Proposal for hazard map-making of natural slope failure due to a heavy rainfall and disaster prevention actions based on observed several issues in the mountainous area of Asano River in July of 2008

摘要

The heavy rainfall with over 250mm in 3 hours that struck the mountainous area of Asano River in Kanazawa City on July 28, 2008, has caused extensive damage to the large-scale collapse of natural slopes at a lot of locations. The above collapse showed, in natural slopes of mountainous area, high possibility of this area which had not hazard map as a disaster prevention potential, became larger further by a rapid change of intensity due to heavy rainfall. The paper describes the actual damages caused by this heavy rainfall, investigations on its causes and a necessity of hazard map for natural slope failure. Moreover, a case study of a hazard map- making executed by the Multi-variable Analysis utilizing the Geographical Information System has shown in order to find the proper solutions on several issues to be extracted from the observed damages and disaster prevention actions there.