基于RUSLE的卧虎山水库流域土壤侵蚀特征分析

通过RUSLE模型对卧虎山水库流域土壤侵蚀进行全面评价验证和总结。结果表明：① 水库流域平均侵蚀模数为462 t/(km²·a),该数值与通过水库淤积等资料推算评估结果基本一致,表明本研究结果具有较高的可信度;水库流域年均侵蚀量达到2.6×10⁶t,其中高于容许土壤流失量的面积为176 km²,占到流域总面积的31.51%。从不同侵蚀级别来看,占流域面积27.77%的轻度侵蚀,对流域侵蚀总量的贡献率为54.64%; 面积占比3.74%的中度及以上侵蚀,侵蚀量贡献率达到30.94%。② 流域内土壤侵蚀空间差异较大,回归分析发现地形因子是导致各子流域土壤侵蚀模数差异的主要因素;就土地利用类型而言,旱地和农村居民点是流域内的主要侵蚀土地利用类型;流域内土壤侵蚀模数随着坡度增加呈现相应增大趋势,8°~25°坡度段面积比例不仅最大,而且侵蚀量占比最高,是水库流域的主要侵蚀坡度段。

Soil Erosion Characteristics Based on RUSLE in the Wohushan Reservoir Watershed

Soil erosion of the Wohushan Reservoir was calculated based on RUSLE(Revised Universal Soil Loss Equation). The calculated mean soil erosion modulus is 462 t/ km²·a, which is consistent with the data estimated by the deposition from both reservoir and main watercourses. This indicated that the calculation is accurate and the result is reliable. The annual average soil erosion amount is 2.6×10⁶t. According to standards for classification and gradation of soil erosion issued by the ministry of water resources of PR China, the area above soil loss tolerance is about 176 km², which amounts to 31.51% of total area of the Wohushan Reservoir. With reference to the erosion intensity, the slight erosion area occupies 27.77% of total area in reservoir watershed, but contribute 54.64% of the total load of soil erosion in the Wohushan Reservoir Watershed. while the moderate and above intensity erosion area only occupies 3.74% of the study area and contributes 30.94% of the total load of soil erosion. It was found that there are large spatial differences for soil erosion intensity in the reservoir watershed. Based on hydrological module in arcgis platform, we got 11 sub-basins. Their soil erosion intensity were found to have a consistent change with their geomorphology factors, which indicates that slope length and slope gradient should be the main factors leading to the difference of soil erosion modulus in each sub-basins. Compared the ratio of erosion amount with that of different land uses, it’s found that dry land and rural settlements are the main land use types which suffered serious erosion. The soil erosion intensity increases with the increase of slope gradient. The main erosion slope ranges from 8° to 25°, in which the percentage of area is not only the largest, but also the erosion rate is the highest.