关键词: 青海湖湖东沙地, 地表沉积物, 粒度特征, 地形, 垂直变化

Abstract:  The sandy land on the eastern shore of Qinghai Lake is the biggest area in the decertified land of Qinghai Lake Basin. Some measures have been taken to prevent and control desertification in Kutu district since 2008. The article chose 4 sandy dune styles on the eastern shore of Qinghai Lake，78 sediment samples were collected at 26 sites in 7 landform parts respectively. Then, grain-size range was determined by Malvern Mastersize 2000 laser particle size analyzer in order to analyze the grain-size characteristics of horizontal change of surface sediments and vertical change with the depths from 0cm to 20 cm. It can be seen that on the surface of natural fixed dune, fine materials content is 42.25%，and the dune is primarily made up of fine materials，while medium sand is widely distributed on other sand dunes. The characteristics of surface deposits are medium because sorting coefficient is 0.78. Sand dunes’ partial degree values range between 0.04 and 0.24，half-artificial fixed dunes’ are near symmetrical, and other dunes’ are positively partial. Peak state ranges between 0.90 and 1.50，natural fixed dune is with narrow peak state, and other dunes are in secondary peak condition. Meanwhile，the particle size parameters as the terrain of ups and downs have different characteristics of the change. The same depth, the higher the degree of sand dunes fixed，fine materials are more. Along with the change of the depth, coarse particles increase gradually，and fine particles reduce. With the increase of the depth, particle size parameters decrease in the trend of fluctuations. Through the comparison of the grain-size characteristics of different types’ sand dunes, artificial control measures have a great influence on sand surface environment，promoting fine particle depositing, and can effectively reduce the surface wind erosion.

Key words: Sandy land in eastern shore of Qinghai Lake, Surface sediments, Grain-size characteristics, Terrain, Vertical change