AEOLIAN MOBILITY AND STABILITY OF THE CENTRAL ASIAN ERGS, A STUDY BY REMOTE SENSING AND GEOGRAPHIC INFORMATION SYSTEMS

摘要

Ergs are large, relatively flat, areas of deserts covered by wind-swept sand with a varying degree of vegetation cover. Central Asian ergs span from Turkmenistan to the Syr-Darya River in Kazakhstan, crossed by the Amu-Darya River; to the north lies Kyzyl-Kum and to its south the Kara-Kum. Ergs are sensitive to climate change and observable dune forms contain information on past wind directions and power. Additional environmental factors such as rainfall, grazing and human activity also affect dune development. This research focuses on identifying and mapping the ergs of Central Asia, and analyzing climate factors that have set the dunes in motion and later stabilized them. The vast area and the ground inaccessibility make traditional mapping methods virtually impossible. A variety of spaceborne imagery with varying spectral and spatial resolutions is used. These images provided the base for mapping the sand distribution, dune forms, and vegetation cover. Spectroscopy and lab analysis (X-ray diffraction, electron microscope) were used for mineral identification. Wilson (1973) defined these ergs as active ones based on precipitation. Our results show that these ergs are mostly stabilized, and the estimated sand mantled area of the Kara-Kum desert is 260,000 square kilometers and 200,000 square kilometers of the Kyzyl-Kum. The age of the sand samples is being determined by optically stimulated luminescence, providing insights into past climate. GIS analysis along side field work provides validation and verification.