Analysis of discharge rates in rectangular slit, ogee, and sharp-crested weirs

Climate change has made flash floods increasingly common. It's crucial to have confidence in the structural integrity of dams during a flash flood. According to the International Commission on Large Dams (ICOLD), approximately one-third of dam failures are attributed to inadequate spillway capacity. The current study aims to compare the discharge of slit weirs with that of ogee spillways and sharp-crested weirs. Various experiments were conducted using rectangular slit weirs with different opening ratios ( b/B = 2/24, 3/24, 4/24, 5/24, 6/24, 7/24, 8/24, and 10/24). The results indicate that ogee spillways have an average discharge capacity of 13–68 times greater than that of the slit weirs, while sharp-crested weirs have a discharge capacity of 1.39–7.3 times that of the slit weirs. The ratio of ogee spillway discharge to the slit weir ( r ) and sharp-crested weir discharge to the slit weir ( r' ) increases with the rise of h/P . Moreover, the highest average values of r and r' are observed at b/B = 2/24, measuring 65.46 and 7.3, respectively. Conversely, the lowest values, 11.53 and 1.22, are associated with b/B = 10/24. Notably, the maximum values of r and r' , 71.2 and 7.61, respectively, also occur at b/B = 2/24.