沂蒙山区土壤侵蚀强度的垂直动态变化研究

Vertical Dynamic Change of Soil Erosion in Yimeng Mountainous Area

以具北方土石山区的典型特征的沂蒙山区为研究区,以TM影像和地形图为源数据,借助GIS和RS技术,根据全国土壤侵蚀分类分级标准,获取1986和2004年2期土壤侵蚀强度数据,在垂直分布上分析了土壤侵蚀强度等级间转化的分布特征。结果表明,1986—2004年期间,土壤侵蚀强度转化以向微度和相邻级别转化为主;土壤侵蚀强度加剧的面积为810.7km2,占总面积7.15%,侵蚀强度减缓的面积为1913.8km2,占总面积16.88%,在海拔150～400m间土壤侵蚀加剧和减缓的面积分别占其总变化面积的81.51%和73.43%。各等级土壤侵蚀强度面积随高程均呈现先增大后减小趋势,且其峰值出现的高程随着侵蚀强度级别的增加而升高。微度、轻度和中度等级发生变化的高程范围随着转向侵蚀级别的增大呈升高趋势;强度、极强度和剧烈转向微度等级的高程范围位置相对较低,极强度和剧烈等级转向轻度和中度侵蚀的高程范围位置相对较高。

This study aimed to explore the characteristics of the vertical distribution of the conversion between soil erosion degrees by taking the Yimeng mountainous area,one of the most representative areas in the rocky area of Northern China,as a case study.The study was based on the national standards for classification and gradation of soil erosion and supported by the GIS and RS technology and the data from Landsat TM image and relief map.Results showed that from 1986 to 2004,soil erosion was mainly converted to minimal degree and adjacent degrees.The area of aggravated soil erosion was 810.7 km2 and the area of alleviated soil erosion was 1913.8 km2,accounting for 7.15% and 16.88% of the total changed area,respectively.About 81.51% of the aggravated areas and 73.43% of the alleviated areas occurred between 150 and 400 m above mean sea level.The areas for all the soil erosion degrees ascended at first and then descended subsequently with rising elevation.Elevation for peak value of the erosion area rose with increased soil erosion degree.Elevation ranges for minimal,slight,and moderate erosion degrees rose with increased soil erosion degree.Locations of the elevation range from intense,very intense,and severe erosion to minimal degree were relatively low and those from very intense and severe erosion to moderate degree were relatively high.