Experimental investigations for Telengiri dam spillway, irrigation project, Odisha

Experimental investigations for Telengiri dam spillway, irrigation project, Odisha – A case study

Gadge, Prajakta P. / Bhajantri, M. R. / Bhosekar, V. V.

Water resource projects are broadly categorized in irrigation and hydroelectric projects. Telengiri is a medium irrigation project across the river Telengiri, a tributary of river Indravati in Odisha. The project envisages irrigation to a gross command area of approximately 11,6664.34 ha in Koraput district. Overflow spillway has been proposed to pass the design discharge of 2272 m³/s. A ski-jump is provided as an energy dissipator. Many of the hydraulic design problems are unique and complex due to their site-specific conditions. Physical model study is an indispensable tool to optimize various components of reservoir and appurtenant structures. This paper discusses the hydraulic model studies conducted on 1:50 scale three-dimensional comprehensive model of spillway at CWPRS, Pune, India. The performance of spillway was assessed in respect of discharging capacity of spillway, pressures over spillway surface, water surface profiles, performance of energy dissipator and downstream flow conditions for the entire range of discharges. The downstream flow conditions in the tail channel were a crucial part in the present study. Return flows were observed on either side of tail channel due to heading up of water levels after the impingement of ski-jump jet owing to sharp bend and constriction of river cross section. Dressing of the left bank improved the flow conditions in the downstream reach. Hydraulic model studies played a very important role in finalizing the design of spillway tail channel to improve the flow conditions. The results obtained from the study and recommendations made thereof have been discussed in detail in the paper.