Numerical Simulation of Soil moisture under Subsurface tape Drip Irrigation

To design drip irrigation system، the distribution and changes in soil moisture should be determined in situ that it is very costly and time consuming. This study evaluated the performance of HYDRUS-2D model to estimate soil moisture after irrigation under subsurface line source was in a heterogeneous heavy soil. Irrigation was done at three tape installation depths of 10، 20 and 30 cm with three volumes of، 15 and 20 litters in silty clay soil with three repeating. Observed and simulated data were compared using statistical indices i. e. RMSE، nRMSE and CRM. Results showed that the minimum and maximum of RMSE values were 0. 013 and 0. 045 cm3. cm-3، respectively. nRMSE of all treatments except of one، the second replication of 10 liters of irrigation water with installation depth of 20 cm، were less than 10% categorized in the excellent class of soil moisture simulation. Maximum and minimum values of CRM were 0. 100 and -0. 065، respectively. Results from the model showed this model can be used in the design and management of subsurface drip irrigation systems in heterogeneous soils with heavy texture.