Mejian Bai

• China Institute of Water Resources and Hydropower Research

Unreasonable fertilizer and irrigation applications and dosages in orchards in northern China result in poor vegetative growth and fruit quality. To reveal the combined effect of water and fertilizer coupling on vegetative growth and fruit quality, this study used pear as a field experiment material, considering: (1) irrigation lower limits (55%, 6...

Surface irrigation is the most widely used irrigation method in China. Surface irrigation performance is affected by many factors, such as land levelling precision, irrigation system layout, irrigation control rules and irrigation management. Compared to pressure irrigation, surface irrigation is more difficult to control. At present extensive surf...

Understanding the response of crop growth to water and fertilizer is helpful to improve their management and use efficiency. Three water and fertilizer coupling treatments were designed to carry out a two-season trial on two cabbage (Brassica oleracea L. var. capitata) cultivars in spring and autumn in the Beijing–Tianjin–Hebei region. The irrigati...

Two-dimensional shallow water and advection-dispersion equations were applied to describe the surface water and solute transport processes in basin fertigation. Then the fully implicit temporal solution was constructed for all terms of the governing equations in triangular spatial grid and an iterative coupled model for basin fertigation was develo...

The interaction between surface and subsurface water flows plays an important role in surface irrigation systems. This interaction can effectively be simulated by the physical-based models, which have been developed on the basis of the numerical solutions to the Saint-Venant and Richards’ equations. Meanwhile, the spatial variability of field physi...

Numerical models are convenient for the management of basin fertigation. However, the characteristic line approach, commonly applied to solve the advection-dispersion equation, presents disadvantages such as numerical oscillation at the vertical position of the solute concentration wave caused by cubic spline interpolation. To address this problem,...

Soil surface elevation and infiltration are two key variables that affect basin irrigation performances. A number of sets of spatially variable surface elevation and infiltration parameters were generated using stochastic modeling, and a 2D basin irrigation model was used to simulate irrigation for the generated sets. Strip, narrow, and wide basins...

Zero-inertia equations are more easily numerically solved than complete hydrodynamic equations. Thus, the zero-inertia equations were applied to describe the surface water flows in 2D basin irrigation. Then, finite-volume and finite-difference approaches in the spatial cell and cell interface spatially were applied to discretize the continuous and...

Full implicit solutions are constructed for all terms of the Saint–Venant equations and advection–dispersion equation. Thereafter, a global coefficient matrix for forming algebraic equations is established to realize the simultaneous solution of both surface water flow and solute transport equations and a full-coupled model between the surface wate...

Saint-Venant equations are accurately solved by a fully implicit solution, and a numerical model for furrow water flow is proposed with unconditional stability. Furthermore, this numerical model is extended to furrow networks. There are continuous hydraulic connections among multiple furrows by network junctions, thus the surface water flows of all...

The two-dimensional zero-inertia equations for basin irrigation were formulated as a standard scalar diffusion equation subject to Neumann boundary conditions. The formulation can handle anisotropic variations in hydraulic resistance. A numerical solution was developed using finite-volume method on unstructured triangular cells. The simulation perf...

The concept of major direction correction is proposed, which includes complete major direction correction, major direction correction without roughness, and no major direction correction, based on the dimensional splitting expression of a two-dimensional surface water flow model in surface irrigation. The dimensional splitting finite-volume methods...

Simulating basin surface water flow with anisotropic roughness has practical significance. Based on the complete hydrodynamic model, a two-dimensional surface water flow model of basin irrigation with anisotropic roughness was developed in this study by constructing an anisotropic roughness model in the source terms of the governing equation. Then,...

A two-dimensional coupled model is proposed for the diffusion and channeling of both surface water and solute in all possible directions in basin fertigation. In the spatial discretization of the governing equation based on the unstructured triangle grid, the physical variables at grid interfaces are reconstructed by means of the grid center values...

In surface irrigation, interaction between surface and subsurface water flows plays an important role, and this process can be effectively simulated by iterative coupled model of surface and subsurface water flows for surface irrigation. The water flow of surface irrigation exhibits a major characteristic which is the existence of wet-dry boundary....

Basin irrigation experiments were performed using conventional fertilization and fertigation methods under different inflow rate during the reviving irrigation of winter wheat. The spatial–temporal distribution of nitrogen in the basin surface water flow and soil with different fertilization methods was analyzed, the factors affecting the distribut...

Border coupled surface-subsurface flow model can well simulate, in physical mechanism, the non-linear interactions between surface flow and soil water, as well as soil water redistribution after border irrigation, playing an important role in large-scale border irrigation system evaluation. In this study, the one-dimensional complete hydrodynamic m...

A highly efficient and accurate numerical model of surface water flow and solute transport is useful in the design and evaluation of a basin fertigation system. In this study, a coupled model of surface water flow and solute transport for basin fertigation was first formulated. On the basis of the implicit-explicit time scheme of governing equation...

The authors propose a two-dimensional surface flow and solute transport model of basin irrigation with conventional fertilization. Specifically, based on the mean velocities and water depth obtained from the complete hydrodynamic model, the nonmean water flow velocities along the basin surface plane and vertical direction was constructed by use of...

The coupled surface-subsurface flow model for surface irrigation can effectively simulate the non-linear interaction processes of surface-subsurface flow as well as the soil moisture redistribution processes. In this study, a new coupled surface-subsurface flow hydrodynamic model is constructed based on the governing equations of a 1D complete hydr...

A basis of contrast for advanced basin fertigation method can be provided by simulating the one-dimensional surface flow and solute transport process of basin irrigation in traditional surface application of fertilizer. A nonuniform distribution field of water flow velocity and solute concentration along the basin and its arbitrary cross section we...

Land microtopography unevenness is a key variable affecting basin irrigation performances. Using stochastic modeling, a number of sets of spatially variable surface elevations were generated, and a two-dimensional basin irrigation model was used to simulate irrigation for the generated sets. Strip, narrow and wide basins, as well as graded and zero...

Improvement of stability, convergence and computational efficiency in numerical modeling of surface water flow and solute transport for border fertigation is useful to design and evaluation of border fertigation systems. In this study, a one-dimensional model for coupling surface water flow with solute transport for border fertigation is developed...

Based on the coupled model of surface-subsurface flow and solute transport for border strip fertigation established by the authors, the combination modes of technical factors of border strip fertigation were simulated to analyze the effect of the factors on performance of border strip fertigation system and determine the optimal ranges of the facto...

Based on the field experiments for border irrigation after scattering urea in the growing season of winter wheat, the distribution of soil water and nitrate before and after irrigation 2d under different inflow rate and amount of fertilizing were analyzed, meanwhile the storage efficiency in the crop root zone and the uniformity along basin length...

A two-dimensional irrigation model was used to simulate the effect of spatial variability of infiltration on basin irrigation performances under different microtopography, inflow and basin slope. The relationship among the influence degree, their spatial variance degree and other irrigation factors are discussed. The results show that following the...

Microtopography is among the most important factors affecting the performance of basin irrigation system due to its influence on the advance and recession processes. This study is based on field-measured surface elevation of 116 basins in North China. The spatial variability of basins microtopography was analyzed using geostatistics; the spatial st...

Based on the field experiments for fertilizing the urea at the regreening stage and anthesis stage of winter wheat, the distribution of soil water and nitrate nitrogen under different border strip fertigation strategies were analyzed. Meanwhile the border strip fertigation performance was evaluated, and the suitable border strip fertigation strateg...

Based on the field experiments for fertilizing urea of winter wheat in the growing season, the distributions of soil water and nitrate as well as their variation under different border fertigation strategies are investigated. The distribution uniformities of soil water and nitrate in the effective root zone are analyzed. The results show that the i...

The reliability of numerical simulating the micro-topography spatial variability effect on basin irrigation system is verified by field experimental data. Two kinds of micro-topography including the stochastically generated and generated according to measured land surface relative elevation are considered. The 2-D irrigation model is applied to sim...

The influences of microtopography undulation degree Sd and the discrepancy of undulation location distribution on horizontal border irrigation system were analyzed by using numerical experiments for evaluating the effect of microtopography spatial variability on irrigation quality. The result shows that microtopography undulation degree obviously a...

Based on a great amount of field survey data, the semi-variance methodology is applied to analyze the spatial variability characteristics of field surface relative elevation (SRE) in different type of border fields. The correlation between the field geometry parameters and spatial variability characteristics of SRE is evaluated, and the ability of...

A statistic analysis was conducted for surface relative elevation data from typical field experiment under different survey grid spaces. The feasible survey grid space for the field with small dimension was discussed by comparison of the manpower input of the survey, description of the microtopography conditions and the precision of the estimated e...