修正的通用土壤流失方程中各因子单位的确定

Determination of Units for Various Factors of Revised Universal Soil Loss Equation

[目的]明确和规范修正的通用土壤流失方程(RUSLE)中各因子的单位,使得RUSLE在中国具体应用过程中更加科学和便捷。[方法]通过对国内外RUSLE应用实践的总结和对比研究,并分析其科学合理性,找出最为普遍应用的、准确的RUSLE各因子的单位,明确不同单位类型之间的转化系数。[结果]国内RUSLE的应用,大部分是通过各地区建立的各因子统计模型转换成国际制单位系统,最后相乘得到的是以国际制单位表示的土壤侵蚀量,另一部分则是通过相应的各因子统计模型计算得到各个因子以美制单位系统表示的计算结果,最后再乘以224.2将土壤侵蚀量转换为国际制单位。国内主流侵蚀估计中使用的单位焦耳系统,单位面积有两种即km^2和hm^2。土壤流失量A常用的国际制单位为t/hm^2或t/km^2;降雨侵蚀力因子R常用的国际制单位为(MJ·mm)/(hm^2·h·a)或(MJ·mm)/(km^2·h·a);土壤可蚀性因子K的常用国际制单位为(t·hm^2·h)/(hm^2·MJ·mm)或(t·km^2·h)/(km^2·MJ·mm)。不同地区建立的计算方法通过相应的转换系数转换成国际制单位。最后,R和K因子的单位系统的一致性是RUSLE应用的关键步骤。[结论]R和K因子通过相应的单位转换系数转换为国际制单位以及两者的单位一致性是土壤侵蚀评估的重要基础。

[Objective] To clarify and standardize the units of the revised universal soil loss equation （RUSLE）, we aim to make RUSLE more useful in China.[Methods] By comparing the studies of RUSLE at home and abroad, we determined the most widely applied and accurate units of RUSLE factors and clarified the conversion coefficient between different units.[Results] The application of RUSLE in China, most of the statistical model established by regional units were converted to international units system by multiplying the conversion factor, and finally obtained the amount of soil erosion in international units. The others were the results of various factors represented by US units system through each factor of the corresponding statistical model calculation, the amount of soil erosion in the international system of units was obtained by multiplied by 224.2. The Joule unit system was widely used in the erosion estimation in China, and there were two area units, namely km2 and hm2. The unit of soil loss amount A was commonly used by international units as t/ha （t/hm2） or t/km2, the rainfall erosivity factor R was （MJ·mm）/（hm2·h·a） or （MJ·mm）/（km2·h·a）, the soil erodibility factor K was （t·hm2·h）/（hm2·MJ·mm） or （t·km2·h）/（km2·MJ·mm）. The results of calculation methods established in different regions were converted into international units through the corresponding conversion coefficients. The consistency of the unit system of R and K factors was a critical step in the RUSLE application.[Conclusion] The conversion of R and K factors into international units through the corresponding unit conversion coefficient and the unit consistency of the two factors is the important basis for soil erosion assessment.