Morphologic changes of simple star dunes during the growth process in Dunhuang,China

Star dune is one typical kind of aeolian geomorphology in global sand seas.It has attracted scholars in various research fields for years because of its unique morphologic features like Egyptian pyramid.The landform pattern of star dune is mainly dominated by factors such as regional wind regime,sand availability,and local topography.Star dunes grow vertically as they accumulate sand brought in from different directions;however,little is known regarding morphologic changes during this process.The stability of star dunes based on quantitative data is another unsolved question due to the limitation in measuring equipment or other factors.And whether the star dune can grow into star sand hills is another scientific problem which needs to be discussed.In this paper,the heightening development process and morphological changes of star dunes were monitored in Mingsha Mountain of Dunhuang with the 3D laser scanner.Results show that the star dunes in Mingsha Mountain were formed by a group of relatively steady winds,which were northwest,northeast and south winds.With the increase of the height of the star dunes,the morphological parameters of the dune,such as the volume and bottom area,did not show regular changes.The surface erosion of both Dune 1 and Dune 2 during the observation period was closely related to the regional wind conditions.During the growth of the star dunes,the overall trend of the dunes was relatively steady and the dune shape maintained its stability although the aspect and slope of the sand dunes changed,indicating that the stability of star dune was not complete and was dynamic.Moreover,the variation range of the dune slope was proportional to the volume change of the dune.