Abstract:

Classical aeolian geomorphology theory holds that each types of dune has individual wind regime and development environments， implying that different types of dunes should not coexist under nearly same wind regime. However， the coexistence of barchan and dome dunes has been observed on both Earth and Mars， contradicting traditional aeolian geomorphology theories， and the development environment and dynamics of such coexisting landforms are currently unclear. This study focuses on the area in the Qaidam Basin where barchan and dome dunes coexist， comprehensively analyzing the morphological characteristics， dynamic changes， and wind regime to explore the causes of their coexistence. The results indicate that the dune morphology in the coexisting areas of the Qaidam Basin is relatively small. Dome dunes are nearly circular or elliptical， while the barchans are characterized fat or short fat. The relationship between the annual migration rate and bottom area of barchan and dome dunes in the same region follows the same power function distribution， and the morphological changes of the dunes exhibit two patterns： evolution from dome dunes to barchan and transformation from barchan to dome dunes. The wind regime is characterized by a bidirectional wind with a distinct prevailing wind and a certain strength of secondary winds. There is a seasonal variation between 78°-95° in the direction of sand transport， and the seasonal variation in the main wind direction or sand transport direction provides the driving force for the coexistence of crescent and dome shaped sand dunes and the transformation of sand dune morphology.

Key words: dune coexistence, wind regime, dune migration, Qaidam Basin