Mangroves vs Seawalls: Ecosystem-Based Coastal Defence
Why in the news
Cyclone Dana’s landfall near Bhitarkanika on the Odisha coast showed how well mangroves shield the shore. An editorial used it to argue for nature-based defences over costly concrete.
Key facts
- Spending: coastal states put ₹2,641 crore into engineered protection such as seawalls and groynes over ten years.
- Mission budget: the National Coastal Mission allocation dropped from ₹195 crore (2022-23) to ₹50 crore (2024-25).
- Exposure: an 11,000 km coastline and about 250 million people nearby.
- Recommendation: move to Ecosystem-based Adaptation (EbA) using mangroves, seagrass meadows and coral reefs.
| Aspect | Mangroves | Seawalls |
|---|---|---|
| Wave and surge impact | Aerial roots absorb wave energy | Rigid barrier |
| Durability | Self-repairing, stronger with time | Degrade under cyclone and tidal stress |
| Cost | Natural system | Costly to build and maintain |
| Side effects | Trap sediment, helping land build up | Can push erosion to nearby stretches |
| Co-benefits | Biodiversity, carbon storage, livelihoods | None of these |
About EbA and blue carbon
- EbA is a nature-centred climate strategy that relies on biodiversity and ecosystem services; habitats include mangroves, seagrass, coral reefs, salt marshes, wetlands and forests.
- It differs from “grey” infrastructure such as concrete walls and groynes.
- Blue carbon is carbon dioxide stored by coastal and marine ecosystems; mangrove soil is a long-term sink, so protecting them helps both mitigation and adaptation.
- Research cited calls India a global hotspot for coastal EbA, with mangroves shielding more people per hectare than almost anywhere.
Background: mangroves in India
- Salt-tolerant trees and shrubs of intertidal zones in tropical and subtropical coasts.
- Sundarbans (West Bengal): world’s largest mangrove forest and a UNESCO World Heritage Site.
- Bhitarkanika (Odisha): saltwater crocodiles and Olive Ridley turtles.
- Others: Pichavaram and Muthupet (Tamil Nadu), Coringa (Andhra Pradesh), Mahanadi, Krishna and Godavari deltas, Gulf of Kutch and Gulf of Khambhat (Gujarat), Andaman and Nicobar Islands.
Policy tools
- National Coastal Mission: central scheme under MoEFCC for mangroves, coral reefs, biodiversity and coastal communities; part of NAPCC.
- MISHTI: Mangrove Initiative for Shoreline Habitats and Tangible Incomes, announced in Union Budget 2023-24.
- ICZM Project: World Bank-supported coastal management in selected states.
- CRZ Notification: rules for activities along the coast.
Exam angle
- Expansion of MISHTI and EbA.
- Largest mangrove forest: Sundarbans.
- Nodal ministry of the National Coastal Mission: MoEFCC.