The Dune Distribution And Grain Size Characteristics Analysis Of Northern Margin Of Tengger Desert

Sandstorm landscape is forming of the wind erosing, transport and accumulating surface material of loose sand,which is an important part of the geomorphology of the land. Dunes are rapid change of sand landform types. The movement and evolution of the dunes are closely relate to the expansion of the desertification.Along with the sustainable development and human living space threat intensifies, research and management of desert has became an important issue to each country of the world.Tengger Desert, China’s largest desert., lies in the intersection of western arid desert region, the eastern semi-arid steppe and the southwest mountain plateau cold region.which is also the zone that desertification areas to the environmentally fragile areas. So the dune topography, distribution, and studying particle size characteristics in Tengger Desert are great significant.1. The study use DEM and GIS spatial analysis quantitative analysising aspect, slope, curvature, undulation of the study area. And obtain three-dimensional map, the slope change, aspect orientation diagram, curvature plot and undulating change in the study area.Relatively, slope change and undulating change can accurate and intuitive display landscape changes.2. Through the field surveied dunes features and remote sensing image, combine the expert knowledge, interpretating different idesert dunes spectrum in tengery desert. Eventually we get the main desert dunes type in north parter of the tengery including barchan dune and barchan chain,grated dune and grated chain,pyramid dunes and pyramid dunes, linear dunes and linear chain, longitudunal dune, grated longitudunal dune and complex dune and complex chain. grated dune and grated chain are mainly lied in the edge of the tengery desert and area is larger. grated dunes distribute in the north of desert and the area is not large. The linear dunes mainly distributed in the eastern desert and distribute area more. Compound dune and pyramid dune mainly distribute in the internal of desert.3. According to the causes of the study area, morphology and principle of genetic classification, combining with the manual interpretation methods, extracte the sand dunes distruction of the study area. barchan dune mainly appears the edge of desert. the more internal the more complex dunes are.4. Through researching grain size characteristics of north part of the Tengger Desert,we get the results:(1) dunes sediment of north margin of the Tengger Desert donot include gravel, very coarse sand and silt. Very fine sand content range0.83%to10.58%, the average content is3.23%.fine sand content ranged from49.14%to78.50%, the average content is63.92%.medium sand content ranged from10.93%to49.52%, with an average content of32.82%.coarse sand content ranges from0%to0.44%, the average content is0.04%. Actually Tengger Desert dune sediment grain size smaller, mainly is fine sand and middle sand, both of content is more than90%, very fine sand followed.(2) comparing longitudunal dune of Tengger Desert with Hariaori region, Sand grain size are fine sand and medium sand and respectively content are99%and81%. coarse sand and clay content of longitudunal dune in Hariaori region increased significantly, Almostly2.78%and8.51%respectively.(3) comparing barchan dune of both Tengger Desert with Wuliji region, fine sand of barchan dunes of the Tengger Desert is76.72%,greater than Wuliji region. barchan dune in Wuliji region obtain significantly higher content of coarse and medium sand and content of both is30.94%, Tengger Desert is only16.91%.