علوم محیطی (Mar 2024)
Investigating of Water, Energy, and Food Nexus with the Systems Dynamics Approach; a Case Study of Varamin Plain
Abstract
Introduction: Climate and ecosystem changes in coordination with other factors have challengedmany basic paradigms of natural resource management. The purpose of this research was to knowthe correlation between water, energy, and food in Varamin Plain by the method of the mentalmodel and the dynamics of water, energy, and food correlation under political scenarios.Material and Methods: Data and relationships related to the mental model were collectedthrough interviews with the farmers and managers of the region using the Mental Modelersoftware. Data related to the correlation dynamics model was also collected through organizations,regional stakeholders and authoritative articles. The WEF nexus model developed for the studyarea consists of interconnected relationships for modeling water, agriculture and energysubsystems and their interactions. The simulation model was built using Vensim software, and thesimulation period was considered a 20-year period. The equations in each subsystem were createdbased on the basic equations of the system dynamics approach and the causal loop diagrams ofeach subsystem using relationships and positive and negative feedbacks.Results and Discussion: The results of system dynamic modeling showed that the state of surface waterresources and water security of the plain will be 158 million cubic meters and -162 million cubic meters,respectively, during the period of 20 years, which shows the reduction of resources compared to theoriginal situation. The results of the model without applying the scenario showed that the volume of theVaramin Plain aquifer will decrease from 4000 million cubic meters to 2700 million cubic meters duringthe 20-year period. This shows that the policies of providing water resources, including the excessive useof wells, the development of urbanization and the creation of industries, as well as the lack of increase inthe productivity of agricultural water through modern irrigation methods, are the reasons for such aproblem. The application of scenarios for the allocation of the environmental needs of the Bandalikhanwetland showed that the plain will not have the ecological capacity to allocate water to the wetland, sothat in the next 20 years, the water security of the plain will decrease to 180 million cubic meters. Also,applying the scenario of increasing irrigation efficiency without increasing the cultivated area from 58%to 70% was effective in improving the reduction of agricultural water demand and increasing thecultivated area. The increase in cultivated area up to 41,600 hectares had a positive effect on agriculturalwater demand, but more than this amount caused the pressure on water resources to increase. Based onthe limitations of water resources and the reduction of water security in the Varamin Plain, the productionof the plain's products will also face a decrease. Due to its proximity to the city of Tehran, the VaraminPlain plays an important role in meeting the needs of the people of Tehran and the surrounding cities.Conclusion: Examining the results and comparing the data showed that during the 20-year period,Varamin Plain will have an unfavorable situation regarding water resources and food production.The management of the resources of Varamin Plain requires a change in organizational,agricultural and developmental approaches. The development of solar systems in order to meetthe energy needs, the establishment of the wastewater treatment plant in Varamin and thedevelopment of the treatment plant south of Tehran, as well as moving towards sustainablecompression is effective in creating the stability of the plains resources in order to properly exploitthe resources. On the other hand, increasing the irrigation efficiency without increasing thecultivation area can help in balancing the current situation so that with the implementation of thepolicies of the sixth development plan, the demand for agricultural water will be reduced to someextent and the pressure on the underground water resources will be reduced.
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