Determination of discharge coefficient for the combined model of semicircle weir and sluice gate in the circular channel

Many devices and methods are available for the measurement and control of flow rate in open irrigation channels. Among, these devices, sharp crested weirs and sluice gates are commonlyused. In order to minimize the disadvantages of weir and gate, they can be combined together in one device yielding a simultaneous flow over the weir and below the gate. In this study the hydraulic characteristics of combined device of weir-gate such as coefficient of discharge and effective parameter on simultaneous discharge were investigated. The relationship between the experimental and theoretical results of the geometric and hydraulic parameters in the function of the flow statistically was analyzed and a coefficient discharge for combinational flow was presented. The error from the application of equation for 95% of data was ±2.5 percent.