土壤可蚀性动态变化规律研究

通过回顾已有的研究成果，分析评价了现有具有代表性的土壤可蚀性评价指标的优缺点，提出了建立适用于土壤侵蚀预报的可蚀性评价指标的原则。并运用野外观测资料，计算分析了我国黑土、黄土，以及日本火山灰土等土壤可蚀性的季节变化规律，深入研究了土壤可蚀性随次降雨强度、不同强度段降雨组合的变化趋势。结果表明，单位降雨侵蚀力所对应的土壤流失量是反映土壤性质与流失量之间定量关系的最好指标，但不能把目前使用的土壤可蚀性指标直接移植于次降雨模型中。土壤可蚀性具有明显的季节变化，而其变化规律还存在地域差异性。采用最大30分钟雨强大于25－30mm/hr降雨的侵蚀产沙资料，计算的土壤可蚀性值比较稳定且接近该土类可蚀性的多年平均值。

Fluctuation of Soil Erodibility Due to Rainfall Intensity

On the base of evaluation of previous researches about soil erodibility, the advantages and disadvantages of present representative indexes of soil susceptibility to erosion were discussed in this paper , and principle of choosing index of soil for soil loss prediction was suggested. The erodibility values of phaeozem, loess in China and andisol in Japan were calculated using the data from fieldobservations. The variance in erodibility through seasons and the relation of soil erodibility to rain intensity was also analyzed. Results show that the rate of soil loss per rainfall erosivity index used in USLF may be the best index to represent the effect of soil properties on soil erosion. However, the present erodibility factor in use can not be applied directly in predicting soil loss caused by a specific rainstorm. The values of soil erodibility vary obviously through seasons and have different pattern from one place to another. But the field runoff plot data of which the maximum 30-minute rainfall intensity is larger than 25-30mm/hr are used to calculate the soil erodibility, the values appear relatively stable and approaches to annually average erodibility value.