TOPOGRAPHICAL AND GEOLOGICAL CHARACTERISTICS OF ZERO-ORDER BASINS WHERE DEBRIS FLOWS OCCURRED BY HEAVY RAIN IN JULY, HEISEI 30

Bibliographic Information

Other Title
  • 平成30年7月豪雨で土石流が生じた0次谷の地形・地質的特性

Description

<p> Heavy rain in July, Heisei 30 caused an enormous damage mainly around Western Japan. Otsuki-cho, Hata-gun, Kochi-prefecture also suffered human damage by sediment disasters. The sediment disasters of this town included debris flows from Zero-order basins. The flows consisted mainly of rapidly flowing debris and slided farther than in the case of surface failures reaching even the flat fields. Zero-order basins, however, are defined as steep slopes. The countermeasures against sediment flows are not applicable for them. Our research suggests these facts as conditions for Zero-order basins which cause debris flowing ; stream bed deposit is over 2 meters deep, streams is over 100 meters long. Slope of bed stream is over 30 degrees, visible water catchment area is above the Zero-order basins. From the fact that the debris flows occurred at the Zero-order basins with the ratio of opening to depth over 22 percents, it became clear the ratio of opening to depth maybe one of the conditions for defining the Zero-order basins causing debris flows.</p>

Journal

Citations (2)*help

See more

References(2)*help

See more

Details 詳細情報について

Report a problem

Back to top