Research On Water Flow Model And Numerical Simulation For Border And Furrow Irrigation

Worldwide, border irrigation and furrow irrigation are more commonly used compared with pressurized irrigation systems, such as sprinkler and micro-irrigation systems. They have the advantages of lower investment and operating costs and convenient management. But border irrigation and furrow irrigation can have disadvantages, such as possible water wastage and lower irrigation efficiency. So research is justified into the theory of border and furrow irrigation, to improve and perfect irrigation design. From a combination of laboratory and field experiments, a theoretical analysis and numerical simulation is proposed for border irrigation and furrow irrigation practices. The major elements include:1. Mathematical models of border irrigation and furrow irrigation were set up, based on unsaturated soil water movement theory. The software models and simulation results were verified by laboratory experiments, achieving good agreement between predictions and measurement. The main factors influencing border irrigation and furrow irrigation infiltration characteristics were determined. Key parameters of soil wetting movement linked to a two-dimensional infiltration model were established which included the wetted perimeter beneath furrows. The analysis provides understanding of the infiltration mechanism related to border irrigation and furrow irrigation. This is a sound basis for improving surface irrigation practice through optimization.2. The literature on border irrigation and related infiltration functions was examined. Assuming that the trajectory of the advance of the water front in border can be represented by a simple power function relating advance distance and time and that the infiltration function has the familiar Kostiakov-Lewis characteristic form then two methods were proposed to predict infiltration and the water advance process. Assumptions of both methods included using the Lewis-Milne equation to derive a volume balance model. The power function advance parameter was found to take the values 0.70, 0.75 and 0.80 and a simplified analytical model of border irrigation was created. The model was checked using laboratory and field experiment data, showing that the model is reasonable and has some advantages. It has a strict physical foundation, is simple to calculate and gives solutions of high accuracy. It is also found that advance parameter values of 0.7~0.8 are reasonable, and indicated that two solution methods proposed to determine power function advance parameters are reliable.3. Area shape factor parameters for wetted area were derived through theoretical analysis to identify an analytical model of furrow irrigation. An iterative algorithm was developed to solve the model equations using Matlab software. The results show that the problem of getting the figure coefficient of infiltration water directly with difficulty was solved .So the water flow process of furrow irrigation was successfully simulated.4. Using the volume balance approach with a generalized surface water profile, a Philip infiltration formula equivalent to the Kostiakov–Lewis model and an infiltration parameterα= 0.5, then the Philip infiltration parameter and channel roughness values were deduced from border and furrow irrigation data. Analysis by Matlab software suggested that the infiltration parameters do not have major influence but that the Manning roughness is important when the power function advance parameter takes different values. The model was checked using field data to show that determinations of the Philip infiltration parameter and Manning roughness are reliable. It also showed that progress of advance was not very sensitive to the Manning roughness values.5. Field experiments were undertaken to determine field application efficiency and to compare these values with values simulated by the SRFR software. Results show that the margin of error is reasonable, indicating that the SRSF software is appropriate for analysis of border and furrow irrigation. Based on simulation using the SRSF software, the correlation of irrigation technique element was changed, the result discovered that the optimized correlation of reasonable irrigation technique element under different condition of border irrigation and furrow irrigation. It can be used to guide the farmers'irrigation, reduce the waste of water resources, enhance the irrigation application efficiency and distribution efficiency, and attain the aim of saving water.Border and furrow irrigation water movement involves soil water infiltration and surface water movement, the influencing factors are numerous and very complicated. In this paper, border and furrow irrigation model on soil water infiltration and water movement was studied systematically and deeply, but how to combine these two aspects more systematically is a very complex problem in irrigation research, and it needs to do more researchers in future.