DEM精度对土壤侵蚀评价的影响

Effects of DEM Accuracy on Soil Erosion Assessment

  • 摘要: 选取位于东北黑土区的拜泉县为研究区,以高精度的DEM(1:1万比例尺)为基准,探讨低精度的DEM(1:5万比例尺)提取地形因子的差异及其对土壤侵蚀评价的影响.结果表明:在拜泉县的西南平原和缓坡台地区、三河(双阳河、通肯河、润津河)沿岸低洼易涝区,1:5万DEM提取的L因子分别高估11%和25%,提取的S因子则低估25%和31%.在西北和中部漫岗丘陵区、东南丘陵和台地区,L因子分别低估20%和7%,S因子分别低估16%和12%.地形因子的差异所带来的土壤侵蚀评价也有差异,其中在平原区差异较小(为10.67%),但在丘陵区差异较大(达23.14%).因此,在土壤侵蚀评价中,在高精度的DEM难以获取的情况下,平原区可用较低分辨率的DEM来代替;但在丘陵区则不能代替,或者须对其计算的LS因子进行必要的修订,从而在一定程度上保证土壤侵蚀评价的精度.

     

    Abstract: Baiquan county, located in the black soil region of Northeast China, was selected as the study area. Based on the high-precision DEM (1:10 000), the difference of topographic factors extracted by low-precision DEM (1:50 000) and its impacts on soil erosion assessment were compared. The main conclusions were as follows: in the southwestern plain and gentle slope area of Baiquan, and the low-lying and easy-lying areas along the Sanhe River (Shuangyang River, Tongken River and Runjin River), the L factor extracted by 1:50 000 DEM was overestimated by 11% and 25%, respectively. Besides, the S factor was underestimated by 25% and 31%, respectively. In the northwest and central rolling hills, southeast hills and platform, the L factor was underestimated by 20% and 7%, and the S factor was underestimated by 16% and 12%, respectively. Discrepancy existed in soil erosion assessments due to differences in topographic factors. The discrepancy at the plain area is small (10.67%), but at the hilly area was large (up to 23.14%). Therefore, in the soil erosion assessment, in the case where the high-precision DEM was difficult to obtain, the plain area could be replaced by a lower resolution DEM. However, it could not be replaced in the hilly area, necessary modifications must be made of the LS factor to ensure the accuracy of soil erosion evaluation to a certain extent.

     

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