Abstract: Reticulate dunes are more common in the world desert but less understood.The reticulate dunes in the southeastern Tengger Desert are composed of SW-NE trending main ridges and the secondary ridges nearly perpendicular to the main one.Field measurements were made on the reticulate dunes in order to understand their morphology and dynamics.It is found that the dunes develope in bi-directional low energy wind regime.The morphology of the main ridges is mainly controlled by lee face separated flow and thus the ridges are advanced by erosion on the windward slop and deposition on the slip face in the conditions of transverse flow.The secondary ridges are in the oblique flow conditions,the lee side's attached and deflected secondary flow controls its morphology and dynamic processes.It results in sand transportation and erosion taking place on both windward flank and lee flank,and thus leads to elongation of the secondary ridges.It is also found that the magnitude of deflected flow is in a log function with the incident angle of primary wind.Therefore,the main ridges of reticulate dunes are formed by the dominant northwesterly wind,whereas the secondary are developed on the main ridges by a seasonally alternation of the dominant northwesterly wind and sub-dominant northeasterly wind.As for its dynamic morphology,the reticulate dune in the studied area is a complex that transverse dune is superimposed by longitudinal one.

Key words: Tengger Desert, reticulate dune, surface air-flow, dynamics