Improving Model Efficiency of HYDRUS-2D by Considering Temporal Variability in Soil Hydraulic Properties

In recent decades، using drip irrigation has been developed because of water resources deficiency. As irrigation system design and its installation is expensive and time consuming، so its designing should be in a way which the system can supply plant water requirement. Nowadays، there are models that can simulate the soil moisture، according to different conditions. In this study، the performance of HYDRUS-2D has been assessed، by considering temporal variability of soil hydraulic properties. In a field under corn crop and irrigated with tape in south of France، soil moisture at every 10 cm depth until 150 cm of soil measured by a neutron probe was compared to simulated moistures by model according to two statistic indices، i. e. Root Mean Square Error (RMSE) and efficiency factor (EF). By considering soil hydraulic properties variation، RMSE values reduced from 0. 061 to 0. 022 cm3/cm3 and efficiency factor of model increased from 8% to 88%. Significant effect of these differences has been evaluated by using SPSS software and the result showed that the variation of soil hydraulic parameters in first irrigation was considerable and HYDRUS-2D model has a good performance in simulating the soil moisture at different depths. It is suggested that before installing system or implement of irrigation management، the system performance was evaluated by this model، and the best system management and design would be chosen.