Coastal plains

Coastal Plain: Meaning, Formation, Types and Indian Examples (UPSC Notes)

Have you ever wondered why some of India’s biggest cities like Mumbai and Chennai developed along the sea? Or why ports are mostly located on flat coastal land instead of steep hills?

The answer lies in the concept of a coastal plain.

For UPSC aspirants and other competitive exam students, the coastal plain is an important topic in Physical Geography. It is frequently linked with landforms, drainage, ports, agriculture, climate, and economic geography.

In this article, we will understand the coastal plain in a simple and exam-focused way.

What is a Coastal Plain?

A coastal plain is a flat, low-lying stretch of land located between the coast (sea or ocean) and inland highlands such as plateaus or mountains.

It is usually:

• Gently sloping toward the sea
• Made of sediments deposited by rivers or the sea
• Fertile and suitable for agriculture and settlements

In India, coastal plains lie between the Western Ghats and the Arabian Sea and between the Eastern Ghats and the Bay of Bengal.

Formation of Coastal Plain

Understanding formation is important for UPSC Prelims and Mains.

A coastal plain is mainly formed due to:

1. Marine Deposition

Sea waves deposit sand, silt, and clay along the shore. Over time, this builds up flat land.

Example:

• Beaches and sand bars along the Kerala coast.

2. River Deposition

Rivers carry sediments from mountains and deposit them near their mouths, forming deltas and plains.

Example:

• The Ganga-Brahmaputra Delta on the eastern coast.

3. Submergence and Emergence

• Submergent coast: Land sinks, and sea water enters (creates estuaries).
• Emergent coast: Land rises, forming raised beaches and marine terraces.

Western Coastal Plain is an example of submergent coast in parts.

Types of Coastal Plain

For exam clarity, coastal plains are generally classified into two main types:

1. Emergent Coastal Plain

Formed due to uplift of land.

Features:

• Raised beaches
• Marine terraces
• Parallel coastline

Example:

• Parts of the Eastern Coastal Plain

2. Submergent Coastal Plain

Formed when land sinks or sea level rises.

Features:

• Rias (drowned river valleys)
• Estuaries
• Irregular coastline

Example:

• Western Coastal Plain (presence of estuaries like Narmada and Tapi)

Coastal Plain of India

India has two major coastal plains:

1. Western Coastal Plain
2. Eastern Coastal Plain

Let us study them in detail.

Western Coastal Plain

The Western Coastal Plain lies between the Western Ghats and the Arabian Sea.

Key Features

• Narrow (50–100 km wide)
• Submergent coast
• Many estuaries
• Few deltas

Divisions (North to South)

• Konkan Coast (Mumbai–Goa)
• Kannad Plain (Karnataka)
• Malabar Coast (Kerala)

Important Characteristics

• Rivers like Narmada and Tapi form estuaries
• Presence of backwaters (Kerala)
• Natural harbours (Mumbai)

Why More Ports on Western Coast?

• Deep water near shore
• Estuarine conditions
• Natural harbours

Examples:

• Mumbai
• Mormugao
• Kochi

Eastern Coastal Plain

The Eastern Coastal Plain lies between the Eastern Ghats and the Bay of Bengal.

Key Features

• Wider than western coast
• Emergent coast
• Large deltas
• More sediment deposition

Divisions (North to South)

• Northern Circars (Odisha–Andhra Pradesh)
• Coromandel Coast (Tamil Nadu)

Important Characteristics

• Major river deltas:
  • Mahanadi
  • Godavari
  • Krishna
  • Kaveri
• Fertile agricultural land
• Cyclone-prone region

Difference Between Western and Eastern Coastal Plain

This table is highly useful for UPSC revision.

Coastal Landforms Associated with Coastal Plain

When studying coastal plain, link it with these landforms:

1. Delta

Formed by river deposition.
Example: Ganga-Brahmaputra Delta.

2. Estuary

Drowned river mouth.
Example: Narmada estuary.

3. Lagoon

Shallow water body separated from sea.
Example: Chilika Lake.

4. Sand Bars and Spits

Depositional features formed by waves.

These are commonly asked in UPSC Prelims.

Importance of Coastal Plain

A coastal plain is not just a physical feature. It has economic and strategic importance.

1. Agriculture

• Fertile deltaic soil
• Rice cultivation in eastern coast

2. Ports and Trade

• Major trade centers located on coastal plains
• Mumbai, Chennai, Visakhapatnam

3. Fisheries

• Fishing activities
• Shrimp farming in Andhra Pradesh

4. Tourism

• Beaches of Goa
• Backwaters of Kerala

5. Strategic Importance

• Naval bases
• Coastal security

Diagram Suggestion for Exams

For better understanding, you can draw:

1. Simple Cross-Section Diagram

Draw:

• Sea on left
• Flat coastal plain
• Western Ghats/Eastern Ghats on right

Label:

• Coastline
• Plain
• Plateau

2. Map-Based Diagram

Draw outline map of India and mark:

• Western Coastal Plain
• Eastern Coastal Plain
• Major deltas

Even a rough diagram fetches extra marks in Mains.

Coastal Plain and Natural Hazards

UPSC often links geography with disasters.

1. Cyclones

Eastern Coastal Plain is cyclone-prone due to Bay of Bengal.

2. Tsunami

Low-lying coastal plains are vulnerable.

Example:

• 2004 Indian Ocean Tsunami affected Tamil Nadu coast.

3. Coastal Erosion

Waves erode beaches and settlements.

Coastal Plain in World Geography

Globally, coastal plains are found in:

• Eastern USA (Atlantic Coastal Plain)
• Brazil
• China

These areas are densely populated and agriculturally productive.

How to Write Coastal Plain in UPSC Mains

In a 10–15 marker answer:

1. Define coastal plain
2. Explain formation
3. Classify types
4. Explain Indian examples
5. Add diagram
6. Conclude with importance

Keep structure clear and logical.

Conclusion: Coastal Plain – Quick Revision for UPSC

A coastal plain is a flat, low-lying land along the coast formed by marine and river deposition.

India has two major coastal plains:

• Western Coastal Plain (narrow, estuarine, submergent)
• Eastern Coastal Plain (wide, deltaic, emergent)

They are economically important for agriculture, ports, fisheries, and trade.

For UPSC, remember:

• Formation process
• Differences between east and west coast
• Associated landforms
• Map-based understanding

If you revise these points, you can confidently handle any question related to coastal plain in Prelims or Mains.

FAQs on Coastal Plain

1. What is a coastal plain in simple words?

A coastal plain is a flat area of land near the sea formed by deposition of sediments by rivers and sea waves.

2. Why is the Eastern Coastal Plain wider than the Western Coastal Plain?

Because major rivers like Godavari and Krishna deposit large amounts of sediments, forming wide deltas.

3. Why are estuaries common on the Western Coastal Plain?

Due to submergence and steep slope of the Western Ghats, rivers form estuaries instead of deltas.

4. Which Indian rivers form major deltas on the coastal plain?

Mahanadi, Godavari, Krishna, and Kaveri.

5. Why is the coastal plain important for India?

It supports agriculture, ports, fisheries, trade, tourism, and strategic activities.