| There is a serious soil and water loss in our country and the soil erosion is damaging a lot of land resources in our country.Understanding the soil erosion spatial distribution pattern can benefit the decision-making process of the scientific application of soil and water resources and the prevention and control of soil erosion.But the soil erosion spatial distribution pattern involves the effect of different resolution DEM to the spatial distribution of soil erosion,so making a further study of the effect of different resolution DEM on terrain factor and the spatial distribution of soil erosion has important significance.In this study,the four different geomorphologies of the Loess Plateau,the northern Hebei area,the Jinqu basin area and the Yunnan-Guizhou Plateau area are typical study areas,according to the DEM of different resolution,the topographic factors and the influence of different resolution DEM on topographic factors are analyzed.And with situational analysis,keep the rainfall erosive factor R factor,soil erodibility K factor,the surface coverage factor C does not change,replace the DEM(5m,10m,30m,50m),the effects of different resolution DEM on the spatial distribution of soil erosion were discussed.The main conclusions are as follows:(1)DEM resolution has an important effect on terrain factors,that is,the lower the resolution is,the average slope in one region will becoming lower and slower at the same time.In addition,the steep slopes have a relatively obvious change in this process,compared with the gentle slopes.With the decrease of the resolution,there will be a more and more inaccurate and general description of the terrain factors,which consequently may turn steep slopes into gentle ones.For the Loess Plateau,the mountain area of northern Hebei and Jinqu basin area,in areas of 1?3°?35?90° slopes,the slope ratios will be gradually slower and slower with the constantly-decreasing resolutions,while in areas of 3-350 slopes,the slope ratio will change in the opposite tendency.And for plateau areas of Yunnan and Guizhou provinces,in areas of 1?8°slopes,when the resolution is decreasing,the slope ratio will become higher and higher,while in areas of 8-900 slopes,there will be a constantly-slower slope ratio.Besides,the surface roughness has a similar react to the change of the resolution,that is,with the reduction of the resolution,there will be a smaller and smaller ground roughness.What's more,this change is more clear in greatly-undulating terrains than in these flat ones.(2)There are significant differences in the soil erosion spatial distribution of different DEM resolutions.The change of the DEM resolution will have impact on different erosion degree distribution,and the four mild erosion areas have increased in different degrees.The coverage of those areas with extremely strong,intense erosion is decreased to some extent.The soil erosion In loess hilly-gully region has changed from strong erosion to mild erosion,the soil erosion in ji beishan has changed from mild erosion ito micro erosion,the soil erosion in yunnan-guizhou plateau has changedfrom mild erosion to micro erosion,and ithe soil erosion in jin qu basin has also changed from mild erosion to micro erosion.In four areas,the soil calculated with 5m shares the maximum amount of soil erosion and 50m shares the smallest amout.When the resolution decreases from 5 m to 50 m,the average soil erosion modulus also decreases 58.69%-23.79%.The average soil erosion modulus decreases in different research area with the decrease of DEM resolution,it is mainly because the decrease of DEM resolution strengthen the generalization of terrain factor to the cause of the topography;When we calculate the soil erosion modulus,The slope terrains and terrain with a big fluctuation are more sensitive to the change of the DEM resolution.The error in the calculation of soil erosion by low resolution of the flat area is less than that of a slope terrain with a big fluctuation. |
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