Torrential numerical modelling
Torrents are violent streams of water and debris that can cause serious damage to natural and manmade structures. Risk assessment of such environmental threats often includes a numerical modelling approach. However, numerical modelling of the inhomogeneous water and debris components of torrents has proved challenging. Scientists from Cemagref, a public entity active in environmental engineering research in France, may have the answer. They applied the Smooth Particle Hydrodynamics (SPH) theory in order to achieve more accurate simulations. SPH treats the torrent as a flow of individual particles under the influence of hydrodynamic, gravitational and other physical forces. Cemagref put together a 3-D unsteady numerical model based on SPH that can compute both the torrent's flow characteristics and the forces it exerts upon structures in its path, such as a dam. In order to make the package even more attractive to potential users, the ability to visualise model simulation results on topographic maps using standard GIS software was incorporated. This paves the way for significant improvement in torrent hazard assessment. In the framework of the THARMIT project, Cemagref compared its model simulations against field measurements of torrents. This exercise provided insight into which types of debris flows the model was able to accurately predict and where improvement is necessary. Armed with the new model and its GIS capabilities, engineers will be better able to gauge the risks associated with torrent-prone regions and to suggest preventive measures. Further model validation studies are also suggested.
