Journal of Natural Disaster Science

ESTIMATION OF POTENTIAL DEBRIS FLOWS AND THEIR HAZARDOUS ZONES; SOFT COUNTERMEASURES FOR A DISASTER

Tamotsu TAKAHASHI
Associate Professor, Disaster Prevention Research Institute, Kyoto University, Kyoto

(Received 28 October, 1981 and in revised form 15 December, 1981)

Abstract

To establish so-called soft countermeasures for debris flow hazards, first the mechanics of the occurrence of a debris flow are discussed and the contributing parameters are explained. Second, methods for the recognition of potentially hazardous and dangerous rainfall patterns are proposed. The methods are supported by actual sediment hazard cases. Third, the problems in estimating the scale of a potential debris flow are discussed. Fourth, a method for delineating the hazardous zone at the mouth of a ravine is proposed and verified. And finally, some difficulties in the practice of evacuation are discussed. Although there remain many points to be refined, this investigation is the first presenting a consistent method for the planning of soft countermeasures for debris flow hazards.

Key words

debris flow, risk index, dangerous rainfall, potential hazard zone, zonaion, refuge