It is important to warn local inhabitants of sediment disasters and inform them of their types and sizes. It is necessary and important to develop a worldwide standard index to represent the types and sizes of sediment disasters. The authors carried out a questionnaire survey of prefectural office staffs, in order to understand their images of disasters. Based on the results of analysis of the questionnaire survey, the authors proposed a disaster damage index to represent the level of the sediment disasters using several damage factors concerning human societies such as numbers of dead and missing persons, injured persons, completely collapsed houses, half collapsed houses (including partially damaged).

Key words�Fsediment disasters, questionnaire survey, damage index