In this study, using water, energy and food nexus (WEF) as an efficient model in sustainable management of natural systems, to identify the exchange between different sectors, planning and managing strategies in the Zayandehrud basin for the period 2006-2020 paid. The history of water resources development, severe groundwater decline, significant reduction of dam water storage and drying of Gavkhoni wetland show that this basin has been facing a continuous water crisis in recent years. Also, due to population growth and basin development, energy consumption and food needs have increased, all of which have had consequences for the environment. In order to manage the current situation, a model was presented by considering the influential issues of the WEF nexus approach, including economy, social conditions and environment. In addition to analyzing the trend of variables, an index called Water, Energy, Food and Environment Nexus Index (WEFE) was presented to eva‎luate and compare the proposed policies. Which examines each scenario by considering all nexus dimensions. The major part of surface and groundwater consumption (79%) is related to food production, especially agriculture. While the added value of this sector (6%) is lower than other sectors of industry and services, but at the same time food production is necessary to maintain food security, so by defining scenarios such as changing irrigation methods and changing people's diet to reduce demand and profit management and the loss of the farmer was investigated. The results show that by changing the irrigation method and improving the distribution and transmission network, water productivity in the agricultural sector has increased by 27% and if farmers cooperate during the simulation period, a total of 4545.5 million cubic meters of water will be released for Gavkhoni wetland. The policy will not only not improve the situation of the basin, but will also have negative effects if the cultivated and agricultural lands are expanded with the released water. Therefore, along with this change, it is necessary to control the conditions of the basin by regulating the price of water and its purchase by the government. In this regard, some concepts of game theory were used to more accurately investigate this issue and predict the upcoming events. As a result of changing the diet to the desired diet of the Ministry of Health, it was observed that the decrease in food security (6.5%) caused the population to decrease by 11.97%, the decrease in population caused the consumption and environmental pollution to decrease. Therefore, the mentioned diet was recognized as the most suitable diet for the basin according to the WEFE index with a score of 52.62%. If production waste is reduced by 10% in the optimal diet, food security will increase by 3.62%. Also, replacing diesel pumps with electric pumps with a 15% increase in efficiency for groundwater extraction has resulted in zero fossil fuel consumption for groundwater abstraction, a 3% reduction in electricity consumption, and a 20.78% reduction in pollution from water extraction. In order to provide an effective solution and taking into account all dimensions, the effect of simultaneous implementation of scenarios in the form of binary scenarios and policy packages was investigated. Finally, a combined scenario is presented, which includes changing the diet to the optimal diet, reducing feed production wastes by 10%, replacing groundwater pumps with high-efficiency pumps, improving the transmission and distribution network, and using drip irrigation at a reasonable price. Water is for the cooperation of farmers, was selected as the most effective scenario to improve the condition of the basin. The score of this scenario in the WEFE index is 76.35 percent, which is an increase of 27 percent compared to the current situation.

عليرضا گوهري

محمد شايان نژاد

سعيد اسلاميان، عليرضا علي پور