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1.
基于Hydrus-1D的滴灌土壤水分运移数值模拟 总被引：3，自引：0，他引：3
为探索滴灌土壤水分运移、土壤水分再分布及土壤水力特性参数等,利用Hydrus-1D软件对室内有机玻璃箱滴灌条件下土壤水分运动进行了模拟,并对其土壤导水率和土壤水分特征曲线进行了求解和拟合,并利用均方根误差RMSE和决定系数R2进行评价。结果表明Hydrus1-D软件对滴灌条件下土壤水分分布的模拟具有较高的精度,在滴头处实测的土壤含水率和模拟的土壤含水率其RMSE和R2可以达到0.021 6和0.856 2,并对土壤水分特征曲线和扩散率曲线进行了模拟,发现其能较好满足V-G模型和指数函数关系,说明Hydrus1-D软件可普遍用在分析评价土壤水分的有效性,研究土壤水分运动等方面。 相似文献
2.
《灌溉排水学报》2020,(6)
【目的】探究南疆滴灌成龄核桃根系分布和根区土壤水分运动规律,为南疆成龄核桃灌溉制度的确立提供科学指导。【方法】以阿克苏地区进行地表滴灌的成龄核桃树为研究对象,基于Hydrus 2D软件进行地表滴灌条件下的土壤水分数值模拟研究。【结果】①水平方向根系主要分布在0～120 cm范围,垂直方向主要分布于0～60 cm范围。②滴灌带应布设于距树60 cm处;中水处理灌后垂直向浸润可达到60 cm,且均匀度87%。;③Hydrus 2D模型率定和验证精度较高,RMSE介于0.016～0.022cm~3/cm~3范围,Re介于0.04～0.12范围,R~2介于81.03%～97.19%范围,表明模型模拟土壤水分运移较可靠。【结论】在研究不同灌水定额条件下成龄核桃树的根系分布和土壤湿润区结合Hydrus2D模型,得出成龄核桃的滴灌带应布设于距树60cm处,灌溉定额为450m~3/hm~2的中水处理作为成龄核桃果树地表滴灌的指导灌溉定额。 相似文献
3.
葡萄组合式滴灌条件下土壤水分运移规律模拟研究 总被引：1，自引：0，他引：1
为探讨葡萄组合式滴灌条件下土壤水分运移规律,为葡萄的滴灌灌溉制度提供理论依据,利用HYDRUS-2D软件模拟了该条件下土壤纵剖面水分分布,并与实测值进行了对比。结果表明,滴头正下方各深度处体积含水率均方根误差(RMSE)在1.82%~2.76%间,模拟具有较高精度,模型参数可靠。再结合模型验证后参数,分别模拟了滴头流量为2.4 L/h时,灌溉8、10、12 h后水分再分布24 h时土壤水分运移规律。结果表明,滴灌12 h时,土体湿润体面积范围较广,有效含水率深度与葡萄根系发育规律较匹配,满足葡萄架下与架外根系生长对土壤水分要求。 相似文献
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5.
新疆棉田地下滴灌土壤水盐运移规律的初步研究 总被引：7，自引：1，他引：7
为探讨新疆棉田地下滴灌条件下土壤水盐运移的规律,在棉花各个生育阶段运用TDR和取样从水平方向和垂直方向测定棉田距滴灌带不同位置的土壤水分和盐分,研究分析后认为地下滴灌条件下棉花整个生育期土壤中盐分运移规律为:苗期较高,花铃期较低,吐絮期又较高。盐分经过长时间的水平和垂直运移,水平方向在距滴灌带较远的地方含盐量较高,最后在滴灌带中间位置积聚;垂直方向在耕作层的盐分含量有所降低,耕作层处于脱盐过程,盐分主要向深层运移,在80 cm以下的土层处于积盐过程。 相似文献
6.
滴灌条件下沙地土壤水分分布与运移规律 总被引：24，自引：1，他引：23
通过对不同流量的滴头,不同灌水历时条件下沙地土壤滴灌湿润体的大小与开头的观测观察,以及对滴灌停止后不同间隔时间的土壤湿润锋运移,湿润体的发展,土壤水分的分布与再分布测量分析,使之对滴灌条件下土壤湿润体的大小及发展,土壤水分的分布与再分布规律等有了比较清楚的认识,本文不进行理论上的土壤水分分布模拟,仅从众多的实测资料分析着手,揭示土壤水分分布与运移规律,旨在为砂壤地玉米滴灌的参数确定提供基本依据。 相似文献
7.
以棉花各生育期适宜土壤含水率上、下限差值为灌水控制指标,设置3水平灌水处理,开展膜下滴灌大田试验,分析研究适宜试验区棉花生长、水分利用效率高的灌溉制度及膜下滴灌棉田土壤水盐运移规律。结果表明:适宜土壤含水率上、下限差值形成的灌溉制度,决定了土壤水盐运移规律、盐分分布和积累特征。总体表现为:空间上土壤水分分布与滴灌带间距呈负相关系,盐分分布则相反,0~40 cm深度土壤水分在灌后重分布,盐分在滴灌水分的淋洗作用下定向运移,至湿润体边缘积聚。综合分析关键点与主根层的土壤水盐时间序列变化,T2处理(385 mm/18次)主根层0~40 cm深度水分处于棉花生长的适宜含水率范围,并形成淡化脱盐区,对盐分的调控最佳。T2处理棉田产量最高,为6 083 kg/hm~2,水分利用效率为1.05 kg/(mm·hm~2),为适宜的灌溉制度。 相似文献
8.
基于非饱和土壤水分运动理论和单点源滴灌中土壤水分迁移特征,应用HYDRUS-2D/3D模型对33种土壤质地(分属11类土质类型,美国制土壤质地分类系统)、不同滴灌流量(1,2,3 L/h)下的湿润体运动过程进行了数值模拟,然后根据不同土壤质地和滴灌流量下湿润体动态变化的HYDRUS模拟结果,以滴灌量和土壤饱和导水率与滴灌流量的比值作为输入变量,构建了描述滴灌湿润体在不同土质和滴灌流量下迁移变化的人工神经网络模型.该模型输入变量少、易于操作,且将模型计算结果与实测情况对比表明,计算的入渗过程与实测的入渗过程基本一致,相关系数的平方(R2)均在0.82以上,因此该模型对不同土质中湿润体运移规律的预测效果较好. 相似文献
9.
反演分析土壤-秸秆水分运动参数 总被引：1，自引：1，他引：0
通过潜水均衡试验站土壤测渗仪资料,以新疆具有一定代表性的轻粘土为例,利用无秸秆覆盖和地表以下35 cm秸秆覆盖的实测资料,研究作物生长条件下土壤水分和盐分运移模型参数,通过HYDRUS模型反演确定了土壤水分运动参数和秸秆水分参数。并与测筒实测数据进行了比较。通过计算,无论是模拟计算的土壤水分运动参数还是秸秆水分参数都与相应的测筒观测值具有良好的一致性,模拟值与实测值吻合较好,这表明了轻粘土土壤水分运动参数和秸秆水分运动参数的确定是合理的。这些参数的确定将为更好地模拟秸秆覆盖条件下土壤水盐运移规律,研究秸秆覆盖层阻止土壤潜水蒸发抵制土壤盐分向上运动提供科学数据。 相似文献
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基于二维畦灌全水动力学模型模拟的地表水深及畦面任意点垂向均布的流速场,通过把湍流垂向流速分布律由标量推广为矢量形式,并结合不可压缩流体力学连续性方程,构造了沿二维畦面及垂向非均布的三维流速场;利用能够描述二维畦面及垂向三个维度的溶质浓度场非均布变化特征的对流-扩散方程,描述传统撒施下的二维畦灌地表溶质运移过程,采用构造的三维流速场,基于湍流近壁模型构造了溶质扩散系数,从而构建了肥料撒施畦灌地表水流溶质运移控制方程;借助于畦灌地表水流模型中的薄水层假设,构建畦面溶质浓度初始条件,并采用一级动力学方程和任意点的固态溶质总量守恒特征,构建了撒施的肥料溶解与输运过程边界条件,从而构建起撒施肥料下的二维畦灌地表水流溶质运移模拟模型. 相似文献
12.
模拟撒施肥料下的一维畦灌地表水流与溶质运移过程可为采用先进的畦灌液体施肥方式提供对比依据。该文基于湍流理论垂向流速线性与对数分布规律及不可压缩流体力学连续方程,构造沿畦长及任意垂向断面的非均布流速场和溶质浓度场,建立起撒施肥料下的一维畦灌地表水流与溶质运移模型,并利用典型畦灌施肥试验结果,检验该模型的模拟效果。结果表明,建立的模型不仅具有在撒施肥料状况下较好模拟地表水流运动和溶质浓度时间变化过程的能力,还具备较佳的水量和溶质质量守恒性,从而为评价撒施肥料下的畦灌施肥系统性能及与其它施肥方式下的畦灌施肥系统性能对比,提供了实用的数值模拟工具。 相似文献
13.
Numerical simulations of water movement in a subsurface drip irrigation system under field and laboratory conditions using HYDRUS-2D 总被引：2，自引：0，他引：2
Maziar M. Kandelous 《Agricultural Water Management》2010,97(7):1070-1076
Due to the decreasing availability of water resources and the increasing competition for water between residential, industrial, and agricultural users, increasing irrigation efficiency, by methods like subsurface drip irrigation (SDI) systems, is a pressing concern for agricultural authorities. To properly manage SDI systems, and increase the efficiency of the water/fertilizer use while reducing water losses due to evaporation, the precise distribution of water around the emitters must be known. In this paper, the Windows-based computer software package HYDRUS-2D, which numerically simulates water, heat, and/or solute movement in two-dimensional, variably-saturated porous media, was used to evaluate the distribution of water around the emitter in a clay loam soil. The simulation results were compared with two sets of laboratory and field experiments involving SDI with emitters installed at different depths, and were evaluated using the root-mean-square-error (RMSE). The RMSE at different locations varied between 0.011 and 0.045 for volumetric water contents, and between 0.98 and 4.36 cm for wetting dimensions. Based on these values, it can be concluded that the correspondence between simulations and observations was very good. 相似文献
14.
土壤水热分布状况是作物优质高产的关键环境条件之一，基于土壤水、热运动基本方程，结合地表滴灌水分运动特点，建立了地表滴灌水、热运移数学模型，利用HYDRUS-2D软件对构建的数学模型进行了数值求解，并对数值模拟得到的土壤水热值与田间实测数值进行了对比验证。结果表明， 所构建的数学模型对地表滴灌条件下的土壤水分运动和土壤温度变化及分布的动态变化具有较好的模拟效果；当土壤、气象以及灌水资料等可知时，利用该数学模型可以较准确地预测地表滴灌条件下水热耦合迁移与分布规律，模型可用来适时监测和调控地表滴灌条件下作物生长所需的土壤水、热环境条件。此外，数值模拟值和实测结果都显示，地表滴灌条件下上层土壤的水分和温度值较下层土壤易受到土壤蒸发和大气温度剧烈波动的影响。 相似文献
15.
Simulation of soil water dynamics under subsurface drip irrigation from line sources 总被引：2，自引：0，他引：2
A mathematical model which describes water flow under subsurface drip lines taking into account root water uptake, evaporation of soil water from the soil surface and hysteresis in the soil water characteristic curve θ(H) is presented. The model performance in simulating soil water dynamics was evaluated by comparing the predicted soil water content values with both those of Hydrus 2D model and those of an analytical solution for a buried single strip source. Soil water distribution patterns for three soils (loamy sand, silt, silty clay loam) and two discharge rates (2 and 4 l m−1 h−1) at four different times are presented. The numerical results showed that the soil wetting pattern mainly depends on soil hydraulic properties; that at a time equal to irrigation duration decreasing the discharge rate of the line sources but maintaining the applied irrigation depth, the vertical and horizontal components of the wetting front were increased; that at a time equal to the total simulation time the discharge rate has no effect on the actual transpiration and actual soil evaporation and a small effect on deep percolation. Also the numerical results showed that when the soil evaporation is neglected the soil water is more easily taken up by the plant roots. 相似文献
16.
Laboratory experiments and calculations were carried out to analyze the effect of subsurface drip irrigation (SDI) design
features on soil wetting patterns for a point source. Experimental and simulated soil wetting patterns, using the SWMS-2D
(simulating water movement and solute transport in two-dimensional) Galerkin finite element model, were investigated to maximize
the efficiency of water saving. The analysis addressed the influence of water pressure head, back pressure and emitter diameter
on wetting patterns. Predictions of water content distributions in the soils made with SWMS-2D were found to be in good agreement
with the observed data. Results showed that this model provides confidence that model predictions are not too sensitive to
back-pressure effects. 相似文献
17.
为了探明滨海盐碱地不同灌溉方式及氮肥施用量对水肥盐迁移过程及作物生长的影响,基于大田试验,研究不同灌溉方式及灌水量(F:漫灌,360 mm;D1:滴灌,360 mm;D2:滴灌,288 mm;D3:滴灌,216 mm)、氮肥处理(N1:280 kg/hm2;N2:196 kg/hm2;N3:112 kg/hm2)对盐碱地土壤水肥盐分布含量及对春玉米各生长指标的影响.结果表明,在滴灌模式下,同一灌水量,N1的剖面平均含水量最低,D1,D2出现洗盐点,存在适合作物生长的浅盐区;灌水后D1N1的硝态氮含量增加最显著且含量最高,滴灌处理对应的低氮处理无明显硝态氮积累点,相同灌水量下,漫灌的有效氮含量均高于滴灌,但其有效氮利用率低于滴灌处理;不同施氮对春玉米干物质的差异随灌水量增加而增加.各处理水分利用效率与肥料偏生产力之间产生明显差异,高水低氮肥料偏生产力明显提高,但其水分利用效率低下,D1N1产量最高;在考虑作物产量及水肥利用效率时,采用滴灌方式,则灌水量288~360 mm、施氮量196 kg/hm2为推荐水肥措施. 相似文献
18.
Neelam Patel 《Agricultural Water Management》2008,95(12):1335-1349
Subsurface drip irrigation provides water to the plants around the root zone while maintaining a dry soil surface. A problem associated with the subsurface drip irrigation is the formation of cavity at the soil surface above the water emission points. This can be resolved through matching dripper flow rates to the soil hydraulic properties. Such a matching can be obtained either by the field experiments supplemented by modeling. Simulation model (Hydrus-2D) was used and tested in onion crop (Allium cepa L.) irrigated through subsurface drip system during 2002-2003, 2003-2004 and 2004-2005. Onion was transplanted at a plant to plant and row to row spacing of 10 cm × 15 cm with 3 irrigation levels and 6 depths of placement of drip lateral. The specific objective of this study was to assess the effect of depth of placement of drip laterals on crop yield and application of Hydrus-2D model for the simulation of soil water. In sandy loam soils, it was observed that operating pressures of up to 1.0 kg cm−2 did not lead to the formation of cavity above the subsurface dripper having drippers of 2.0 l h−1 discharge at depths up to 30 cm. Wetted soil area of 60 cm wide and up to a depth of 30 cm had more than 18% soil water content, which was conducive for good growth of crop resulting in higher onion yields when drip laterals were placed either on soil surface or placed up to depths of 15 cm. In deeper placement of drip lateral (20 and 30 cm below surface), adequate soil water was found at 30, 45 and 60 cm soil depth. Maximum drainage occurred when drip lateral was placed at 30 cm depth. Maximum onion yield was recorded at 10 cm depth of drip lateral (25.7 t ha−1). The application of Hydrus-2D confirmed the movement of soil water at 20 and 30 cm depth of placement of drip laterals. The model performance in simulating soil water was evaluated by comparing the measured and predicted values using three parameters namely, AE, RMSE and model efficiency. Distribution of soil water under field experiment and by model simulation at different growth stages agreed closely and the differences were statistically insignificant. The use of Hydrus-2D enabled corroborating the conclusions derived from the field experimentation made on soil water distribution at different depths of placement of drip laterals. This model helped in designing the subsurface drip system for efficient use of water with minimum drainage. 相似文献
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Effect of temporal variability in soil hydraulic properties on simulated water transfer under high-frequency drip irrigation 总被引：2，自引：0，他引：2
Ibrahim Mubarak Jean Claude Mailhol Rafael Angulo-Jaramillo Sami Bouarfa Pierre Ruelle 《Agricultural Water Management》2009,96(11):1547-1559
The effect of changes in the hydraulic properties of a loamy topsoil on water transfer under daily drip irrigation was studied over a cropping cycle. Soil water contents were measured continuously with neutron probes and capacitance sensors placed in access tubes (EnviroSMART) and were compared to predications made by the Hydrus-2D model. Three different sets of hydraulic parameters measured before and after irrigation started, were used.Our results demonstrated that, based on the assumptions used in this study, the accuracy of the Hydrus predictions is good. Graphical and statistical comparisons of simulated and measured soil water contents and consequently the total water storage revealed a similar trend throughout the monitoring period for the all three different sets of parameters. The soil hydraulic properties determined after irrigation started were found to be much more representative of the majority of the irrigation season, as confirmed by the accuracy of the simulation results with high values of the index of agreement and with values of RMSE similar in magnitude to the error associated with field measurements (0.020 cm3 cm−3). The highest RMSE values (about 0.04 cm3 cm−3) were found when the model used input soil parameters measured before irrigation started.Generally, changes in topsoil hydraulic properties over time had no significant effect on soil moisture distribution in our agro-pedo-climatic context. One possible explanation is that daily water application was conducted at the same time as maximal root water uptake. This meant the soil did not need to store total daily crop water requirements and consequently that the water redistribution phase represented a very short stage in the irrigation cycle. It is probable that irrigating in the daytime when crop evapotranspiration is highest could prevent the effects of a temporal change and other problems connected with the soil. Moreover, water will be always available for the crop. Further experiments are needed to justify the results and to study the effects of low frequency drip irrigation on soil hydraulic characterization and consequently on soil water transfer in order to improve irrigation scheduling practices. 相似文献