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    2种空间数据结构对县域尺度土壤侵蚀评价的影响

    Effects of two spatial data structures on soil erosion assessment at county scale

    • 摘要: 县域尺度土壤侵蚀评价多以栅格结构为计算单元, 导致单个矢量地块存在多个栅格、多种侵蚀强度, 较难用于以矢量地块为对象的水土流失治理和规划。以河南省汝州市为对象, 采用基于栅格数据的3种方法和矢量数据的2种方法, 结合CSLE模型和遥感监测, 分析土壤侵蚀差异性。结果表明: 1)栅格统计法用时8 min, 可快速反映土壤侵蚀情况, 但成图效果差, 适用不需成图的县域尺度土壤侵蚀评价。2)软件判断法与栅格统计法侵蚀面积相差0.05 km2, 差异率0.01%, 能准确反映土壤侵蚀情况, 运算13 min, 成图效果好, 适合县域尺度土壤侵蚀评价及制图。3)地块评价法运算16 min, 计算侵蚀面积相差64.63 km2, 差异率16.02%, 且无法生成不同侵蚀强度面积, 不适于县域尺度土壤侵蚀评价。4)基于矢量的2种方法侵蚀计算结果差异较大, 原始矢量法和细化矢量法数据量分别为180和337 MB, 运算分别用时29和45 min, 成图效果好, 适于地块内部相对均一的平原区土壤侵蚀评价。研究成果可为县域尺度水力侵蚀评价、水土流失动态监测成果应用提供参考。

       

      Abstract:
      Background The existing county-scale soil erosion evaluation method mostly uses raster structure as the basic calculation unit, leading to multiple raster numbers and multiple erosion intensities in a single vector plot, which makes it difficult to directly apply to vector plot-based soil erosion control and planning. Therefore, studying the impact of different spatial data structures of raster and vector on soil erosion calculation and evaluation is of great significance to the dynamic monitoring of soil erosion and the application of results, and to serve soil and water conservation planning and soil erosion control.
      Methods This study used Ruzhou city, Henan province as the research area, based on two different spatial data structures of raster and vector, combined with China's soil loss equation and remote sensing monitoring, the differences in soil erosion among 5 methods were compared and analyzed.
      Results 1) The raster statistics method based on raster calculation took 8 min, which quickly and accurately calculated the soil erosion area and intensity, and accurately described the erosion area and intensity of different land uses, but the mapping effect of aggregation index was bad. This method was suitable for soil erosion evaluation at county scale that did not require mapping. 2)The software judgment method presented the smallest difference in calculation results, and demonstrated the best effect in drawing. Compared with the raster statistics method, the software judgment method had a difference of 0.05 km2 in the erosion area, with a difference rate of 0.01%, and it had a small difference in the erosion area of different erosion intensity and different land use, which took 13 min. The aggregation index was 96.81%, which was good mapping effect. It is suitable for soil erosion evaluation and mapping at county level. 3)The calculation time of the land parcel evaluation method was moderate, which was 16 min. But the erosion area difference was 64.63 km2, the difference rate was 16.02% and the area of different erosion intensity cannot be provided. It was not suitable for soil erosion evaluation at the county scale. 4) There were large differences in soil erosion area, intensity and erosion area of different land use between two vector calculation methods. The large amount of vector data led to longer calculation time, but the advantage was that the mapping effect was better. These two methods were suitable for calculation and evaluation of soil erosion in plain areas with relatively consistent soil types, terrain slopes, and vegetation coverage.
      Conclusions The research results may provide reference for water erosion evaluation, dynamic monitoring of soil and water loss and application of the results at county level.

       

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