Calibration of unsteady flow in Crump Weir

Crump weir is widely used to calculate flow rate in open channels with unsteady flow regimes. In this study, flow rate calibration was experimentally investigated for unsteady free flow in crump weir using two different flow rate-time patterns. These patterns with either increasing or decreasing trends were considerd for different timeperiods. Experimental tests were performed in a laboratory flume equipped with real time data acquisition and recording system. The flume was 10 meter long and 8 meter wide and crump weir was located at 5.2 m corresponding to the enterance of the channel. The behavior of the flow rate coefficient was investigated as a function of weir height to the weir water height ratio, the weir length to weir water height ratio and weir width to weir water height ratio. Results show that flow rate coefficient is in reverse correspondence with all dimensionless parameters so that with an increase in each of these parameters, flow rate coefficient decreases. Finally using genetic algorithm, the optimization of the flow rate coefficient was performed. It was shown that the calibrated flow rate coefficient varies between 0.4 to 0.7.