Author(s): M. I. Rusyda; M. Kusukubo; M. F. Maricar; S. Ikematsu; H. Hashimoto
Linked Author(s): Muhammad Islamy Rusyda
Keywords: Flood; Large woody debris; Driftwood; Debris blockage; Jam
Abstract: A significant amount of woody debris deposition was caused during the flood event along the Nayoshi River. The field survey showed two types of woody debris deposition; one is the deposition of individual wood pieces and the other is accumulation or jam of woody debris. Furthermore, two kinds of the woody debris accumulation were found on the field along the river and at the bridges without piers. The statistical analysis of individual wood pieces shows that the mean of the length was 3.4 m in Site 2 and 3.5 m in Site 3. Their probabilistic distribution was log-normal. A comparison of the scale of wood pieces and bridges shows that the wood pieces were longer than the depth from the riverbed to the bridge deck and were as long as the bridges. A flume experiment was also carried out to explore the formation of woody debris accumulation by modeling a bridge without pier. The results present that woody debris accumulation at the model bridge is determined by shaded area of an obstruction in a channel. An empirical equation for predicting the volume of woody debris accumulation at an obstruction is also proposed.
Year: 2014