Mechanisms of land degradation and their environmental implications in a middle‐latitude desert area of China

The movement of aeolian materials and dynamics of dune landforms are results of the transportation and accumulation of sandy sediments under the influence of climate, in which the processes that gave birth to sand dune formations are complex as the arid area has experienced different periods of humidity and aridity. These dynamics are still not well understood at present, especially at the inter‐decadal time scale. Based on a comprehensive analysis of geomorphological, sedimentological, geochemical, and ecohydrological data, this study discussed the dynamical changes of different dune landforms during the past half‐century and their formation mechanism in the Hexi Corridor, northern China. The results show that on the inter‐annual and inter‐decadal scales, the crescent‐shaped dunes move the fastest among different dune types. Dunes in Minqin move the fastest (at 6.2 ± 0.5 m yr−1) and dunes in Dunhuang move the slowest (at 0.8 ± 0.2 m yr−1). The dune sands are mainly medium sand (21.7%–57.4%) and fine sand (23.2%–53.0%) with an average grain size of 0.07 ± 0.01 mm ~0.24 ± 0.06 mm, similar to the world's average particle size of sand dunes. Annual precipitation and spring precipitation, annual average wind speed, and number of annual strong wind days are the main factors affecting the dynamic changes of dunes in the Corridor, indicating a major influence of climatic factors. STC (sufficient transport capacity) is evidenced for both the western and eastern Hexi Corridor, however, SSS (sufficient sand supply) and SA (sand availability) are the favourable factor for dune formation in the east part but is the limiting factor for the west. In the past half‐century, although the vulnerability of land degradation is a function of climate change, geomorphological processes, and anthropogenic pressure in the Hexi Corridor, water resource limitations have been more important.