淡水入渗模型对咸水入渗过程的适用性

Applicability of fresh water infiltration model in saline water infiltration process

由于咸水中含有各种盐分离子,当咸水进入土壤后,会引起土壤物理特性改变,从而影响土壤的入渗特性.为了分析单因素对土壤入渗能力的影响,在中国科学院南皮生态农业试验站进行了不同矿化度和钠吸附比(SAR)的咸水一维垂直积水入渗试验.结果表明:咸水的土壤表征饱和导水率在2.99 g/L时存在突变现象,并达到最大值;当矿化度为3 g/L,而SAR不同的水入渗时,SAR在8.15(mmol/L)1/2时,饱和导水率达到最大值;当SAR大于8.15(mmol/L)1/2时,饱和导水率呈下降趋势.利用Green-Ampt模型及一维代数入渗模型,对试验结果进行对比分析,结果表明两种模型都可以描述咸水入渗特征,但相关参数具有不同于淡水的变化特征.通过对累积入渗量的理论值与实测值的分析得知,长历时入渗的情况下,Green-Ampt模型较精确;在短历时入渗情况下,一维代数入渗模型较精确.

The exploitation and utilization of saline water is becoming one of the most important approaches for alleviating shortage of fresh water resources. However,the infiltration properties of soil can be affected by ions in saline water. Hence a series of vertical one-dimensional infiltration experiments were conducted using saline water with various salinities and sodium adsorption ratios( SAR) in door at Nanpi Ecological Experimental Station in Hebei province. According to the experiment results, there was mutation effect at 2. 99 g / L salinity where the maximum infiltration occurred for infiltration capacity. The soil saturated hydraulic conductivity was increased with SAR and reached the maximum value when the SAR was 8. 15( mmol / L)1 /2at 3 g / L salinity. The Green-Ampt model and algebraic model for one-dimensional infiltration were compared in terms of fitted relationships between cumulative infiltration and time. The results showed that both the models could describe the saline water infiltration process,whereas relevant hydraulic parameters differed from those of fresh water. Based on an analysis on theoretical and measured cumulate infiltration curves,it was turned out the Green-Ampt model was more accurate in a long duration infiltration experiment,but the algebraic model for one-dimensional infiltration was more suitable for a short duration experiment on the saline water infiltration process.