A Discussion of Mathematical Models Used to Simulate the Vertical Mass Flux Profile of the Mega-Dune

Abstract

The research of the sand transport profile is significant for the calculation of sediment transport rates and the improvement of previous models. However, there are few suitable mathematical models to simulate the “stratification pattern” of the vertical mass flux profile in sandy lands. The present study measured the sand flux vertical distribution within 30cm height with 2cm division at the windward slope and the top of the mega dune in the hinterland of Badain Jaran Desert in winter and used the method of function fitting to analyze the flux density profiles above each observation site. The results show that: (1) The sand-drift activity at each site of the mega-dune is in the erosional state. (2) Low temperature and snow cover have little effect on the vertical mass flux profile. (3) The slope is the key factor to affect the vertical mass flux profile. It is significant in the middle and upper-middle of the windward slope, the sediment transport rate decreases exponentially with the increase of the height. At the top of the slope, the sediment transport rate increases at the beginning and then decreases with the increase of the height, which is an Extreme function distribution. The present study use suitable mathematical models to simulate the stratification pattern of the sand transport profile in sandy lands, explains the physical significance of each fitting coefficients in the function, discusses the effect of the slope on the vertical mass flux profile, and provides theoretical support for the practice of sand-control.