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 activities of rivers and the erosional work of the sea. They are narrow strips of land lying between the Peninsular Plateaus and the coastline. These regions are significant for agriculture, trade, and fishing, supporting a large population. The distinct geological history and river systems have shaped their unique features, making them important study areas in Indian geography.

Western Coastal Plain

The Western Coastal Plain stretches from the Rann of Kutch in the north to Kanyakumari in the south. It lies between the Western Ghats and the Arabian Sea. This plain is generally narrower than its eastern counterpart, averaging about 10-25 kilometers in width. It is a submerged plain, meaning parts of the land have sunk below sea level, leading to the formation of natural harbors like Mumbai and Marmagao. The plain is divided into three main sections: the Konkan Coast (Mumbai to Goa), the Karnataka 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 and inland navigation. Rivers flowing through this plain are short and swift, forming estuaries rather than deltas due to the steep gradient of the Western Ghats.

Eastern Coastal Plain

The Eastern Coastal Plain lies between the Eastern Ghats and the Bay of Bengal, stretching from the Subarnarekha River in West Bengal to Kanyakumari in Tamil Nadu. This plain is broader and more level than the Western Coastal Plain, with an average width of 80-100 kilometers. It is an emergent plain, formed by the upliftment of the land. Major rivers like the Mahanadi, Godavari, Krishna, and Kaveri flow across this plain, forming large and fertile deltas. These deltas are known as the 'Granaries of South India' due to their rich alluvial soil, supporting extensive rice cultivation. The plain is divided into two main parts: the Northern Circars (between Mahanadi and Krishna rivers) and the Coromandel Coast (between Krishna and Kanyakumari). Chilika Lake, India's largest brackish water lagoon, is a prominent feature of the Northern Circars.

Key Differences and Significance

The Western and Eastern Coastal Plains differ significantly in their geological formation, width, and riverine features. The Western Plain is narrow, submerged, and characterized by estuaries and backwaters, while the Eastern Plain is broad, emergent, and marked by large deltas. The rivers of the Western Plain are short and fast-flowing, whereas those of the Eastern Plain are long and form extensive deltas. Both plains are economically crucial. The Western Plain is important for its natural harbors, fishing, and petroleum reserves (e.g., Mumbai High). The Eastern Plain is vital for agriculture, especially rice, and has significant port cities like Chennai, Visakhapatnam, and Paradip. These regions also host diverse ecosystems, including mangroves and coral reefs, contributing to India's biodiversity.

Important Keywords Explained

Kayalsplace

Kayals are the local name for the backwaters found along the Malabar Coast, a section of the Western Coastal Plain in Kerala. These are shallow lagoons or inlets of the sea, separated from the ocean by sandbars. They are significant for inland navigation, fishing, and tourism, playing a crucial role in the local economy and ecology. The famous Nehru Trophy Boat Race is held in the Punnamada Kayal.

Estuaryconcept

An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Unlike deltas, estuaries typically have a funnel shape and are characterized by strong tidal currents. Rivers on the Western Coastal Plain of India, such as the Narmada and Tapi, form estuaries because they flow through hard rocks and have a steep gradient, preventing sediment deposition.

Deltaconcept

A delta is a landform that forms from deposition of sediment carried by a river as its flow leaves its mouth and enters slower-moving or stagnant water. This occurs where a river enters an ocean, sea, estuary, lake, reservoir, or another river that cannot carry away the supplied sediment. Major rivers on the Eastern Coastal Plain like the Mahanadi, Godavari, Krishna, and Kaveri form extensive and fertile deltas.

Additional Facts & Context

• The total length of India's mainland coastline is about 6,100 kilometers.
• Mumbai, Goa, and Mangaluru are important port cities on the Western Coastal Plain.
• Chennai, Visakhapatnam, and Paradip are major port cities on the Eastern Coastal Plain.
• The Western Coastal Plain is tectonically more active due to submergence.
• The Eastern Coastal Plain is wider, averaging 80-100 km, compared to the Western Plain's 10-25 km.