地形因子计算方法对土壤侵蚀评价的影响

The Influence of Terrain Factors’ Calculation Methods on Soil Erosion Evaluation

选取嫩江县、怀来县、吴起县、开州区、长汀县5个区域1∶1万地形图,生成5 m分辨率的DEM作为数据源。分别用分段坡长法和汇流面积法计算了坡长坡度因子,并用中国土壤流失方程(CSLE)计算了土壤侵蚀模数,评价了土壤侵蚀强度,对比分析了分段坡长法和汇流面积法对坡长因子及水土流失面积的影响。结果表明:采用汇流面积法提取的坡长因子值和空间分布差异比分段坡长法更大,2种方法的低值区差异较小,高值区差异较大。2种方法计算水土流失面积比例差异不大,而在计算土壤侵蚀强度上显示出明显的差异。研究结果为不同地形区土壤侵蚀的地形因子和土壤侵蚀评价提供了数据支撑和理论基础。

The universal soil loss equation(USLE)and Chinese soil loss equation(CSLE)are widely used for soil erosion evaluation.Different methods for calculating slope length factor could cause differences in topographic factors and soil erosion.The purpose of this study was to evaluate the effects of different methods for calculating slope length factor(L)on topographic factor and then on the soil erosion.The 1∶10000 topographic maps from five regions of Nenjiang,Wuqi,Kaixian,Huailai and Changting were selected and 5 m×5 m DEMs were generated.The segment slope length method(SSLM)and the catchment area method(CAM)were used to calculate the slope length factor.The CSLE was used to calculate soil erosion.The results showed that the average L factor value and spatial variation from the CAM were greater than those from the SSLM.The area with low L factor values had less difference and the area with high L factor value greater difference between the two methods.The proportions of soil erosion area calculated by the two methods in different terrain areas were not obviously different.However,the soil erosion intensities showed significant differences between the two methods.The results could provide data support and theoretical basis for the study of soil erosion topographic factors and soil erosion assessment in different topographic regions.