Open AccessDistribution and Characteristics of Slope Movements in the Southern Part of Hiroshima Prefecture Caused by the Heavy Rain in Western Japan in July 2018
Author(s) -
Hideaki Goto,
Yasuhiro Kumahara,
Seiichi Uchiyama,
Yoshiya Iwasa,
Tomoru Yamanaka,
Rinako Motoyoshi,
Shun Takeuchi,
Sho Murata,
Takashi Nakata
Publication year - 2019
Publication title -
journal of disaster research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.332
H-Index - 18
eISSN - 1883-8030
pISSN - 1881-2473
DOI - 10.20965/jdr.2019.p0894
Subject(s) - landslide , crest , debris flow , movement (music) , geology , physical geography , distribution (mathematics) , debris , hydrology (agriculture) , geography , geomorphology , oceanography , geotechnical engineering , mathematical analysis , philosophy , physics , mathematics , quantum mechanics , aesthetics
Record-breaking heavy rainfall in July 2018 caused an extremely large number of slope movements over a broad area of western Japan. We mapped the distribution of slope movements in the southern part of Hiroshima Prefecture through an interpretation of aerial photographs that were acquired after the rainfall by the Geospatial Information Authority of Japan, and counted a total of 8,497 slope-movement starting points. The widespread distribution of slope movements – from Etajima City of Hiroshima Prefecture to Kasaoka City of Okayama Prefecture – suggests that the heavy rain affected a very large area. The starting points of debris flow during this disaster were commonly close to the crest of mountain ranges. We compared the distribution of slope movements to the 24-hr rainfall accumulation during the heaviest rainfall event to clarify the factors that caused regional difference in slope-movement distribution. We found the area of highest density of the slope movements was consistent with the area receiving a cumulative rainfall of >250 mm. This observation indicated that the position of slope-movement starting points was not related to differences in geology.