The Influence of Hydrogeology Characteristics on Nebkhas morphometry (Case study: Daranjir playa)

Nebkhas, as one of the Eoelian Landforms in dry and semi-dry areas, have significant influence in controlling aeolian erosion and the environment stability. The main question of this study concerns different morphometry of nebkhas in two neighbor sites in Daranjir playa and the main factors which control these landforms. area special properties, the variety  of  hydrogeology properties, and the locality difference of nebkha morphomrtry introduce the  hypothesis  which hydrogeology properties have direct influence on nebkha morphomrtry. To attain this aim, remote sensing techniques, field data and geochemistry analysis have been used. Therefore, initially two sites which had  nebkha different vegetations were detached. In the next stage, nebkhas morphometry parameters in each site were measured. Thus utilizing hand auger, 8 bores were dug  with an average depth of 2.60 meters and sediment samples were collected.  The dig with hand  auger was achieved to Water table (an average 2.06 m) and was measured Water table for each bore. In addition, in each bore 300 millilitres of water was collected for chemical analysis through water sample collector device. Altogether, 46 sediment samples from the first site, 58 sediment samples from the second site and 8 water samples from eight bores were collected. After transferring the samples to geomorphology laboratory, the chemical analysis of water samples was carried out through a multi parameter device, version HI9811-5. Following that, by taking the saturated paste of sediment samples, the amounts of TDS, EC, pH were measured. The results of examinations on the qualitative nad quantitative features of the groundwater indicated that the average of ground water depth, TDS, and EC are respectively 1.69 m, 18850 ppm, 37750 µS/cm in the first site and 2.44m, 27500 ppm, and 54950 µS/cmin the second site. The chemical analysis of sample sediments indicated that the salinity of the sediments is influenced by the depth and quality of ground water, respectively. Overall, the findings show that the hydrogeology properties of the examined sites are not only the main factor in the formation  of Nebkhas, but also in control of the morphometric properties of Nebkhas.