DefinePK

Abstract

The River Analysis System (HEC-RAS) software was used to simulate the free flow over the broad-crested single-step weir. The software was used to compute the water surface profile, determine the location of the hydraulic jump, and establish the head-discharge relationship for the weir. The simulation results were verified by a series of laboratory measurements using a horizontal flume 5 m long, 0.45 m deep and 0.30 m wide. The tested weir has the following dimensions: total length was 48 cm; length of the downstream step of the weir was 24 cm; total height was 24 cm; height of the downstream step of the weir was 12 cm. Different inflow rates were applied to the weir for tail water depths of 6, 8, 10, 12 and 14 cm under free flow conditions. It was found that HEC-RAS could capture the overall features of the flow profile over the weir with reasonable accuracy. HEC-RAS could also determine the location of the hydraulic jump. It also produced a head-discharge relationship well close to the measured data. Besides, HEC-RAS was found easy to use for this specific flow problem and performed the computations in a short time.