Simulation of Water Movement in Unsaturated Soil Affected by Different Irrigation Management (Case Study: Mohammadshahr Plain of Karaj)

Simulation of water movement in soil profile and recognition of the effect of irrigation systems on soil moisture dynamics is of great importance. For this purpose, one-dimensional LEACHW numerical model was used in selected agricultural areas of Mohammadshahr plain of Karaj. By describing 9 profiles the soil in 3 selected fields and gardens and taking into account the initial moisture conditions and monitoring their changes during the crop season or simulation period, the LEACHW model was implemented and the estimated moisture values of the model were measured with measured moisture values. The results were compared by means comparison test, sensitivity analysis of the model, and the model was again run on the basis of calibrated parameters and the amount of water lost and remaining in the soil profile during the growing season. At the output of the model, the amount of water lost and remaining in the soil profile was estimated. The results showed that modern irrigation systems were not effective in aquifer nutrition; therefore, one of the ways to increase water productivity is to reform traditional irrigation systems and move towards the development of new irrigation systems. Undoubtedly, the main task of developing new irrigation systems to ensure the country's food security is to optimize water use in the agricultural sector as the main consumer of water resources in the country.