A Study About Flow-Front Velocity of Experimental Debris-Flows

Debris flows are movement of masses containing water and saturated granular material and are able to travel long distances at high speeds over steep channels. These phenomena are caused by intense rainfalls, thawing, dam-breaks or other factors and they can affect communities, infrastructure, farms, etc. So, they must be investigated to improve the understanding about their behavior.

The present study is focused in the evaluation of the influence of some parameters in the behavior of flow front velocities of debris flows. A series of 15 controlled flow simulations were developed in an experimental model located in a natural catchment through sudden releases of mixtures of water and granular material. Every simulated flow was tracked over the all path from the release until the stopping using a group of video cameras in order to evaluate their flow front position. From this step, flow front velocities could be evaluated respect to the track position, volumetric concentration and source volume.

Results from the analysis reveal that there is a consistent development of flow-front velocities respect to the track, showing a great accelerating process, then a slight deceleration and finally a constant main velocity. Then, the parameters such volumetric concentration and source volume exhibit important influence in the velocity values being an inverse relationship in the first case and a direct relationship in the other one. The results manifest that, although the complexity of debris flow processes, flow front velocities has a regular behavior and could be suited to formulate some empirical relationships for prevention.