干旱区生态环境知识资源中心

The near-bed airflow and the movement of sand dune sediments by wind are fundamental dune geomorphological processes. This research measured the wind profiles and sand mass flux on the rounded top of a transverse dune at the southern edge of the Tengger Desert to examine how to best predict the vertical profile of sand flux. This work also tested the accuracy of previously developed models in predicting the apparent roughness length during saltation. Results show that mass flux vertical distribution over the dune top is underestimated by an exponential function, overestimated by a power function, but closely matches the predictions made using the LgstcDoseRsp function. Given suitable values of alpha, beta and gamma according to the grain size composition, Sorensen equation with the peaked shape of the mass transport curve will well predict the dimensionless mass flux qg/rho u*(3) against dimensionless shear velocity u*/u* (t) . The modified Charnock model works best of the previously published models tested, with an R (2) of 0.783 in predicting the enhanced roughness over the moving sand surface, as opposed to an R (2) of 0.758 for the Owen model and an R (2) of 0.547 for the Raupach model. For the rounded dune top in this study, C (m) =0.446 +/- 0.016.