Simulation of movement of water and solutes in soil by HYDRUS model to determine the suitable depth of dripper

Irrigation with saline waters and solute transport to soil surface by capillary can accumulate solutes. Current study have been carried out to simulate the water flow and solute transport in soil by Hydrus model in order to determine the suitable depth of dripper in the grape garden that was located in Amirabad village in Birjand city in 2015.Samples were taken from the 0, 30, 60 and 90 cm of soil during the 3 irrigation interval and then the amount of soil sample moisture have been determined in the laboratory then the amount of moisture have been entered in Hydrus- 1D model. The amount of soil hydraulic parameters have been determined by inverse solution. Outputs of Hydrus- 1D have been entered in Hydrus- 3D model and the model have been executed. Results indicated that the amounts of Root Mean Square Weighted Error (RMSE), Mean Weighted Absolute Error (MAE) were 9 and 6 percent, respectively. According to the moisture and salinity profiles obtained from Hydrus-3D model, it was suggested to place dripper in depth of 32 cm. In order to check the accuracy of suggested depth Some Scenarios have been considered in Hydrus-2D model. In this scenarios, the dripper have been placed in the depths of 15, 20 and 25 cm. According to the obtained concentration profiles at the end of the simulation period for the mentioned depths, when the dripper have been placed in the depth of 25 cm, the amount of solute accumulation reaches to zero at the soil surface that confirms the results obtained by Hydrus- 3D so it is better to place dripper in the depth of 25-32 cm.