Determining the Suitable Emitter Installation Depth Under Subsurface Drip Irrigation Using HYDRUS 3D Model

In the present study, field experiments were carried out at the research fields of the Agricultural Faculty of the University of Tabriz in a sandy-loam soil in order to determine the wetting pattern dimensions and soil moisture distributions in the vicinity of an emitter and also in a domain between the two adjacent emitters in a subsurface drip irrigation system. The obtained data from experiments were compared to the results from HYDRUS two-dimensional and three-dimensional simulations. Results showed that HYDRUS-3D was more efficient than HYDRUS-2D in simulating wetting pattern dimensions on the constructed soil profiles one just at the emitter location and the other between the two adjacent emitters with RMSE values of 2.54 and 3.96, respectively. Comparison of the obtained values from the two and three dimensional simulations showed that the two models had acceptable accuracy in simulating the soil water distributions on the profile at the emitter location. Also, by increasing the irrigation duration from 1 hour to 4 hours, the value of RMSE between soil moisture values obtained from the two and three dimensional models decreased from 0.068 to 0.025. Considering the good accuracy of the three dimensional model, the calibrated model was run for three different emitter installation depths and the suitable emitter installation depth for sweet corn production in the studied soil was recommended to be 30 cm based on the plant maximum water need, minimum deep percolation and evaporation losses and the plant rooting system.