The Effect of Gabion Stepped Spillway Porosity on Energy Dissipation and Characteristics of Downstream Hydraulic Jump of Weir

Today, gabion structures and especially gabion stepped spillways have become more popular due to the significant effect of stairs on flow energy dissipation, appropriate stability, being economic, easy implementation, and raising the oxygen level in the water. This type of weirs has more flexibility compared with its impervious type and is resistant to loads due to water pressure. The resistance to water load is likely to be related to flow passing through the porous media, and the gabion stairs can assist with the faster water drainage and reduce the water load behind the structure (Zhang & Chanson, 2016). Extensive studies have been performed on impervious stepped spillways, namely Gonzalez et al. (2016) and Zhang and Chanson (2015).Reeve et al. (2019) used a numerical model to investigate the flow hydraulic properties on gabion stepped spillway. They studied gabion stepped spillways with four different stair geometries under similar conditions. Their results indicate that flat gabion steps can dissipate more energy than overlapping, inclined, and pooled steps.Despite extensive investigations on impervious stepped spillways, there has not been sufficient research on gabion stepped spillways. Hence, the primary purpose of this study is to investigate the gabion stepped weirs features, including energy dissipation and characteristics of downstream hydraulic jump.