Complete Physiographic Divisions of Bihar for BPSC and Other Competitive Exams in 2025

Geography-3

Complete Physiographic Divisions of Bihar for BPSC and Other Competitive Exams in 2025

Physiographic Divisions of Bihar is broadly divided into

1. The Shivalik Ranges and Terai Region (North-Western Hilly Zone)
2. The Ganga Plains (Middle Gangetic Plains)
3. The Southern Plateau Region

Understanding these Physiographic divisions of Bihar is crucial for BPSC and other competitive exams, as they influence the state’s climate, soil, agriculture, population distribution, and resource potential.

Physiographic Division of Bihar

1. The Shivalik Ranges and Terai Region

This region represents the northernmost part of Bihar and is the only hilly zone in the state.

• Location: Primarily located in the northwestern part of West Champaran district. It forms a narrow belt along the Nepal border.
• Geological System: Represents the Tertiary Rock System, forming part of the outer Himalayas (Sub-Himalayan foothills).
• Area: Spans approximately 932 sq. km.
• Sub-Divisions: This division further comprises:
  • Ramnagar Doon: The southernmost part of the Terai, with an elevation around 240 meters.
  • Someshwar Ranges: The northernmost and highest part of Bihar, extending over 75 sq. km. Its maximum altitude is 874 meters, which is the highest point in Bihar. It stretches from Triveni Canal (West) to Bhikhnathori (East) and contains important passes like Someshwar, Bhikhnathori, and Marawat Pass, serving as routes to Nepal.
  • Harha Valley (Doon Valley): A valley situated between the Ramnagar Doon and Someshwar Ranges.
• Key Features:
  • Characterized by steep slopes, dense moist deciduous forests, and seasonal streams.
  • Has relatively sparse human habitation due to the rugged terrain.
  • Plays a crucial role in ecological balance and acts as a transition zone between the Himalayas and the plains.

2. The Ganga Plains (Middle Gangetic Plains)

This is the most extensive and dominant physical division of Bihar, covering the majority of the state’s area. The Ganga River bisects this plain into two unequal parts: the Northern Plains and the Southern Plains.

• Location: Stretches from the Terai region in the north to the Southern Plateau in the south, and from West Champaran in the west to Katihar in the east.
• Area: Covers about 45,000 sq. km, which is nearly 50% of Bihar’s total area.
• Formation: Formed by vast alluvial deposits brought down by numerous rivers originating from the Himalayas and the Peninsular Plateau.
• Soil: Consists of highly fertile new (Khadar) and old (Bangar) alluvium, making it exceptionally suitable for agriculture.
• Population & Economy: This region is densely populated, agriculturally productive, and forms the heartland of Bihar’s economy.

A. Northern Plains (North of Ganga)

• Location: Lies between the Ganga River and the Nepal border. Covers districts like West Champaran, East Champaran, Sitamarhi, Madhubani, Darbhanga, Muzaffarpur, Supaul, Saharsa, Araria, Kishanganj, etc.
• Rivers: Drained by major Himalayan rivers and their tributaries, including Gandak, Ghaghara (Saryu), Burhi Gandak, Bagmati, Kamla-Balan, Kosi, and Mahananda. These rivers flow southward from the Himalayas.
• Terrain: Characterized by flat and low-lying floodplains. The slope is generally from north-west to south-east.
• Soil: Rich in new alluvium (Khadar) due to annual floods, making it highly fertile. Also contains Bangar (old alluvium) in higher areas.
• Agricultural Relevance: Most fertile region of Bihar, supporting a dense population. Major crops include paddy (rice), wheat, maize, sugarcane, and pulses.
• Challenges: Highly prone to annual floods, especially from rivers like the Kosi River (known as the “Sorrow of Bihar”), leading to waterlogging and river shifting. Formation of Chaurs/Chharan lakes (oxbow lakes).

B. Southern Plains (South of Ganga)

• Location: Lies between the Ganga River in the north and the northern edge of the Chotanagpur Plateau in the south. Includes districts like Patna, Gaya, Nalanda, Jehanabad, Aurangabad, Bhojpur, Rohtas, Munger, Bhagalpur (parts), Banka (parts), etc.
• Rivers: Crossed by peninsular rivers like Sone, Punpun, Phalgu, Karmanasha, which originate from the Southern Plateau.
• Terrain: Slightly elevated and generally well-drained land, making it less prone to widespread floods compared to the Northern Plains. It is narrower than the Northern Plains and often triangular in shape. The western portion is wider than the eastern.
• Soil: Primarily consists of old alluvium (Bangar), making it less fertile than the new alluvium of the northern plains. Some regions near the plateau fringe have laterite and red soils.
• Agricultural Relevance: Supports double cropping in irrigated areas. Major crops include wheat, rice, pulses, and oilseeds.
• Challenges: Some regions, particularly in summer, face drought conditions. Soil erosion can occur in undulating areas. Notable for the presence of ‘Tal’ lands (swampy areas) along the southern bank of the Ganga (e.g., from Badh to Bhagalpur). Features isolated hills like those of Gaya, Rajgir, Giriyak, Bihar Sharif, Sheikhpura, Jamalpur, and Kharagpur hills.

3. Southern Plateau Region

This region forms the southern border of Bihar, extending into the Chotanagpur Plateau of Jharkhand.

• Location: Located in the southwestern part of Bihar, bordering Jharkhand. It stretches from Kaimur in the west to Banka in the east. Districts include Rohtas, Kaimur, Aurangabad, Gaya (parts), Nawada, Jamui, Banka, Bhagalpur (parts).
• Geological System: Composed mainly of ancient igneous and metamorphic rocks like Granite, Gneiss, and Schist, indicating a geologically stable formation. This region represents the Dharwar Rock System (oldest) and Vindhyan Rock System (in Kaimur plateau).
• Terrain: Characterized by undulating hills, rocky terrain, and interspersed with narrow valleys. Features isolated conical hills such as Pretshila, Ramshila, and Jethian Hills, which are batholithic in origin (formed from cooled magma intrusions). The Kaimur Plateau is a significant part of this region. Altitude varies generally from 300 to 1,200 meters.
• Soil: Dominated by laterite and red soil, which are typically low in fertility and acidic. Thin soil cover over a rocky base makes it unsuitable for extensive agriculture.
• Natural Resources: Rich in mineral resources like quartzite, mica, bauxite, limestone (especially in Rohtas). Industrial exploitation is still limited. Also features dry deciduous forests with species like sal, teak, and bamboo.
• Population & Development: Relatively less populated. There is scope for forestry and mining development in this region.
• Challenges: Poor soil fertility, lack of extensive irrigation infrastructure, and issues of forest degradation and soil erosion.

Comparison Table: Physical Divisions of Bihar

Focus for BPSC Prelims MCQs:

• Names and key features of each physiographic division.
• Specific rivers and soil types associated with each region.
• Flood-prone areas (Northern Plains, especially Kosi basin) and drought-prone areas (parts of Southern Plains).
• Agricultural patterns and key crops in each zone.
• Location of plateaus and hills, such as the Kaimur Plateau in the Southern Plateau region, and hills like Rajgir, Gaya, Kharagpur, Someshwar.
• Geological formations (Tertiary, Quaternary, Igneous/Metamorphic, Dharwar, Vindhyan) associated with each division.
• Highest point in Bihar (Someshwar Fort in Someshwar Range, 874 m).