Changing morphology of Crescent dunes to parabolic dunes (Case Study: Damghan Erg)

The sand dunes of Damghan erg underwent a changes during the last few decades. In the past, the barchan and transverse dunes were shaped by strong northwesterly winds. In recent decades, Due to increase in intense human activity (agricultural and residual) on The removal region of the erg (upward area), aeolian process activity including Aeolian Sediment Supply, Aeolian Sediment Availability and Transport Capacity of the Wind are shifted from upstream to downstream (transportation and sedimentatin areas).the desert combating activity during the last decades has brought about a renewal of natural vegetation on the dune. The establishment of vegetation on the dunes changes the dynamics of barchan and transverse dunes, so that not all of the sand eroded from the windward side is carried to the lee slip-face; some is trapped by plants. Consequently, there is a change in the shape of the windward slope from convex to concave, and the dune gradually becomes parabolic. This paper is an attempt at explaining the influence of various land cover change affects in removal region (aeolian process) on the change and morphological characteristics sand dunes.

Keywords:

parabolic dunes , sand dunes , aeolian processes