Avalanche hazard maps are prepared by engineers and land use planners. These experts rely both on practical experience and calculation models to predict avalanche runout distances and flow velocities. Both dense flow and powder snow avalanche dynamics models are using sophisticated numerical schemes to track the motion of avalanches from initiation to runout. Since avalanche experts are seldom numerical specialists, the software must be stable and user-friendly and model limitations must be clearly communicated. AVAL-1D does meets these requirements. This program is intended to be used by avalanche practitioners to supplement the well-tested Voellmy-Salm model.
AVAL-1D consists of three components: a one-dimensional flowing and a powder snow avalanche calculation module connected by a graphical user interface. One-dimensional refers to the fact that a single velocity component parallel to the avalanche track is used to describe the motion of both the flowing avalanche or powder snow saltation and suspension layers. The avalanche track is described by a two-dimensional topography with known width (flowing avalanches) or unit width (powder snow avalanches). The two avalanche models, FL-1D and SL-1D, were developed in C. The graphical user-interface was programmed in IDL (Interactive Data Language), a portable software for data analysis and visualization.