| The Taklimakan Desert,located in the central part of the Tarim Basin in southern Xinjiang,is rich in dune types and cultural heritage,which has received extensive attention from geomorphologists and explorers.However,there exist serious aeolian hazards in the Taklimakan Desert due to natural and human factors.Dune migration,as one of the main forms of aeolian hazards,causes a serious threat to oasis,agriculture,roads,settlements and fragile ecosystems in the vicinity of the desert.The study on dune migration is of great practical significance to the prevention and control of dune advance and regional aeolian hazards,and helps to enrich and develop the content of regional aeolian geomorphology and to improve our understanding of the formation and evolution of sand dunes on Earth and other planets.In this study,we systematically monitored the migration direction and rate,and their morphological changes during migration in the Taklimakan Desert,by comparing Google Earth satellite images acquired in 2002 and 2016,and discussed and analyzed the factors affecting the dune migration.The results show that:(1)The migration direction of dunes in the Taklimakan desert ranged from 630 to 293°,mainly in the southwest,which closes to the resultant drift direction.Overall,there exists an obvious spatial variation in migration direction.The dunes in the eastern desert migrated southwest under the influence of northeast wind,and the dunes in the western desert migrated southeast under the influence of northwest wind.The boundary between them is roughly in the line between Jiashi and Minfeng,which presents a slow and regular arc change in this direction.There are differences in migration direction of dunes in each region and the changes in migration direction of dunes within each region are different.The migration direction of dunes within the southern region is more complex and the difference is the greatest,and the change within the central region is the smallest.(2)The migration rate of dunes in Taklimakan desert ranged from 0.3 to 32.1 m/a.The main types are medium(ranged from 1 to 5 m/a).Overall,it decreased from southeast to northwest,but there was no obvious trend of change,showing regional high and low values,especially in the vicinity of Ruoqiang,Qiemo,Minfeng and central region,where the migration rate was higher,while other regions were relatively low.There are differences in migration rate of dunes in each region and the changes in migration rate of dunes within each region are different.The difference in migration rate of dunes within the eastern region is greatest,while the difference in that of dunes within the western region is smallest.(3)The dune migration rate in the Taklimakan Desert was affected by the wind speed,wind direction and its variation,dune morphology,dune density,vegetation cover,precipitation and temperature.Although there are correlations between dune migration rate and above factors,the intensity of dune migration was undoubtedly a function of wind regime,especially wind speed,dune morphology,especially height and basal area,and dune density for the vast region of the Taklimakan Desert which is lack of vegetation,bare surface,scarce precipitation and extreme drought.(4)There existed good correlations among their morphometric parameters of barchan dunes,linear dunes and pyramid dunes,but they do not have good correlations in theory,which indicated the dunes may reach a balance with the complex aeolian environment around them.However,due to the complexity of the factors affecting the dune migration and their interactions,this equilibrium state has changed to a certain extent.During dune migration,the changes of the morphometric parameters of dunes were complex,and there was no uniform rule.It showed that the formation and development of dunes are the result of the interaction of many factors,which together affect the formation,evolution and migration of dunes in the Taklimakan desert. |
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