Comparing the performance of different hydraulic models and provide a BMA model to simulate water movement in soil

There are several different hydraulic models to estimate unsaturated conductivity, but a few researches have evaluated the ability of these models for simulation of water movement in porous media. In this study, we evaluated the performance of 5 different hydraulic models, which used in HYDRUS-2D model (van Genuchten-Mualem, modified van Genuchten, Brooks and Corey, Kosugi and Durner) in simulation of water content profile in surface drip irrigation. Moreover, in order to improve results, a combinational averaging model using BMA method, based on weighting to the hydraulic models performance is presented. In this study, a sandy-loam soil was irrigated using T-Tape drip tubing. Two drip irrigation trials (8 and 24 hour) were carried out. Evaluation of simulated and measured soil water content was performed by using adjusted coefficient of correlation, RMSE and normalized root mean square errors (NRMSE). Based on the results, the NRMSE in soil water content prediction for 8 and 24 (hour) times was calculated in the range of 20 to 29 and 26 to 39 percent, respectively. In addition, the RMSE for 8 and 24 (hour) times was calculated in the range of 0.04 to 0.06 and 0.05 to 0.09 (cm3cm-3), respectively. The average regression coefficient for 8 and 24 (hour) times was calculated 0.93 and 0.89, respectively.