Document Type : Research Paper
Abstract
An assessment of irrigation networks shows that their utility is less than expected because of poor design
and operation, lack of sufficient maintenance and poor management. Poor performance of irrigation
networks is partly because of old components that require rehabilitation. Rehabilitation of irrigation
systems are done case-by-case, which lacks integration and a systemic approach and has not led to
appreciable improvement. The involvement of so many components in irrigation rehabilitation and their
complex interactive relation on system performance requires a system dynamics approach. Simulation
techniques must be explored that represent complex dynamic systems in a realistic way. System dynamics,
a feedback-based object-oriented simulation approach, was used to model the rehabilitation of irrigation
networks. The ease of model modification in response to changes in the system and the ability to perform
sensitivity analysis make this approach attractive for modeling the rehabilitation. In this paper, the
proposed approach was applied to rehabilitate irrigation networks where the main elements affecting the
network utility were efficiency, adequacy, equity, flexibility and stability in water delivery. Several
rehabilitation scenarios were considered and their effects on the performance element (efficiency) were
investigated. The long-term impact of the system utility was determined using system dynamics modeling
and the appropriate policies were selected. The Qazvin Irrigation Network was selected as a case study.
The three scenarios for network rehabilitation were fixing the area under cultivation, decreasing drawdown of groundwater and increasing investment in rehabilitation projects. The effect of the scenarios on the
efficiency of the system was calculated and the final impact on the system utility was determined. The
results showed that all three scenarios improved system utility, however, fixing the area under cultivation
showed the best improvement.
Keywords
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