System dynamics modeling for assessment of water-food-energy resources security and nexus in Gavkhuni basin in Iran

In this study, a spatiotemporal disaggregated simulation model was developed based on water-food-energy (WFE) nexus approach to assess water and food supply security considering ecosystem provisioning services in Gavkhuni Basin in central Iran. The main components of the developed model in this study (SD-WFE model), which is the first of its kind in Iran, are population, water, agriculture, and energy modules. The model, which was developed using System Dynamics (SD) approach, was utilized to simulate effectiveness of sectoral municipal, industrial, and agricultural water and energy consumption management and environmental protection policies in improving ecosystem provisioning services during a 10-year period. The results indicated that the combined policies proposed by the agriculture and environment sectors were the most effective in changing the status of WFE system and meeting the Gavkhuni wetland environmental demand. Implementing a combination of ACP (changing crop pattern and enhancing crop productivity) and EGP (controlling groundwater withdrawal) policies not only increased surface water security (4%) and groundwater security (5%) but also diminished water for food production (18%) and energy for water (26%). The policies proposed by the energy sector were not influential in improving the ecosystem provisioning services. Overall, the results showed that the security of water supply and status of energy subsystem in the basin were highly dependent on the food sector. The results also reflected proper performance of SD-WFE model in representing the impacts of policies proposed by water, agriculture and energy sectors, and therefore it proved to be a useful tool for cross-sectoral coordination and planning.