Study of the Effect of Stepped Weir with Roller Bucket Stilling Basin Type on Water Jump Length and Energy Dissipation
Jaji Abdurrosyid *
Department of Civil Engineering, Engineering Faculty, Universitas Muhammadiyah Surakarta, Jl. Ahmad Yani Tromol Pos1, Pabelan Surakarta 57102, Indonesia.
Fauzan
Department of Civil Engineering, Engineering Faculty, Universitas Muhammadiyah Surakarta, Jl. Ahmad Yani Tromol Pos1, Pabelan Surakarta 57102, Indonesia.
*Author to whom correspondence should be addressed.
Abstract
A stepped weir is a modification of a spillway structure that forms a series of steps from the crest to the downstream foot. Its primary purpose is to dissipate the energy of strong, supercritical flow, thereby reducing the risk of downstream riverbed erosion. The increase in water level caused by the weir changes the flow from supercritical to subcritical conditions, which may lead to erosion in the channel below the spillway. A roller bucket stilling basin is therefore used to reduce scour.
The research was conducted in the Hydraulics Laboratory of the Civil Engineering Study Programme, Faculty of Engineering, Muhammadiyah University of Surakarta. The study used an open flume measuring 30 x 60 x 1000 cm with a channel bed slope of 0.0058. Ogee spillways were tested in three-stage, two-stage and one-stage weir configurations, each combined with a roller bucket stilling basin. The experiments were conducted at five discharge levels. The results showed that the three-stage stepped weir with a roller bucket stilling basin was the most effective configuration for dissipating flow energy because it reduced flow turbulence and hydraulic jump length.
Keywords: Stepped weir, ogee overflow, roller bucket stilling basin, water jump length, energy reduction