ISWC OpenIR  > 水保所知识产出(1956---)
垄沟灌溉土壤水分入渗模拟研究
张勇勇
Subtype博士
Thesis Advisor吴普特
2013-05
Degree Grantor中国科学院研究生院
Place of Conferral北京
Keyword垄沟灌溉 Hydrus-2d 入渗 湿润体特征 沟垄比例
Abstract

垄沟灌溉是在垄作沟播间(套)作种植基础上,通过改变地面微地形形成宽“垄
沟结构”,利用灌水沟输水并借助土壤毛管力作用,将水分侧渗到宽垄种植带的地面
灌水方式。其仅对沟内种植作物进行灌溉,并依靠土壤水分侧渗实现水分在垄沟间的
分配,满足垄沟种植带的作物需水要求。如果灌溉系统设计和管理不善,导致土壤水
分交汇和深层渗漏严重,灌水均匀度差,因此需要确定垄沟灌溉适宜的沟垄比例,而
灌溉土壤水分运动和空间分布规律是确定适宜沟垄比例的重要依据。本研究通过室内
土槽模拟垄沟灌土壤水分入渗过程,利用 HYDRUS-2D 软件数值模拟垄沟灌土壤水
分运动过程;定量评价分析土壤物理性质、耕作技术参数和灌水技术等因素对垄沟灌
入渗过程的影响程度和湿润体特征的影响;建立垄沟灌土壤入渗的人工神经网络模
型;通过理论分析和模拟计算确定垄沟灌适宜的垄宽和沟垄比例,为田间试验和灌水
技术优化管理提供理论支撑。初步得出以下主要研究结果:
(1)基于非饱和土壤水动力学理论,修正了土壤入渗动力学模型使其适用于垄
沟灌土壤入渗过程。推导出重壤土和砂壤土垄沟灌土壤水分运动参数,确定出垄沟灌
土壤入渗的初始条件和边界条件,利用 HYDRUS-2D 软件数值求解并通过试验验证
垄沟灌土壤水分入渗的动力学模型,该模型能较好地模拟垄沟灌土壤水分入渗过程。
土壤水动力学模型在模拟垄沟灌累积入渗量和湿润锋运移距离精度较高,而土壤含水
量空间分布方面模拟精度稍偏低。
(2)通过数值模拟,分析了不同影响因素对垄沟灌湿润体水分分布和入渗量的
影响。相同灌水条件下,土壤质地对水分分布和累积入渗量影响明显,在垄沟灌工程
设计中需根据土壤质地对灌溉系统进行设计和优化,在质地重的土壤下应用垄沟灌技
术较好;沟底覆膜改善土壤水分在垄沟间的分配,使垂向入渗距离减小,有利于土壤
水分侧向入渗,灌水后土壤含水量在垄沟间分配更加均匀,因此,沟底覆膜是垄沟灌
溉较为理想的田间措施;沟底宽度对垄沟灌水分分布和累积入渗量影响显著,对于浅
根系作物应选择宽沟种植,深根系作物应选择窄沟种植;灌溉水深对垄沟灌溉累积入
渗量有影响,同时对水平侧渗影响显著,相同灌水条件下,灌溉水深增加,土壤水分
从沟向垄的侧渗过程更加明显,累积入渗量亦增加,较高的灌溉水深有利于提高灌溉
水利用效率和灌水均匀度。(3)通过统计学方法,评价了不同因素对垄沟灌溉土壤入渗影响的显著程度和
入渗模型的适用性。通径分析方法表明,灌水湿周、容重、过水断面面积和初始含水
量对累积入渗量变化的影响程度分别为 51.62%、47.2%、38.12%和 6.44%,垄沟灌土
壤入渗主成分因素为灌水湿周和土壤容重。统计学指标评价了 Kostiakov-Lewis 模型、
Philip 模型、Kostiakov 模型和 Horton 模型在模拟垄沟灌入渗过程中的适应性,其中
Kostiakov-Lewis 模型模拟效果较好。在上述研究基础上,建立了以湿周为主成分因
素的垄沟灌累积入渗量简化计算模型,该模型计算结果较好,可用于推算垄沟灌入渗
量的变化过程。
(4)采用空间矩分析法研究了不同因素对垄沟灌溉湿润体特征量的影响。不同
影响因素的矩分析湿润体呈扁平椭圆状,土壤初始含水量增加,湿润体椭圆重心纵坐
标 z c 、椭圆的长轴 σ x 和短轴 σ z 均增大,椭圆面积亦增大,初始含水量对椭圆的特征
量影响较其它因素小;土壤质地对椭圆特征量的影响差异明显;灌水沟底宽对椭圆的
特征量影响非常明显,随着沟底宽度增大,椭圆重心纵坐标 z c 、椭圆的长轴 σ x 和短
轴 σ z 均增大,椭圆面积亦增大;随着入渗水头的增大,土壤水分分布的椭圆重心纵
坐标 z c 减小,而椭圆长轴 σ x 和短轴 σ z 随之增大,椭圆面积亦增大,椭圆的偏心率 e
较大,土壤水分侧向入渗过程明显。
(5)基于矩分析的垄沟灌溉入渗湿润体的特征量,改进 BP 神经网络,采用贝
叶斯快速学习算法,建立垄沟灌溉土壤水分入渗的人工神经网络模型,改进的 BP 人
工神经网络模型模拟矩分析的湿润体特征量精度高,预测结果较好,利用具有高度非
线性映射功能的BP人工神经网络模型能较好刻画垄沟灌溉土壤水分空间分布的复杂
特性。
(6)基于土壤水分运动模拟,初步提出了垄沟灌溉适宜沟垄比例的确定方法,
并进行了实例研究。通过土壤水分运动模型模拟了不同垄宽下土壤水分空间分布,并
采用欧式距离,计算了其与间(套)作种植适宜土壤含水量相互匹配程度,最终确定
了模拟条件下重壤土垄沟灌适宜的沟垄比例为 60 cm : 75 cm,砂壤土为 60 cm : 70
cm,可为间(套)作垄沟灌溉系统的合理设计提供依据。
关键词: 垄沟灌溉;HYDRUS-2D;入渗;湿润体特征;沟垄比例

Other Abstract

Ridge-furrow irrigation was birthed and developed in accompany with ridge-furrow
intercropping fields. The ridge-furrow configuration is built by shaping the soil surface
with alternate ridges and furrows along the contour. In ridge-furrow irrigation, the flow
water only transports on furrows and supplies water to crops. The flow water on furrows
infiltrates into ridge-furrow configuration by capillarity forces, and lateral infiltrated water
volume must meet the needs of the plants grown on the ridges of soil or raised beds.
Improper ridge-furrow irrigation design and management in fields has some disadvantages,
such as interference infiltration, higher deep water percolation, and lower irrigation
uniformity. Soil water dynamics and distribution under ridge-furrow configuration can
provide guidance to design the appropriate width ratio of furrows to ridges in ridge-furrow
intercropping fields. Soil infiltration characteristics in ridge-furrow irrigation were
investigated in laboratory experiment by using rectangular soil chambers. Soil water
movement was numerically simulated by using HYDRUS-2D software. The effects of
variables—soil physical properties, cultivation technique parameters, and irrigation
technique parameters—on irrigated soil infiltration process and wetting patterns were
quantitatively evaluated. The optimized artificial neural networks model was developed to
predict soil infiltration characterization under ridge-furrow irrigation. The appropriate
width ratio of furrows to ridges under ridge-furrow irrigation was investigated by
optimized method and simulated calculation, which provide theoretical guidance to
irrigation technique optimization and management in field experiments. The mainly results
are as follows:
(1) Soil water movement equation was revised to simulate water infiltration in
ridge-furrow irrigation based on variably saturated flow theory. Soil hydraulic parameters
in heavy loam soil and sandy loam soil were deduced. The initial and boundary conditions
were determined in ridge-furrow irrigation. Soil water movement equation was solved by
using HYDRUS-2D software and accurately simulated soil water dynamics under  ridge-furrow irrigation. There were higher simulated precision in cumulative infiltration
and wetting distances, while a low simulated precision was shown in soil water distribution
in ridge-furrow irrigation through the hydrodynamic model.
(2) The effect of different variables on soil water distribution and cumulative
infiltration was investigated by using numerical simulation. Soil texture had a significant
effect on soil water distribution and cumulative infiltration during the same ridge-furrow
irrigation event. Ridge-furrow irrigation design and optimization is relied on soil texture,
and the irrigation method should be implemented in finer soil. Film-covering furrow
regulated water distribution between ridges and furrows. The vertical infiltration distance
was significantly reduced, while lateral infiltration distance was increased. Film-covering
furrow should be implemented in ridge-furrow irrigation fields. Furrow size had an effect
on soil water distribution and cumulative infiltration. We should select narrow furrows for
crops with deep rooting depth and wide furrows for crops with shallow rooting depth.
Furrow water depth had an effect on lateral infiltration distance and cumulative infiltration.
Lateral infiltration distance and cumulative infiltration tended to increase with increase of
furrow water depth. The higher furrow water depth is recommended in ridge-furrow
irrigation to improve water use efficiency and irrigation uniformity.
(3) The effect of different variables on soil infiltration characteristics and infiltration
models were quantitatively evaluated by using statistical methods. Ridge-furrow irrigation
was conducted in laboratory experiment, and the path analysis method was applied to
quantify the effect of variables on cumulative infiltration. The results showed that 51.62%,
47.2%, 38.12%, and 6.44% of variability in cumulative infiltration was explained by total
variations in wetted perimeter, bulk density, flow section area, and initial soil water content.
The principal component variables were bulk density and wetted perimeter under
ridge-furrow irrigation. The performance of four infiltration models—Philip model,
Kostiakov model, Kostiakov-Lewis model, and Horton model—was investigated on the
basis of evaluation indices. The Kostiakov-Lewis model provided the best description of
the relationship between cumulative infiltrations with infiltration time. A furrow
cumulative infiltration model taking wetted perimeter into consideration was developed.
The validations by experimental data indicated that the variation of cumulative infiltration
against infiltration time could be effectively simulated by the furrow cumulative infiltration
model.
(4) The spatial moment analysis method was applied to quantify the effect of variables
on the wetting pattern. The results showed that the wetting pattern was like an ellipse with  a long axis in the horizontal direction. The longitudinal coordinate of the mass center of the
ellipse, z c , the long axis, σ x , and the minor axis, σ z , were increasing with the increase of
initial soil water content, respectively, and the area of the ellipse was also increasing.
Initial soil water content had a minor effect on the ellipse characteristics compared with
other variables. Soil texture had a significant effect on the ellipse characteristics. z c , σ x , and
σ z were increasing with the increase of furrow size, and the area of the ellipse was also
increasing. σ x and σ z were increasing with the increase of furrow water depth, and the area
of the ellipse was also increasing. However, z c was decreasing with the increase of furrow
water depth because of higher water depth. The eccentricity of higher furrow water depth
was greater and lateral infiltration distance was further.
(5) Back propagation artificial neural network (BP-ANN) model in ridge-furrow
irrigation was established based on water moments data to predict irrigated soil infiltration.
The Bayesian arithmetic was used in the BP-ANN model. The results showed that the
optimized BP-ANN model is reasonably accurate and can provide an easy and efficient
mean of estimating complex soil water distribution in ridge-furrow irrigation.
(6) The method of determining the appropriate width ratio furrows to ridges was
proposed in ridge-furrow irrigation. Soil water distribution in different ridge widths was
simulated in ridge-furrow irrigation by using numerical simulation. The appropriate width
ratio of furrows to ridges was determined by soil water content matching principle. The 60
cm: 75 cm and 60 cm: 70 cm width ratio of furrows to ridges are recommended in heavy
loam soil and sandy loam soil in ridge-furrow irrigation, respectively. These results can
provide guidance to reasonable design of irrigation design and field extension in
ridge-furrow intercropping fields.
Key words: ridge-furrow irrigation; HYDRUS-2D; infiltration; wetting pattern; width
ratio of furrows to ridges

Language中文
Document Type学位论文
Identifierhttp://ir.iswc.ac.cn/handle/361005/8984
Collection水保所知识产出(1956---)
Recommended Citation
GB/T 7714
张勇勇. 垄沟灌溉土壤水分入渗模拟研究[D]. 北京. 中国科学院研究生院,2013.
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