عنوان مقاله [English]
To drainage design and management it is necessary water flow toward drain, water table variation between drains and drainage discharge have been simulated. With recent development in numerical method, it is possible the none-linear differential equation governing saturated-unsaturated flow in soil is numerically solved. In this study a computer model has been developed in which two dimensional equation of saturated-unsaturated flow in soil is solved using finite volume method and Crank-Nicolson scheme. The soil hydrodynamic properties function and soil moisture characteristic curve proposed by Van Genuchten were employed. After model calibration and evaluation, water table variation between two drains with 20 m distance and installation depth of 1.2 m was simulated. The result showed during discharge phase water table falls very fast at the first and then falling speed reduces until reach a constant value. During recharge phase water table raises very low at the first and then rising speed increase. Drainage discharge has similar behavior same as water table. Drainage discharge has a lag time related to time that recharge begins. In this study the lag time was 3.125 day.