Key Highlights
- The Tehri Dam stands at 260.5 m, making it the tallest dam in India and one of the world’s highest.
- Located on the Bhagirathi River in Uttarakhand’s Himalayan foothills, it serves multiple functions: power, irrigation, drinking water, flood mitigation, and tourism.
- Its rock‑fill with a central clay core design enables it to endure seismic events up to magnitude 8.4.
- With an installed capacity of 2,400 MW, the dam functions as a peaking hydro‑electric plant for northern India.
- The reservoir, known as Tehri Lake, has reshaped local livelihoods, creating new settlements and a tourist economy.
Detailed Insights
Construction of the Tehri Dam commenced in 1978 and reached completion in 2006 after navigating the challenges posed by a seismically active zone and rugged Himalayan terrain. Engineers adopted a rock‑and‑earth‑fill methodology, embedding a central clay core that acts as a flexible spine, allowing the structure to absorb and dissipate earthquake energy. This innovative approach distinguishes Tehri from conventional concrete gravity dams.
The dam’s reservoir stores a massive volume of water, which is judiciously allocated for four primary purposes. First, the hydro‑electric turbines generate up to 2,400 MW, supplying clean electricity to Uttarakhand, Uttar Pradesh, Delhi and the national grid during peak demand. Second, the regulated discharge waters irrigate approximately 270,000 hectares of agricultural land, bolstering food security. Third, the reservoir provides a reliable source of potable water for millions in Delhi and surrounding regions. Fourth, during monsoon surges, the dam’s spillways—including unique “Morning‑Glory” shafts—manage excess flow, mitigating downstream flooding in Rishikesh, Haridwar and other vulnerable locales.
Beyond its utilitarian roles, Tehri Lake has emerged as a recreational hub, attracting tourists for boating, jet‑skiing and kayaking. The displacement of the historic town of Old Tehri led to the planned development of New Tehri, illustrating how large‑scale infrastructure can reshape human settlement patterns.
Key Concepts
- Rock‑fill Dam: A dam constructed primarily from compacted rocks and earth, often featuring an impermeable core to prevent seepage.
- Peaking Power Plant: A generation facility designed to ramp up electricity output quickly during periods of high demand.
- Morning‑Glory Spillway: A circular, vertical shaft spillway that allows water to flow over its lip and descend through a tunnel, used for rapid flood discharge.
- Dead Storage: The portion of a reservoir’s capacity below the lowest outlet, intended to capture silt and extend the useful life of the storage.