Journal of the Japan Society of Erosion Control Engineering, Vol.60,No.3,2007

Characteristics of large woody debris transportation and deposition by rainfall in the Kanaso Creek, Miyake Island

Kota KIKUCHI, Yoshiharu ISHIKAWA and Katushige SHIRAKI


Abstract

In this paper, we report the results of field measurement on transport and deposition of large woody debris at rainfall in the Kanaso Creek, Miyake Island. Mud flows and floods are prone to occur in the Kanaso Creek, because the watershed were devastated by deposition of volcanic ash and affected by volcanic gas after the eruption of Mt. Oyama in 2000. At the lower reach of Kanaso Creek, large number of large woody debris were transported frequently at normal rainfall about 25mm/h which occur several times every year on average. The number of transported large woody debris was greater during high intense storm events. The maximum length of large woody debris transported during the observed period was relatively smaller than channel width. The maximum length of large woody debris deposited at the upper of the Kanaso Creek. Percentage of deposited large woody debris with orientation ranging from 60 to 90‹was two fold greater than values reported by Mizuhara (1979).


Key wordsFlarge woody debris, transportation, deposition, creek in volcanic area

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