2D- Numerical Modeling and Investigating the Effect of Surface Slop on Water Content Distribution in Surface Drip Irrigation Using Finite Volume Method

Numerical simulation is a fast and inexpensive approach to studying optimal management practices. Therefore different model to simulation water content distribution in drip irrigation have been developed in which the general equation of water flow in soil (Richards equation) numerically is solved. In this study 2D equation of saturated-unsaturated flow in soil (2D Richard’s equation) was solved using finite volume method and Crank-Nicolson scheme. The soil hydraulic properties were modeled using the van Genuchten-Mualem relationships. The derived equation set was solved using Jacobi iteration method. Model calibration was done using measured water content distribution around thin-walled drip tubing installed at a depth of 6 cm in irrigated sandy loam soil carried out by Skaggs et al.(2004). Also present model result compared with the result of HYDRUS-2D. The results show with considering suitable boundary condition around the drip, present finite volume model predictions of water content distribution are found with good agreement by the HYDRUS-2D model and measured data. Also present model predicts the water content distribution with mean error less than 7 percent. After, with calibrated model, water content distribution during and after irrigation was investigated when the drip tube was installed in oriented soil surface.