Geographical Structure of Bihar PDF Download

Geographical Structure of Bihar

Physiography: Bihar's landscape has been primarily shaped by rivers. The northern part of Bihar features a younger geological structure, while the southern part has an older geological formation. The oldest rocks in Bihar are Dharwarian, and the youngest are Quaternary rocks. Physiographically, the state comprises:

• Terai Region: Located in the North-West.
• Gangetic Plain: Found in the central part of the state.
• Plateau: Situated in the Southern region of Bihar.

Location and Size: Bihar is in the eastern part of India, covering an area of 94,163 square kilometers, making it the 12th largest state in the country. This area represents 2.86% of India's total geographical area.

Geographical Coordinates: Bihar is located between 24º21¢10¢¢ N to 27º31¢15 ¢¢N latitudes and 83º19¢50¢¢E to 88º17¢40¢¢ E longitudes. Its latitudinal extent is 3º, and its longitudinal extent is 5°. The entire state lies in the Northern Hemisphere, north of the Tropic of Cancer.

Shape and Dimensions: Bihar has a rectangular shape, measuring 483 km in width (east to west) and 345 km in length (north to south). The state's average elevation is 53 meters (173 feet) above sea level.

Connectivity: Bihar is connected through National Waterways No-1, which runs from Allahabad to Haldia. The state is located 200 km from the nearest coastline.

Boundaries: Bihar is a land-locked state bordered by:

• North: Nepal
• West: Uttar Pradesh
• South: Jharkhand
• East: West Bengal

International Border

Bihar shares a 729 km long international border with Nepal. This border is divided among seven districts:

• West Champaran
• East Champaran
• Sitamarhi
• Madhubani
• Supaul
• Araria
• Kishanganj

State Boundaries

Districts with West Bengal: Three districts in Bihar share a border with West Bengal to the east. These districts are:

• Kishanganj
• Purnea
• Katihar

Districts with Jharkhand: Seven districts in southern Bihar share a border with Jharkhand. These districts are:

• Bhagalpur
• Banka
• Nawada
• Jamui
• Gaya
• Aurangabad
• Rohtas

Districts with Uttar Pradesh: Eight districts in western Bihar share a border with Uttar Pradesh. These districts are:

• Rohtas
• Kaimur
• Buxar
• Bhojpur
• Saran
• Siwan
• Gopalganj
• West Champaran

Districts without State or Country Boundaries: There are 15 districts in Bihar that do not share a boundary with any other state or country. These districts are:

• Darbhanga
• Samastipur
• Vaishali
• Sheohar
• Khagaria
• Saharsa
• Madhepura
• Begusarai
• Munger
• Lakhisarai
• Sheikhpura
• Nalanda
• Jahanabad
• Arwal
• Patna

Geological Structure of Bihar

Bihar's geology includes both ancient and recent rock formations. The northwestern hills date back to the Tertiary period. The Bihar plain, the youngest geological formation, was created by river deposits from the Himalayas. This plain formed when a vast trough was filled with detritus carried by swiftly flowing rivers from the newly uplifted Himalayas.

Bihar's formation involves rocks ranging from the Pre-Cambrian period to Quaternary rocks of the Pleistocene period. The northern part of Bihar is associated with Quaternary rocks, while North Champaran relates to Tertiary rocks. Rohtas and Aurangabad are linked to the Vindhyan rock period.

The rocks in Bihar can be categorized into four types based on their structure:

The Dharwar Rocks

The Dharwar rocks, which are among the youngest rocks, date back to the Pre-Cambrian era. These rocks were formed through metamorphism and are characterized by coarse, medium, and fine textures. The Dharwar group includes rocks such as:

• Archaean sediments
• Quartzite
• Phyllite
• Gneiss
• Schist
• Slate

In Bihar, these rocks are predominantly found in the southeastern districts, including Munger, Jamui, Nawada, Gaya, Nalanda, and Nawada, where mica-schists are the dominant type. The hills in these regions are part of the Chota Nagpur plateau, and the Dharwar rocks here are roughly equivalent in age to the Archaean rocks.

The Vindhyan Rock

The Vindhyan rock group, formed during the Pre-Cambrian period, is composed of horizontally bedded sedimentary rocks such as sandstone, quartzite, limestone, dolomite, and shale. These rocks are rich in limestone and pyrites, which are used in the cement industry. The Vindhyan rocks are divided into two parts: the Lower Vindhyan group and the Upper Vindhyan group.

These rocks are found in the South-Western part of Bihar, between the Kaimur district and the Son river valley in the Rohtas district. They form a natural dividing line between the Ganga plain and the Deccan plateau.

Uses and Features

• Vindhyan rocks are widely used in the construction of monuments and buildings. Examples include the Maner Dargah, Sasaram, Agra, Delhi, Jaipur, Sarnath, and various Buddhist stupas.
• Alluvial deposits are found over the Vindhyan rocks in the Son river valley.
• Evidence of volcanic activity has been discovered in Nabinagar, located in the Aurangabad district of Bihar.
• A significant portion of the Vindhyan rock system is represented by the Kaimur series.

The Tertiary Rocks

• The Himalayas were formed during the Tertiary period through the uplift of sediments that were deposited in the Tethys Sea, located between the Eurasian plate and the Indian plate.
• Tertiary rocks are found in the Himalayan Terai region of Bihar and in the Shiwalik hills.
• These rocks were formed during the Mesozoic era, Miocene era, and Paleocene era.
• Examples of Tertiary rocks include sandstone, boulder clay, and conglomerate.
• Tertiary rocks also contain deposits of petroleum and natural gas, as they were formed from sediments that originated in the Tethys Sea.

Quaternary Rocks

Formation and Composition

• Formed during the Pleistocene and recent periods.
• Composed of sandstones, alluvium, conglomerate, and coarse gravels.

Geological Development

• During the Pleistocene, the Shiwalik hills were uplifted, leading to the deposition of alluvium in the downwarped section between the Himalayas and the Chota Nagpur Plateau, as well as in the Indus-Ganga trough.
• This period marked the shaping of the country into its present form, along with the establishment of current flora and fauna.

Ganga Plain Region

• Quaternary rocks are found as sedimentary rocks in the Ganga plain region.
• The depth of alluvium in this plain can reach about 6000 meters, with the greatest depths surrounding the Patna district.

Types of Alluvium

• Bhangar (Old Alluvium) : Consists of coarse grains, sands, and calcium carbonate. Found in relatively higher areas, making it less susceptible to flooding.
• Khadar (New Alluvium) : Composed of sand, silt, and clay. Located in lower areas, these regions are more prone to frequent flooding.

Harha Valley

• The Harha Valley is situated between the Someshwar and Ramnagar ranges. It spans 21 km in length and has a height of 152 m, covering an area of 214 sq km. The valley's maximum height reaches about 240 m, making it higher than the alluvial plain of the Ganga plain.
• This valley is also known as the “Doon Valley.”

The Bihar (Indo-Gangetic) Plain

• The Bihar Plain, also known as the Indo-Gangetic Plain, is located between the Northern mountains and the Southern plateau region, extending from Nepal to the Chota Nagpur plateau.
• This plain is formed by the Ganga River and its tributaries, covering about 96.7% of the total area of the state. It is bounded by the 150 m contour line both in the North and South.
• The Bihar Plain spans an area of 90,650 sq km and is partly the bed of the ancient Tethys Sea, over which rivers from the Himalayas and the Chota Nagpur plateau have deposited their sediments.
• In the North, the topography is smooth, while in the South, there are outliers of hills such as Gaya, Rajgir, and Kharagpur.
• The plain slopes from West to East, being wider in the Western part compared to the East. The average slope is about 5-6 cm per km, with an average height ranging from 75 m to 120 m and an average depth of 1000 m to 1500 m.
• The Ganga River divides this plain into two parts: the Northern Bihar plains and the Southern Bihar plains.

i. The Northern Bihar Plain/North Gangetic Plain

• The Northern Bihar Plain, also known as the North Gangetic Plain, is located north of the Ganga River, covering an area of about 56,980 sq km. It includes the Tirhut, Saran, Purnea, Darbhanga, and Kosi divisions, extending from the Ghaghara-Gandak doab in the West to the Mahananda valley in the East.
• This plain is formed by alluvial deposits from rivers such as the Gandak, Ghaghara, Burhi Gandak, Bagmati, Kamla, Kosi, and Mahananda.
• The North-Western part of the Northern Bihar Plain, particularly in the East and West Champaran districts, is known as the Terai area, characterized by high elevation. The soil in this region is rocky and porous, with a higher percolation level resulting in a higher water table. The Terai region is also home to sal forests and tall reedy grass, while the area south of the Terai is marshy land.
• The slope of this plain is from North to South and from North-West to South-East.
• This region is prone to flooding, with about 76% of the area being flood potential. The Northern part of this plain is relatively higher and is a place of alluvial fans formed by the sediments of the Gandak, Burhi Gandak, Kosi, and Mahananda rivers, which are known for changing their courses. The Kosi River is especially notorious and is referred to as “The Sorrow of Bihar.”
• An important feature of this region is the Chuars, which are oxbow lakes or abandoned river channels found in districts such as Begusarai, Samastipur, Saharsa, and Katihar.
• The Northern Bihar Plain is divided into Doabs, such as the Ghaghara-Gandak Doab, Gandak-Kosi Doab, and Kosi-Mahananda Doab. A Doab is land situated between two converging rivers. Diara land, created by the deposition of sand and alluvial soils over the decades, is also a significant feature of this plain.

Division of Northern Bihar Plain

On the Basis of Drainage System

Mahananda Plain:

• Location: Easternmost part of North Bihar Plain.
• Boundaries: North (West Bengal), East (West Bengal), South (Ganga River), West (Kosi River).
• Formation: Influenced by the Mahananda River, creating marshy land, levee land, and older alluvium.
• Slope: From North to South.
• Area Coverage: About one-tenth of North Bihar Plain.

Kosi Plain:

• Location: North Bihar Plain.
• Boundaries: North (Nepal border), East (Mahananda Plain), South (Ganga River), West (Kamla River).

Northern Plains of Bihar

Kosi Plain

• Districts Covered: Supaul, Saharsa, Madhubani, Darbhanga, and Madhepura.
• Slope: From North to South.
• Area: Approximately one-sixth of the North Bihar plains.
• River Characteristics: The Kosi river is known for its changing course, shifting from East to West, which has caused this plain to shift westward as well.
• Flooding: Due to its shifting nature, this area is the most flood-affected in the state.

Kamala Plain

• Location: Central part of the North Bihar plains.
• Boundaries: Indo-Nepal border (North), Kosi plain (East), Ganga river (South), Bagmati plain (West).
• Slope: From North-West to South-East.
• River Characteristics: The Kamala river also changes its course, leading to the formation of numerous chaurs (low-lying areas) in this region.

Bagmati Plain

• Location: Between Gandak plain (West) and Kamala plain (East).
• Districts Covered: Sitamarhi, East Champaran, Muzaffarpur, Samastipur, and Sheohar.
• River Characteristics: Important tributaries of the Bagmati river include Lal Bakaiya, Lakhandei, and Adhwara.
• Marshy Lands: The plain features marshy lands formed by abandoned river courses, meanders, and uneven deposition of sand and loam.
• Slope: From North-West to South-East.

Gandak Plain

• Location: Between Ghaghara plain and Bagmati plain.
• River Characteristics: The Gandak river enters the North-Bihar plain near Balmikinagar in West Champaran and meets the Ganga river near Hajipur.
• Slope: North to South in the North; South-Eastwards in the South.
• Land Features: Due to the shifting course of rivers, the plain has vast low-lying tracts resembling long semi-circular chaurs.

Ghaghara Plain

• Location: Westernmost part of the North Bihar plain, covering Siwan, Gopalganj, and Saran districts.
• Regional Characteristics: Part of the Ghaghra-Gandak interfluvial region, known as ‘Ghaghra-Gandak Doab’ or ‘Sarvan plain’.
• Land Features: Includes Diara land (riverine land), Chaur (vast low-lying areas), and higher levees.
• Seasonal Changes: During the rainy season, lowlands along river channels are flooded but dry up during the dry season. Notable chaurs include Manjhi, Ekma, Giaspur, and Barauli.

Distribution Based on Regional Variation

Bhabar Region

• Location: South of the lower Himalayas and Shiwalik hills, in a narrow belt of about 10 km wide from West to East.
• Districts Covered: East Champaran, West Champaran, Sitamarhi, Supaul, Madhubani, Kishanganj, and Araria.
• Soil and Composition: Deposition of sand and gravels.

Bangar Region

• Soil Type: Old alluvial soil.
• Flooding: This region is free from frequent floods.
• Location: North-Western part of Bihar.

Khadar Region

• Soil Type: Newer alluvium, deposited annually through sediments and silt brought by floodwater.
• Location: North and North-Eastern plain, from Gandak in the West to Kosi in the East.

Chaur (Man)

• Definition: Low-lying regions and oxbow-lakes formed by rivers and excessive rain in the North Gangetic plains.
• Notable Chaurs: Lakhani Chaur (West Champaran), Sundarpur Chaur (East Champaran), Tetariya Chaur (West Champaran), Madhopur Man, Saraiya Man, etc.

ii. South Bihar Plain/South Gangetic Plain

The South Bihar Plain, also known as the South Gangetic Plain, is smaller in size compared to the North Bihar Plain. It is situated to the south of the Ganga River and to the north of the Chota Nagpur Plateau.

The northern boundary of this plain is marked by the Raj Mahal Hills and the Kaimur Plateau, which separate it from the North Bihar Plain. The plain is shaped like a triangle, with a wider western part and a narrower eastern section.

Hills in the South Bihar Plain

• The South Bihar Plain is home to several hills, including:
• Gaya Hill (266 meters)
• Rajgir Hill (466 meters)
• Barabar Hills
• Giriak Hill
• Sheikhpura Hill
• Jamalpur Hill
• Kharagpur Hill (510 meters)

These hills are located in the Jahanabad, Nalanda, and Munger districts of Bihar. They are considered outliers of the Chota Nagpur Plateau and are referred to as residual hills.

Alluvial Formation

• The plain is primarily composed of alluvium deposited by rivers such as the Karmanasa, Son, Punpun, Paimur, Phalgu, Kiul, Harohar, and Man rivers, along with their tributaries, which originate from the southern hilly areas.
• Unlike the North Bihar Plain, the South Bihar Plain is higher in the south and slopes down towards the Ganga River, although the slope is not as gradual as in the northern part.

Stability and Flooding

• The South Bihar Plain is generally stable and less prone to flooding compared to the North Bihar Plain. However, there are some limited areas within the South Bihar Plain that are susceptible to floods.
• The South Bihar Plain can be further divided into several subdivisions:

(a) Chandan Plain

• The Chandan Plain is located in the easternmost part of the South Bihar Plain, covering the Banka and Bhagalpur districts of Bihar.
• This plain is formed by the Chandan River, which originates from the Digaria Hills, a part of the Rajmahal Hills, along with its tributaries.
• The Chandan Plain is bordered by the Ganga River Plain to the north, Godda to the east, Deoghar to the south, and Jammu to the west.
• The northern part of the Chandan Plain is characterized by homogeneous and fertile soils, while the southern part is relatively undulating and wooded.
• The plain covers about one-tenth of the area of the South Bihar Plain and slopes from south to north.
• Areas such as Mandar Hill in Banka, Katoria, Belhar, and Bhitia have rough terrain, while places like Rajaun, Amarpur, and Shambhuganj are more homogeneous with loam soils.

(b) Kiul Plain

• The Kiul Plain is situated to the west of the Chandan Plain, east of the Mokama Tal region, and north of the Chakai Plateau.
• It includes areas such as Jhajha, Sikandra, Lakshmipur, Patsanda, and Majhwa development blocks.
• The southern part of the Kiul Plain is rolling in nature, covering development blocks such as Chakai, Simutala, Godai, and Bishunpur.
• The northern parts of the Kiul Plain have fertile soil, while the southern parts have coarser soils.
• To the north, the Kiul Plain is bordered by the fertile alluvial plain of the Ganga River. To the south, the Kharagpur Hills form a watershed between the Kiul River, which drains west, and the Man River, which drains east.
• The Kiul Plain slopes from south to north.

(c) Tal Region

• The Tal Region is a saucer-shaped low-lying area that fills with water during the monsoon season, resembling a large lake.
• It is located south of the higher levee of the Ganga River, west of the Kiul Plain, and east of the Central South Bihar Plain. The Tal Region is approximately 25 km wide and extends from Patna to Mokama.
• Mokama Tal, also known as the Sickness of Bihar, stretches from Fatuha to Lakhisarai. Around 106,200 hectares of this region are low-lying and filled with rainwater during the monsoon.
• The Tal Region is formed by alluvium brought by rivers from the southern hills. This alluvium is of fine quality.
• Rivers such as the Punpun, Paimar, and Phalgu do not join the Ganga River directly due to the higher southern levee of the Ganga. Instead, these rivers turn eastward before reaching the levee and flow parallel to the Ganga for some distance, creating a vast water body in this region.
• Some rivers in the Tal Region form distributaries and become extinct, such as the Phalgu River, which becomes extinct here, leaving sand that makes the land infertile.

(d) Central South Bihar Plain

• The Central South Bihar Plain, also known as Magadh, is a triangular-shaped plain.
• It is bordered by the Ganga River to the north, the Tal Region to the east, the southern hilly terrain to the south, and the Son River to the west.

Landforms of Bihar

Bihar's diverse landscape features various landforms, including plains, plateaus, and hills, each with its unique characteristics and geological history.

The state is primarily known for its fertile plains, which are part of the larger Gangetic Plain, but it also has significant hilly and plateau regions, especially in the south.

1. Northern Alluvial Plain

The Northern Alluvial Plain in Bihar is a flat and fertile region formed by the deposition of alluvial soil by rivers, primarily the Ganga and its tributaries. This plain is characterized by its rich agricultural potential, supporting the cultivation of various crops due to the nutrient-rich soil.

a. Area and Districts:

• Covers approximately 1,230 sq km.
• Includes districts like Gaya, Jehanabad, Aurangabad, Patna, Nalanda, and Nawada.

b. Formation:

• Formed by the Ganga River and its tributaries, including the Punpun, Son, and distributaries of the Phalgu River.

c. Slope:

• The slope of the plain is from South-West to North-East.

d. Sub-Divisions:

• Flood Plain of the Ganga: Fertile area prone to flooding, rich in silt.
• Older Alluvium Plain: Older deposits with slightly different soil characteristics.
• Rising Plain with Swells: Slightly elevated areas bordering the plateau fringe.
• Low Lying Area: Adjacent to the Ganga levee, flat and low-lying.

2. Shahabad Plain

The Shahabad Plain is an extensive low-lying region located in the western part of the South Bihar Plain. It is bordered by the Ganga River to the north, the Son River to the east, the Kaimur Plateau to the south, and the Karmanasa River to the west. This plain is characterized by its flat alluvial terrain, rich in nutrients and suitable for agriculture.

a. Area and Districts:

• Covers districts like Bhojpur, Buxar, and parts of Kaimur district.

b. Formation:

• Formed by the Ganga River and its tributaries, including the Karmanasa and Son Rivers.

c. Sub-Divisions:

• Flood-Prone Region: Area between the Ganga River and the Eastern Railway line, prone to flooding but with fertile soil due to silt deposition.
• Flat Alluvial Plain: South of the railway line to the foot of the Kaimur Plateau, covering about 5,700 sq km.

3. Southern Narrow Plateau

The Southern Narrow Plateau is an undulating region characterized by hills and plateaus, located in the southern part of the South Bihar Plain. This area forms the northern frontier of the Chota Nagpur Plateau and is known for its hard rock formations, including gneiss, schist, and granite.

a. Location:

• Extends from the Kaimur district in the west to the Munger and Banka districts in the east.

b. Geological Features:

• Composed of ancient hard rocks, part of the Peninsular Plateau of India.
• Contains older rocks like gneiss and schist, with a variety of crystalline rock formations.

c. Major Regions:

• Kaimur/Rohtas Plateau: Covers most of the Kaimur district, with an average height ranging from 300 m to 450 m.
• Gaya Hilly Region: Located in the southern parts of Gaya, Aurangabad, and Nawada districts, featuring isolated hills and outcrops of the Chota Nagpur Plateau.

d. Significant Hills:

• Gidhour Hills: Located across the southern boundary of Gaya and Nawada, composed of highly metamorphosed Dharwar rocks.
• Ramshila Hills: A prominent hill in Gaya town, surrounded by other hills like Katari, Brahamyani, and Pretshila, with varying elevations.

e. Soil and Vegetation:

• The region consists of a mix of fertile and barren lands, with areas unsuitable for cultivation due to rocky outcrops and steep slopes.
• Vegetation includes brushwood jungles at the base of hills and patches of forested areas in higher regions.

Other Important Hills in the Region

• Maher Hill (482 m) - The highest point in this region.
• Prahara Hill (358 m)
• Bayari Pahar (408 m)
• Tari Pahar (357 m)
• Satgharwa Pahar (343 m)
• Loharawa Pahar (334 m)
• Barabar Hill (307 m)
• Murgara Pahar (305 m)
• Harha Pahar (300 m)
• Songa Pahar (300 m)
• Gidh Pahar (281 m)
• Dwar Pahar (275 m)
• Ranidih Pahar (269 m)

Barabar and Nagarjuna Hills

Location: On the border of Gaya and Jehanabad districts.

Nawada Hilly Region

Location: From the Ganga River in the north to the southern part of the Nawada district.

Features: Spurs in the form of hills and ranges extending from the Chota Nagpur Plateau, separated by smaller valleys. Some spurs reach elevations of about 360 m.

Important Hills:

• Sringirikhi (555 m)
• Durvasarshi Hill (661 m)
• Mahabar Hill (549 m)

Naming: The hills Durvasarshi, Lomashrishi, Gotami, and Sringirikhi are named after saints who once lived on these hills.

Waterfalls: Mohana and Kakolat waterfalls are also located in this region.

Rajgir Hilly Region

Location: Amidst the fertile alluvial plain of the Central South Bihar plain, in Nalanda and Gaya districts.

Description: Extended part of the Gaya hills, these hilly ranges extend from Bodh Gaya and terminate near Giriak.

Features: Two parallel ranges that become broader to the south of the Rajgir urban centre, enclosing the valley of ancient Rajgriha. Beyond Baibhargiri and Saonagiri hills, these ranges meet again.

Important Hills:

• Vaibhavgiri Hills (380 m, highest peak)
• Bipulgiri Hill (320 m)
• Ratnagiri Hill (313 m)
• Udayagiri Hill (231 m)
• Saonagiri Hill (222 m)
• Bihar Sharif or Pirpahari Hill (108 m)

Shanti Stupa: Located east of Bipulgiri peak.

Northern vs. Southern Portion: The northern portion is green, while the southern portion is relatively barren due to the rain shadow effect of the hills.

Composition: These hills are mainly composed of quartzite and slate.

Munger Hilly Region

Location: Southern part of Bihar state, including Jamui and Munger districts.

Features: Characterized by low ranges and isolated peaks.

Kharagpur Hills: Form the most extensive range, extending from Jamalpur to Jamui railway station. Composed of steep irregular ridges not following a uniform direction.

Gidheshwar Hills: A block of hills located to the southwest of the Kharagpur hills, part of the Nawada district.

Satpahari Hill: At 542 m, located in the extreme west part of this region.

Hot Springs: Near Kachu, Kharagpur hills have several hot springs.

Chakai Plateau: Located close to the southern border, surrounded by hills and largely covered with jungles. Separated from the northern undulating tract by Batia hill range, extending from Barwe, north of Simutala to the Hazaribagh plateau and Nawada border.

Geographical Regions of Bihar

A geographic region is defined as an area of land that shares common features such as climate, soils, vegetation, land use patterns, cropping patterns, types of settlements, and socio-cultural elements.

Division of Bihar: Prof. Inayat Ahmad and Prof. Ram Pravesh Singh have divided Bihar into 10 geographical regions based on natural and socio-cultural elements.

Regions: The specific regions are not listed in the provided content, but they would encompass various areas of Bihar, each with its unique combination of the aforementioned features.

Different Regions of Bihar

Terai Region

The Terai Region is the wettest area in Bihar. It is located just south of the Himalayan foothills and is characterized by its marshy land and dense forests. The region is bordered by the Someshwar range and Ramnagar Doon in the north-west, and by Araria and Kishanganj in the north-east.

The Terai Region is known for its rugged terrain, which makes it difficult for permanent settlements to thrive. However, it is an important agricultural area where crops such as paddy, jute, and sugarcane are commonly grown. The region receives heavy rainfall, contributing to its lush vegetation but also making it prone to flooding.

Ghaghra-Gandak Doab

The Ghaghra-Gandak Doab is a roughly square-shaped alluvial plain located in the districts of Saran, Siwan, and Gopalganj. This region receives an annual rainfall of about 120 cm, which supports the cultivation of sugarcane. The abundance of sugarcane has led to the development of a thriving sugar industry in this area.

Gandak-Kosi Doab

The Gandak-Kosi Doab extends through the districts of Sitamarhi, Sheohar, Begusarai, Darbhanga, Muzaffarpur, Vaishali, and Madhubani. This region is known for its well-developed industries, including sugar, fruit processing, and dairy industries. Additionally, there are facilities such as a fertilizer factory, oil refineries, and a thermal power station. Barauni is a notable industrial town in this region.

Kosi-Mahananda Doab

The Kosi-Mahananda Doab includes the districts of Madhepura, Saharsa, Khagaria, Kishanganj, Araria, and Purnea. This region is prone to flooding due to its high rainfall, which has hindered the development of industries, agriculture, and transportation. Despite these challenges, the area is known for its rich biodiversity and natural resources.

Karmanasa-Son Doab

The Karmanasa-Son Doab is situated in the districts of Bhojpur, Kaimur, and Buxar. This region receives less rainfall compared to others, making irrigation necessary for agriculture. Canals are the primary source of irrigation here. The Karmanasa-Son Doab is predominantly a rural area where people are engaged in agricultural activities. Paddy is a major crop in this region, leading to the establishment of rice mills to process the harvested grain.

Son-Kiul Doab

The Son-Kiul Doab encompasses the southern districts of Bihar, including Patna, Jehanabad, Arwal, Nawada, Lakhisarai, Aurangabad, Nalanda, and Gaya. This region faces annual drought conditions due to its low rainfall. Despite the harsh climate, various industries have developed here, such as the silk textile, cement, edible oil, and handicraft industries. The resilience of the local population and the establishment of these industries contribute to the region's economic activities.

8. East-Central Bihar Plain

• Districts: Bhagalpur, Munger, Banka.
• Agriculture: Not well-developed.
• Industry: Limited development.
• Notable Industries:
  • Bhagalpur: Silk textile industry.
  • Munger: Tobacco and dairy industries.

9. Ganga-Diara Region

• Definition: Diara refers to land that emerges in flood-affected areas after water drains away. This land is formed annually following floods.
• Crops: Known for Rabi crops and vegetable cultivation.
• Districts: Includes districts along the banks of the Ganga River:
  • Buxar
  • Bhojpur
  • Saran
  • Vaishali
  • Samastipur
  • Begusarai
  • Munger
  • Patna
  • Lakhisarai
  • Bhagalpur
  • Katihar

10. Kaimur Plateau

• Location: South-West districts of Bihar, specifically Kaimur and Rohtas.
• Industries: Stone-based industries.
• Notable Regions:
  • Amjhore: Pyrites-based sulphur industry.
  • Banjuri: Limestone-based cement industry.

11. Mica Region

• Location: Districts of Munger, Jamui, Gaya, and Nawada in Bihar.
• Mica Type: Found in the form of Balthar soil.
• Industries: Timber, silk, and lac industries.

Important Mountain Peaks/Hills of Bihar