Abstract
The number of areas in danger of sediment disasters is about 180, 000 in Japan, and countermeasures were carried out only for 20% of them. As a result, many people still have been killed by the disasters. That is the reason why the inhabitants and local governments in such areas need to establish the proper warning and evacuation systems. For that, we have to know when we warn the people of evacuation. The standard rainfall, estimated by the past data of rainfall, is effective to know it. It is decided by the analysis of dangerous amount of rainfall which caused sediment disasters. Though each local government already set the standard rainfall based on the new guideline of Ministry of Construction, it is not precise. This is for how to improve it.
