Geographical Structure of Bihar
Bihar is situated in the Eastern part of India. It has geographical area of 94,163 sq km which makes it the 12th largest state of India and covers 2.86% of the total geographical area of the country.
Geographical Location of Bihar (Bihar GK in English)
➤ The geographical location of Bihar is 24º2110N to 27º3115 N latitudes and its longitudinal extent is 83º1950E to 88º1740E. Its latitudinal extent is 3º and longitudinal extent is 5°. It lies entirely in the North Hemisphere and North of Tropic of Cancer.
➤ It is rectangular in shape. It has 483 km width from West to East and 345 km length from North to South.
➤ It is a land-locked state which is surrounded by Nepal country in the North, Uttar Pradesh in the West, Jharkhand in the South and West Bengal in the East.
➤ Its average height is 53 m (173 feet) from mean sea level. It is connected through National Waterways No-1 (Allahabad to Haldia). It is located 200 km from sea shore.
Boundaries of Bihar (Bihar GK in English)
International Boundary
Bihar has 729 km international boundary with Nepal. Around 7 districts share their boundaries with Nepal such asWest Champaran, East Champaran, Sitamarhi, Madhubani, Supaul, Araria and Kishanganj.
The district boundaries of Bihar with other states:
Districts having Boundary with Jharkhand Seven districts share their boundary with Jharkhand state, which is located in Southern Bihar. These are Bhagalpur, Banka, Nawada, Jamui,Gaya, Aurangabad and Rohtas districts.
Districts having Boundary withWest Bengal Three districts share their boundary withWest Bengal, which is located to the East of Bihar. These are Kishanganj, Purnea and Katihar districts.
Districts having Boundary with Uttar Pradesh Eight districts share their boundary with Uttar Pradesh which is located inWestern part of Bihar. These are Rohtas, Kaimur, Buxar, Bhojpur, Saran, Siwan,Gopalganj andWest Champaran districts.
Other Districts There are 15 districts in Bihar which do not share their boundary with any state or country. These districts are Darbhanga, Samastipur, Vaishali, Sheohar, Khagaria, Saharsa,Madhepura, Begusarai,Munger, Lakhisarai, Sheikhpura, Nalanda, Jahanabad, Arwal and Patna.
Geological Structure of Bihar (Bihar GK in English)
The Geology of Bihar represents both older and younger formation of rocks. The North-Western hills were formed in tertiary period. The river deposition from the Himalayas created Bihar plain which is youngest on the basis of time period.
This plain was formed by the filling up of a vast trough by the heavy loads of detritus carried by swiftly flowing rivers down the Southern slopes of the newly uplifted Himalayas.
The formation of Bihar is the contribution of the rocks from Pre-Cambrian period to Quaternary rocks of Pleistocene period.
The northern part of Bihar is related to Quaternary rock period.North Champaran of Bihar is related to Tertiary rock period and Rohtas and Aurangabad of Bihar are related to Vindhyan rock period.
The rocks found in Bihar on the basis of structure can be classified into four types:
The Dharwar Rocks
➤ Dharwar rocks are one of the youngest rocks. These rocks are of Pre-Cambrian age in which rocks were formed as metamorphosed which are coarse, medium and fine textured.
➤ Archaean sediments, quartzite, phyllite, gneiss, schist and slate are rocks of Dharwar group. These rocks are found in South-Eastern part of Bihar like Munger, Jamui, Nawada, Gaya, Nalanda and Nawada districts. In this part, Dharwar rocks are dominated by mica-schists.
➤ The hills found in these regions are part of Chota Nagpur plateau. There rocks are equivalent in age with Archaean rocks.
The Vindhyan Rock
➤ These rocks were also formed in the Pre-Cambrian period. These rocks are rich in limestone and pyrites (use in sulphur) which are used in cement industry.
➤ Alluvial deposits are found over the Vindhyan rocks in the Son river valley.
➤ Vindhyan rock group is divided into two parts, i.e. Lower Vindhyan group and Upper Vindhyan group.
➤ These rocks have been used in the construction of monuments like Maner Dargah, Sasaram, Agra, Delhi, Jaipur, Sarnath, Sanchi and other Buddhist Stupas.
➤ These rocks form a dividing line between Ganga plain and the Deccan. They are confined in South-Western part of Bihar in between Kaimur district and Son river valley in Rohtas district.
➤ A large part of this system is represented by Kaimur series.
➤ Evidences of volcanic structure have been found in the Nabinagar of Aurangabad district. These are horizontally bedded sedimentary rocks like sandstone, quartzite, limestone, dolomite and shale.
The Tertiary Rocks
➤ The Himalayas were formed in tertiary period. It was formed by uplifting of sediments deposited in Tethys Sea between Eurasian plate and Indian plate.
➤ The tertiary rocks are found in the Himalayan Terai region of Bihar and Shiwalik rocks.
➤ These tertiary rocks are found in the Ramnagar Doon and Someshwar hills which lie in the North-Western part of West Champaran district.
➤ These rocks were formed in the period of Mesozoic era, Miocene era and Paleocene era.
➤ The examples of these rocks are sand stone, bolder clay and conglomerate.
➤ These rocks have deposits of petroleum and natural gas as these were formed by sediments of Tethys sea.
The Quaternary Rocks
➤ These were formed in Pleistocene and recent periods. During Pleistocene and recent period, when Shiwalik hills were uplifted, alluvium was deposited in the downwarped section between Himalayas and Chota Nagpur plateau and in the Indus-Ganga trough. During this period the country attained its present form and flora and fauna established.
➤ These rocks are made of sandstones, alluvium, conglomerate, coarse gravels, etc.
➤ These rocks are found as sedimentary rocks in the Ganga plain region.
➤ A vast plain with gentle slope has been formed by the deposition of sediments brought by rivers, which is known as Bihar plain.
➤ The depth of alluvium in this plain is about 6000 m. The highest depth of alluvium is found in the surrounding parts of Patna district. The alluvium is of two types. These are Bhangar i.e. old alluvium and Khadar i.e. new alluvium.
Bhangar The older alluvium consists of coarse grain, sands and calcium carbonate. It occupies relatively higher places and is therefore free from floods.
Khadar The newer alluvium i.e. Khadar consists of sand, silt and clay. It occupies lower parts and is frequently flooded.
Physiographical Division of Bihar (Bihar GK in English)
The physiographical structure of a place largely depends on the climate, soil, vegetation and land use of that particular region. The regional study of Bihar also depends on its varied relief, natural features, soils land and vegetation.On the basis of physical and structural conditions, Bihar can be divided into three physiographic units.
Shiwalik Range
This region is a part of the Himalayan mountains and it comprises an area of about 932 sq km. It is located in the North-Western part of Bihar in the Northern region ofWest Champaran district over an area 32 km long and 6-8 km wide. Its average height is about 80-250 m. It was formed in the Cenozoic era. This region is sub-divided into three parts based on local variation. These :
i. Someshwar Range
➤ This range was formed in the Tertiary period. These hills are located in the North Gangetic plain and surrounded the North-Western part of Bihar.
➤ It is Northern range which spreads from the point where Triveni canal begins and ends near Bhikhna Thori pass.
➤ This range forms the international boundary between Nepal and India.
➤ There are many passes formed by river action such as Someshwar, Bhikhna Thori and Marwat passes formed by Turipani, Kudi and Harha rivers, respectively.
➤ Highest peak of the state, Someshwar fort (880 m) is situated in this range.
ii. Ramnagar Doon
➤ This broken hilly range lies on the Southern side of the Someshwar hills. Highest peak of this range is near Santpur (242 m).
➤ Ramnagar Doon is a range of many smaller hills. It can be seen in the form of Southern range.
➤ Harha river valley lies in the North-East of Ramnagar Doon.
iii. Harha Valley
➤ This valley lies between Someshwar and Ramnagar ranges. The maximum height of this valley is about 240 m. It is higher than the alluvial plain of the Ganga plain.
➤ It is also known as ‘Doon Valley’
The Bihar (Indo-Gangetic) Plain (Bihar GK in English)
➤ This plain is spread between Northern mountains and Southern plateau region (from Nepal to Chota Nagpur plateau).
➤ It is partly the bed of Tethys Sea over which rivers from Himalaya and Chota Nagpur plateau have filled their depositions.
➤ The Ganga river bifurcates this plain into two parts i.e. the Northern Bihar plains and the Southern Bihar plains.
➤ It is formed by the Ganga and its tributaries and comprises about 96.7% of the total area of the state.
➤ Its topography in the North is smooth while in the South outliers of Gaya, Rajgir and Kharagpur hills are found.
➤ Its slope is from West to East. It is wider in the Western part than the East.
i. South Bihar Plain/South Gangetic Plain
➤ It is smaller in area than North Bihar plain. It lies from South of Ganga river to the North of Chota Nagpur plateau.
➤ Raj Mahal hill and Kaimur plateau demarcate its boundary in the North-East and North-West, respectively. It is triangular in shape with wider West and narrower East part.
➤ This plain has been built of the alluvium brought by Karmanasa, Son, Punpun, Paimur, Phalgu, Kiul, Harohar, Man river and their feeders from the Southern hilly areas.
➤ Many hills are located in the South Bihar plain such as hills of Gaya (266 m), Rajgir (466 m), Barabar, Giriak, Sheikhpura, Jamalpur and Kharagpur (510 m) hills.
➤ These hills are located in Jahanabad, Nalanda and Munger districts of Bihar. These hills are the outliers of Chota Nagpur plateau and termed as residual hills.
➤ The South Bihar plain is stable and not prone to floods except in limited areas as compared to North Bihar plain which is prone to floods.
➤ Unlike the North Bihar plain, the South Bihar plain is higher in the South and slopes towards the Ganga, but its slope is not as gradual as of the North Bihar plain.
The South Bihar plain is divided into the following divisions:
Kiul Plain
➤ This plain is located in the West of Chandan plain, East of Mokama Tal region and North of Chakai plateau.
➤ The Southern part of this plain is rolling in nature which covers areas of the development blocks of Chakai, Simutala, Godai, Bishunpur, etc.
➤ The Northern parts of this plain have fertile soil while the Southern parts have coarse soils.
➤ The fertile alluvial soil plain of the Ganga river lies in the North of this Kiul region. In the South of this alluvial belt, the Kharagpur hills form a watershed between Kiul river (drains West region) and Man river (drains East region). The slope of this plain is from South to North.
Chandan Plain
➤ This plain forms the Eastern most part of the South Bihar plain. This plain is surrounded by plain of the Ganga river in the North, Godda in the East, Deoghar in the South and Jammu in the West.
➤ This plain has been formed by Chandan river which originates from the Digaria hills, a part of Rajmahal hills and its tributaries.
➤ The Northern part of this plain is homogeneous and has fertile soils while its Southern part is relatively undulating and wooded.
➤ The plain covers about one-tenth area of the South Bihar plain and it slopes from South to North.
Tal Region
➤ This is a saucer shaped low lying area which gets filled with water during monsoon season and looks like a large lake.
➤ It lies South of the higher levee of Ganga river, west of Kiul plain which has relatively higher land and east of Central South Bihar plain. It is 25 km wide and located fromPatna toMokama.
➤ A Major area of this region is low lying which gets filled by rain water during monsoon.
➤ This plain has been built by alluvium brought by rivers from the Southern hills. This is a fine quality alluvium.
➤ The rivers Punpun, Paimar and Phalgu does join the Ganga river straightly due to higher Southern levee of Ganga river.
➤ Thus, these rivers before reaching levee turn towards east and flow parallel to Ganga river for some distance. Thus, a vast water body is created in this region.
➤ At some distance, some rivers form distributaries and become extinct in Tal region. For example, Phalgu river which extinct here and its sand makes the land unfertile. Mokama Tal is extended from Fatuha to Lakhisarai. It is also known as Sickness of Bihar.
The Shahabad Plain
➤ This is an extensive low lying plains. It is located to the Western most part of the South Bihar plain.
➤ It is surrounded by Ganga river in the North, Son river in the East, Kaimur plateau in the South and Karmanasa river in the West.
➤ It has been formed by the Ganga river and its tributaries such as Karamnasa and Son.
The plain is divided into two sub-divisions such as:
— The first part lies between the Ganga river and the main line of Eastern railway. The low lying land along the Ganga river is a flood prone region which is well fertilised by the silt and has fertile soil.
— The second large tract of land lies South of the railways to the foot of the Kaimur plateau. It comprises an area about 5.7 thousand sq km. It is also a flat alluvial plain.
Central South Bihar Plain
➤ It is a triangular shaped plain and it is also known as Magadh. It is surrounded by Ganga river in the North, Tal region in the East, the Southern hilly terrain in the South and Son river in the West.
➤ The slope of this plain is from South-West to North-East.
➤ This plain has been formed by the Ganga river, its main tributaries like, Punpun, Son and distributaries of Phalgu river.
➤ Although, there is absence of any significant boundary in the South, however, the Southern hilly terrain forms its Southern boundary.
➤ This plain is divided into four sub-divisions such as the flood plain of the Ganga, elongated adjoining low lying area parallel to the Ganga levee, plain land of older alluvium and rising plain with slight swells bordering plateau fringe.
ii. The Northern Bihar Plain/North Gangetic Plain
➤ It is located to the North of the Ganga river. It covers the area of Tirhut, Saran, Purnea, Durbhanga and Kosi divisions. extends from Ghaghara-Gandak doab in West to Mahananda valley in the East.
➤ This plain is formed by alluvial deposits by the rivers like Gandak, Ghaghara, Burhi Gandak, Bagmati, Kamla, Kosi and Mahananda.
➤ The slope of this plain is from North to South and from North-West to South-East. The Northern part of this plain is comparatively higher. It is a place of alluvial fans which have been formed by the sediments of Gandak, Burhi Gandak, Kosi and Mahananda rivers. These rivers are famous for changing their courses. Kosi is known as ‘The Sorrow of Bihar’.
➤ The North-Western part of Northern Bihar plain in East and West Champaran district is known as Terai area with high elevation. The soil of this region is rocky and porous with higher percolation level resulting in higher water level. The Terai region has sal forests and tall reedy grass. South of the Terai is marshy land.
➤ This region is a flood prone area. About 76% area of this plain is flood potential area.
➤ This Northern Bihar plain is divided into Doabs such as Ghaghara- Gandak Doab, Gandak-Kosi Doab, and Kosi-Mahananda Doab. Doab is a land lying between two converging rivers.
➤ Important feature of this region is Chuars which are basically oxbow lakes or abandoned channels of the rivers. These are found in Begusarai, Samastipur, Saharsa and Katihar districts.
➤ Diara (a land created by deposition of sand and alluvial soils over the decades) is also an important feature in this plain.
Division of Northern Bihar Plain
The North Bihar plain is divided on the basis of drainage system and on the basis of regional variations.
Distribution on the Basis of Regional Variation
On the basis of regional variation, the North Gangetic plain can be divided into four divisions, such as:
Bangar Region
➤ This region has deposits of old alluvial soil. This region is free from frequent floods. It is located in the North-Western part of Bihar.
Bhabar Region
➤ Bhabar is a region of South of the lower Himalayas and Shiwalik hills.
➤ This is located in the Northern part of Bihar in the form of a narrow belt of about 10 km wide from West to East.
This region has a deposition of sand and gravels.
Khadar Region
➤ This region has deposits of newer alluvium. Newer alluvium is deposited every year through the sediments and silt brought by the flood water.
➤ This region is extended in the North and North-Eastern plain from Gandak in theWest to Kosi in the East.
Chaur (Man)
➤ Chaurs are low-lying regions and oxbow-lakes which are formed by rivers and excessive rain in the North Gangetic plains.
➤ Important Chaurs are Lakhani Chaur (West Champaran), Sundarpur Chaur (East Champaran), Tetariya Chaur, (West Champaran), Madhopur Man, Saraiya Man, etc. These are important source of fresh and deep water.
➤ Rajmahal hills and Kaimur plateau demarcate its boundary in the North-East and North-West, respectively which lies from South of Ganga river to the North of Chota- Nagpur plateau.
On the Basis of Drainage System
Kosi Plain
➤ This plain is surrounded by Nepal border in the North, Mahananda plain in the East, Ganga river in the South and Kamla river in the West. The slope of this plain is from North to South.
➤ The Kosi river is known to change its course and has also shifted from East to West. Thus, this plain also got shifted Westward. Due to its shifting nature, it is the most flood affected area of the state.
Mahananda Plain
➤ It is located to the Easternmost part of the North Bihar in the North, West Bengal in the East, the Ganga river in the South and Kosi river in the West.
➤ The slope of this plain is from North to South. It covers about one-tenth area of the North Bihar plain.
➤ The Mahananda river formed this plain, especially the upper surface. Kosi and Mahananda rivers also contributed to the lower lying areas.
Kamala Plain
➤ This plain is located in the central part of the North Bihar plains. This plain is surrounded by Indo-Nepal border in the North, Kosi plain in the East, Ganga river in the South and Bagmati plain in the West. The slope of this plain is from North-West to South-East.
➤ Kamala river is also known to change its course, as a result chaurs have been formed in this region.
Gandak Plain
➤ This plain lies between Ghaghara plain and the Bagmati plain. The Gandak river enters in the North-Bihar plain near Balmikinagar in West Champaran and meets the Ganga river near Hajipur.
➤ In the North, the plain has a slope from North to South and in the South, it has a slope to South-Eastwards.
➤ Due to shifting course of rivers, the plain has a vast low lying tract which appears like long semi-circular Chaurs.
Bagmati Plain
➤ This plain is located between Gandak plain in the West and Kamala plain in the East. The plain covers Sitamarhi, East Champaran, Muzaffarpur, Samastipur and Sheohar districts of Bihar. This region has a number of Chaurs.
➤ The plain has gentle slope which goes from North-West to South-East.
➤ This plain also has a number of marshy lands which have formed by abandoned river courses, meanders and unequal deposition of sand and loam.
➤ Important tributaries of Bagmati river are Lal Bakaiya, the Lakhandei and the Adhwara.
Ghaghara Plain
➤ This is theWestern most part of the North Bihar plain.
➤ It is considered a part of the Ghaghra-Gandak interfluvial region, which is known as ‘Ghaghra-Gandak Doab’. It is also known as ‘Sarvan plain’.
➤ Important features of this plain are Diara land within the river, Chaur or vast low-lying areas and higher levees. Ekma, Giaspur and Barauli are known for their important Chaurs in this plain.
The Southern Narrow Plateau
➤ The hilly and plateau region lies in the extreme South of the South Bihar plain (Southern part of Bihar). It is the frontier of Chota Nagpur plateau.
➤ It is a narrow belt which extends from Kaimur district in the West to Munger and Banka districts in the East.
➤ It is an undulating tract of land which is full of hills and extending from Kaimur plateau in the West to the hilly areas of the Banka in the East.
➤ It is one of the oldest parts of Bihar. It is the extended part of the Peninsular plateau of India, which is spread in Kaimur, Rohtas, Nawada and Munger districts.
➤ As it is the part of Peninsular plateau, it is formed by hard and ancient rocks like gneiss, schist and granite.
The Southern Hilly Region is divided into the following regions:
Kaimur/Rohtas Plateau
➤ It extends along the Southern boundary of Kaimur district in the South to Shahabad plain in the North.
➤ The region is mostly comprised of Vindhyan rocks and thus is a part of Vindhyan range.
➤ The region has several hills which have deep gorges formed by the hill streams. It is the oldest physiographic region of Bihar.
➤ Rohtasgarh is the highest point of this region.
Gaya Hilly Region
➤ This broken undulating part lies in the Southern part of the Gaya, Aurangabad and Nawada districts. This region merges into long ranges of hills and a wide belt of brush wood jungle lies at its base.
➤ This part is high, barren and is not fit for much cultivation. Gidhour hills lie across the Southern boundary of Gaya and Nawada and are composed of Dharwars. They are highly metamorphosed and have mica.
➤ The older rocks of this region are mostly foliated (consisting of thin sheets) gneiss and have a great variety of crystalline rocks. There lie isolated hills in the form of outcrops of Chota Nagpur plateau surrounded by alluvial plains.
➤ Ganjas Bhindas and Jethian are located in this region which are long low outlying ranges. They extend from Bodh Gaya North-Eastward and rise at the Hadiya hill to a height of 441 m.
➤ A ‘king of hills’ lies in Gaya town as Ramshila hills (214 m) on the North, Katari hills (136 m) on the West, Brahamyani hill (238 m) on the South and Pretshila hill (262 m) on the North-West.
➤ Other important hills in the region are Maher hill (482 m) highest point of 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), etc.
➤ Barabar and Nagarjuna hills are located on the border of Gaya and Jehanabad.
Nawada Hilly Region
➤ This hilly region is located from Ganga river in the North to the Southern part of the Nawada district.
➤ Spurs are found in this region in the form of hills and ranges which extend from Chota Nagpur plateau and separated by smaller valleys. At some point these spurs get an elevation about 360 m.
➤ Durvasarshi, Lomashrishi, Gotami and Sringirikhi hills got their name after the name of the saints like Durvasa, Lomas, Gautam and Sringi who once lived on the hills of Nawada.
➤ Important hills of this region are Sringirikhi (555 m), Durvasarshi hill (661 m) and Mahabar hill (549 m).
➤ Mohana and Kakolat waterfalls are also located in this region.
Rajgir Hilly Region
➤ This hilly region lies amidst the fertile alluvial plain of the Central South Bihar plain. It is located in Nalanda and Gaya districts. It is the extended part of Gaya hills.
➤ These hilly ranges extend from Bodh Gaya and terminate near Giriak. From here they become two parallel ranges.
These two parallel ranges became broader in the South of the Rajgir urban centre and enclose the valley which was once the ancient town of Rajgriha. Beyond Baibhargiri and Saonagiri hills, these two parallel ranges meet again.
➤ The Northern portion of this region is green while its Southern portion is comparatively barren because of rain shadow part of the hills. These hills are mainly composed of quartzite and slate.
➤ Important hills of this region are Vaibhavgiri hills (380 m, highest peak), Bipulgiri hill (320 m), Ratnagiri hill (313 m), Udayagiri hill (231 m), Saonagiri hill (222 m) and Bihar Sharif or Pirpahari hill (108 m).
➤ Shanti stupa is located East of Bipulgiri peak.
Munger Hilly Region
➤ This hilly region (Jamui andMunger) is located in the Southern part of Bihar state.
➤ It has a number of low ranges and isolated peaks. Kharagpur hills form the most extensive range which extends from Jamalpur to Jamui railway station. These hills are consisted of a number of steep irregular ridges which do not run in any uniform direction.
➤ Gidheshwar hills form a block of hills which lie to the South West of this region. These hills are a part of the hills in Nawada district.
➤ Satpahari hill (542 m) lies on the extreme West part of this region. Near Kachu, Kharagpur hills have several hot springs. Chakai plateau is located close to the Southern border which is surrounded by hills and largely covered with jungles.
➤ This plateau is separated by Batia hill range from the undulating tract to the North which extend from Barwe, North of Simutala to the Hazaribagh plateau and Nawada border.
Geographical Regions of Bihar (Bihar GK in English)
A geographic region is an area of land that has common features such as climate, soils, vegetation, land use pattern, cropping pattern, types of settlement and socio-cultural elements. Prof. Inayat Ahmad and Prof. Ram Pravesh Singh divided Bihar into 10 geographical regions on the basis of natural and socio-cultural elements.
These are given below
Ghaghra-Gandak Doab
This is a square-shaped alluvial plain which lies in the districts of Saran, Siwan and Gopalganj. This place receives 120 cm annual rainfall. Sugarcane is extensively grown here thus, sugar industry has well flourished in the place.
Terai Region
It is the rainiest region of Bihar. Someshwar range and Ramnagar Doon of Shiwaliks are located in the North-West of this region while Araria and Kishanganj are in the North-East part. It is a marshy and dense forest area. Paddy, jute and sugarcane are grown here. This land is rugged thus, temporary settlements are found here.
Gandak-Kosi Doab
This region is extended in the districts of Sitamarhi, Sheohar, Begusarai, Darbhanga,Muzaffarpur, Vaishali and Madhubani. The region has well developed sugar industry, fruit-processing industry and dairy industry. The place also has fertiliser factory, oil-refineries and Thermal Power Station. Barauni is the well-known industrial town of this region.
Karmanasa-Son Doab
It is extended in the districts of Bhojpur, Kaimur and Buxar. This region receives less rainfall, thus, irrigation is done by canals. It is a rural region thus, people are engaged in agricultural activities. Paddy crop is extensively grown here, due to which rice mills are found here.
Kosi-Mahananda Doab
This region is extended in the districts of Madhepura, Saharsa, Khagaria, Kishanganj, Araria and Purnea. It is a flood-prone region due to maximum rainfall, thus, this region does not have well developed industries, agriculture and transport system.
Son-Kiul Doab
This region is extended in the South Bihar districts such as Patna, Jehanabad, Arwal,Nawada, Lakhisarai, Aurangabad, Nalanda and Gaya.
This region is frequently affected by drought like situation every year, as this region receives less rainfall.Many industries have been developed in this region such as silk-textile industry, cement industry, edible oil industry and handicraft industry.
Ganga-Diara Region
Diara is land which is seen in the flood-affected region after draining out of water. This land is formed every year after flooding. This region is famous for Rabi crops and vegetable crops. This region is extended in the districts which are situated on the banks of Ganga river, such as Buxar, Bhojpur, Saran, Vaishali, Samastipur, Begusarai, Munger, Patna, Lakhisarai, Bhagalpur and Katihar.
East-Central Bihar Plain
This region is extended in the districts of Bhagalpur,Munger and Banka. This region is not well-developed in agriculture and industrial region. Silk textile industry has been developed in Bhagalpur district and tobacco and dairy industries have been developed in Munger district.
Kaimur Plateau
This plateau is extended in the South-West districts of Bihar i.e. Kaimur and Rohtas. The region has stone-based industries. Amjhore region has pyrites based sulphur industry whereas Banjuri region has limestone based cement industry.
Mica Region
This region lies in Munger, Jamui,Gaya and Nawada districts of Bihar. Mica is found in the form of Balthar soil here. The region has timber, silk and lac industries.
Important Mountain Peaks/Hills of Bihar
| Peaks/Hills | Elevation (in metres) |
| Baibhargiri Hill | 343 |
| Barabar Hill | 307 |
| Bayari Pahar | 408 |
| Bihar Sharif/ Pirprahari Hill | 108 |
| Bipulgiri Peak | 320 |
| Brahamyoni Hill | 238 |
| Durvasarhi Hill | 661 |
| Dwar pahar | 275 |
| Gidh Pahar | 281 |
| Hadiya Hill | 441 |
| Harha Pahar | 300 |
| Katari Hill | 136 |
| Kharagpur Hill | 510 |
| Loharawa Pahar | 334 |
| Mahabar Hill | 549 |
| Maher Hill | 482 |
| Pahara Hill | 358 |
| Pretshila Hill | 262 |
| Rajgir Hill | 466 |
| Ramshila Hill | 214 |
| Ranidih Pahar | 269 |
| Rohtasgarh Hill | 447 |
| Saonagiri Hill | 222 |
| Satgharwa Pahar | 343 |
| Satpahari Hill | 542 |
| Someshwar Hill | 880 |
| Songa Pahar | 300 |
| Sringirikhi Hill | 555 |
| Tari Pahar | 357 |
| Tatanagiri Peak | 313 |
| Udayagiri Hill | 231 |
