Evaluation of Hydraulic Performance of Regulators and Distribution Structures in Varamin Irrigation Network

In irrigation networks, different structures are used in regulating water level and off-takes. Duckbill weirs and Neyrpic module off-takes are among these structures which are used in many irrigation networks. To improve the operation of irrigation networks, hydraulic performance assessments of these structures and the efficiency of present condition should be part of the maintenance and operational management programs. Less attention has been paid to this subject by the operation managers. The aim of this study is to evaluate the technical performance and operational condition of regulator structures, distribution and flow control in Varamin Irrigation Network. For this purpose, with the use of precise measuring equipment, performance of 15 Neyrpic module off-takes and 7 duckbill water level regulators were evaluated. Comparison of the nominal and measured flow rate shows that Neyrpic gates have error in the range of -8% to 83% and on the average deliver 22% more than the specified volume of water. Improper water level regulation by the duckbill structures, sediment accumulation and water leakage from the edge of the gates are the main reasons for these flow differences. Water regulators are also faced with structural damage due to improper services. As a result, the average amount of discharge coefficient in duckbill weirs have increased to 1.55. By solving the technical and maintenance problems, resulted from this study, the proper model of water distribution can be implemented.