Migration of sand dunes on the northern Alxa Plateau, Inner Mongolia, China

Rates of dune migration in the Alxa Plateau of Inner Mongolia were derived from Landsat images taken in 1973, 1991, and 2000. Ten dunes (six transverse dunes, three barchans, and one hybrid dune) were studied. Migration rates ranged from 4.0 to 7.4 m year−1, and averaged 5.3 m year−1, from 1973 to 2000. Between 1973 and 1991, migration rates ranged between 3.4 and 5.9 m year−1, but between 1991 and 2000, this rate ranged between 3.7 and 12.9 m year−1; for all dunes, migration rates had increased. During dune migration, the vertical projection areas and dune outlines also changed. In 1973, the total area of all ten dunes was 2.28 km2, and this increased to 2.37 km2 in 1999 and 2.42 km2 in 2000. This increase of 0.14 km2 suggests that the mean dune volume also increased from 1973 to 2000, but because we could not know changes of dune heights of this period, we could not confirm this. The mean direction of dune migration ranged from 92° to 136° (ESE to SE), with an overall mean of 107°. The migration direction was close to the sand drift direction (RDD) calculated for the study area.