Geography of West Bengal

Overview

West Bengal occupies a unique geographical position in eastern India, stretching from the Himalayas in the north to the Bay of Bengal in the south. This north-south elongation gives the state remarkable physical diversity — from snow-capped peaks to deltaic plains — within a relatively compact area of approximately 88,752 sq km. The state shares international boundaries with Bangladesh, Nepal and Bhutan, making it strategically significant.

For WB TET Social Studies, questions frequently test factual recall of physical divisions, major rivers, climate zones and natural resources. Expect questions on district-wise features, comparisons between northern and southern Bengal, and the economic importance of resources. Mastering the four-fold physical division and the river systems is essential.

Key Concepts

• **Four Physical Divisions**: West Bengal divides into (1) Northern Mountain Region (Darjeeling Himalayas), (2) Terai and Duars (sub-Himalayan plains), (3) Rarh Region (western undulating plateau), and (4) Gangetic Delta (southern alluvial plains including Sundarbans).

• **North-South Gradient**: Elevation decreases from over 3,600 m in Darjeeling to sea level in the Sundarbans. This gradient controls climate, vegetation and agriculture.

• **Monsoon Dominance**: The state experiences a tropical monsoon climate. The southwest monsoon (June–September) brings 70–80% of annual rainfall.

• **River Systems**: The Ganga (locally Bhagirathi-Hooghly) and its tributaries dominate southern Bengal; the Teesta, Torsa and Jaldhaka drain the north.

• **Sundarbans**: The world's largest mangrove delta, shared with Bangladesh, is home to the Royal Bengal Tiger and is a UNESCO World Heritage Site.

• **Laterite Soils in Rarh**: The western plateau has red laterite soil — less fertile than alluvial but supports specific crops like paddy, pulses and mango orchards.

• **Resource Richness**: Coal deposits in Raniganj-Asansol, tea gardens in Darjeeling and Dooars, and fertile alluvium supporting rice and jute cultivation define economic geography.

Key Facts

| Feature | Details | |---------|---------| | Total Area | 88,752 sq km (approx.) | | Highest Peak | Sandakphu — 3,636 m (Darjeeling district) | | Major Rivers | Ganga (Bhagirathi-Hooghly), Teesta, Damodar, Ajay, Mayurakshi, Rupnarayan | | Annual Rainfall | 125 cm to 350+ cm (north receives more) | | Soil Types | Alluvial (delta), Laterite (Rarh), Mountain soil (north) | | Key Minerals | Coal (Raniganj), China clay, Dolomite | | Forest Cover | About 19% of state area; sal, teak, sundari trees | | Climate Type | Tropical monsoon with three seasons: summer, monsoon, winter |

**Important Districts by Region**:

• Northern Hills: Darjeeling, Kalimpong
• Terai-Dooars: Jalpaiguri, Alipurduar, Cooch Behar
• Rarh: Purulia, Bankura, Birbhum, West Burdwan
• Delta: North & South 24 Parganas, Howrah, Hooghly, Nadia, Murshidabad

Worked Examples

**Example 1**: *Which physical region of West Bengal is characterised by red laterite soil and undulating terrain?*

**Solution**:

• Step 1: Identify soil type — laterite soil is formed in areas with heavy rainfall followed by dry spells, causing leaching of silica.
• Step 2: Recall physical divisions — the Rarh region (western plateau fringe) has this characteristic.
• Step 3: Districts involved — Purulia, Bankura, parts of Birbhum and West Burdwan.
• **Answer**: Rarh Region.

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**Example 2**: *The river Teesta originates from which region and flows through which districts of West Bengal?*

**Solution**:

• Step 1: Origin — Teesta originates from Tso Lhamo Lake in Sikkim (near the Tibet border).
• Step 2: Course in West Bengal — enters through Darjeeling district, flows through Jalpaiguri and Cooch Behar.
• Step 3: Confluence — joins the Brahmaputra (Jamuna) in Bangladesh.
• **Answer**: Originates in Sikkim Himalayas; flows through Darjeeling, Jalpaiguri and Cooch Behar districts.

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**Example 3**: *Why does Darjeeling receive more rainfall than Purulia?*

**Solution**:

• Step 1: Darjeeling is in the northern hills, directly in the path of moisture-laden southwest monsoon winds.
• Step 2: Orographic rainfall occurs when winds rise over the mountains.
• Step 3: Purulia lies in the rain-shadow of the Chotanagpur Plateau and receives winds after they have shed much moisture.
• **Answer**: Darjeeling's orographic position causes heavy rainfall (300+ cm); Purulia's interior location and rain-shadow effect result in lower rainfall (125–140 cm).

Common Mistakes

• **Confusing Bhagirathi and Hooghly**: Students treat them as separate rivers. *Correct view*: Bhagirathi is the upper course; below Nabadwip, the same river is called Hooghly after receiving the Jalangi.

• **Misplacing Sundarbans**: Some believe Sundarbans is entirely in West Bengal. *Correct view*: About 40% lies in India (South 24 Parganas); 60% is in Bangladesh.

• **Treating Terai and Dooars as identical**: Terai is the marshy, swampy belt immediately south of the Himalayas; Dooars (meaning "doors" or passes) refers to the forested plains east of Teesta. Both are sub-Himalayan but geographically distinct.

• **Ignoring Damodar's dual character**: Students forget that Damodar was once called "Sorrow of Bengal" due to floods but is now dammed (DVC) for irrigation and power. Questions often test this transformation.

• **Overlooking Kalimpong as a separate district**: Since 2017, Kalimpong is no longer part of Darjeeling district. Exam questions may test current administrative divisions.

Quick Reference

1. **Four Divisions** — Northern Mountains → Terai-Dooars → Rarh → Gangetic Delta (north to south).

2. **Sandakphu (3,636 m)** — highest point; Tiger Hill is a viewpoint, not the highest peak.

3. **Ganga enters at Farakka** (Murshidabad) and splits into Bhagirathi-Hooghly and Padma (to Bangladesh).

4. **Raniganj Coalfield** — oldest and one of the largest in India; lies in West Burdwan district.

5. **Sundarbans** — mangrove delta, UNESCO site, Royal Bengal Tiger, "sundari" tree gives its name.

6. **Climate range** — 10°C winter (north hills) to 40°C+ summer (Rarh); rainfall 125 cm (west) to 350 cm (north).