AEOLUS II: an interactive program for the simulation of aeolian sedimentation

A computer program has been developed to simulate two- or three-dimensional topographic change associated with aeolian sediment transport. Because predictions generated by available models of aeolian transport can vary by about an order of magnitude for a given set of environmental conditions, selection of an appropriate model is problematic. This program includes a number of models and provides for interactive selection of a desired model combination(s), to allow for comparison between model predictions. Topography, represented by a set of coordinates in two or three dimensions, is defined by ‘bins’ of sediment. Differential rates of transport between adjacent bins, resulting from variations in grain size, slope, and surface moisture content, are used to determine mass flux and to adjust the topography in an iterative fashion. Sub-routines allow the simulation of temporally varying levels of surface moisture resulting from evaporation, and periodic restoration of upwind boundary conditions. The wind field can be represented by a constant shear velocity, by a spatial (cross-shore) distribution of shear velocities, or by a time series of values representing multiple wind events. Output is in the form of a graphic display or tabulated results written to disk. Example results are presented which (qualitatively) suggest that simulated topographic changes are reasonable. Areas where further refinement is needed to improve correspondence with reality are identified and discussed.