基于USLE的东江流域土壤侵蚀量估算

基于通用土壤流失方程(USLE),运用遥感和地理信息技术,对东江流域年均土壤侵蚀量进行估算。结果表明:东江流域年均土壤侵蚀总量为16.2×108t,土壤侵蚀模数为18.73t/(hm2.a),侵蚀强度属轻度。占流域面积94.62%的区域土壤侵蚀强度在中度以下,对流域土壤侵蚀量的贡献率为9.94%,而占流域面积仅5.38%的中度以上侵蚀区域对流域土壤侵蚀量的贡献率达90.06%。流域土壤侵蚀空间差异性大,分析土壤侵蚀与土地利用类型和坡度之间的关系表明:裸地和灌草地为区内主要侵蚀地带,土壤侵蚀模数随着坡度的递增呈先增加后减小的趋势,5°~25°为区内主要土壤侵蚀坡度段。通过以上研究分析以期为构建东江流域水生态功能分区指标体系提供科学依据。

Estimating Soil Erosion in the Dongjiang River Basin Based on USLE

In this paper, the Dongjiang River Basin with an area of 3.49×10⁴ km² was chosen as the study area .The Universal Soil Loss Equation(USLE) was use to estimate the erosion amount of the Dongjiang River Basin. The factors R, K, L, S, C and P were determined according to 1 ∶ 250000 DEM of the Dongjiang River Basin, NDVI data in January of 2009 and other basic data using remote sensing and geographic information system software. The annual average soil erosion amount is 16.2×10⁸ t, and the mean soil erosion modulus is 18.73 t/(km²·a), and the erosion intensity is classified as slight degree erosion. The slight and moderate erosion area occupied 94.62% of the area, but merely contributed 9.94% of the total load of soil erosion in the Dongjiang River Basin, while the serious erosion area only occupied 5.38% of the study area, and contributed 90.06% of the total load of soil erosion. The impact of slope gradient and land use on soil erosion were analyzed. Results show that the spatial distribution of soil erosion is obvious in the Dongjiang River Basin. The nudation and shrub-grassland are the main land use types which suffered serious erosion. The soil erosion rate increases with the increase of slope gradient until to a certain value, after which the erosion rate decreases. The main soil erosion slope ranges from 5° to 25°. These results could offer basic information for aquatic ecological function regionalization in the Dongjiang River Basin.