湖南省衡山不同海拔高度土壤的入渗特征

目的]探究衡山不同海拔高度土壤入渗性能的差异及其影响因素,为山体大尺度土壤入渗性能研究提供思路和方法。方法]在衡山不同海拔高度区域选取9个试验点进行野外点源入渗试验。结果]①从各试验点入渗率角度分析,稳定入渗率随海拔上升逐渐增大(山顶山腰山麓)且入渗率变化显著。从入渗开始到稳定入渗减小了50%～86%,且入渗过程呈现出一定规律性,即初始入渗率很大,随着入渗过程的推进,前10 min入渗率迅速减小,10～30 min缓慢减小,最终在30 min后趋于稳定。②影响土壤入渗性能的因素较多,在衡山试验中稳定入渗率与0.25 mm水稳性团聚体含量和海拔高度分别呈极显著正相关和显著正相关关系,而与有机质、土壤容重和质地相关性较低。③Kostiakov模型,Philip模型、Horton模型在各试验点的决定系数R~2均大于0.95,都能较好地对衡山各试验点入渗速率进行拟合,而Philip模型的参数中表征稳定入渗率的参数A均为负数,使其物理意义不明确。结论] Horton模型能反映不同海拔区域稳定入渗率的特征(山顶山腰山麓),Kostiakov模型能较好地反映入渗速率的变化特征(山麓山顶山腰),也说明点源入渗法测量山地入渗是可行的。

Soil Infiltration Characteristics at Different Altitudes in Hengshan Mountains of Hu'nan Province

Objective] The difference of soil infiltration performance at different altitudes and its influencing factors in Hengshan Mountains were studied to provide ideas and methods for the reseraches of large-scale soil infiltration.Methods] Using point-source infiltration method test at 9 points in different altitude areas of Hengshan Mountains.Results] From the point of view of infiltration rate, the infiltration rate changed significantly and the stable infiltration rate increased gradually with the rising of elevation (top > hillside > foothill). From the beginning of infiltration to stable infiltration, the infiltration rate decreased by 50%~86%, and the infiltration process showed a certain regularity. The initial infiltration rate was very large. With the process of infiltration, the infiltration rate decreased rapidly in the first 10 minutes and continued to decrease slowly in the succedent 10~30 minutes. Finally, it got stable after 30 minutes. There are many factors affecting soil infiltration performance. In this experiment, the stable infiltration rate had a significant positive correlation with the content of>0.25 mm water-stable aggregates and with the altitude, but had a low correlation with organic matter, soil bulk density and texture. Kostiakov model, Philip model and Horton model all had more than 0.95 determinant coefficients R² in each test site, which can fit the infiltration rate of Hengshan Mountains test site well. The parameters A of Philip model were negative, meaning that their physical meaning is not clear. Therefore, that model has some limitations in fitting the infiltration rate of Hengshan Mountains.Conclusion] Horton model can reflect the characteristics of stable infiltration rate at different altitudes (top > mountainside > foothill). Kostiakov model can better reflect the variation characteristics of infiltration rate (foothill > top > mountainside). It also shows that point-source infiltration method is feasible to measure mountainous infiltration.