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Due to water scarcity, providing reliable amounts of water is not possible for most of the irrigation districts in arid regions. In such conditions, equitable water delivery becomes one of the main concerns. Applying a centralized controller to achieve the high level of equity in water delivery along the main canal is not a practical solution in many irrigation districts due to high costs of the implementation, maintenance and inspections; and vandalism of equipment. In this paper, a water level difference control strategy is applied to keep the water level errors equal in adjacent reaches by using decentralized controllers. Local downstream and distant downstream configurations of the control method are designed for the Dez main canal, located in the southwest of Iran, consisting of 13 canal reaches. The designed controllers are tested on two extreme water off-taking scenarios for normal operation and operation under water shortage. The tests show the capability of the difference control strategy to deal with the mismatches between supply and demands under water shortage conditions. Also, acceptable operational performances in operational conditions with drastic increasing or decreasing of water off-taking in the system are achieved. As no telemetry system is required for the decentralized local downstream configuration, this difference control method is proposed as best option for implementation in the Dez canal. (C) 2013 American Society of Civil Engineers.