Dynamics of Barchan dune in the sand belt between Badain Jaran and Ulan Buh Desert, China

In the Alxa Plateau of China, there is a narrow sand belt composed of sparse barchan dunes between Badain Jaran Desert and Ulan Buhe Desert. However, the dynamics of sand dunes and the age of formation of the sand belt are still unclear, and it is even thought that this sand belt is the result of recent desertification. Based on the regional meteorological observation data of the past 20 years, we analyzed the rate and direction of dune migration and morphological changes of sand dunes. The results show that the movement and morphological changes of sand dunes in this sand belt have obvious spatio-temporal variation due to topography, wind conditions and the shape and size of sand dunes. The dune migration rate ranged from 2.09 to 40.93 m·a^-1, and the direction was 102°~152°. Under the influence of terrain, the dune migration rate in the piedmont area is higher than that in the high plain area. Over time, the sand movement rate in each region decreased, and the direction tended to be northward in the high plain, and southward in the foothill; Most of dunes in the belt are slim and normal in shape, with only a few being short-fat and fat. However, there are differences in the dune morphology parameters in each region, with the main area of the high plain sand transport belt generally having larger parameters than other areas. In the process of dune movement, the dune circumference and area on the north and south sides of the high plain sand transport belt fluctuated slightly, while the main area and the foothill belt tended to increase. The length of the dune and their windward slope increased to different degrees, the height decreased, and the southern wing prolonged obviously. The external environment and its own morphology jointly affected the change of dune morphology. Considering the width of the sand transport belt and the proportion of dunes, the sand transport flux calculated in the high plain area reached 138.04 t·m^-1·a^-1, and the foothill zone was 95.20 t·m^-1·a^-1, which provided an estimate that the Badain Jaran Desert contributed nearly 773,800 tons of sand to the Yamaleike Desert annually through sand transport, and nearly 550,000 tons of sand contributed to the Ulan Buh Desert through the pedimont zone.