Chilika Lake (Chilika Lagoon) Explained | World’s Largest Brackish Water Lake | UPSC Geography

Chilika Lake, also known as Chilika Lagoon, is the world’s largest brackish water lake, located along the Odisha coast on the eastern side of India. It is one of the most important geographical and ecological sites for UPSC aspirants, frequently asked in Prelims and Mains under Indian physical geography and wetlands.

Chilika is connected to the Bay of Bengal, which is why its water is saline. More than 50 rivers and streams drain into the lake, making it a classic example of a coastal lagoon ecosystem.

Geographical Location and Dimensions

Chilika Lake extends over:

• More than 60 km in north–south direction
• Spreads across Puri, Khurda, and Ganjam districts of Odisha
• Lies parallel to the eastern coastal plain of India

It acts as a transition zone between freshwater inflow and marine water, creating a highly productive ecological system.

Geological Origin of Chilika Lake

Chilika’s origin is linked to Pleistocene upliftment along the eastern coast.

During the Pleistocene epoch, parts of the seabed experienced tectonic uplift, leading to the formation of shallow coastal depressions. These depressions later evolved into a brackish water lagoon when connected with the sea.

Thus, Chilika is a product of:

• Marine transgression and regression
• Tectonic uplift
• Sediment deposition by rivers

Islands Inside Chilika Lake

Chilika has several small islands, many of which are of limestone origin, giving them a whitish appearance. These islands are also covered with guano (bird droppings), rich in nitrates.

Some islands also have:

• Temples
• Cultural significance
• Naval infrastructure

One prominent island houses INS Chilika, an important Indian Navy training base.

Chilika Lake and Biodiversity

Chilika is one of the largest wetlands in the world and a major biodiversity hotspot.

Migratory Birds

The Nalbana Bird Sanctuary inside Chilika is a major wintering ground for:

• Siberian birds
• Flamingos
• Pelicans
• Herons

Olive Ridley Turtles

Chilika is globally famous for the mass nesting (arribada) of Olive Ridley turtles, especially near:

• Rushikulya river mouth
• Southern and northern sectors of the lake

This makes Chilika critical for marine conservation in India.

Chilika as a Ramsar and UNESCO Site

Chilika Lake is:

• A Ramsar Wetland of International Importance
• Often referred to as a UNESCO-recognised wetland ecosystem
• Among the most important coastal wetlands of Asia

It supports:

• Fisheries
• Livelihood of local communities
• Carbon sequestration
• Cyclone buffering for Odisha coast

Physical Hazard: Whirlpools in Chilika

A unique geographical feature of Chilika is its uneven lake-bottom topography.

Due to local deep depressions, during:

• Cyclones
• Strong winds
• Storm surges

Powerful whirlpools form, which have historically caused:

• Boat capsizing
• Navigation hazards

This shows how physical geography can directly affect human activities.

Why Chilika Lake Is Important for UPSC

Chilika connects:

• Physical geography (lagoon formation)
• Environment & ecology (wetlands, biodiversity)
• Climate resilience (coastal protection)
• Human geography (fisheries, livelihoods)

It is relevant for:

• Prelims (location-based questions)
• GS-1 (Indian geography)
• GS-3 (Environment & Disaster)

Conclusion

Chilika Lake is not just a water body. It is a living laboratory of coastal geomorphology, wetland ecology, and human-environment interaction. For UPSC, it is one of the most high-yield static geography topics.

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FAQs

1. #ChilikaLakeUPSC: Why is Chilika Lake called the world’s largest brackish water lake?
2. #BrackishWaterLakeUPSC: How is a brackish water lagoon formed along coastal regions?
3. #RamsarSitesUPSC: Why is Chilika Lake designated as a Ramsar wetland?
4. #OliveRidleyTurtlesUPSC: What is the ecological significance of Olive Ridley turtles in Chilika Lake?