The performance of an open irrigation system is a complex function of many factors such as the hydraulic capacity of the system, the types of the utilized structures, control systems, delivery strategies, and management policies for water distribution. The impact of each factor on the operational performance of an irrigation system is very difficult to determine. The hydraulic condition in the network for the variety of possible operations and control systems that might be applied could not be determined manually. To achieve reliable assessment of the network performance, advanced computational facilities (hardware and software) should be utilized. Only with such facilities the effect of various delivery strategies could be determined and the influence of different factors on the operational performance evaluated. The main objectives of the current paper are to introduce some performance indicators that have been used recently in the literature and to determine the best operation (water delivery strategy) for Qurichay irrigation network based on performance indicators given by Molden and Gates. In this research a hydrodynamic model called ICSS-POM was utilized. Three delivery strategies were considered and simulated by the model. These delivery strategies are: continuous flow with a fixed flow rate, continuous flow with variable flow rates, and non-continuous flow. The performance indicators were evaluated for these strategies using the output of the simulation. Based on the
determined indicators the second delivery strategy was chosen as the most appropriate for the studied network.
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