Barrage across Tungabhadra River – Project Significance & Preliminary Designs

Project Significance

• Local representatives requested a diversion structure across the Tungabhadra River near Valaballary to guarantee reliable drawl for three Lift-Irrigation Schemes (LIS):
  • Channabashaveshwara LIS (Existing – "E")
  • Thimmapur LIS (Under Construction – "U/C")
  • Siddalingeshwara LIS (Proposed – "P")
• Without a storage/diversion structure, cumulative abstraction for these schemes would exceed the river’s free-flow availability at lean stages.
• Two technical alternatives were examined:
  1. Option 1 – Barrage (gated, low-level storage)
  2. Option 2 – Weir (ungated, fixed-crest).
     Comparative studies favoured the gated barrage for precise regulation and larger live storage.

Geographical Location

• Site: Up-stream of Timmapur-LIS drawl point, downstream reach of Tungabhadra River at Valaballary village, Sindhanur Taluk, Raichur District, Karnataka.
• Coordinates: Latitude $15^{\circ}46'2.30''\text{ N}$; Longitude $76^{\circ}57'14.04''\text{ E}$.
• Survey of India Topo-sheets: 57 A/14 & 57 A/15 (Map scale $1:50\,000$).

Accessibility

• Roads
  • State Highway 128 links Sindhanur with Bengaluru, Hubballi, Belagavi, Vijayapura (Bijapur), Kalaburagi (Gulbarga), Hospet, and Raichur.
  • Barrage approach road length: $1020\text{ m}$ (to be freshly constructed, revenue land).
• Rail
  • Nearest junction: Kupgal (KGL) on South-Central Railway, $\approx 32\text{ km}$ from Sindhanur; barrage is $\approx 25\text{ km}$ from Sindhanur.
• Airports
  • Hubballi $\approx 220\text{ km}$; Dharwad $\approx 219\text{ km}$.

Mapping & Survey Inputs

• SOI topo-sheets mosaicked to produce a composite planning map at $1:50\,000$.
• Figure 2-2 marks service-area sheets 57 A/14 (D43E14) & 57 A/15 (D43E15).

Scheme Components (Common to Either Option)

• Diversion structure itself (Barrage/Weir).
• Fabrication, supply and commissioning of: gates, stop-logs, hoisting arrangements.
• Two Nos. monorail lifting hoists (5-ton each).
• Store rooms (2 Nos.).
• Approach road ((1020\,\text{m})).
• O&M for five years.

Option 1 – Barrage (Selected)

Hydrologic & Hydraulic Parameters

• Type: Low-level gated barrage with vertical lift radial/sliding gates.
• Number of vents: $98$ (each $5\,\text{m}\times3\,\text{m}$).
• Sill (Crest) Level: $337.000\,\text{ m}$.
• Full Reservoir Level (FRL): $340.000\,\text{ m}$.
• Height of gate: $3.0\,\text{ m}$ (sill to FRL).
• Design discharge: $1470\,\text{m}^3\,\text{s}^{-1}$ (through vents at FRL).
• Observed High-Flood Level (HFL): $350.163\,\text{ m}$ (later refined to $350.198\,\text{ m}$).
• Total length (between abutments): $587\,\text{ m}$.
• Stop-log units: $5\,\text{m}\times0.5\,\text{m}$; quantity $588$.

Structural Components

• Abutments: Left & Right Bank mass-concrete blocks tied with cut-off walls.
• Cut-off walls: Up-stream (U/S) & Down-stream (D/S) on both banks, protecting against piping.
• Aprons: U/S & D/S to absorb scour energy.
• Wing & Return walls: Channel transition and anti-erosion.
• Piers: Reinforced-concrete pier noses support gates & provide roadway/cat-walk.
• Cat-walk: Operable deck for inspection, gate operation & hoist beam.
• Approach Embankments: Earth bunds to integrate structure with natural ground.

Preliminary Design Conformity

• All calculations follow latest BIS Codes (IS 4410, IS 7365, IS 4997, etc.) with allowable‐stress method and flood-frequency checks.

Cost Estimate (Option 1)

• Civil, mechanical & electrical works aggregated cost: $\text{Rs.}\;451.50\,\text{ lakh}$ (≈ $\text{Rs.}\;4.515\,\text{ crore}$).
• Detailed head-wise breakup enclosed in Annexure 1 (not provided in transcript).

Lifting Hoist System

• Configuration: Single-girder monorail crane traversing along the barrage deck; limited to longitudinal (forward/back) motion + vertical lift.
• Mechanisms:
  • Hoist with wire-rope, hook, pulley block.
  • Trolley travelling mechanism along I-beam top flange.
  • Crane end-carriage integrated with cat-walk steel framework.
• Advantages: Compact, light-weight, minimal lateral load, economical for linear gate arrays.
• Provision: 2 units, each $5\,\text{ton}$ SWL (Safe Working Load).
• Power: Sourced from existing KPTCL sub-station at Timmapur LIS.
• Budget: $\text{Rs.}\;9.76\,\text{ lakh}$ (supply, installation, testing, commissioning).

Operation & Maintenance

• Five-year O&M lump-sum: $\text{Rs.}\;0.52\,\text{ lakh}$ (covers routine inspection, gate greasing, hoist upkeep, minor civil repairs).

Land Acquisition

• Total land required: $1.10\,\text{ ha}$ (revenue dry land encompassing barrage footprint, two store rooms & 1.02-km approach road).
• Compensation rate: $\text{Rs.}\;30.00\,\text{ lakh per ha}$ (per state norms).
• Allocation: $\text{Rs.}\;33.00\,\text{ lakh}$ (rounded, Annexure 4).

Option 2 – Weir (Only Reconnaissance Level Mentioned)

• Ungated fixed crest; would not guarantee regulated head for simultaneous operation of three LIS, therefore set aside at concept stage.

Inter-linkages & Wider Relevance

• Supports irrigation modernisation in Tungabhadra left-bank command, enhancing reliability for approx. Sindhanur–Gangavathi paddy belt.
• Reduces energy cost for individual LIS by allowing lower static head due to raised FRL.
• Aligns with state objective of conjunctive use & equitable distribution across Taluks.
• GIS & topo inputs form baseline for future sedimentation, flood routing & environmental studies.

Ethical / Practical Notes

• Acquisition confined to dry revenue land to minimise displacement; no habitation submergence reported.
• Environmental clearance will still require assessment of aquatic ecology due to raised FRL.
• Design must ensure fish-pass or ecological sluice (not discussed in transcript – flagged for future study).