Numerical Solution for Unsteady Two-Dimensional Infiltration in Irrigation Furrows

ABSTRACT Atwo-dimensional computer model was developed to simulate infiltration in an irregular furrow cross-section with a variable depth of water. The Crank-Nicolson method was used to differentiate the defining parabolic and elliptic partial differential equations. The system of linear and nonlinear equations were solved using Newton's generalized method. To improve the solution, the Kirchoff intergral transformation was defined such that it could be used for both saturated and unsaturated conditions. The computer simulation of infiltration was in close agreement with measured results. The model simulates one- and two-dimensional infiltration processes in surface irrigation and predicts the amount of infiltration as well as the position of the wetting front in the soil. Using the model to simulate infiltration in different sections along a furrow will lead to a more accurate evaluation of irrigation uniformity and efficiency. The model is applicable for continuous and surge flow irrigation. It can also be used to estimate the water loss in unlined canals.