Author(s): Linda Prasetyorini; Nadjadji Anwar; Wasis Wardoyo
Linked Author(s): Linda Prasetyorini
Keywords: Stilling basin; Froude number; Tail water depth; Effectiveness
Abstract: This paper presents experimental result about the modification of stilling basin on the downstream area. Stilling basin on the end of chuteway was designed to protect riverbed from scouring by reducing energy over the spillway. Way Apu Dam is located at Buru Island, Indonesia. Irrigation, water supply, and power plant is the main purpose of building this dam. At the weir site, the volume of the reservoir about 15 million m³. The dam was constructed with overflow spillway type and stilling basin on the downstream area. The structure of spillway was designed for a 100 years to return period flood discharge is 2384.147 m³/s with the scale of 1 to 100 in the laboratory. According to the hydraulic calculation results, a standard Type III stilling basin was designed for a Froude number of 6 with incoming depth 1.65 m (0.5 ft). The stilling basin of 35.00 m with U.S. Bureau Reclamation (USBR) Type III length was arranged in the downstream of chute way. Several parameters such as water level, velocity, and Froude number were calculated by theoretical analysis and measured on the laboratory. The average flow discharge showed that stilling basin could not reduce the energy from spillway effectively without 10 m of tail water recommended design. Therefore, the stilling basins model was replaced by baffle blocks size modification to reduce the energy from over the spillway of a dam that has 4.5–10 Froude number in range with lower tail water depth.
Year: 2018