A fully predictive model for aeolian sand transport

This paper presents the development, calibration and verification of a fully predictive model for wind-blown dry sand. The model is based on the modification of the well-known Bagnold equation by including the threshold shear velocity, which is also slightly modified to ensure a smoother transition from the non-transport regime to the transport regime. The sand transport rate is related to the static and dynamic grain roughness by using a semi-empirical roughness predictor, which is calibrated based on sand transport data from wind tunnel experiments with a flat mobile sand surface. The model input for dry sand is the wind velocity at one height above the surface and the sand characteristics (d(50), d(90)). The effects of moisture, vegetation and shells on the sand transport. process are included by fairly simple expressions which are acting on the shear velocity, the threshold value and the transport rate. In all, 105 high-quality data sets have been used for verification of the proposed predictive model. About 72% of the predicted values are within a factor of 2 of measured values of the transport rate.