Due to the increasing crisis and scarcity of water, the proper allocation of available water resources is a major challenge for authorities in the Zayandehrood Basin. Agriculture, especially cultivation, has the highest water use in the basin. Therefore, how to allocate water in this section should be carefully considered. This study seeks to determine optimal water allocation based on increasing the welfare of consumption by estimating the economic value and functions of water in the cultivation sector using the Genetic algorithm method and the Kinked demand curve model in the Zayandehrood basin. In order to reduce agricultural risk, four years of data were considered and for this, two scenarios were considered. The results showed that the water allocation in most of the agricultural activities in the west of Zayandehrud has a negative economic value, which has led to a decrease in water welfare in this area. So, the best allocation in the agriculture sector was in the center and east of the basin. Also, the water demand function graph in Isfahan province is higher than the water demand function in Chaharmahal and Bakhtiari province and welfare surplus due to water consumption in Isfahan province is about 694900268888 Rials. The results and suggestions in this study will help decision makers and managers to achieve optimal water use and sustainable planning in this basin.