Performance Assessment of Water distribution in Tajan Irrigation and Drainage Network

Delivery of adequate water in suitable time is one of the main objectives of water distribution systems in the irrigation network. Tajan irrigation network is one of the important networks in the Northern of Iran which irrigates a major part of Sari plains since 1376. In this study, the performance of a main canal of Tajan irrigation network was evaluated by using efficiency, adequacy, equity and stability indicators. To measure Indicators, firstly the Q-H relationship was obtained for each sub-channel and inlet as well as outlet sections of the main canal using field measurements. By using automated water level measuring devices and Q-H relationships, the exact amount of flow delivered to each water intake and the flow discharges in the main channel were then measured in two irrigation periods at one minute time intervals. Water requirement of each water intake was calculated using the NETWAT computer program. Using water requirement computed by software, performance indicators were calculated for main canal and water intakes. Overall, the performance of the canal is low. Traditional distribution of water in irrigation network despite its mechanization, lack of precise knowledge of Mirab about exact water required for each water intake and poor maintenance of control and intake structures prevent the proper management of water distribution. Based on the results, removing the barriers and introduce strategies for managing and operation irrigation network can increase the performance of the irrigation network.