Coastal Erosion in India: Shoreline Assessment & East Coast Risks

Overview

India's coastline is retreating fast. National Centre for Coastal Research assessments reveal that 33.6% of mainland India's coastline is actively eroding. Intense cyclonic surges, disrupted littoral drift, and deltaic sediment deprivation place a heavy toll on the eastern seaboard. In contrast, accretion accounts for 26.9% of the shoreline while 39.6% remains stable.

Vulnerability is concentrated along the east coast. West Bengal and the Union Territory of Puducherry now record erosion across more than half their coastal frontage. Mapping these shifts directs spatial planning, disaster mitigation, and climate-resilient coastal infrastructure under the Coastal Regulation Zone framework.

Recent parliamentary disclosures from the Ministry of Environment, Forest and Climate Change present updated shoreline data across maritime states. As of February 2025, official records confirm that eastern littoral states face severe shoreline retreat compared to western coasts.

State-level findings highlight sharp regional contrasts:

• West Bengal: Most vulnerable nationwide, with 60.5% (323.07 km) of its 534.35 km coastline undergoing active retreat.
• Puducherry: Experiences 56.2% shoreline erosion along the Coromandel Coast.
• Tamil Nadu: Records active erosion along 42.7% of its 991.47 km shoreline.
• Odisha: The primary maritime outlier where deposition dominates, logging 51.0% (280.02 km) accretion against 25.6% erosion.
• Andhra Pradesh: Documents a 49.6% accreting coast across 1,027.58 km of shoreline, alongside 28.7% eroding sections.

The National Centre for Coastal Research, an attached office of the Ministry of Earth Sciences, oversees the assessment across mainland India. Operating from Chennai, this nodal body monitors shoreline dynamics, charts vulnerability, and designs site-specific Shoreline Management Plans (SMPs).

Three specialized scientific bodies drive monitoring and regulation:

• National Centre for Coastal Research (NCCR): Monitors baseline shoreline change, models sediment transport, and provides mitigation frameworks to coastal states.
• National Centre for Sustainable Coastal Management (NCSCM): Operates under the Ministry of Environment, Forest and Climate Change to support coastal zoning, map Ecologically Sensitive Areas, and demarcate the composite Hazard Line.
• Indian National Centre for Ocean Information Services (INCOIS): Maps multi-hazard vulnerability by issuing a 1:100,000 scale Coastal Vulnerability Index (CVI) Atlas.

The index developed by INCOIS tracks seven physical parameters. These include shoreline change rate, sea-level change rate, coastal elevation, coastal slope, geomorphology, significant wave height, and regional tidal range.

NCCR maps coastal stretches at 1:25,000 scale to determine long-term morphological change. Using multi-temporal satellite imagery alongside the Digital Shoreline Analysis System (DSAS), scientists quantify net shoreline shifts over multi-decadal baselines. Coasts are categorized into High, Moderate, and Low erosion, stable, or accreting zones.

India's 6,907.18 km mainland coastline breaks down into three baseline categories:

Eastern states bear an uneven burden. West Bengal leads with 60.5% coastal retreat, triggered by powerful hydrodynamic energy in the estuarine delta.

Severe meteorological hazards, high hydrodynamic energy, and starving fluvial sediment supplies drive eastern coastal retreat. The regional oceanography of the Bay of Bengal combines with upstream hydrological barriers to generate chronic sediment deficits.

Four drivers govern this vulnerability:

1. Disproportionate Cyclonic Frequency: The Bay of Bengal generates cyclonic storms at roughly four times the frequency of the Arabian Sea. Eastern barrier beaches and mudflats endure repeated, severe wave battering.
2. High-Energy Littoral Drift: A strong northerly drift operates along the East Coast during the Southwest Monsoon. It moves an estimated 0.5 to 1.5 million cubic metres of sand along the shoreline each year.
3. Hard Engineering Interventions: Breakwaters and training walls at ports like Visakhapatnam, Chennai, and Paradip block this sediment flow. These structures trigger heavy updrift sediment accumulation alongside severe downdrift erosion.
4. Upstream Fluvial Sediment Deprivation: Dams and reservoirs across the Godavari, Krishna, Mahanadi, and Cauvery have curtailed deltaic sediment discharge by over 70% in specific basins. This deprives delta fronts of vital replenishment.

Geological origin separates the broad shelf of the East Coast from the steep, faulted margin along the West Coast. These distinct structures dictate wave interaction and erosion susceptibility.

Shoreline loss displaces coastal fishing settlements and damages infrastructure across eastern maritime ecosystems. When beaches retreat, local communities face compounding socio-economic disruptions.

Artisanal fishing settlements experience immediate operational losses. Ongoing landward retreat destroys beach landing sites, boat berths, and drying areas, forcing families to abandon customary operations.

Groundwater salinisation compounds the crisis. Shoreline retreat and storm surge flooding cause saltwater intrusion into freshwater aquifers, polluting drinking water and degrading deltaic farm soils.

Ecological habitats also suffer direct damage:

• Mangrove Buffer Degradation: Persistent wave energy destabilises seaward mangrove fringes in the Sundarbans and Bhitarkanika, eroding the primary bio-shield against severe cyclonic storms.
• Loss of Mass Nesting Sites: Erosion narrows sandy rookeries utilized by endangered Olive Ridley sea turtles across Odisha's Gahirmatha and Rushikulya shores.

Public finance mechanisms now recognise these displacement risks. The 15th Finance Commission set aside a ₹1,000 crore allocation under the National Disaster Response Fund (NDRF) Recovery and Reconstruction window to resettle populations displaced by coastal and river erosion.

Coastal governance in India functions under the Coastal Regulation Zone (CRZ) Notification of 2019, issued under the Environment (Protection) Act, 1986. The framework balances development, port trade, and ecological protection across fragile littoral margins.

Three statutory mechanisms direct management:

• Hazard Line Demarcation: The Survey of India and NCSCM mapped a Hazard Line incorporating 1-in-100-year flood levels, sea-level rise projections, and long-term erosion rates.
• Mandatory Shoreline Management Plans: Under the 2019 notification, maritime states must embed a Shoreline Management Plan (SMP) into their statutory Coastal Zone Management Plans before building erosion defenses.
• Integrated Coastal Zone Management (ICZM): Promotes spatial planning to balance port expansion and local rehabilitation with natural sediment cells.

Sustainable coastal planning requires moving past rigid engineering toward hybrid, nature-based protections. Seawalls, revetments, and groynes often aggravate downdrift erosion by reflecting wave energy rather than absorbing it.

Soft engineering interventions offer sustainable alternatives:

• Sand Bypassing and Beach Nourishment: Pumping sand past port breakwaters restores natural downdrift transport, as demonstrated at Puducherry and Visakhapatnam.
• Submerged Geotextile Reefs: Deploying offshore geotubes dissipates wave energy and encourages sand deposition without harming the visible shoreline.
• Mangrove and Bio-shield Restoration: Expanding vegetative coastal buffers stabilises fine sediments, absorbs storm surges, and protects local ecology.
• Risk-Informed Spatial Planning: Enforcing development bans seaward of the demarcated Hazard Line directly aligns with the Sendai Framework for Disaster Risk Reduction.

• NCCR assessments indicate that 33.6% of mainland India's coastline is eroding, 26.9% is accreting, and 39.6% is stable.
• Eastern states experience the highest erosion rates, led by West Bengal (60.5%), Puducherry (56.2%), and Tamil Nadu (42.7%), whereas Odisha registers 51.0% accretion.
• Vulnerability along the East Coast stems from fourfold higher cyclonic frequencies, port-driven interruption of littoral drift, and over 70% sediment starvation behind river dams.
• Monitoring and spatial planning rely on the Coastal Vulnerability Index (INCOIS), the statutory Hazard Line (NCSCM), and mandatory Shoreline Management Plans under the CRZ Notification, 2019.
• National policy promotes nature-based solutions such as sand bypassing, submerged reefs, and mangrove restoration, backed by a ₹1,000 crore resettlement fund from the 15th Finance Commission.