Wind regime for long-ridge yardangs in the Qaidam Basin,Northwest China

Yardangs are typical aeolian erosion landforms, which are attracting more and more attention of geomorphologists and geologists for their various morphology and enigmatic formation mechanisms. In order to clarify the aeolian environments that influence the development of long-ridge yardangs in the northwestern Qaidam Basin of China, the present research investigated the winds by installing wind observation tower in the field. We found that the sand-driving winds mainly blow from the north-northwest, northwest and north, and occur the most frequent in summer, because the high temperature increases atmospheric instability and leads to downward momentum transfer and active local convection during these months. The annual drift potential and the ratio of resultant drift potential indicate that the study area pertains to a high-energy wind environment and a narrow unimodal wind regime. The wind energy decreases from northwest to southeast in the Qaidam Basin, with the northerly winds in the northwestern basin changing to more westerly in the southeastern basin. The strong and unidirectional wind regime for the long-ridge yardangs in the northwestern Qaidam Basin results from the combined effects of topographic obstacles such as the Altun Mountains and of the interaction between the air stream and the yardang bodies. Present study suggests that yardang evolution needs such strong and unidirectional winds in high- or intermediate-energy wind environments. This differs from sandy deserts or sandy lands, which usually develop at low- or intermediate-energy wind environments. Present study clarifies the wind regime corresponding to the long-ridge yardangs' development, and lays firm foundation to put forward the formation mechanisms for yardangs in the Qaidam Basin.