关键词: 蚀积平衡, 蚀积强度, 下垫面, 输沙率, 输沙通量

Abstract: Wind erosion, aeolian sand transportation and deposition are complex and closely linked aeolian processes. An aeolian region can be looked upon as an open system that exchanges aeolian sand with its surrounding regions. A region’s aeolian erosion and deposition play decisive roles in the development of the region’s aeolian landform. More specifically, the relationship between importing and exporting aeolian sand, or the balance between boundary mass input and output of sand, determines the resultant aeolian landform. The rate of regional erosion and deposition or the intensity of erosion can be expressed as: Re=We/S, where We is the balance between boundary mass input and output during a certain period of time and S is the areal size of the region. Field observation was conducted in the Shanxi-Shaanxi-Nei Monggol border area and different formulas between wind velocity and the transport rate of sand drift on different types of land surface were established. The rate of transport increases rapidly with increasing surface sand mobility and wind velocity. Three specific factors that have decisive effects on sand transportation are identified as wind velocity ( V ), blowing time ( T ) and wind direction. An analysis of the data on erosive wind collected by local weather stations determined the total annual quantity of sand transport flux on different types of surface. Vector analysis and charting ascertained that the prevailing direction of sand transport flux is mainly from the northwest to the southeast, with varying azimuth angles of between 288 7° to 303 6°, revealing clearly that the basic direction of aeolian sand movement and encroachment in the region is southeastward. Based on the interpretation of boundary land surface types from TM imagery, the boundary balance, quantity and intensity of aeolian erosion and deposition in different counties in the study area are calculated. The results show that the entire study area, which lies in the transitional belt between sand desert and loess plateau, is an aeolian erosion region. The region’s annual quantity of aeolian sand erosion is 109 million tons and the average intensity of sand erosion is about 160 t/a·km². Erosion increases from the sandy loessial region in the southeast to the desert region in the northwest as rainfall decreases, wind velocity increases, and vegetation cover declines. Thus the quantity of regional aeolian erosion increases with increasing interaction between the erosive agents of wind and water.

Key words: Aeolian sand erosion and deposition, regional input and output balance, land surface type, transport of san drift