Characteristics And Formation Of The Wind Eroded Landforms On Shaling Sand Hills

Wind eroded landforms not only reflect the regional environment and atmospheric circulation, but also provide materials for the aeolian sediments. Thus, it is meaningful to study the evolution of wind eroded landforms for understanding regional climate and environment change. At present, wind eroded landforms in subhumid and humid zones have attracted much less attention than those in coastal dunes, arid and semi-arid zones. They are poorly understood. The sand hill on the shore of the Poyang Lake is generally regarded as a large scale wind accumulated landform formed in a humid region. On the Shaling sand hill (29.361°N,116.016°E), unique linear wind eroded landforms are developed and aligned along the dominant northeast wind, which indicating the environment has undergone significant changes. However their genesis, evolutionary progress is still not clear. The study about the wind erode landforms on shaling will enrich the content of Aeolian Landforms in humid region, as well as provide effective suggestions for the control of sandy desertification in humid region.In this paper, we classify the linear wind eroded landforms and analyze their morphological characteristics, distribution and interrelation through field geomorphological surveys and lab analyses. We also investigate the formation conditions of the wind eroded landforms by comprehensively analyzing the wind regimes, Drift Potential, terrain and strata in this area. Optically stimulated luminescence (OSL) dating is carried out in order to determine the formation age of wind eroded landforms.(1) Our field geomorphological survey confirms that the linear wind eroded landforms can be divided into4types:blowout, wind eroded trough, wind eroded ridge and wind eroded relic mound. Blowouts are located at the windward slope and ridge of the sand hill, wind eroded trough and wind eroded ridge are syngenetic and mainly distribute in the windward slope, wind eroded relic mounds appear on both the upper part of the windward slope and the ridge.(2) Today, Shaling sand hill belongs to a high energy environment and has a narrow unimodal directional variability, which facilitates the wind erosion. Since the sand hill is high, the wind velocity increases significantly along the slope, which strengthens the wind erosion correspondingly. The formation of wind eroded ridge and wind eroded relic mound is related to the intercalated silt layers.We put forward an evolution mode through analyzing the morphological characteristics, distribution, interrelation and OSL ages of the4types of wind eroded landforms. The so-called3Phases and2Stages Mode can depict the evolution of wind eroded landform. The blowouts firstly formed during Phase1, and then the wind eroded troughs and ridges developed during Phase2, the wind erosion relic mounds lastly shaped during Phase3. The wind erosion of Stage1occurred ca.6-7ka ago and the Stage2occurred ca.0.3ka ago. At present, stage2is still in the phase1, that is to say blowout.By correlating the formation age of wind eroded landforms with the regional records of climate change, historical documents, archaeological data, we conclude that the leading factor inducing the wind erosion in this humid region is the human activity. Previous study found that blowouts will evolve into wind-accumulated landform, such as parabolic dunes or linear dunes. However, blowout in this area can evolve into other types of wind eroded landforms.