Development of Mathematical Model for BIVAL Downstream Control System in Irrigation Canals

Document Type : Research Article



The control systems and related structures have an important role in water distribution in irrigation networks, and the success of irrigation networks highly depends on their proper functioning. Control structures behave differently under different control systems. Providing higher flexibility in water delivery and reducing water losses by application of downstream control systems is an important factor for performance improvement of irrigation networks. One of the downstream control systems which is suitable for sloping canals is constant volume control system named BIVAL system. In this system while the water volume in canal reaches is kept constant, demand variation is satisfied quickly and canal earthwork is reduced. In order to study hydraulic behavior of irrigation canals in coordination with control systems which is unsteady, using hydrodynamic model is inevitable. In this research mathematical model of constant volume downstream control system (BIVAL) is developed and linked with ICSS model. For calibration and evaluation of developed model on local and global scale, El-RI branch of Dez canal network in Iran and the standard canal introduced by ASCE are chosen respectively. Each system was calibrated in wide ranges of different flow rate and different values of numerical coefficients and the proper coefficients were derived. Afterward each one of control systems were operated under different operational schedule and performance indices, MAE (Maximum Absolute Error), IAB (Integral of Absolute Error) and SRT (System Response Time) in 5% and I% levels were computed. Performance indices for a reach with highest variation derived as 2.57, 0.28 and 0 respectively. Depth, flow rate and gate opening fluctuations for local testing, and depth fluctuations for global testing at middle of reaches are calculated and depicted. Performance indices and hydraulic behavior of the system indicates proper functioning of the developed model.