The evaluation of effect of increase irrigation efficiency along with increased acreage on the return water and underground water storage using SWAT model

The continued increase in demand in arid and semi-arid countries, increasing the gap between supply and demand for water in the future. Therefore, in these areas, especially in the agricultural sector an urgent need for water resources management, demand management and allocation is to avoid critical situations. The aim of this study was to evaluate the effects of increasing irrigation efficiency along with the development of cultivation on return water, and the reserves of underground water using SWAT model. SWAT model is a conceptual and half- distribution model at the basin scale that has high computational efficiency. After the simulation basin during the period 2005 to 2014 in base conditions and perform calibration and validation of model outputs, two scenarios of increased irrigation efficiency without increasing the area under cultivation and increasing irrigation efficiency along with increased cultivation was introduced to the models. Based on the results, by increase irrigation efficiency, the water used in agricultural production decreased from 330 million cubic meters per year to 186 million cubic meters per year in base conditions. Also the volume of return flow to the area decreased of 133 million cubic meters per year in base scenario to 0.22 and 1.96 million cubic meters per year in the scenario of increased irrigation efficiency without increasing the area under cultivation and increasing irrigation efficiency along with increased acreage respectively. The return of the amount of water feeding the aquifer from 29.6% in basic conditions with increasing irrigation efficiency reaches zero.