In determining the water that can be allocated for different uses, including agriculture (as the main consumer), the most important step in this era is the proper management of groundwater resources. The observance of water consumption within the limit of allocated water ensures that the consequences of the exploitation of groundwater resources and the sustainability of development are guaranteed, and operators use technological methods to increase the efficiency of using water resources for more production in proportion to the amount tend to available water. In this article, first, the method of calculating the water allocated to the agricultural sector in the country has been studied and criticized. In this study, it was found that in the formula for calculating the current allocated water, the component of agricultural return water as an effective parameter causes a huge error in the calculation of allocated water. Then, a new formula for the calculation of allocated water was proposed, and an attempt was made to correct and apply the effect of the input component of agricultural return water on the amount of allocated water based on the calculation of allocated water in the new proposed method, taking into account the aquifer capacity based on the parameters of the water resources balance.
