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土壤水力參數(shù)對點源入滲濕潤體形狀的影響
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國家自然科學基金面上項目(51679190、51979220)、國家自然科學基金重點項目(41830754)和國家重點研發(fā)計劃項目(2016YFC0501401-02)


Influence of Soil Hydraulic Parameters on Soil Wetting Pattern Shape of Point Source Infiltration
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    摘要:

    為探究點源積水入滲的運移機理,以達西定律和質量守恒原理為基礎,利用HYDRUS軟件對點源積水入滲過程進行數(shù)值模擬分析與驗證,分析點源積水入滲條件下土壤水平濕潤鋒與垂直濕潤鋒的比值(濕潤鋒比)和土壤水力參數(shù)(進氣吸力、形狀系數(shù)以及飽和導水率)之間的關系,并基于土壤飽和擴散率建立水平濕潤鋒運移模型。結果表明:細質土壤(進氣吸力大于11cm)的濕潤體形狀近似為以積水中心為橢圓心、以垂直濕潤鋒和水平濕潤鋒為長半軸和短半軸的橢圓體,而粗質土壤(進氣吸力小于8.7cm)濕潤體的橢圓心位于積水中心下方,從而導致短半軸大于水平濕潤鋒、長半軸小于垂直濕潤鋒;細質土壤的濕潤鋒比隨時間變化較小,可近似為常數(shù),土壤濕潤鋒比與形狀系數(shù)和飽和導水率之間無顯著的函數(shù)關系,但與進氣吸力呈線性遞增關系,決定系數(shù)R2為0.999;濕潤鋒運移過程可以采用入滲時間的冪函數(shù)進行擬合,且冪函數(shù)系數(shù)和指數(shù)可以分別用土壤飽和擴散率的一次多項式和二次多項式進行估計,經驗證得到的模型在誤差允許范圍內具有較好的效果。本研究可為分析點源積水水鹽運移等問題提供機理性依據(jù),也為我國北方干旱半干旱地區(qū)合理規(guī)劃設計滴灌系統(tǒng)、提高農業(yè)灌溉用水效率提供科學依據(jù)。

    Abstract:

    In order to research the migration mechanism of the surface ponding infiltration, the HYDRUS software was used to simulate and verify the process of surface ponding infiltration based on Darcy law and mass conservation principle. The relationship between the ratio of horizontal wetting front to vertical wetting front and soil hydraulic parameters (air-entry suction, shape coefficient and saturated water conductivity) was analyzed, and a horizontal wetting front migration model was established by using soil saturated diffusion rate. The results showed that the shape of wetting pattern of fine soil was approximately an ellipsoid with the center at ponding center, and the vertical and horizontal wetting fronts were the long and short semi-axes, respectively. However, the center of the coarse soil wetting pattern was located below the ponding center, thus the short semi-axis was larger than the horizontal wetting front, and the long semi-axis was smaller than the vertical wetting front. Wetting front ratios of fine soil was changed little with time and can be assumed as a constant. There was no significant functional relationship between wetting front ratio and shape coefficient or saturated water conductivity, but it was linearly increased with the increase of air-entry suction with R2=0.999. The power function of infiltration time can be used to describe the wetting front migration and the coefficient and index in power function can be estimated by the first and second polynomials of soil saturated diffusivity. It was verified that wetting front model had a good effect within the allowable error range. The research result can provide a more rational tool for the analyzing of surface ponding water migration. Meanwhile, it also provided a scientific theory for design of drip irrigation system in arid and semi-arid regions in northern China and improving the agricultural irrigation water use efficiency.

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蘇李君,藺樹棟,王全九,王康.土壤水力參數(shù)對點源入滲濕潤體形狀的影響[J].農業(yè)機械學報,2020,51(1):264-274. SU Lijun, LIN Shudong, WANG Quanjiu, WANG Kang. Influence of Soil Hydraulic Parameters on Soil Wetting Pattern Shape of Point Source Infiltration[J]. Transactions of the Chinese Society for Agricultural Machinery,2020,51(1):264-274.

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  • 收稿日期:2019-10-15
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  • 在線發(fā)布日期: 2020-01-10
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