黄丘区野外草被坡面土壤入渗参数变化规律与模拟研究

Study on the Change and Simulation of Soil Infiltration Parameters on the Field Grass Slope in the Loess Hilly Region

利用黄丘区第三副区野外坡面模拟降雨试验,研究了3种覆盖度(30%,60%,90%)和5种降雨强度(1,1.5,2,2.5,3mm/min)下15°草地坡面土壤入渗过程变化规律。结果表明:(1)土壤入渗率随着草被覆盖度和降雨强度的增加不断增大,草被覆盖度越大,土壤入渗率的增加效果越显著,土壤初始入渗率与降雨强度呈指数函数关系,土壤稳定入渗率与降雨强度呈幂函数关系。(2)土壤累积入渗量与降雨时间呈良好的幂函数关系,草被覆盖度越大,土壤累积入渗增量越明显,降雨强度对土壤累积入渗量的影响存在阶段性差异。(3)草被覆盖度的增加能明显提高土壤入渗系数,随雨强的增大,土壤入渗系数不断减小,自然草被覆盖度(60%)下,草被增加土壤入渗系数的有效降雨强度为1~1.5mm/min。(4)利用4个入渗模型对土壤入渗速率与降雨时间的关系进行拟合,研究结果表明Horton公式能较好的模拟该区土壤入渗过程。

Effects of grass coverage degree（30%,60%,90%）and rainfall intensity（1,1.5,2,2.5,3 mm/min）on the soil infiltration process on the 15°grass slope were studied under simulated rainfall condition in the third subregion of loess hilly region.The results were as follows：（1）Soil infiltration rate increased with the increase of grass cover and rainfall intensity,while the soil infiltration rate increased significantly with the increase of grass coverage rate.The initial infiltration rate of soil and rainfall intensity presented exponential relationship.The soil stability infiltration rate and rainfall intensity showed the power function relations.（2）The cumulative soil infiltration and rainfall time had a good power function relationship.The cumulative infiltration of soil increased significantly with the increase of grass coverage rate.The effect of rainfall intensity on soil cumulative infiltration showed phase-based difference.（3）The increase of grass cover could significantly increase the soil infiltration coefficient,the soil infiltration coefficient decreased with the increase of rain intensity.Under the coverage of field grass（about 60%）,the effective rainfall intensity of grass cover in increasing soil infiltration coefficient was between 1-1.5 mm/min.（4）The relationship between soil infiltration rate and rainfall time was fitted by four infiltration models,and the Horton formula was found could well simulate the soil infiltration process.