Land Use and Soil Erosion at Multiscale
摘要
Improper land use by mankind is one of the main causes of soil erosion. Through changing vegetation cover, soil property and runoff velocity, land use affects the occurrence and development of soil erosion. As scale changes, notable changes will occur in the interactive mechanisms between land use and soil erosion. Currently, research on land use and soil erosion is changing from slope scale to small watershed, watershed, and regional scales. Examining the influence of land use on soil erosion at different scales has become a frontier field in contemporary research in physical geography. At slope scale, vegetation offers protection against soil erosion by reducing runoff and increasing soil resistance to sediment entrainment. Research has verified that the effects of different land use types on soil erosion vary obviously, and farmland may be the most susceptible land use to runoff and soil erosion for different areas. Land management practices, such as changing micro-terrain, exert important influence on soil erosion, and the common soil erosion models used at slope scale are USEL/RUSLE and WEPP. At small watershed scale(or watershed), more attentions are paid to the impacts of land use structure and land use pattern on soil erosion. There is correlation between some land use types and sediment yields, and changes in land use structure have a significant impact on soil erosion. The spatial variability of land use pattern may change the interception ability of land parcel, the hydrological structure and soil erosion systems, which impact the final sediment load at watershed scale. In order to identify the relationship between land use pattern and soil erosion, some distributed soil erosion models are often applied to simulate soil erosion rate under different land use patterns, such as LISEM, AGNPS, EUROSEM and SEDEM. At regional scale, there are some methods to carry out soil erosion evaluation. One way is by means of up-scaling methods to study soil erosion of lar