Reservoir and Appurtenant Structures


Reservoir and Appurtenant Structures (RAS) Group undertakes studies for evolving efficient, economical and safe hydraulic designs of spillways and energy dissipators, water conductor systems and other appurtenant structures such as protection works, high head gates, sluices and outlets, surge tanks, tunnels, penstocks, galleries, sedimentation and flushing of reservoirs, sediment control and exclusion devices. The studies are carried out with the help of hydraulic models, mathematical models and desk studies. There are four technical divisions under this discipline viz. Spillways and Energy Dissipator (SED), Control Structures and Water Conductor Systems (CSWCS), Sediment Management (SM) and Hydraulic Analysis and Prototype Testing (HAPT).

Spillways and Energy Dissipators (SED)

SED Division was established in 1958 to study the spillways of dams constructed immediately after independence, for irrigation, generation of power and flood control. Many of the projects taken up in early years such as Bhakra, Hirakud and Koyna were among the large dams in the world and involved several complex problems. So far model studies for more than 150 projects have been carried out both in India and abroad.

Major Research Activities

  • Approach flow conditions upstream of spillway
  • Assessment of discharging capacity with full and partial gate openings
  • Pressures on spillway and design of aerators
  • Observations of water profiles for design of training walls, divide walls and location of trunnion beam
  • Performance of energy dissipating arrangement
  • Scour downstream of energy dissipator and plunge pool design
  • Construction stages of spillway
  • Protection works near spillway
  • Assessment of prototype performance

Control Structures and Water Conductor Systems

Major Research Activities

  • Layout, location and dimensions of power intake
  • flow conditions in the vicinity of intake
  • Transient analysis for water hammer effect and water level variations in surge shaft
  • Flow conditions in head race channel / tunnel
  • Tailrace Channel / tunnel: layout and alignment, flow conditions and velocity distribution, and draft tube submergence
  • Gates & Stoplogs: overall layout, hydrodynamic uplift and downpull forces, and air demand downstream of gates
  • Air water column separation and assessment of necessity of airvents
  • Flow conditions and water levels in surge shafts

Sediment Management

Major Research Activities

  • Design of desilting chamber to achieve maximum sediment settling and flushing efficiencies
  • Silt flushing tunnel for maintaining settling efficiency of desilting basin
  • Estimation of reservoir sedimentation profile using mathematical modelling
  • Sedimentation assessment through remote sensing technique
  • Reservoir flushing: optimization of discharge, duration and frequency and gate regulation for effective flushing
  • Diversion tunnel for bypassing high sediment load from reservoirs

Hydraulic Analysis and Prototype Testing

Major Research Activities

  • Stream gauging and sediment sampling
  • Calibration of gauging site of river and canal
  • Rating of discharge measurement structures
  • Measurement of sediment concentration and analysis for suspended sediment distribution
  • Transmission losses in water conductor systems