The secret of nabkha development–From the inspective of surface wind erosion and sand accumulation

Abstract

Nabkhas can effectively reduce wind speed and intercept sand, slowing down the rate of land desertification and playing an important role in the stability of the oasis ecosystem and the conservation of biodiversity. The purpose of this study is to explore the evolutionary mechanism of nabkha development and wind erosion and sand accumulation of different nabkhas during nabkha development in the oasis region. Five typical nabkhas (Nitraria tangutorum, Haloxylon ammodendron, Krascheninnikovia ceratoides, Kalidium foliatum and Artemisia desertorum nabkhas) were selected. Morphological indicators and surface wind erosion and sand accumulation during nabkha development were investigated. Our results confirmed that from the nascent stage to the stable stage, the length, width and height of five nabkhas showed a significant correlation. As nabkha develops, the different parts of nabkha were mainly sand accumulation occurred first on the apex part, then on the windward slope and finally on the leeward slope. When the lateral area of the nabkha was close to the semi-ellipsoidal shape, the nabkha reach the stable stage. The sand accumulation height of Nitraria tangutorum nabkhas is the highest. Haloxylon ammodendron nabkha is able to intercept sand sources from multiple directions due to the pike-shaped branching structure. Kalidium foliatum nabkhas have a high sand accumulation height in the pre-developmental stage. Krascheninnikovia ceratoides and Artemisia desertorum nabkhas are morphologically irregular with limited sand accumulation height. The results indicate that the surface wind erosion and sand accumulation changes during the development of nabkhas were mainly related to the interaction between vegetation growth and nabkha formation.