Large dam and reservoir projects in ecologically sensitive zones often fragment wildlife habitats irreversibly. Discuss with reference to elephant corridors in South India.

The Nilgiri Biosphere Reserve — 5,520 sq km spread over Karnataka, Kerala and Tamil Nadu [3] — carries India's largest wild elephant population. Reservoirs built inside such landscapes deliver irrigation and power, but they also sever the corridors these long-ranging herds depend on, and that loss is rarely recoverable.

How reservoirs fragment sensitive habitats

• Permanent submergence claims valley floors and riparian forest — the gentle, water-rich tracts elephants use as dry-season refuge and passage.
• Barrier effect: the waterbody, plus canals, access roads and resettlement colonies, converts one contiguous forest block into two.
• Induced encroachment along backwaters — as recorded in the vested forest of Pulpally, Kerala — steadily eats into the remaining habitat [1].

The South Indian evidence

• The Kabini reservoir, on the Kapila (a Cauvery tributary), drowned forest linking Nagarahole and Bandipur. An ecological reconnaissance of the proposed Jawahar National Park (2,000 sq km covering Bandipur, Nagarahole, Mudumalai and Wayanad) found the habitat almost completely split into two, cutting several traditional migration routes [1].
• MoEFCC's Right of Passage: Elephant Corridors of India, 2023 ground-validated 150 corridors across 15 range States, of which about 13% are interstate — exactly the situation in this three-State landscape, where protection needs joint action [2].

Why the damage is largely irreversible

• A reservoir cannot be revegetated or fitted with underpasses the way a highway can.
• Gene flow between sub-populations is blocked, leaving small isolated herds vulnerable.
• Displaced herds move into plantations and settlements of Wayanad, the Nilgiris and Kodagu, deepening human-elephant conflict and retaliatory killings [2].

Where mitigation is still possible

• 33 Elephant Reserves in 14 States and central advisories to States to secure validated corridors [4].
• Corridor land consolidation, encroachment removal under the Wildlife (Protection) Act, 1972, and basin-level cumulative impact assessment instead of project-by-project clearance.

Kabini shows that the ecological cost of a reservoir outlives its economic life. Development in ecologically sensitive zones must therefore be planned at landscape scale, with corridors treated as non-negotiable infrastructure for wildlife — the surest way to honour both Article 48A and India's biodiversity commitments under SDG 15.