Wind Erosion during Sandstorm Events in Hetian, China

摘要

Hetian in Xinjiang is a region with extensive wind erosion, severe desertification and various aeolian sand hazards. To assess the variation in wind erosion of surface soil in the region, the quantity of wind-eroded soil and some surface properties (vegetation cover and surface soil moisture) were concurrently measured and analyzed in six land use types during two sandstorm events in 2004. The amount of surface soil transported varied in the following order:abandoned farmland ＞ intermediate zone of desert and rural section ＞ active sand dunes on the edge of the desert ＞ the country roads ＞ film-mulched cotton plot ＞ alfalfa. On 20 May 2004, the quantity of eroded soil in the abandoned farmland was 76.8 g cm- 2, 40 times greater than film-mulched cotton plot and the Alfalfa. When the vegetation cover was about more than 50% or the water content of soil was above 4%, the rate of sand transport was reduced. With an increase in distance, the amounts of sand transported from Taklimakan Desert to other surfaces varied exponentially. At 400 m, the amounts of sand transported declined from 30 gcm-2 to 1 g cm-2, and the difference was not too much among surfaces after that point. Under the vegetation cover, the amounts of sand transported from the film-mulched cotton and alfalfa plots were more than their down tuyering and increased with sampling height, but those in the abandoned farmland, intermediate zone of desert and rural section, country roads and active sand dunes on the edge of the desert were more at 20 cm and decreased with height. The quantity of eroded soil and damage from wind erosion was extremely high in the abandoned farmland, intermediate zone of desert and rural section, country roads and active sand dunes on the edge of the desert. These were the most potent sources of dust in the area of Hetian. Measures are needed to reduce wind erosion and sandstorm in Hetian, such as expanding the area under winter-wheat, planting perennial herbs and green crops, implementing protective cultivation systems, avoiding over-grazing and laying the country roads with Gobi, gravel, and asphalt.