土壤容重对海涂垦区粉砂土水分垂直入渗特征的影响研究

Study on Impact of Soil Bulk Density on Infiltration Properties of Silt Soil in Coastal Reclamation Regions

为探明土壤容重变异对海涂围垦区粉砂土水分入渗性能及变化过程的影响,该文通过室内土柱一维垂直入渗试验,比较分析了围垦区粉砂土和南京菜地黄棕壤不同容重下土壤水分入渗率、累积入渗量及湿润锋等的动态变化。结果表明容重对2种试验土壤入渗过程有较大影响,表征土壤入渗能力的稳定入渗速率、累积入渗量和湿润锋深度均随容重增大递减,呈显著负相关关系。模拟2种土壤入渗过程的考斯加科夫模型中,表征初始入渗速率的参数K值随容重增大递减,而表征入渗能力衰减速度的参数α随容重增大未表现出显著差异。简略的Philip入渗方程的幂级数解可以很好地拟合2种土壤湿润锋深度随时间变化过程,拟合的参数λ和x变化规律表明随着容重的增大,基质势梯度、重力作用都呈逐渐减弱的趋势。采用一维代数模型可以较好的模拟粉砂土入渗剖面含水率分布规律,土壤容重越高,模型的理论值越准确。

In order to determine the effects of soil bulk density on infiltration properties of silt soil in coastal reclamation regions, the dynamic changes of infiltration rates, cumulative infiltration, and wetting front of soil water under different bulk density of silt soil and yellow brown soil were explored by one dimension vertical infiltration experiment in this paper. The results showed that soil infiltration processes were greatly affected by soil bulk density. Infiltration capacity indicated by infiltration rate, accumulative infiltration and wetting front depth of the two experimental soils decreased along with increasing soil bulk density. The indexes of infiltration capacity had significantly negative correlation with soil bulk density. For the two experimental soils, the parameter of K in Kostiakov infiltration equations which meant initial infiltration rate decreased along with increasing soil bulk density, but there were not significant differences of the another parameter of a which meant infiltration decaying rate. The relationship between the wetting front and time can be fitted well by one short power progressional solution of the Philip infiltration equation. The changing trends of the parameters of A and x indicated that the both actions of matrix potential gradient and gravity decreased gradually with increasing soil bulk density for the two experimental soils. Profile soil moisture of silt soil was simulated well by a 1-D algebraic model, and the theoretical values were more accurate as the soil bulk density increased.