A fully predictive model for aeolian sand transport, part 2: Description and calibration of models and effect of moisture and coarse materials

This paper presents new research results on the effect of moisture and coarse materials (gravel and shells) on aeolian transport and is a continuation of earlier work. Two mini wind tunnels have been designed and used to study the effect of moisture and coarse materials on the threshold shear velocity and on the sand transport rate at wind velocities in the range of 10-16 m/s. Extensive attention was given to the determination of the drying time of the beach surface after a period with rainfall for a range of temperatures and wind conditions. A new equation to include the effects of coarse materials on aeolian sand transport is derived from the mini wind tunnel data. Two prediction methods for aeolian sand transport were evaluated: the modified Bagnold-transport equation and the new VR-transport equation. Both methods include the effects of sand diameter and the threshold shear stress, which is essential for accurate determination of sand transport at low wind speeds. The cessation-related threshold shear velocity produces the best results. The grain-related shear velocity is the basic driving parameter of both prediction methods. The wind tunnel data of Belly (1964) have been used to calibrate the new VRsand transport equation.