Driftwood deposition from debris flows at slit-check dams and fans

• Published in: Natural hazards (Dordrecht) Vol. 61; no. 2; pp. 577 - 602
• Main Authors: Shrestha, Badri Bhakta, Nakagawa, Hajime, Kawaike, Kenji, Baba, Yasuyuki, Zhang, Hao
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01-03-2012; Springer; Springer Nature B.V
• Subjects: Check dams; Civil Engineering; Computer simulation; Dams; Debris; Debris flow; Deposition; Detritus; Drift; Driftwood; Earth and Environmental Science; Earth Sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Environmental Management; Environmental policy; Exact sciences and technology; Flumes; Geophysics/Geodesy; Geotechnical Engineering & Applied Earth Sciences; Hydrogeology; Jamming; Mathematical models; Natural Hazards; Natural hazards: prediction, damages, etc; Numerical analysis; Original Paper; Planning; Trapping; Wood; Trapping process; Debris flow; Large woody debris; Fan deposition; Slit-check dam; experimental studies; orientation; thickness; probability; simulation; rotation; coordinates; debris flows; dams; numerical models; discharge; debris; geometry; flumes
• ISSN: 0921-030X; 1573-0840
• DOI: 10.1007/s11069-011-9939-9

Experience shows that debris flows containing large woody debris (driftwood) can be more damaging than debris flows without driftwood. In this study, the deposition process of debris flows carrying driftwood was investigated using numerical simulations and flume experiments. Debris-flow trapping due to driftwood jamming in a slit-check dam was also investigated. A numerical model was developed with an interacting combination of Eulerian expression of the debris flow and Lagrangian expression of the driftwood, in which the fluctuating coordinates and rotation of the driftwood were treated stochastically. The calculated shapes and thicknesses of a debris-flow fan and the positions and orientations of the deposited driftwood on a debris-flow fan were consistent with experimental flume results. The jamming of driftwood in a slit-check dam was evaluated based on geometry and probability. The simulated results of outflow discharge and the proportion of driftwood passed through the slit-check dam also agreed with the experimental results.