Abstract:

Based on high-resolution images of the western fringe of the Hobq Desert， the migration and morphological changes of the reticulate dunes and dune fields in the region were analyzed， and their dynamic mechanism and evolutionary process were explored in combination with regional meteorological data. The study showed that from 2003 to 2012， the primary ridges of the reticulate dunes rose straight eastward， and some parts of them fractured to form gaps. At the same time， the primary ridges were locally curved and connected to adjacent secondary ridges to form a "long sand ridge". From 2012 to 2020， the primary ridges deformation decreased with some positions becoming straight， but new small secondary ridges appeared on the surface. In terms of migration rate， the primary ridges decreased from 4.66 m·a^-1 between 2003-2012 to 3.74 m·a^-1 between 2012-2020， and the secondary ridges increased from 5 m·a^-1 between 2003-2012 to 5.70 m·a^-1 between 2012-2020. In addition， from 2003 to 2012， the secondary ridges extended eastward as a whole， and during 2012-2020， the secondary uplift extended eastward and southward. The morphological changes and migration characteristics were mainly affected by regional wind condition changes. That is， the wind regime in the study area gradually transitioned from a single wind regime dominated by westerly winds from 2003 to 2020 to a multi-wind regime with the coexistence of northerly， westerly and southwesterly winds. The enhancement of the secondary wind direction has caused the development pattern of the sand dunes to shift from transverse dunes to the co-development of primary and secondary ridges with new small secondary ridges developing on the stoss slope of the primary ridges. The development of secondary ridges changes the airflow structure of the stoss slope of the sand dunes， thus altering the morphology of the primary ridges. Wind regime changes were the main reason for the migration and morphological changes in the west fringe of the Hobq Desert， that is， the regional wind condition changed from moderate wind energy from 1970 to 1979 with the wind direction concentrating in two or more obtuse angles to low wind energy from 1980 to 2009 with the wind direction concentrating in two or more acute angles or distributing in one wide direction. From 2012 to 2020， the regional wind condition becomes a medium wind energy with the wind direction concentrated in two or more acute angles. Changes in wind conditions altered development mode of the reticulate dunes， which in turn affect their migration and deformation characteristics， indicating that the development of the reticulate dunes requires the maintenance of multiple wind directions. The regional condition are the main factors in the formation of the reticulate dunes.

Key words: reticulate dune, the Hobq Desert, dune morphology parameter