云蒙湖流域土壤侵蚀时空分布及影响因素分析

Temporal and Spatial Distribution of Soil Erosion and Factors in the Yunmeng Lake Watershed

以小流域为研究尺度,选取云蒙湖流域为研究区,以TM遥感影像和DEM为数据源,在RS和GIS支持下,以最新的全国土壤侵蚀分类分级标准(SL190-2007)为模型基础,得到研究区1986年和2010年2个时段的土壤侵蚀强度及分布数据,分析土壤侵蚀时空格局特征及主要影响因素。结果表明:1)从1986—2010年,土壤侵蚀强度呈减小趋势,变化面积比例为29.47%,主要以中度、强烈、极强烈侵蚀等级面积向轻度、微度等级及相邻较低侵蚀等级面积转化为主。2)通过将研究区划分为88个小流域的研究表明,25年来小流域土壤侵蚀强度指数降低趋势明显,76%的小流域侵蚀强度指数减少10%以上;侵蚀加强的有5个小流域,增加幅度最大者为6.23%,主要分布在中西部和西南部地区。3)影响因素的岭回归分析表明,坡度因子始终是影响土壤侵蚀时空分布的最主要因素,但影响程度逐渐降低,贡献率由1986年的85.36%下降到2010年的80.79%;土地利用结构对侵蚀格局的影响逐渐增强,2010年贡献率达到19.21%;因此当植被覆盖度达到一定程度后,流域内土地利用结构的改变是制约土壤侵蚀时空分布的主要影响因素。

To investigate the characteristics of soil erosion in temporal and spatial patterns and main factors by taking the ~unmeng Lake watershed as a case study, based on the national standards for classification and gradation of soil erosion （SL190-2007） and supported by RS and GIS, with the data from Landsat TM image and DEM. Results show： 1 ） During 1986 and 2010, soil erosion intensity was decreasing and the changed erosion area accounts for 29.47% , of which mainly the moderate, severe, and more severe erosion degree converted to light, slight, and adjacent degree; 2） The soil erosion intensity index （SEI） was decreasing observably over the watershed. About 76% of the alle- viated small watershed reduced more than 10% ; while the soil erosion intensity of five small water- shed, located in the midwest and southwest of the study area, still increasing, of which the biggestwas 6.23% ; 3） Results of influencing factors by ridge regression analysis showed that slope was the most critical factor affecting soil erosion distribution, but the contribution rate （CR） fell from 85.36% in 1986 to 80.79% in 2010. While the effect of land use structure which was closely related to human activities had been gradually enhanced, and the CR reached 19.21% in 2010. This study demonstra- ted that land use structure was a main significant factor on the soil erosion spatiotemporal distribution after the rehabilitation of vegetation.