Continental Shelf of India

The Continental Shelf is a geological and legal concept defined under Article 76 of the United Nations Convention on the Law of the Sea (UNCLOS). It represents the natural prolongation of a coastal state’s land territory underwater.

Spatial Demarcation Under UNCLOS

• Standard Limit: Every coastal state has an inherent right to a continental shelf extending up to 200 nautical miles ($370.4 \text{ km}) from its coastal baseline, co-extensive with its Exclusive Economic Zone (EEZ), regardless of the actual geological formation. </li> <li> <b>Extended Continental Shelf (ECS):</b> If the physical continental margin extends beyond 200 nautical miles, a state can claim an extended continental shelf up to a maximum limit of 350 nautical miles (%%IAS_DOLLAR_AMOUNT₁%%.2 km) from the baseline, or 100 nautical miles from the 2,500-meter isobath (a line connecting points of equal underwater depth).
• Commission on the Limits of the Continental Shelf (CLCS): To claim boundaries beyond 200 nautical miles, nations must submit scientific and technical data demonstrating the geological continuity of their continental margin to this UN body.

Sovereign Rights of the Coastal State

• The coastal state exercises exclusive sovereign rights over the continental shelf for the purpose of exploring it and exploiting its natural resources.
• Resource Scope: These rights apply strictly to non-living resources (such as petroleum, natural gas, and minerals) and living organisms belonging to sedentary species (organisms which are immobile on or under the seabed at the harvestable stage, like corals, crabs, and sponges).
• Distinction from the EEZ: Unlike the EEZ, the coastal state’s rights over the continental shelf do not depend on occupation or express proclamation. If the state does not explore or exploit the resources, no other nation can undertake these activities without its explicit consent. Crucially, these rights do not extend to the superjacent waters (the water column) or the airspace above.

Geological and Geographical Profile of India’s Continental Shelf

The Indian subcontinent is bounded by distinct marine basins—the Arabian Sea to the west and the Bay of Bengal to the east. The nature of India’s continental shelf varies dramatically between these two coasts due to tectonic history and riverine sedimentation patterns.

The Western Continental Shelf (Arabian Sea)

• Physical Characteristics: Wide, shallow, and gently sloping. The shelf width varies from about 60 km off the southern coast of Kerala to over 300 km off the coast of Mumbai and the Gulf of Khambhat.
• Geological Evolution: Formed primarily due to the faulting and submergence of the western western flank of the Indian peninsula during the breakup of Gondwanaland.
• Sediment Profile: Dominated by biogenic carbonate sediments and terrigenous deposits, creating thick sedimentary basins highly conducive to hydrocarbon generation.

The Eastern Continental Shelf (Bay of Bengal)

• Physical Characteristics: Narrower and steeper compared to the western shelf. The average width ranges between 30 km to 60 km, widening slightly near the deltas of major rivers.
• Geological Evolution: Dominated by progradation, where massive river systems continuously deposit sediment into the sea.
• Sediment Profile: Dominated by immense terrigenous siliciclastic inputs from the Ganga-Brahmaputra, Mahanadi, Godavari, and Krishna river systems. This continuous influx has created the Bengal Fan, the largest submarine mud fan system on Earth.

Strategic Resource Wealth of India’s Continental Shelf

The legal shelf of India holds vast economic reserves that are central to achieving energy security and transitioning toward sustainable marine industrialization.

Hydrocarbon and Natural Gas Reserves

• The Mumbai Offshore Basin: Located on the western continental shelf, it hosts Mumbai High, Bassein, and Vasai structures. It remains India’s premier domestic crude oil producing region.
• The Krishna-Godavari (KG) Deepwater Basin: Situated on the eastern shelf slope, it holds massive deep-water natural gas reserves (e.g., KG-D6 block), critical for India’s clean energy transition.
• The Cambay and Cauvery Offshore Basins: Prolongations of terrestrial rift basins onto the shallow continental shelf, yielding consistent oil and gas outputs.

Marine Placer Deposits (Heavy Minerals)

• The shallow inner continental shelf of India, particularly along Kerala, Tamil Nadu, Andhra Pradesh, and Odisha, contains significant placer deposits.
• These beach and inner-shelf sands are rich in strategic heavy minerals such as Ilmenite, Rutile, Monazite (a source of thorium for India’s three-stage nuclear power program), Zircon, Garnet, and Sillimanite.

Methane Gas Hydrates

• Gas hydrates are crystalline solids formed by water and methane gas under high pressure and low temperature conditions.
• Extensive reserves have been mapped along the continental slope and rise of the Krishna-Godavari, Mahanadi, and Andaman basins, estimated to hold energy reserves that far exceed conventional fossil fuel volumes.

Geopolitical Claims and Border Issues

Because the continental shelf dictates ownership over lucrative underwater resources, its delineation has been a point of bilateral negotiations and legal arbitration for India.

India’s Submission to the CLCS

• Under UNCLOS provisions, India submitted its scientific data data to the UN Commission on the Limits of the Continental Shelf (CLCS) in 2009.
• India claimed an Extended Continental Shelf (ECS) beyond 200 nautical miles, seeking to add an additional 0.6 million square kilometers of seabed to its jurisdiction based on the physical limits of the continental margin in the Bay of Bengal and the Arabian Sea.
• If fully approved, India’s total underwater resource jurisdiction (EEZ + ECS) would expand substantially.

Overlapping Boundaries and Bilateral Settlements

• India and Bangladesh: The maritime boundary arbitration in 2014 by the Permanent Court of Arbitration (PCA) resolved overlapping claims in the Bay of Bengal. The ruling allowed Bangladesh a pathway through India’s EEZ to access its own continental shelf in the deeper waters of the open ocean, ending a long-standing impasse over hydrocarbon exploration blocks.
• The Sir Creek Disparity: The maritime boundary between India and Pakistan in the Arabian Sea remains un-demarcated at Sir Creek. The deadlock prevents the formal finalization of the maritime boundary line, which directly impacts the allocation of the continental shelf in the potentially oil-rich Indus eco-region.

Fact File and Trivia for Prelims

• Isobath: An imaginary line on a map connecting points of equal underwater depth. The 200-meter isobath is traditionally used to mark the geological edge of the shallow continental shelf.
• Monazite Sands: Found extensively along the Malabar and Coromandel coasts; it serves as the primary source of Thorium, which is essential for the third stage of India’s Indigenous Nuclear Power Program.
• Bengal Fan: The largest submarine fan on Earth, measuring around 3,000 km in length and 1,400 km in width. It is fed entirely by the sediment eroded from the Himalayas and transported by the Ganga-Brahmaputra river system across the eastern shelf.
• Bombay High Discovery: Oil was first struck at Bombay High in 1974 by the research vessel Sagar Samrat, leading to the commencement of commercial production by ONGC in 1976.
• Sedentary Species Rule: Under UNCLOS Article 77, foreign vessels can catch swimming fish in a nation’s EEZ if agreements exist, but they can never harvest organisms belonging to sedentary species on the Continental Shelf without express permission from the coastal state.