Simulation of Wetting Pattern Dimensions in the Subsurface Drip Irrigation with Empirical, Analytical, and Numerical Models

Today, use of drip irrigation systems for row crops is widespread. One of these systems is subsurface drip irrigation. Knowing the dimensions of the wetting pattern is essential for drip irrigation system design. To design a proper system, as field experiments are time consuming and expensive, using computer models is recommended. In this regard, the present study examined the performance of three models including empirical Kandelous et al. model, analytical WetUp, and numerical HYDRUS-2D models in subsurface tape irrigation. Treatments included three volumes of water i.e. 10, 15, and 20 liters per meter length of tape and three installation depths of 10, 20, and 30 cm, in three replications. Comparison between the measured and simulated wetting dimensions were made by using four statistical indices i.e. RMSE, nRMSE, CRM, and MAE. RMSE values of horizontal wetting extension for Kandelous et al and HYDRUS-2D models were 0.051 and 0.066 m, respectively, while for vertical wetting extension, the values of RMSE were 0.052 and 0.078 m, respectively. nRMSE values of horizontal wetting extension for Kandelous et al. and HYDRUS-2D models were 15.46% and 19.71 %, respectively, being in class ‘good’. nRMSE values of vertical wetting extension for Kandelous et al and HYDRUS-2D models were 15.99 and 23.74 %, respectively, considered as ‘good’ and ‘fair’, respectively. Statistical indices calculated for WetUp model was not in acceptable range. For horizontal and vertical wetting dimensions, CRM and MAE indices for Kandelous et al model were the lowest values. Overall, the Kandelous et al model had the best estimation.