| 砂性层状土柱蒸发过程实验与数值模拟 |
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| 引用本文： | 任利东,黄明斌.砂性层状土柱蒸发过程实验与数值模拟[J].土壤学报,2014,51(6):1282-1289. |
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| 作者姓名： | 任利东 黄明斌 |
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| 作者单位： | 西北农林科技大学资源环境学院,西北农林科技大学黄土高原土壤侵蚀与旱地农业国家重点实验室 |
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| 基金项目： | 国家自然科学基金(No. 91025018、41171186) |
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| 摘 要： | 为了了解不同类型层状土柱蒸发特性,利用砂土和砂黄土2种土壤,设置3种不同厚度分层土柱(11.25、22.5、45 cm)和2种均质对照土柱,测定了土柱蒸发过程中累积蒸发量、相对蒸发速率和剖面含水量的变化;同时利用2种均质土柱排水过程优化的土壤水力参数和Hydrus-1D模型对2种均质土柱和3种不同类型层状土柱蒸发过程进行模拟分析。结果表明,均质砂黄土蒸发第一阶段持续长达34 d,累积蒸发量显著高于均质砂土和其他3种不同类型分层土柱,土柱剖面含水量变化进一步证明表层覆盖砂土可显著抑制土壤蒸发。利用排水过程优化的水力参数,HYDRUS-1D可以较好地模拟层状土柱蒸发过程。研究结果对干旱半干旱区土壤水分管理具有指导意义。
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| 关 键 词： | 蒸发速率 累积蒸发量 剖面含水量 Hydrus-1D模型 |
| 收稿时间： | 2013/12/26 0:00:00 |
| 修稿时间： | 2014/7/11 0:00:00 |
Experiment and numerical simulation of soil evaporation from layered sandy soil columns |
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| Ren Lidong and Huang Mingbin.Experiment and numerical simulation of soil evaporation from layered sandy soil columns[J].Acta Pedologica Sinica,2014,51(6):1282-1289. |
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| Authors: | Ren Lidong and Huang Mingbin |
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| Institution: | College of Resources and Environment, Northwest A&F University,State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Northwest A&F University |
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| Abstract: | To understand how soil water evaporates from soil columns different in layered structure and soil columns homogeneous in soil texture, five soil columns were prepared by filling soil into Plexiglas cylinders, 90 cm in height, 23.5 cm in inner diameter and 0.9 cm in thickness of the wall. Three of them were packed with sandy soil and sandy loess, layer by layer alternatively but different in thickness of the layers (11.25, 22.5 and 45 cm) and two with sandy soil and sandy loess separately and homogeneously. The soil columns were irrigated till they were saturated and then let drain with a 2 cm water layer at their bottoms for 30 days and then they were ready for the evaporation experiment. The columns were sealed at the bottom to ensure zero flux from the lower end. During the experiment, cumulative evaporation, relative evaporation rate and profile water content were monitored and AE/PE ratios (actual evaporation rate / potential evaporation rate) were calculated and meanwhile, evaporation processes from the five soil columns were simulated and analyzed using the HYDRUS-1D model and optimized soil hydraulic parameters based the drainage processes of the two homogeneous soil columns. The soil hydraulic parameters were obtained through optimization of the calculation of profile water contents during the drainage processes in the two homogeneous soil columns. Then the optimized hydraulic parameters were used to simulate drainage processes in the three layered soil columns with much better effect that lowered the relative error by 1% to 9%. Besides, the optimized hydraulic parameters based on variation of profile water content in the two homogeneous soil columns during the drainage processes were used to simulate evaporation processes of the soil columns. Actual evaporation from the columns was determined by weighing the columns on D 0, 2, 4, 9, 14, 22, 30, 34, 40, 45, 49, 53 and 56. Moreover, 12 cm long TDR probes were placed in the columns, one every 10 cm to measure profile water content on D 0, 8, 14, 22, 30, 40 and 56. Analysis of the measurements and simulations show that in the homogeneous column of sandy loess the first phase of evaporation lasted 34 days, and as a result, its cumulative evaporation was the highest, reaching 110.8 mm, while in the homogeneous column of sandy soil and the other three layered columns, the first phase evaporation lasted only one day, so their cumulative evaporation was as low as around 6 mm. The layered soil column with sand on the surface was relatively stable in profile water content, indicating that sand mulch could dramatically reduce soil evaporation. In addition, the three layered soil columns did not differ much in soil evaporation, demonstrating that an 11.25 cm-thick overlay of sandy soil is enough to reduce soil evaporation significantly. Although the simulations agreed well with the observations, the simulation of soil evaporation could be further improved in precision by using drainage-process-based optimized hydraulic parameters and the HYDRUS-ID model. Improving the accuracy of the simulation of soil water characteristic curve and soil hydraulic conductivity and taking into account the coupling effect of water, vapor and heat in soil columns is the major approach to reducing simulation deviation. The findings in the experiment may have some important significances in guiding soil water management in arid and semiarid regions. |
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| Keywords: | Soil evaporation rate Cumulative evaporation Profile soil water content Hydrus-1D |
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