Formation mechanism and development pattern of aeolian sand landform in Yarlung Zangbo River valley

Aeolian sand landforms in the Yarlung Zangbo River valley can be divided in to 4 classes and 21 types. The river valley has favourable environment cond itions for the development of aeolian sand landforms. Simulation of MM4 mid -scale climate model showed that the near-surface flow field and wind vecto r field during the winter half year in the river valley are generally favou rable for the aeolian sand deposition and as a whole they also affect the d istribution zones and sites of aeolian sand landforms. Sand dunes and sand dune groups in the river valley developed mainly in three ways, namely wind ward retarding deposition, leeward back flow deposition and bend circumflue nce deposition. Through alternating positive-reverse processes of sand dune formation under wind actions and sand dune vanishing under water actions, sand dunes developed from primary zone through main-body zone then to vanis hing zone where climbing dunes and falling dunes are declining and are even disappearing.