Investigation of energy dissipation in Gabion stepped weirs

Weirs are widely used in hydraulic structures to control and regulate flow in open channels. Gabion weirs are frequently used in rivers, small dams, energy dissipaters, flood control works, and check dams, among other uses, and can be used to build a stepped weir. Dissipation of the energy (kinetic energy) on spillways or weirs is important to protect both hydraulic structures and downstream channels. This study aims to investigate the energy dissipation in gabion stepped weirs. For this purpose, six lab scale models of gabion stepped weirs each with six levels of impervious stepped weirs were investigated, which includes two downstream slopes (1:1 & 1:2, V:H) and three step face geometry (normal, end sill, and inclined steps). The rock fill material is crushed stone of nominal size (13.2 mm–19.0 mm), with a porosity of 0.42. Results showed that gabion weirs have more energy dissipation than impervious weirs around 20% at low discharge and only 3% at high discharge. Moreover, the step face geometry is more effective at medium discharge (nappe and transition flow regimes), while there is no effect at low and high discharge (through and skimming flow regimes). Finally, it was found that the energy dissipation increased with decreases in the downstream slope for all step configurations.