SaltMod model performance in simulating water level, volume and salinity of drainage in free and controlled drainage

Drainage systems are used to control soil and water salinity, which requires time and money to know. Drainage simulation models can be used to save cost and time. The present study evaluated the performance of the SaltMod model in simulating the water table, volume and salinity of the drain. Simulations were performed for three important crops of Moghan plain (wheat, barley and corn) and three treatments of FD, CD70 and CDch. To evaluate the controlled drainage in the model, the drainage control coefficient (Frd) was considered. FD treatments for calibration, CD70 and CDch treatments were selected for validation. After simulation, the degree of correspondence between the real and simulated values ​​was checked. In water table simulation, the mean RE for wheat, barley and corn was 17.3, 11.3 and 11% and the mean RMSE was 0.13, 0.07 and 0.07, respectively. The same indices were obtained for drainage volume of 16, 22 and 17% as well as 0.05, 0.07 and 0.06. These results confirm the acceptable accuracy of the model. Then the model was used to investigate the effect of drainage control factor, irrigation water depth and drainage installation depth on water table, volume and salinity of the drain. Therefore, the model can simulate different irrigation and drainage managements in Moghan plain.