【作者】 聂卫波；

【导师】 马孝义；

【作者基本信息】 西北农林科技大学 ， 农业水土工程， 2009， 博士

【摘要】 畦灌和沟灌是我国目前最主要和使用最广泛的灌水方式之一，与微、喷灌等压力灌溉相比，其具有田间工程设施简单、运行成本低、易于实施等优点；但畦灌和沟灌同时存在田间水浪费严重和低的田间灌水效率等一些缺点。因此研究畦灌和沟灌的理论，改进、完善畦灌和沟灌灌水技术，是灌溉农业发展的一个重要课题。故本研究选取畦灌和沟灌作为研究对象，在理论分析和数值模拟的基础上，结合室内和大田试验，对畦灌和沟灌的土壤水分入渗和水流运动模型进行了系统研究，得出了以下几点结论：1．以非饱和土壤水分运动理论为基础，分别建立了畦灌和沟灌的土壤水分入渗动力学模型，对所建模型进行求解，并用试验资料对模拟结果进行对比验证，两者基本吻合。用所建模型分别对不同试验处理下畦灌一维入渗过程和沟灌二维入渗过程进行模拟，得出了影响畦灌和沟灌入渗过程的主要因素；并在此研究基础上建立了以湿周为主要参数的沟灌累积入渗量简化计算模型和多参数的沟灌湿润锋运移距离预测模型；通过以上研究可进一步了解畦灌和沟灌入渗过程的入渗机理，为改进畦灌和沟灌灌水技术、优化设计其灌溉系统提供理论依据。2.以水量平衡原理为基础，建立了畦灌水流推进解析模型。通过分析畦灌下渗水形状系数zσ的变化规律，发现zσ主要受入渗参数α的影响，并对大量的文献资料数据进行分析，提出了确定畦灌过程中zσ值的两种计算方法；并对畦灌水流推进过程中地表储水形状系数hσ分别取值为0.70、0.75、0.80，以研究hσ的不同取值对模型精度的影响。结合已有文献资料和大田试验对所建的畦灌解析模型进行验证，结果表明模型计算方便，精度较高，具有较强实用性，且说明畦灌时地面储水形状系数hσ在0.7~0.8之间取值是合理的；也表明所提出的计算下渗水形状系数zσ的公式是可靠的。3.以水量平衡原理为基础，建立了沟灌水流推进解析模型。通过理论分析并结合沟灌过程中水力学特点，避开了沟灌过程中难以准确测定的沟首平均过水断面面积这一难题；对下渗水形状系数zσ与水流推进关系的进行理论分析；并采用matlab软件对所建沟灌水流推进解析模型进行迭代计算，克服了下渗水形状系数zσ难以直接给定的问题，并成功的模拟了沟灌的水流运动过程。结合已有的文献资料和田间试验对模型进行验证，结果表明建立的沟灌水流推进解析模型有高的精度。4.针对畦灌和沟灌田间平均入渗参数和综合糙率系数难以确定的问题，建立了利用水流推进过程同步推求田间平均Philip入渗参数和田面综合糙率的模型。通过分析畦灌和沟灌地面水流运动规律，对畦灌和沟灌水流推进过程中地表水面线进行概化，并将Philip入渗公式等同为α= 0.5的Kostiakov修正模型的情况下,利用灌水过程中多组不同灌水时间t和相应的水流推进距离l值,采用matlab软件进行参数寻优计算,得出不同地表储水形状系数σh取值下的入渗参数S、f和田面综合糙率n值,发现σh的不同取值对入渗参数S和f值无影响,对田面综合糙率n值有较大影响;结合现有的文献资料和田间试验对所建模型进行验证,结果表明所建模型同步推求不同地表储水形状系数σh取值下各灌水田块平均Philip入渗参数S、f和田面综合糙率n值是可靠的,同时表明田面综合糙率对水流运动过程的敏感性较低。5.通过对大田灌水试验的灌水质量进行评价,然后采用SRFR软件对大田灌水试验的灌水质量进行模拟,将实测结果与模拟结果进行对比,结合田间工程实际可认为两者误差在一个合理的范围内,表明SRFR软件模拟畦灌和沟灌灌水质量是可行的。通过分析本文的研究结果,得出SRFR软件模拟时所需输入的基本参数。以SRFR软件模拟为基础,通过改变不同灌水技术要素组合,找出了不同条件下的畦灌和沟灌灌水技术要素的合理组合。研究的结果可用来指导农民的生产灌溉工作,减少水资源的浪费,提高灌溉水利用效率和灌水均匀度,达到常规地面灌溉的节水灌溉目的。畦灌和沟灌水流运动是一个十分复杂的问题,涉及到土壤水分入渗和地表水流运动两个方面,其影响因素众多。论文对畦灌和沟灌的土壤水分入渗和水流运动模型进行了较为系统深入的研究,但如何将两者有机的结合起来,形成更加系统完整的畦灌和沟灌水流运动模型体系,是目前国内外研究中一个仍待突破的难题,这还需今后做进一步深入的研究。更多还原

【Abstract】 Worldwide, border irrigation and furrow irrigation are more commonly used compared with pressurized irrigation systems, such as sprinkler and micro-irrigation systems. They have the advantages of lower investment and operating costs and convenient management. But border irrigation and furrow irrigation can have disadvantages, such as possible water wastage and lower irrigation efficiency. So research is justified into the theory of border and furrow irrigation, to improve and perfect irrigation design. From a combination of laboratory and field experiments, a theoretical analysis and numerical simulation is proposed for border irrigation and furrow irrigation practices. The major elements include:1. Mathematical models of border irrigation and furrow irrigation were set up, based on unsaturated soil water movement theory. The software models and simulation results were verified by laboratory experiments, achieving good agreement between predictions and measurement. The main factors influencing border irrigation and furrow irrigation infiltration characteristics were determined. Key parameters of soil wetting movement linked to a two-dimensional infiltration model were established which included the wetted perimeter beneath furrows. The analysis provides understanding of the infiltration mechanism related to border irrigation and furrow irrigation. This is a sound basis for improving surface irrigation practice through optimization.2. The literature on border irrigation and related infiltration functions was examined. Assuming that the trajectory of the advance of the water front in border can be represented by a simple power function relating advance distance and time and that the infiltration function has the familiar Kostiakov-Lewis characteristic form then two methods were proposed to predict infiltration and the water advance process. Assumptions of both methods included using the Lewis-Milne equation to derive a volume balance model. The power function advance parameter was found to take the values 0.70, 0.75 and 0.80 and a simplified analytical model of border irrigation was created. The model was checked using laboratory and field experiment data, showing that the model is reasonable and has some advantages. It has a strict physical foundation, is simple to calculate and gives solutions of high accuracy. It is also found that advance parameter values of 0.7~0.8 are reasonable, and indicated that two solution methods proposed to determine power function advance parameters are reliable.3. Area shape factor parameters for wetted area were derived through theoretical analysis to identify an analytical model of furrow irrigation. An iterative algorithm was developed to solve the model equations using Matlab software. The results show that the problem of getting the figure coefficient of infiltration water directly with difficulty was solved .So the water flow process of furrow irrigation was successfully simulated.4. Using the volume balance approach with a generalized surface water profile, a Philip infiltration formula equivalent to the Kostiakov–Lewis model and an infiltration parameterα= 0.5, then the Philip infiltration parameter and channel roughness values were deduced from border and furrow irrigation data. Analysis by Matlab software suggested that the infiltration parameters do not have major influence but that the Manning roughness is important when the power function advance parameter takes different values. The model was checked using field data to show that determinations of the Philip infiltration parameter and Manning roughness are reliable. It also showed that progress of advance was not very sensitive to the Manning roughness values.5. Field experiments were undertaken to determine field application efficiency and to compare these values with values simulated by the SRFR software. Results show that the margin of error is reasonable, indicating that the SRSF software is appropriate for analysis of border and furrow irrigation. Based on simulation using the SRSF software, the correlation of irrigation technique element was changed, the result discovered that the optimized correlation of reasonable irrigation technique element under different condition of border irrigation and furrow irrigation. It can be used to guide the farmers’irrigation, reduce the waste of water resources, enhance the irrigation application efficiency and distribution efficiency, and attain the aim of saving water.Border and furrow irrigation water movement involves soil water infiltration and surface water movement, the influencing factors are numerous and very complicated. In this paper, border and furrow irrigation model on soil water infiltration and water movement was studied systematically and deeply, but how to combine these two aspects more systematically is a very complex problem in irrigation research, and it needs to do more researchers in future.更多还原