| 摘要: |
| 【目的】为得到利用沙壤土粘粒量预测土壤入渗量和湿润峰深度的模型。【方法】设计11种沙壤土不同粘粒百分含量的质量混合比处理，通过室内土柱积水入渗模拟试验，研究在干容重一致的条件下，粘粒量的变化对沙壤土累积入渗量和湿润峰运移深度的影响。【结果】试验和分析结果表明：在干容重为1.41 g/cm3条件下，粘粒量从4.51%增加至12.03%，沙壤土湿润锋运移至45 cm深度处所需时间由103 min增加至310 min，增幅为2倍；达到相对稳定的入渗速率时沙壤土累积入渗量由8 cm减小至1 cm，减少87.5%。沙壤土湿润锋运移深度随时间变化模型经验系数、累积入渗量随时间变化模型中吸湿率和稳渗率均与粘粒量呈指数衰减模型关系，拟合优度均大于0.968。【结论】利用沙壤土粘粒量预测土壤入渗量和湿润峰深度的模型具有较高的精度，能够快速预测沙壤土入渗量和湿润峰深度，预测值与实测值之间绝对误差小于10%。 |
| 关键词: 沙壤土；入渗；粘粒含量；稳渗率；预测模型 |
| DOI： |
| 分类号:S152.3 |
| 基金项目:国家自然科学基金项目（51469027）；宁夏自治区重点研发计划重大项目（2018BBF02022）；宁夏高等学校一流学科建设项目（NXYLXK2017A03） |
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| Predicting Cumulative Infiltration and Wetting Front Distance of Sandy Loam Soil Using Clay Content as an Indicator |
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XIA Tian1, TIAN Juncang1,2
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1.College of Civil and Hydraulic Engineering,Ningxia University;2.Ningxia Research Center of Technology on Water-saving Irrigation and Water Resources Regulation
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| Abstract: |
| Abstract: The one-dimensional, vertical infiltration into soil with the surface of which ponded with a depth of free water is one of the most commonly encountered forms of infiltration. The measurement for cumulative infiltration and the advance of wetting front have been carried out for many years. Studies on soil water infiltration have been focused on theoretical and experimental aims. For theoretical study, researchers mainly focused on some infiltration models i.e. physical, semi-empirical, and empirical. Physical models based on Darcy’s law and law of mass conservation include the Green-Ampt model, Philip model, and Richards equation. Semiempirical models based on some simple hypotheses include Horton model and Singh and Yu model. Empirical models based on field observed data mainly include Kostiakov model and improved Kostiakov model. For experimental study, researchers mainly focused on soil texture, structure, bulk density, organic content, water content, temperature, and some other factors that influence the infiltration characteristics of soil. For texture variables on soil infiltration characteristics, the clay content has been considered as the indicator for soil texture by some researchers. Main results obtained are as follows: 1) the steady-state infiltration rate shows negative correlation with clay content by a power function relationship; 2) the sorptivity and steady-state infiltration rate shows a negative correlation with clay content by a logarithmic function. Despite the above results, problems arise that it may not be in accordance with the actual infiltration process in natural conditions by adopting the above model forms. For example, the calculated values for soptivity or the steady-state infiltration rate may be divergent when the clay content is approaching zero, when the above forms of model have been adopted for curve fitting. 【Objective】The aim of this study is to derive the models for predicting the cumulative infiltration and wetting front distance of sandy loam soil using clay content as an indicator.【Method】Totally 11 mass percentage treatments of combined sandy loam soils were designed. Influence on cumulative infiltration and wetting front distance of sandy loam soil posed by the clay content under the same dry bulk density was studied by ponded infiltration experiments using soil column in the laboratory. 【Result】Results show that under the dry bulk density of 1.41g/cm3, while the clay content increases from 4.51% to 12.03%, the time span for wetting front reaching the depth of 45cm increases from 103 min to 310 min, relatively increasing 2 times. At the same time, the cumulative infiltration decreases from 8 cm to 1 cm, relatively decreasing about 87.5%. In addition, the relation between the coefficient of model describing relationship between wetting front and time and the clay content, as well as that between parameters of model describing relationship between cumulative infiltration and time including sorptivity and the steady-state infiltration rate and clay content, can all be well described using exponential decay models with adjusted square higher than 0.968.【Conclusion】The derived predicting models are examined to be of high accuracy. Quick predictions for wetting front and cumulative infiltration of sandy loam soil can be obtained with the absolute error less than 10%. |
| Key words: sandy loam soil; infiltration; clay content; steady-state infiltration rate; predicting model |
