The compilation of water balance at the basin level requires processing a large amount of information based on the use of GIS tools and an appropriate conceptual model. The aim of this study is to explain the framework provided by the United Nations for water accounting in the Godar-Chai River basin. The SWAT model for hydrological simulation of the basin and the SUFI-2 algorithm for sensitivity analysis using the Nash-Sutcliffe criterion as the objective function were calibrated and validated monthly at 5 hydrometric stations. The results showed that the calibrated model for the Godar-Chai basin has a desirable performance. One of the approaches to achieve a comprehensive understanding of the conditions of the basin, which is also evaluated in this study, is the SEEA_W environmental-economic accounting for water introduced by the United Nations. The tables for each user show a water cycle and the equation of balance and exchange of water between the field of activities and the environment. In order to complete the tables of consumption and physical supply in the agricultural sector, the necessary information to complete it has been taken from the outputs of the SWAT software. Finally, in order to increase the agricultural and economic productivity of crops in the basin, the optimal crop area change scenario was applied to the model, according to which the amount of irrigation in the basin was reduced by 55 percent, and water accounting tables for the optimal agricultural development scenario were also prepared and presented.