UAV-SfM based field quantification of barchan dune celerity and morphodynamics in Gonghe Basin

Barchan dunes do not often coexist with grasslands. However, in Gonghe Basin, north-eastern part in Qinghai-Tibetan Plateau (QTP), China, many barchan dunes are distributed on the grassland at high altitude. Identifying celerity and morphodynamics of barchan dunes and exploring the interaction between barchans and grassland landscape can help us better understand aeolian system sand mitigate damages. In this work, we tracked dune celerity and observed three-dimensional changes of symmetrical and asymmetrical barchan dunes in Ertala based on high-resolution UAV-SfM reconstruction in short-term monitoring and discussed the factors influencing dune celerity and deformation at high altitude. The results revealed that the barchan dunes are highly mobile with an average celerity of 0.85 m/M for the whole study area. Based on observations of dune morphology and dynamics, we found the following: (1) The dune deformation degree in a short time is not large but is widespread, especially in the elongated arm of asymmetric dune. The deformation of symmetric dune is symmetrical, whereas that of dune with extended horn is asymmetrical; (2) the sand supply, vegetation and airflow at low air density all influence the celerity and deformation degree in the development of barchan dunes; (3) the asymmetric airflow and sediment supply are important cause of dune asymmetry. The above results help us understand the deformation of barchan dune from the three-dimensional, especially the difference reflected by the symmetry of barchan dune at high altitude.