Flow and deposition characteristics of sediment mixture in debris flow flume experiments

Abstract

This study was conducted in order to identify the flow and deposition characteristics of immature debris flows, which occur frequently in urban areas. We carried out a series of flume experiments involving different flume gradients and sediment mixture viscosities using a small-scaled flume, which reproduced the flow and deposition behaviors of immature debris flows. We found that high flume gradient and low viscosity of mixture led to faster flow velocity, but flow depth was rarely affected by the flume gradient and mixture viscosity had no significant impact on flow depth. The experiments showed a positive relationship between deposition shape (length and width) and flow velocity, with runoff length more sensitive to flow velocity than deposit width. The results help inform standard guidance applied in practice to the design of prevention structures against immature debris flow in urban areas.