基于RS和GIS的陕北黄土高原退耕还林区土壤侵蚀定量评价

目的]分析陕北黄土高原退耕还林区2000,2007和2012年土壤侵蚀量时空变化特征,为该地区开展退耕还林(还草)工程提供参考。方法]在GIS和RS的技术支持下,以陕北黄土高原退耕还林区为研究区域,应用美国通用土壤流失预报方程(RUSLE模型)为评价模型,利用ArcGIS 9.2的栅格数据空间分析功能,对研究区域2000,2007和2012年土壤侵蚀强度进行了估算,在此基础上分析了其时空变化特征。结果]陕北黄土高原退耕还林区2000—2012年土壤侵蚀量呈下降趋势,2012年较2000年下降了1 162t/(km2·a);以子长县为例,2000年土壤侵蚀模数在2 500t/(km2·a)以下的面积仅占区域总面积的0.1%,2012年上升为55.2%;2000年研究区主要土壤侵蚀强度为中度侵蚀,2012年为轻度侵蚀,变化剧烈的区域主要集中在黄土高原丘陵沟壑区的子长、安塞、志丹等县。结论]植被覆盖因子是影响区域内土壤侵蚀的最主要因素,由此可见大力开展退耕还林(还草)工程可以有效抑制区域内土壤侵蚀状况。

Quantitative Assessment of Soil Erosion in Areas Under Grain for Green Project in Loess Plateau of Northern Shaanxi Province Based on GIS and RS

Objective] To analyze the temporal and spatial variability of soil erosion intensity in Loess Plateau of Northern Shaanxi Province in 2000, 2007 and 2012, and to provide the support for the implementation of grain for green project in this region.Methods] With the support of GIS and RS technology, we conducted a quantitative research based on the RUSLE model and ArcGIS 9.2 and analyzed the temporal and spatial variability of soil erosion intensity in Northern Shaanxi in 2000, 2007 and 2012.Results] During the 13 years, soil erosion tended to decrease over time, and the soil erosion in 2012 dropped by 1 162 t/(km²·a) compared with 2000. Compared with the 2% of the total area in 2000, the area with an erosion modulus less than 2 500 t/(km²·a) in Zichang County accounted for 26% in 2012. The soil erosion was moderate in 2000, but was slight in 2012 in most areas. The drastic change mainly occurred in the hilly areas in Zichang, Ansai and Zhidan Counties.Conclusion] Vegetation coverage was the main factor affecting the soil erosion, and conversion of slope cropland to forest or pasture is playing an important role in decreasing soil loss.