The Study Of Regulation And Numerical Simulation Of Soil Water Movement Of Lower Presure Subsurface Drip Irrigation

This paper has studied the soil water movement regulation of subsurface drip irrigation. It has important academic significance and using value to improve the design precision of Subsurface Drip Irrigation (SDI) and guide the run of the irrigation system. This paper has based on the principle of soil water dynamics bulk density in Yangling Shaanxi through experiment, and simulated water movement regulation of SDI. The results were as follows:1) This paper has studied dripper outflow characteristics of simple drip irrigation pipe, tested the dripper outflow regulation under conditions of different water head pressure, different diameter of aperture, sleeved pipe and non-sleeved pipe etc, got the changes outflow increased with the increase of the water head pressure and diameters of aperture, which presented the power series relationship. Under the same conditions, the outflow changes of sleeved pipe and non-sleeved pipe were prominent, has found no matter under the condition of sleeved pipe or non-sleeved pipe, the index trend of outflow and pressure curve showed decreasing, and the variation range was between 0.4m and 1.0m. There was established the formula about outflow, which was approaching to the actual value according to verification.2) The soil water characteristic curve and diffusivity of loam of two kinds of density was measured, and the parameters were also simulated, by which the VG model parameters were obtained, and got the figure of soil water characteristic curve was similar except volumetric moisture content; the relationship of soil water diffusivity and soil moisture content accorded to the index series relationship.3) There has established mode of SDI soil water movement of lower presure, deduced the solving of finite element, and through soil box experiment of gravity type SDI, which was designed with orthogonal included 9 kinds, measured the dynamic moisture content changes of soil infiltrated water and dripper fluctuation in discharge process under SDI conditions, and got the water movement process and distribution experiment data in soil, simulated the changes of moisture content movement distribution and fluctuation in discharge under SDI used established model in this study, compared simulated values with measured values, which has analyzed, the results were showed, the simulated compute accorded to experiment results;4) Using the established model, the effect of irrigation technical elements, which concluded different apertures, different water pressure, different buried depth trickle and...