The Effect of Improvement of Rehabilitation on the Improvement of the Network Utility Index with the Constrain of Improvement in the NEXUS Index based on System Dynamic Analysis (Case Study: Qazvin Irrigation Network)

The involvement of many factors in a complex model such as the improvement of irrigation networks and their complex interactive relationship on the performance of the water, food and energy system (Nexus) in the long term makes the use of the system dynamics approach inevitable. The aforementioned approach in addition to being holistic, explains the system simulation realistically. The present research modelled the dynamics governing structural and non-structural actions for rehabilitation of irrigation networks to improve the utility of the network, and by supplying the Nexus index, using the strategy of systemic thinking. For this purpose, subsystems of "water productivity improvement", "definition of network utility index" and "description of Nexus in networks" were compiled and conceptualized using system dynamics tools based on the years 2006 to 2016. A quantitative model was developed and validated in 2016-2023 based on the developed conceptual model. According to the results of the research, the use of structural and non-structural solutions had the greatest effectiveness in the Nexus index and the network utility index, compared to the use of each of the solutions separately; thus, for the scenarios of increasing 25, 50 and 75% of structural and non-structural solutions together, the amount of Nexus index improved by 17.37, 23.83 and 26.89%, respectively.