The physical and numerical modeling to design the breast wall spillway - AS case study

• Published in: ISH journal of hydraulic engineering Vol. 30; no. 5; pp. 730 - 743
• Main Authors: Gadhe, Vaishali, Patnaik, S. R., Bhate, R. R.
• Format: Journal Article
• Language: English
• Published: Taylor & Francis 19-10-2024
• Subjects: breast wall spillway; discharging capacity; Himalayan River; numerical model studies; physical model studies
• ISSN: 0971-5010; 2164-3040
• DOI: 10.1080/09715010.2024.2411282

The river systems in the Himalayan region exhibit year-round flow due to precipitation during the rainy season and snow/glacier melt in summer. These rivers carry massive sediment loads, especially during monsoons. Hydraulic engineers face the challenge of designing infrastructure capable of managing this sediment. Breast wall spillways are recommended for their ability to handle floodwaters and sediment disposal. The hydraulics of breast wall/orifice spillways changes with the varying reservoir level. The flow is free flow for reservoir water levels below the top of the sluice, whereas for higher water levels the flow is orifice flow. Orifice spillways are designed to pass water through openings or gates, where the flow is primarily governed by the hydraulic head and the orifice size. The flatter bottom profile helps in smoothly directing the flow through the opening without causing significant turbulence or separation, especially when the gate is partially open. Hence, the crest profile is flatter as compared to the overflow crest profile to avoid flow separation and negative pressures on the crest for small gate openings. Kwar Hydro Electric Project is one such Himalayan region project planned across the Chenab River in which a breast wall spillway has been provided to serve the dual-purpose of flood and sediment disposal. The present paper describes the physical and numerical hydraulic model studies conducted for Kwar H .E. Project, Jammu and Kashmir, to evolve a breast wall spillway profile, ski jump type energy dissipator at the toe of the spillway.