Coastal Plains of India: East and West Explained for UPSC SSC

Introduction to Coastal Plains

India has a long coastline, approximately 7,516.6 kilometers, including the mainland and island territories. This extensive coastline is bordered by two broad coastal plains: the Western Coastal Plain and the Eastern Coastal Plain. These plains are formed by the depositional work of rivers and the erosional and depositional activities of the sea. They are narrow strips of land between the Peninsular Plateau and the Arabian Sea in the west, and between the Peninsular Plateau and the Bay of Bengal in the east. These plains are significant for agriculture, trade, and fishing, supporting a large population and contributing substantially to the national economy. Their distinct geological formations and climatic conditions lead to varied agricultural practices and settlement patterns across the regions.

Western Coastal Plain

The Western Coastal Plain stretches from the Gulf of Kachchh in the north to Kanyakumari in the south. It is a narrow plain, generally 10-25 km wide, and is largely submerged. This plain is characterized by numerous small, swift-flowing rivers that form estuaries rather than deltas, due to its narrowness and the steep gradient of the Western Ghats. It is divided into three main sections: the Konkan Coast (Mumbai to Goa), the Karnataka Coast or Kanara Coast (Goa to Mangaluru), and the Malabar Coast (Mangaluru to Kanyakumari). The Malabar Coast is known for its backwaters, locally called 'kayals,' which are used for fishing, inland navigation, and tourism. Important ports like Mumbai, Mormugao, and Kochi are located on this plain, facilitating significant maritime trade. The plain receives heavy rainfall due to its proximity to the Western Ghats.

Eastern Coastal Plain

The Eastern Coastal Plain lies between the Eastern Ghats and the Bay of Bengal, extending from the Subarnarekha River in the north to Kanyakumari in the south. Unlike its western counterpart, this plain is broader, with an average width of 80-100 km, and is an emergent coast. It is well-watered by large east-flowing rivers like the Mahanadi, Godavari, Krishna, and Kaveri, which form extensive and fertile deltas. These deltas are known as the 'Granaries of South India' due to their rich alluvial soils and high agricultural productivity, especially for rice. The Eastern Coastal Plain is divided into three main parts: the Utkal Plain (Odisha), the Andhra Plain (Andhra Pradesh), and the Tamil Nadu Plain (Tamil Nadu). Chilika Lake, a brackish water lagoon, is a prominent feature of the Utkal Plain. Major ports include Chennai, Visakhapatnam, and Paradip, which are crucial for India's trade with Southeast Asian countries.

Key Differences and Features

The Western and Eastern Coastal Plains exhibit several key differences. The Western Plain is narrow, submerged, and characterized by estuaries, while the Eastern Plain is broad, emergent, and features well-developed deltas. Rivers on the west coast are short and fast-flowing, whereas east coast rivers are longer and form large deltas. The Western Plain experiences higher rainfall due to the Western Ghats acting as a barrier to monsoon winds, while the Eastern Plain receives rainfall from both the Southwest and Northeast monsoons, often experiencing cyclones. The presence of 'kayals' is unique to the Malabar Coast of the Western Plain. The Eastern Plain's deltas are highly fertile, supporting intensive agriculture, particularly rice cultivation. These geographical distinctions have shaped the economic activities, population distribution, and cultural landscapes of the respective regions over centuries.

Important Keywords Explained

Kayalsplace

Kayals are shallow lagoons or backwaters found along the Malabar Coast of the Western Coastal Plain in Kerala. They are formed by the accumulation of sandbars that separate parts of the sea from the mainland. These unique water bodies are used for fishing, inland navigation, and are a major tourist attraction, particularly for houseboat cruises. Vembanad Lake is the largest kayal in Kerala.

Emergent Coastconcept

An emergent coast is formed when a part of the seabed rises above sea level, or when the sea level falls relative to the land. This often results in a broad coastal plain with features like marine terraces and well-developed deltas, as seen in the Eastern Coastal Plain of India. It indicates a recent uplift of the land or a drop in sea level.

Submerged Coastconcept

A submerged coast is formed when a part of the land sinks below sea level, or when the sea level rises relative to the land. This typically results in a narrow coastal plain, often characterized by estuaries and fjords (though not prominent in India). The Western Coastal Plain of India is an example of a submerged coast, indicating a recent subsidence of the land.

Additional Facts & Context

• The average width of the Western Coastal Plain is 10-25 km.
• The average width of the Eastern Coastal Plain is 80-100 km.
• The largest delta on the Eastern Coastal Plain is formed by the Ganga-Brahmaputra system, though the Indian part is primarily formed by Mahanadi, Godavari, Krishna, and Kaveri.
• Vembanad Lake, the longest lake in India, is a kayal on the Malabar Coast.
• The Eastern Coastal Plain is often hit by tropical cyclones, especially during October-November.