrees.