Dynamics of dunes and climate variability over the last five decades: A remote sensing analysis of regional contrasts on the northeastern Tibetan Plateau and the adjacent Hexi Corridor

Dunes react quickly to climatic changes, with the main drivers being the dominating wind regime (e.g. magnitude and direction), precipitation, and temperature. Furthermore, human impact can alter dune movement by fixation of active dunes through greening projects, or reactivation of fixed dunes through overgrazing or neglect of former human structures. The northeastern Tibetan Plateau shows a high variability of climatic parameters like wind, temperature, and precipitation within a high elevation environment, situated between the mid-latitude westerlies and the East Asian Summer monsoon. This study assesses changes in the movement of active barchans and sand sheets in three different regions of the northeastern Tibetan Plateau and additionally the adjacent Hexi Corridor to evaluate the different impact of climate change and anthropogenic activities in the past 54 years. Over 500 active barchan dunes and 46 sand sheets were studied to assess climatic influence on aeolian deposits. Since weather stations on the Tibetan Plateau are rare and their measurements often cover only a short time span, ERA-5 reanalysis data was utilized. Dune migration rates were deduced from different satellite imagery taken from 1968 onwards. The Normalized Difference Vegetation Index was implemented to observe changes in vegetation. As a further metric, dune field density changes were calculated, to investigate dynamics in dune field settings and human impact from agriculture in the Hexi Corridor.

The results show similar migration rates in the Hexi Corridor and the Gonghe Basin with mean values of 8.54 and 7.33 m y⁻¹, respectively, while in the Source Area of the Yellow River the dunes are migrating slower with a mean of 3.62 m y⁻¹. The Zoige Basin sand sheets show mostly an expansion in size with a mean growth of 65.39 km² y⁻¹ and a sum extension of 3007.95 km² since 1968. The results show the influence of the East Asian Summer Monsoon as a driver for precipitation and subsequent vegetation establishment altering dune movement through fixation. Furthermore, regional dune behavior is influenced by human activities during the past decades, diverting the climatic signal.