Author(s): Su-Chin Chen; Chuan Tang; Szu-Hsien Peng; Chung-Chiang Li
Linked Author(s): Su-Chin Chen
Keywords: Two-layer shallow water equations; Debris flow; Retrogressive deposition
Abstract: The purpose of this study is to describe, based on the flume experiment, the tributary debris flow, which flowed into the main channel and deposited on the confluence. This study shows that the formation of the alluvial fan included two primary processes, which are separated by the appearance of the retrogressive deposition in the tributary. Dimensional analysis has been used to show the maximum deposition volume before the retrogressive deposition of the tributary. In the process of the retrogressive depositing, the sediment continues to flow into the confluence in three typical patterns to cause the expansion of the alluvial fan. Type I represents that sediment is swept to the alluvial fan by hydraulic jump. Type II represents that new debris flow which is formed above the mound of the tributary flows into the alluvial fan. Type Ш represents that the alluvial fan is pushed by the mound of the tributary with stop and go motion due to the excess pressure behind. For Type II, the slope of the tributary, which remains the same, is proved by theoretical analysis. Meanwhile, using two-layer shallow water equations proceeded numerical simulation.
Year: 2013