Numerical Simulation Of Point Source Infiltration Under Gravity Subsurface Drip Irrigation

This paper had deeply studied the soil water movement regulation of the subsurface drip irrigation. It had important academic significance and utilizing value to improve the design precision of Gravity Subsurface Drip Irrigation, extending scientific and technological application of subsurface drip irrigation and guiding the run of the irrigation system. simulated water movement regulation of SDI. The results were shown as follows:1) The characteristic curve of soil moisture detention and soil moisture diffusivity of loam and sandy loam of two kinds of density was measured, and the parameters were also simulated. We also abtaind the VG model parameter, This showed VG model can be used very well to express the soil water retention and diffuivity and soil water content curve.2) We established a three-dimensional axisymmetric model of soil water movement of GSDI and deduced the solving of finite element, The soil box experiment of gravity type SDI, which was designed with orthogonal included six kinds, measured the dynamic moisture content changes of soil infiltrated water under SDI conditions. We also got the water movement procession and distribution experiment data in soil and simulated the changes of moisture content movement distribution and fluctuation in discharge under SDI using established model in this study, compared that simulated values with measured values, which has analyzed, the results showed that the simulated volumes had little difference from experiment results.The established model can be used to simulate the water soil movement under drip irrigation.3) Using the established model, to simulate the effect of irrigation technical elements, which concluded different apertures, different water pressure, different buried depth trickle and different soil density etc. Water pressure and apertures had smaller effects on soil water movement with the same irrigation quantity, so they can be neglected when designing the gravity surface drip irrigation pipes. However, Water pressure and apertures have an evitable influence on trickle discharge rate compared to other factors. We can design water pressure and apertures of the drip irrigation pipes only according to field length and water-head losses of seepage pipes. Smaller water pressure can be also used to lower invest to the project,which could offer definite academic basis for the design and operation of SDI system.The water pressure and apertures had significant effects on the trickle discharge,which could offer definite academic basis for the design and operation of SDI system.4) Parameters of the soil water characteristic curve and diffusivity were simulated according to available date of several soil textures in Loess Plateau, by which the VG model parameters were obtained and soil water movement effect had been simulated in different apertures and water pressures. Which provides a reference for the extend application of gravity subsurface drip irrigation in Loess Plateau.