Evaluation of Different Models to Estimate Wetting Patterns for Drip Irrigation in a Loamy Soil

Decreasing of fresh water resources and increasing competition for water by industrial, agricultural and urban users has been enlightening the needs for using of systems with the least water losses. Drip irrigation system has the least water losses as deep percolation and Evaporation. Dimension of wetting pattern is the most important factor to control deep percolation. Several models have been improved to predict the dimension of wetting patterns. In this study, the accuracy of several approaches used to estimate wetting zone dimensions was evaluated. This models including the numerical Hydrus 2D/3D model, the analytical WetUp software and two empirical models including Amin-Ekhmaj and Schwartzman -Zur. The average of RMSE for both directions was 8 percent for Hydrus 2D/3D, which showed that this model has very good accuracy. The ability of analytical WetUp software to estimate the depth and radius of wetting front was good and poor with 16 and 32 percent of RMSE respectively. Amin-Ekhmaj model has a good accuracy with 13.5 percent average RMSE and finally Schwartzman -Zur estimation of the wetting shape were not satisfactory.