不同入渗水头条件下壤砂土的一维垂直入渗特性

One-dimensional vertical infiltration characteristics of loamy sand at different infiltration heads

通过室内垂直入渗试验,分析了入渗水头对新疆喀什市塔什库尔干县壤砂土一维垂直水分入渗特性的影响。结果表明:累计入渗量与时间的关系符合Kostiakov-Lewis模型和Philip模型,其模型参数A值和吸渗率S随入渗水头的增大而增大,呈良好的线性关系,入渗系数与入渗指数随入渗水头增加呈相反的变化趋势;湿润锋推进距离与时间呈幂函数关系,参数m值随着入渗水头增加而增大,参数n在数值上等于第10个单位时间末和第1个单位时间末湿润锋推进距离比值的常用对数;累计入渗量与湿润锋呈线性关系,其斜率等于湿润区平均含水率与初始含水率之差,且随入渗水头的增大而增大。

Infiltration is the movement of water into the soil profile, which has an important role in field water cycle. The influence of different infiltration head on characteristics of one-dimensional vertical infiltration characteristics of loamy sand has been studied based on vertical infiltration experiments in laboratory. The results showed that the relationship between cumulative infiltration （I）and infiltration time （t）is consistent with Kostiakov-Lewis model [I （ t ） = At^a ＋ Bt] and Philip model [I （ t ） =St^0.5 ＋ B＇ t] ;The parameter A value increases with the increase of infil- tration head （ h ） ; There existed fairly good linearity between the parameter A value, soil water sorptivity S and in- filtration head （ h ）, the slope of them are equal to 0.007 4 and 0.006 6, respectively; the parameter a value ranged from 0.462 2 to 0.538 9, and its mean value is equal to 0.492 6; the parameter B varied between and 0.020 0 to 0.020 1, parameter B＇ changed from 0.018 7 to 0.021 4. The infiltration coefficient （ k ） and infiltration index （ a ） presented the opposite trend with the increase in infiltration heads, which is because of soil water press potential and unsaturated hydraulic conductivity. The relationship between wetting front advancing distance （ Zi ） and infiltration time is a power function （ Zf =mt^n ）. The model parameter m value increases with the increase of infiltration heads and the slope of them is equal to 0.006 4; the parameter n value is equal to common logarithm of the ratio of wetting front advancing distance at the end of the tenth unit time to that at the end of the first unit time. The relationship be- tween the cumulative infiltration and wetting front advancing distance is good linear （ I =βZf ）, and the slope （β）, in- creases with the increase of infiltration heads, is equal to the difference between mean soil water content （θmean ） and initial water content （ θ1 ） in humid region; For any two infiltration heads hi and h2 , a relationship was existed about θmean（ h1 ） - θmean（ h2 ） =β （ h1 ） -β （ h2 ）. This research result is of great theoretical value and practical significanc- es to preventing soil erosion, thwarting desertification and protecting ecological environment.