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 and with varying degrees of vegetation cover. The ergs of Central Asia extend from Turkmenistan to the Syr-Darya River in Kazakhstan. They are crossed by the Amu-Darya River, to the north and south of which lie Kyzyl-Kum and Kara-Kum, respectively. This research focuses on identifying and mapping the ergs of Central Asia and analyzing the climate factors that set the dunes in motion and that later stabilize them. The vast area encompassed by the Central Asian ergs and their inaccessibility make traditional mapping methods virtually impossible. A variety of spaceborne imagery with varying spectral and spatial resolutions was used. These images provided the basis for mapping sand distribution, dune forms, and vegetation cover. Wilson (1973) defined the Central Asian ergs as active based on precipitation. Our results, in contrast, show that these ergs are mostly stabilized, with the estimated sand mantled area for the Kara-Kum desert similar to 260,000 km~2, and for the Kyzyl-Kum it is similar to 195,500 km~2. Meteorological analysis of wind and precipitation data indicate a low wind power environment (DP < 200) and sufficient rainfall (>100 mm) to support vegetation. The age of the sand samples was determined by optically stimulated luminescence (OSL) (similar to 5-7 Ka), which provides insight about past climate characteristics. GIS analysis was performed in parallel with field work to obtain validation and verification.