By contrast, predominant sediments within the nebkha structure mostly were coarse-grained (sand) fractions, illustrating the functioning of aeolian processes. The findings showed that average aggregate size reduced from the interdune areas to the dunes, and the finest aggregates were observed on the dune edge, illustrating the functioning of hydrological processes on the evolution of the nebkha structure. Coppice dunes formed by burial of shrubs (April 2000). The accumulation of aggregates with different sizes along the interdune-dune continuum could exhibit the contribution of hydro-aeolian processes in sediment transport and deposition. In the Dutch coastal dunes, several projects have started in which aeolian activity is stimulated. The measured particles were classified to 5 groups, including clay (> 2 µm), fine silt (2-5µm), medium silt (5-20µm), coarse silt (20-64 µm), and sand (65≤ 2000 µm). Data on the parameters of particle size distribution, hydraulic conductivity and moisture were extracted. For each nebkha, sediment sampling was carried out from the different positions, including upwind and leeward slopes, dune top, edge, and the interdune spaces. Overall, 9 sand dunes were randomly selected. The aim of this study was to investigate the effects of hydrological and aeolian processes on the morphology of nebkha. The interaction between wind performance and the geomorphic characteristics of sand dune leads to heterogeneity in the distribution of sediment particles within sand dune. The appearance and development of the sand dunes can be a sign of the expansion of desertification. Surface temperatures in the Great Sand Dunes can reach 140 degrees. Nebkha is a sand dune formed in many arid and semi-arid regions by the accumulation of sediments around vegetation. Nebkha dunes (also known as coppice dunes) are simple dunes that form around vegetation.
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