基于GIS和RUSLE的黄土高原小流域土壤侵蚀评估

Soil erosion assessment of small watershed in Loess Plateau based on GIS and RUSLE

对基于上坡汇流面积的坡长因子算法进行改进,提出考虑上坡土地利用/覆盖对汇流影响的坡长因子算法,运用GIS和RUSLE评估黄土高原四面窑沟流域的土壤侵蚀强度及其与环境因素的关系。结果表明,流域多年平均侵蚀强度4399.79t/(km2·a),属中度侵蚀;侵蚀强度和侵蚀量均随坡度增加而显著增加,80.59%的侵蚀量来源于占流域总面积59.06%的25°以上坡度带;不同坡向的侵蚀强度表现为正阳坡>半阳坡>半阴坡>正阴坡,其中,占总面积45.07%的阳坡产生56.50%的侵蚀量;不同土地利用类型中,占总面积57.07%的草地产生96.37%的侵蚀量,成为目前流域内主要侵蚀产沙源。研究为应用修正通用土壤流失方程在黄土高原进行侵蚀评估提供技术范例,为该区侵蚀防治和水土资源利用提供有益参考。

The algorithm of slope length factor based on up-slop runoff area was mended and new algorithm of slope length factor considering the effect of land use/cover for up-slop runoff was produced. By using geographic information system （GIS） and the revised universal soil loss equation （RUSLE）, the soil erosion intensity and its relationship with environmental factors in the Simianyaogou watershed, located at Loess Plateau were studied. The results showed that the average annual soil erosion intensity in the watershed was 4 399.79 t/（km^2·a）, which was in the category of moderate degree erosion. Both soil erosion intensity and amount increased significantly with the increasing of the slop gradient. 80.59% of the total soil loss occurred in the region with a gradient more than 25 degree, of which the area was 59.06% of the total watershed area. Soil erosion intensity varied with slope aspects in a trend of sunny slope〉half-sunny slope〉half-shady slope〉shady slope. The area of sunny slope occupyed 45.07% of the total watershed area, but the erosion amount of which occupyed 56.50% of the total erosion amount. In different land use types, the grassland occupyed 57.07% of the total watershede area, but the erosion amount of which occupyed 96.37% of the total erosion amount. So, grassland had became the major erosion and sediment source in the watershed. The study provides technical basis for applying RUSLE to assess soil erosion on Loess Plateau and offers useful references for water and soil resource utilization in the region.