土壤侵蚀景观格局变化分析——以世界银行水土保持庆城项目区为例

Changes of Soil Erosion Landscape Pattern in Loess Hilly Regions——A Case Study of Loess Plateau Qingcheng Project Area

基于遥感融合影像和GIS技术,采用通用土壤流失方程,计算了庆城县水土保持世界银行贷款二期项目区1998和2004年的土壤侵蚀量;通过FRAGSTATS软件计算了多种景观类型参数,并从斑块类型水平和景观水平2个层次上分析项目区土壤侵蚀的分布格局及其变化规律。结果表明,6年间项目区平均侵蚀模数从1998年的7 877.6 t/km2下降到2004年的7 058.4 t/km2,侵蚀面积净减少525.8 hm2,输沙量减少34.11×104t;土壤侵蚀景观类型的主要转化过程是极强度转化为强度和强度转化为中度。在景观尺度上,斑块数量减少,平均面积增大,SDI由1998年的1.720减小为2004年的1.706,SEI由0.960减小为0.952;在斑块类型尺度上,微度、轻度和中度侵蚀类型破碎化程度下降,而极强度和剧烈侵蚀景观类型破碎化程度上升。

Based on the merged remote sensing image and Revised Universal Soil Loss Equation （RUSLE）, the soil erosion amount of Qingcheng project area of Loess Plateau Watershed Rehabilitation Project was calculated during the period from 1998 to 2004. The landscape indexes were calculated using GIS and FRAGSTATS, Quantitative analysis of soil erosion pattern and its dynamic evolution were conducted at class level and landscape level. Results indicated that the soil erosion modulus decreased from 7 877.6 t/km^2 to 7 058.4 t/km^2 during the past 6 years, and eroded area and eroded volume decreased by 525.8 hm^2 and 34. 11 × 10^4 t respectively. The main landscape change processes were that the eroded area of very strong degree was converted into strong degree and eroded area of strong degree into middle degree. Both the SDI and SEI decreased from 1998 to 2004, and the eroded area of very strong and severe degree became more fragmented.