基于HYDRUS模型的一维及三维入渗条件下土壤水盐运移规律研究

发布时间：2018-04-08 16:03

本文选题：HYDRUS　切入点：积水入渗　出处：《石河子大学》2015年硕士论文

【摘要】：滴灌具有明显的节水、增产等特点。滴灌土壤水分和盐分的分布规律是滴灌系统设计和灌溉制度制定的基础,而一维土壤水盐运移规律是研究土壤水盐运移的基础。通常研究土壤水盐运移规律的方式是室外试验,但室外试验研究不但耗费时间、人力、财力,而且在试验过程中容易受到自然和人为因素的影响,所以易产生较大的误差。近几年,计算机科学的发展迅速,国内外许多专家开始利用非饱和水运动理论和溶质运移理论为基础,构建数学模型对土壤水盐运移规律进行模拟,此方法具有简便、快捷、受干扰因素较少等优点,其中HYDRUS软件是目前模拟水分和溶质运移应用比较广泛的计算机软件。因此,本文利用HYDRUS软件对粘壤土的土壤水分和盐分的运移规律进行模拟研究。在以室内试验的基础上,求得土壤水分和溶质运移的相关模型参数,并验证模型。通过模型模拟研究分析土壤容重、积水深度和初始含水率对一维积水入渗的土壤水盐运移的影响,以及土壤容重和滴头流量对点源滴灌土壤水盐运移的影响。通过对不同试验条件下土壤水盐运移规律的分析,主要得出以下结果:(1)一维积水入渗的土壤湿润锋、入渗率和点源滴灌的土壤水平和垂直方向的湿润锋均与时间呈幂函数关系。(2)土壤容重、积水深度、初始含水率对一维积水入渗土壤水分的分布有显著影响。土壤入渗率、湿润锋随容重的增大而减小,土壤容重越大剖面平均含水率越小;土壤入渗率、湿润锋随积水深度的增大而增大,土壤积水深度越大剖面平均含水率越大;初始含水率越大土壤入渗率越小,但湿润锋深度越大,土壤初始含水率越大剖面平均含水率越大。(3)土壤容重对一维积水入渗土壤盐分的分布有显著影响,在相同的初始条件和边界条件下,容重为1.4g/cm3、1.45g/cm3、1.5g/cm3、1.55g/cm3,随着容重的增大脱盐系数减小、积盐系数增大、表层脱盐率和最大积盐量减小,随着容重最大积盐率分别为210.64%、156.55%、110.04%、81.65%,最大积盐位置为36cm、30cm、26cm、22cm。(4)积水深度对一维积水入渗土壤盐分的分布影响较小,积水深度差值较大时影响显著,在相同的初始条件,积水深度为1cm、4cm、7cm、10cm,随着积水深度的增大脱盐系数、积盐系数、表层脱盐率和最大积盐量越大;最大积盐率及其深度分别为156.55%、160.95%、165.09%、168.91%和30cm、31cm、32cm、33cm。(5)初始含水率对一维积水入渗土壤盐分的分布影响有显著影响,在相同的积水深度1cm和容重1.45g/cm3,初始含水率为0.05cm3/cm3、0.1cm3/cm3、0.15cm3/cm3、0.2cm3/cm3,随着初始含水率增大脱盐系数减、积盐系数增大,表层脱盐率减小、最大积盐率减小;最大积盐率及其深度分别为132.15%、100.00%、73.92%、52.91%和43cm、46cm、48cm、49cm。(6)土壤容重和滴头流量对三维点源滴灌土壤水分和盐分分布有显著影响,容重越大垂直湿润锋越小,水平方向湿润锋越大;滴头流量越大垂直方向湿润锋越小,水平方向越大。容重越大盐分在土壤湿润体内分布越均为,脱盐系数越小,积盐系数越大,最大积盐量越小;滴头流量越大,盐分在垂直方向脱盐系数越小,积盐系数越大,在水平方向脱盐系数越大,积盐系数越小。(7)HYDRUS模型能够很好的反映滴灌条件下粘壤土的土壤水分和盐分的运动规律。通过对模型参数的敏感性分析,其中经验参数n对模拟结果影响最大,剩余含水率θr对模拟结果影响最小,饱和含水率θs、α、Ks和αL对模拟结果均有一定影响。HYDRUS软件反推土壤水力参数和溶质运移参数是一种简单有效的方法,反推数据与实测数据可以较好的吻合。
[Abstract]:Drip irrigation has obvious water saving, yield and other characteristics. Distribution of soil water and salt under drip irrigation and irrigation system is the basis for making the design of drip irrigation system, and soil water and salt migration is based on one-dimensional soil water and salt transport. Usually the study of soil water and salt movement way is the outdoor test, but the experiment not only outdoor spend time, manpower, financial resources, and is affected by natural and human factors in the process of the experiment, so easy to produce large errors. In recent years, the rapid development of computer science, many domestic and foreign experts began using the unsaturated water movement and solute transport theory is based on the theory of constructing the mathematical model to simulate the law of soil water salt transport, the method is simple, fast, less interference factors etc., which is the calculation of the current HYDRUS software simulation of water and solute transport is widely used Machine software. Therefore, simulation study of the migration rule of using HYDRUS for the clay loam soil moisture and salinity. In laboratory tests on the basis of the model to obtain the parameters related to soil water and solute transport, and validate the model. Through the model simulation analysis on the influence of soil bulk density, soil water and salt transport in one-dimensional water infiltration of the water depth and the initial water content and soil bulk density and flow to drip irrigation soil water and salt transport. Through the analysis of soil water and salt migration under different experimental conditions, the main results are as follows: (1) the one-dimensional water into the soil wetting front infiltration, wetting front in soil level and the vertical infiltration rate and the point source drip irrigation was a power function relationship with time. (2) the soil bulk density, water depth, initial moisture content has a significant influence on the distribution of one-dimensional ponded water infiltration of soil moisture in soil. The infiltration rate, wetting front decreased with the increase of bulk density, the higher the soil bulk density profile average moisture content is small; the soil infiltration rate, wetting front increased with increasing water depth, soil water depth is large section average moisture content is higher; higher initial water content of soil infiltration rate is small, but the greater the depth of wetting front, the greater the initial soil moisture profile average water content is larger. (3) the soil bulk density has a significant influence on the distribution of one-dimensional ponded water infiltration of soil salinity, under the same initial conditions and boundary conditions, the density was 1.4g/cm3,1.45g/cm3,1.5g/cm3,1.55g/ cm3, with a decrease of increase of desalinization coefficient bulk density, salt accumulation coefficient the surface, desalination rate and maximum salt accumulation amount is reduced, with the maximum density of salt accumulation rate were 210.64%, 156.55%, 110.04%, 81.65%, the largest salt accumulation position is 36cm, 30cm, 26cm, 22cm. (4) water depth of one-dimensional water infiltration of soil salinity Little impact on the distribution of water depth difference effect significantly, in the same initial conditions, the water depth is 1cm, 4cm, 7cm, 10cm, with the increase of the depth of the water desalting coefficient, salt accumulation coefficient, desalination rate and maximum surface salt accumulation is increased; the maximum rate of salt accumulation and its depth is 156.55%, 160.95% respectively. 165.09%, 168.91%, and 30cm, 31cm, 32cm, 33cm. (5) initial water content has a significant influence on the distribution of soil salinity in the one-dimensional water infiltration effect, in the same water depth and density of 1cm 1.45g/cm3, the initial moisture content is 0.05cm3/cm3,0.1cm3/ cm3,0.15cm3/cm3,0.2cm3/cm3, with the initial moisture content. The desalinization coefficient reduction, salt accumulation coefficient, surface the desalting rate decreased, the maximum rate of salt accumulation decreased; the maximum depth and salt accumulation rate were 132.15%, 100%, 73.92%, 52.91% and 43cm, 46cm, 48CM, 49cm. (6) of soil bulk density and flow of 3D point source drip irrigation Have a significant impact and salt distribution, the greater the density of vertical wetting front is smaller, the horizontal wetting front is larger; the emitter flow the greater the vertical wetting front is smaller, the horizontal direction is greater. The greater the density of salt distribution in the soil body are more humid, desalination salt accumulation coefficient is smaller, the greater the number of lines the largest, salt accumulation amount is smaller; the dripper discharge more salt in the vertical direction of the desalinization coefficient smaller, salt accumulation coefficient is larger in the horizontal direction, the desalting coefficient increases, salt accumulation coefficient is small. (7) the HYDRUS model to the motion law of soil water and salt clay loam is a good reflection of drip irrigation next. Through sensitivity analysis of model parameters, the parameter n is the greatest impact on the simulation results, residual moisture content of 9 R with minimal impact on the simulation results, the saturated moisture content of s alpha, theta, and alpha Ks L were on the simulated results will influence the soil hydraulic parameters estimation software.HYDRUS and solute transport The moving parameter is a simple and effective method. The backstepping data and the measured data can be in good agreement.

【学位授予单位】：石河子大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S152.7

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