Abstract
A questionnaire survey of 199 dams was conducted to clarify the volume of woody debris entering dams in Japan. The following results were obtained: 1) Dams managed by the Ministry of Land, Infrastructure and Transport (MLIT) and Japan Water Agency (JWA) had more data on woody debris than prefectural dams; 2) The volume of woody debris was measured based on apparent volume at most dams; 3) The volume of woody debris varied widely and most of it was produced by specific local downpours; 4) Though we could not find factors correlated with the volume of woody debris, large volumes of woody debris are produced at dams throughout Japan every year, indicating that woody debris could be a useful resource.
