Spatial heterogeneity of surface sediment grain size and aeolian activity in the gobi desert region of northwest China

Abstract

Studies have previously discussed characteristics of aeolian activity for different gravel densities on gobi surfaces. However, the significance of the spatial heterogeneity of its surface to sand flow over its surface and to dust emissions from the region has not been clearly demonstrated. This is also the case for spatial variation in the aeolian environment. Accordingly, this study established two observation transects, both through the desert pavement area and the dune field in the gobi desert region of northwest China, to measure surface sediment grain size, wind speed and sand transport along these transects. Results showed that in areas where surface gravel content decreased and mobile sand dunes increased, surface sediments were better sorted and grain-size distribution changed from multimodal to roughly unimodal. Furthermore, sand transport increased significantly and properties of aeolian activity varied markedly within a short distance. This extreme variation in both grain-size parameters and in sand transport indicated that strong spatial heterogeneity exists in the aeolian environment of the study area. Furthermore, dune fields within gobi area are likely the main cause of sand flow over its surface as well as dust emissions from the region itself. The findings in this study have universal applicability in gobi regions with uneven surface properties in other arid areas.