Geography of Bihar — Study Notes

Overview

Geography of Bihar is a core topic in the Environmental Studies section of Bihar TET Paper I. Questions frequently test your knowledge of Bihar's location, major rivers, forest cover and climatic conditions. Since EVS at the primary level emphasises connecting children to their immediate environment, understanding the geographical setting of Bihar helps teachers design locally relevant lessons.

Bihar is one of the most densely populated states in India, situated in the eastern part of the country. Its geography is dominated by the fertile Gangetic plains, making it an agrarian state. The rivers—especially Ganga and its tributaries—shape the economy, culture and even the challenges (floods) faced by the people. Expect 2–4 direct questions from this sub-topic, often combined with rivers or climate data.

Mastering this topic requires remembering specific facts: coordinates, river names, district boundaries, forest percentage and monsoon patterns. Rote learning is unavoidable here, but linking facts to real-life contexts (why Kosi floods, why forests are sparse) makes retention easier.

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Key Concepts

• **Location and Boundaries**: Bihar lies in the middle Gangetic plain, bounded by Nepal (north), Jharkhand (south), West Bengal (east) and Uttar Pradesh (west). It has no international boundary other than Nepal.

• **Latitude and Longitude**: Bihar extends from 24°20'N to 27°31'N latitude and 83°19'E to 88°17'E longitude. The Tropic of Cancer does NOT pass through Bihar—it passes through Jharkhand to the south.

• **Physiographic Divisions**: The state has three broad regions—(i) the northern Himalayan foothills (Terai), (ii) the north Bihar plains (flood-prone), and (iii) the south Bihar plains (relatively elevated, less flooding).

• **River System**: Ganga is the master river, flowing west to east. North Bihar tributaries (Ghaghra, Gandak, Burhi Gandak, Bagmati, Kamla, Kosi) originate in Nepal/Himalayas and cause annual floods. South Bihar tributaries (Son, Punpun, Phalgu) originate in plateaus and are less flood-prone.

• **Kosi—The Sorrow of Bihar**: Kosi carries heavy silt from Nepal, frequently changes course and causes devastating floods in districts like Saharsa, Supaul and Madhepura.

• **Forest Cover**: Bihar has one of the lowest forest covers in India—about 7.7% of total area (against the national average of ~21%). Major forests are in the hilly southern districts like Kaimur, Rohtas and Gaya.

• **Climate**: Bihar has a humid subtropical climate with three distinct seasons—summer (March–May), monsoon (June–September) and winter (November–February). The southwest monsoon brings most of the annual rainfall.

• **Rainfall Pattern**: Average annual rainfall is about 1,000–1,500 mm, with the eastern and northern districts receiving more rain than the western districts.

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Formulas / Key Facts

| Fact | Detail | |------|--------| | **State Capital** | Patna (on the southern bank of Ganga) | | **Total Area** | 94,163 sq km (12th largest state by area) | | **Total Districts** | 38 districts | | **Latitude Range** | 24°20'N to 27°31'N | | **Longitude Range** | 83°19'E to 88°17'E | | **Major River** | Ganga (flows ~445 km through Bihar) | | **North Bihar Rivers** | Ghaghra, Gandak, Burhi Gandak, Bagmati, Kamla, Kosi, Mahananda | | **South Bihar Rivers** | Son, Punpun, Phalgu (Falgu), Karamnasa | | **Forest Cover** | ~7.7% (one of the lowest in India) | | **Average Rainfall** | 1,000–1,500 mm annually | | **Highest Rainfall District** | Kishanganj (eastern Bihar) | | **Summer Max Temperature** | 40–45°C (May–June, especially Gaya belt) | | **Winter Min Temperature** | 5–10°C (January, north-western districts) |

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Worked Examples

**Example 1: Identifying Rivers**

*Question*: Which river is called the "Sorrow of Bihar" and why?

*Solution*:

• River: **Kosi**
• Reason: Kosi carries enormous amounts of silt from the Himalayas. This silt raises the riverbed, forcing the river to change its course frequently. The sudden shifts cause widespread flooding in north Bihar, destroying crops and villages. Hence, it is called the "Sorrow of Bihar."

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**Example 2: Climate-Based Question**

*Question*: Why does Bihar receive most of its rainfall between June and September?

*Solution*:

• Bihar lies in the path of the **southwest monsoon**, which originates over the Indian Ocean.
• As moist winds travel northward, they are blocked by the Himalayas and release moisture over the Gangetic plains.
• Result: June to September accounts for nearly 80–85% of Bihar's annual rainfall.

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**Example 3: Location-Based Question**

*Question*: A teacher wants to explain Bihar's location using neighbouring states. Which states share boundaries with Bihar?

*Solution*:

• **North**: Nepal (international boundary)
• **South**: Jharkhand
• **East**: West Bengal
• **West**: Uttar Pradesh

Memory trick: **N**epal – **J**harkhand – **W**est Bengal – **U**ttar Pradesh → think "**N-J-W-U**" going clockwise from north.

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Common Mistakes

1. **Confusing Kosi with Ganga**: Students often attribute "Sorrow of Bihar" to Ganga because it is the largest river. → **Correct**: Kosi is the "Sorrow of Bihar" due to its frequent course changes and floods.

2. **Placing Tropic of Cancer through Bihar**: Many assume it passes through Bihar since Bihar is in eastern India. → **Correct**: The Tropic of Cancer (23°26'N) passes through Jharkhand, not Bihar (Bihar starts at 24°20'N).

3. **Overestimating Forest Cover**: Students guess Bihar has moderate forests like other eastern states. → **Correct**: Bihar has only ~7.7% forest cover, among the lowest in India.

4. **Mixing North and South Bihar Rivers**: Son is sometimes placed in north Bihar. → **Correct**: Son is a south Bihar river (right-bank tributary of Ganga, originating from Amarkantak plateau in Madhya Pradesh).

5. **Ignoring District-Level Variations in Rainfall**: Students assume uniform rainfall across Bihar. → **Correct**: Eastern districts (Kishanganj, Purnia) receive higher rainfall; western districts (Rohtas, Kaimur) receive less.

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Quick Reference

• **Boundaries**: Nepal (N), Jharkhand (S), West Bengal (E), Uttar Pradesh (W).
• **Kosi = Sorrow of Bihar** — heavy silt, changing course, floods.
• **Forest cover ~7.7%** — among India's lowest.
• **Southwest monsoon** (June–September) brings 80–85% of annual rain.
• **Ganga flows west → east** through Bihar; Patna lies on its southern bank.
• **Tropic of Cancer does NOT pass through Bihar** — it passes through Jharkhand.