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Union Minister for Ports, Shipping and Waterways Sarbananda Sonowal told the Rajya Sabha that 28.3 per cent of Odisha's 564.14-km coastline is eroding.
The figure comes from a shoreline change assessment by the National Centre for Coastal Research for the period 1990 to 2022.
Alongside the eroding stretch, 54.1 per cent of the coastline is accreting and 17.6 per cent is stable.
Jagatsinghpur is worst affected at 47.6 per cent, followed by Ganjam at 45.7 per cent and Kendrapara at 45 per cent.
Sixteen villages in Kendrapara district have already been submerged, and hotspots include Gahirmatha, the Devi river mouth and both sides of the Chilika sea mouth.
Sand does not sit still on a coast; it travels along it. Waves striking the shore at an angle push sediment sideways in a zig-zag path called longshore or littoral drift, so any stretch of beach is a balance between sand arriving from up-drift and sand leaving down-drift. Erosion occurs when that budget goes into deficit. Hard structures - breakwaters, groynes and sea walls built for ports and harbours - interrupt the drift, trapping sand on the up-drift side and starving the coast immediately down-drift, which is why erosion often appears just beside a new port rather than at it. Dams upstream trap river sediment that would otherwise replenish deltas, and beach sand mining removes what little arrives. Cyclonic storm surges then strip the weakened beach in hours, while sea-level rise pushes the whole tidal boundary landward. Accretion is the opposite case, where the sediment budget runs a surplus and the shoreline advances seaward - which is why more than half of Odisha's coast is growing even as more than a quarter retreats.
Simple Analogy: Think of a conveyor belt of sand running along the shore. A groyne is a hand placed on the belt: sand piles up behind it and the stretch just past it runs empty.
The NCCR flagged specific stretches rather than whole districts. In Ganjam these are the coast north of Gopalpur Port, Mayurpada and Bhramarakudi. In Puri they include both sides of the Chilika sea mouth, Keutajanga and the Devi river mouth. Jagatsinghpur's affected stretches run from Kusupur to Sahadabedi and from Sahadabedi to Jatadhartanda. Kendrapara accounts for the largest cluster - Hetamundia, Hukitola, Pentha, Satabhaya and Gahirmatha. Amarnagar is the hotspot in Bhadrak, while Balasore contributes Bagda, Chaumukh, Narayan Mohanty Padia and the Bindhapadmapur-to-Talasari stretch. The list is telling: Gahirmatha and the Devi river mouth are the mass nesting grounds of the Olive Ridley turtle, and Chilika is India's largest brackish-water lagoon and a Ramsar site.
The NCCR's national shoreline assessment found about 33.6 per cent of India's roughly 6,907 km mainland coastline - some 2,318 km - under erosion, 26.9 per cent accreting and 39.6 per cent stable. Over half the coasts of West Bengal and Puducherry are eroding.
The National Centre for Coastal Research is an attached office of the Ministry of Earth Sciences, based at Chennai; it maps shoreline change using multi-spectral satellite imagery combined with field survey data.
Mangrove restoration and casuarina shelterbelts absorb wave energy without interrupting longshore sediment transport, unlike concrete sea walls.
Submerged geotextile tubes and beach sand nourishment are being preferred over indiscriminate hard structures; the Pentha embankment in Kendrapara is the reference pilot.
Gahirmatha hosts the world's largest arribada - mass nesting - of the Olive Ridley sea turtle, which the IUCN lists as Vulnerable.
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The progressive wearing away and landward retreat of beach or dune sediment under waves, tides, storm surges and currents.
The seaward growth of a shoreline where deposition of sediment exceeds removal - the opposite of erosion.
The lateral movement of sediment along a coast caused by waves approaching the shore at an angle.
The synchronised mass nesting of Olive Ridley sea turtles; Gahirmatha in Odisha hosts the world's largest.
A large sediment-filled fabric tube used as a soft, submerged coastal defence in place of concrete sea walls.
National Centre for Coastal Research, an attached office of the Ministry of Earth Sciences at Chennai, which maps India's shoreline change.