Development of a calculation method for blown sand movement above the barchan dunes using spatial analysis

Blown sand movement threatened the ecosystems severely in arid zones. The research on blown sand movement is an important component of the controlling blown sand hazard. In the present study, we developed a method that based on GIS-based spatial analysis to calculate the blown sand movement above the surface of a barchan dune. To do so, we sampled the diameters of sand grains, wind velocity and sand flux above the surface of a barchan dune in Taklimakan Desert. Interpolated the sand grain diameters and wind velocity by means of Kriging and Inverse Distance Weighting, respectively, we got the continuous distribution of sand grain diameters and wind velocity above this dune. Integrated these interpolated results, we computed the aerodynamic roughness length, the friction velocity and the sand flux by blown sand models. By this calculation method, the continuous distribution of the aerodynamic roughness length, the friction velocity and the sand flux were obtained. To test this calculation method, we compared these predicted data with the observed values. The tested results showed that the predicted results (the aerodynamic roughness length, the friction velocity and the sand flux) by this method are all satisfied except the sand flux above the dune's foot. We thought that the not enough accurately modeling result of sand flux above the dune's foot is caused by unsaturated sand flux was generated above there, and the models we used are all based the theory of saturated sand flux. Though cans not accurately modeling the sand flux above the dune's foot, this blown sand movement calculation approach is better than those traditional observation methods on the whole.