Quantifying dune migration patterns and influencing factors in the central Sahara Desert

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Based on Landsat images and ERA5 climate data, here we analyzed geomorphic dune patterns and the spatial characteristics of dune migration in the central Sahara Desert region (SW Libya, SE Algeria), using the COSI-Corr technique. Our results revealed clear observable drift potential (DP) and resultant drift potential (RDP) gradients, these decreasing from a northerly to southerly direction. Moreover, the annual average RDP/DP in most areas was <0.3 (i.e., highly variable). The main dune types in the study area included complex transverse ridges (22.82 %), linear dunes (19.87 %), barchan and barchanoid chains (16.95 %), and star dunes (13.55 %). Of these, barchans and barchanoid chains, as well as complex transverse ridges, appeared in areas of relatively high DP, while complex longitudinal ridges and honeycomb dunes were found in those of low DP. Linear dunes had a simpler wind composition, being mainly distributed in areas with intermediate wind variability. Both the honeycomb dunes and complex longitudinal ridges had nearly always formed in complex multi-directional wind environments. Dune migration displacement in dune fields ranged widely, from 0.5 to 23.57 m (mean = 6.71 m), during the 30-year study period (1993–2022). Barchans and barchanoid chains migrated fastest, with a mean value > 10 m/yr; in contrast, complex longitudinal ridges and honeycomb dunes had the slowest migration rate, always at < 5 m/yr. Overall, the dune migration rate was mainly related to dune height and wind regime. Spatially, the dune migration trend was basically consistent with that of the resultant drift direction (RDD), mainly in a northwesterly direction (28.36 %). The accuracy testing results indicated that the COSI-Corr displacement measurement accuracy was generally higher than the dune migration direction accuracy. This study provides not only valuable reference data for regional aeolian activities, but also insight into the developmental environments and migration dynamics of differing dune types, which could be used for prospective regional aeolian geomorphology research in the Sahara Desert.