Numerical Analysis And Simulation Of Soil Water Movement Under Subsurface Irrigation

Numerical simulation is one very important method for apprehending law of soil water movement. It can provide theoretic guidance for design of irrigation pipe network and establishment of irrigation system. Through summarizing on numerical simulation of soil water movement and development of numerical simulation software, it can be found that the methods of dealing with subsurface irrigation pipe's boundary condition are not perfect, and some numerical simulation software for soil water movement at present are restricted on inputting soil hydraulic parameters. These are the main problems, which will be solved in this project.Based on the principle of soil water dynamics, a two-dimension mathematical model of soil water movement is presented for subsurface irrigation. A mathematical model whose variable is water head can simulate the effects of water head and properties of subsurface irrigation pipe on irrigation. The methods how to deal with the pipe boundary condition, and how to calculate were discussed detailedly. Alternative direction implicit technique (ADI) that is used to solve the subsurface irrigation mathematical model was introduced minutely.After setting up mathematical model for subsurface irrigation, a software system called after WMTrace for numerical simulation of soil water movement under subsurface irrigation was developed by analyzing, designing, programming, testing, repeated proceeding and progressing based on the object-oriented method. Building soil hydraulic parameters automatically and inputting data of initial water content or data of initial water head in soil profile are supported. WMTrace was tested strictly. The software run reliably for numerical simulation under subsurface irrigation, and can be operated expediently. The software may be used to simulate one dimensional or two dimensional soil water movements. At the same time, it has the function to simulate redistribution of soil water in soil profile.By indoor experiment, the mathematical model, boundary condition and calculation methods are validated. It shows that mathematical model has good...