Indo-Gangetic Plain – Northern Plains of India

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• Indo-Gangetic plain lies to the south of the Shissalik mountain separated by the Himalayan Front Fault (HFF).
• Indo-Gangetic plain also known as Northern plains of India or Great plain of India.
• It is a transitional zone between the Himalayas of the north and Peninsular India
• Indo-Gangetic-Brahmaputra Plain is the largest alluvial tract of the world.
• It stretches for about 3,200 km from the mouth of the Indus to the mouth of the Ganga.
• Indian sector of the plain accounts for 2,400 km.
• The western boarder is marked by Sulaiman and Kirthar ranges.
• On the eastern side, the plains are bordered by Purvanchal hills.
• Average elevation of the Northern plains of India is about 200 m above mean sea level.

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Formation of the Indo-Gangetic plain

• The rivers which were previously flowing into Tethys sea deposited huge amount of sediments in the Tethys Geosyncline.
• Himalayas are formed out of these sediments which were uplifted, folded and compressed due to northern movement of Indian Plate.
• Northern movement of Indian Plate also created a trough to the south of Himalayas.

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Depositional Activity

• During the initial stages of upliftment of sediments, the already existing rivers changed their course several times
• Rivers also rejuvenated each time for that reason.
• Head-ward erosion and vertical erosion of the river valley contributed huge amount of sediments.
• These sediments were deposited in the depression between peninsular India and the convergent boundary.

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New Rivers & more Alluvium

• The raising of Himalayas and subsequent formation of glaciers gave rise to many new rivers.
• These rivers along with glacial erosion supplied more alluvium.
• Those alluvium intensified the filling of the depression.
• With the accumulation of more and more sediments, the Tethys sea started receding.
• With passage of the time, the depression was completely filled with alluvium, gravel, rock debris.
• The Tethys completely disappeared leaving behind a monotonous aggradation plain.
• Upper peninsula rivers have also contributed to the formation of plains, but to a very small extent.
• Since few million years, depositional work of three major river systems, The Indus, the Ganga and the Brahmaputra have become predominant.

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Division as per Soil Types

Bhabar Soil Region

• The Bhabar soil region is a narrow, porous, northern most stretch of Indo-Gangetic plain.
• It is about 8-16 km wide along the foothills of the Shiwaliks.
• Bhabar show a remarkable continuity from the Indus to the Tista.
• Porosity of bhabar is unique feature, due to deposition of huge number of pebbles and rocks.
• The streams disappear once they reach the bhabar region because of this porosity.
• The area is not suitable for agriculture and only big trees with large roots thrive in this belt.

Terai Region

• Terai region is an ill-drained, damp (marshy) and thickly forested narrow tract.
• It is located to the south of Bhabar running parallel to it.
• Terai region is about 15-30 km wide.
• The underground streams of the Bhabar belt re-emerge in the Terai Region.
• Terai soils are rich in nitrogen and organic matter.
• This soil is deficient in phosphate.
• Terai region is covered with thickly forest, provides shelter to a variety of wild life.
• Terai region is wider in the eastern part because of higher amount of rainfall.
• Most of the Terai land, in Punjab, Uttar Pradesh and Uttarakhand, has been turned into agricultural land.
• Terai region land gives good crops of sugarcane, rice and wheat.

Dooars Region

• Terai region of east side of Teesta River is called Dooars.
• It stretches over about 350 km up to Dhansiri River in Assam.
• Dooars means ‘doors’ in different local languages.
• This region is gateways between Bhutan and plains in India.
• Economy of Dooars region is based on Tea, Tourism and Timber.
• Many protected forests are located in this area.

Bhangar Region

• The Bhangar is the older alluvium along the river beds of Indo-Gangetic plain.
• It forms terraces higher than the flood plain.
• Bhangar contains concretions and nodules of impure calcium carbonate known as ‘Kankar’.
• It contains fossils of animals like rhinoceros, hippopotamus, elephants, etc.
• The Barind plains in the delta region of Bengal is a part of Bhangar region.
• The Bhur formations in the middle Ganga and Yamuna doab are regional variations of Bhangar.

Bhur

• Bhur denotes an elevated piece of land situated along the banks of the Ganga river
• It developed mainly in the upper Ganga-Yamuna Doab.
• This has been formed due to accumulation of wind–blown sands during the hot dry months of the year

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Khadar Region

• The Khadar is composed of newer alluvium and forms the flood plains along the river banks.
• A new layer of alluvium is deposited by river flood almost every year.
• The Khadar is the most fertile soils of Indo-Gangetic plain.
• In Punjab, the Khadar rich flood plains are locally known as Betlands or Bets.

Reh or Kollar

• Reh or Kollar comprises saline efflorescence of drier areas in Haryana.
• Reh areas have spread in recent times with increase in irrigation.
• The capillary action brings the underground salts to the surface.

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West to East Division of Indo-Gangetic Plain

• Sindh Plain
• Rajasthan Plain
• Punjab Plain
• Gangetic Plains
  
  • Upper Gangetic Plain
  • Middle Gangetic Plain
  • Lower Gangetic Plain
• Ganga – Brahmaputra Delta
• Brahmaputra Plain

Sindh Plain

• Sindh Plain is mainly formed of Bhangar Plains by Indus and its tributaries.
• Dhors is long narrow depressions which are the remnants of the course of former rivers.
• Dhand is alkaline lakes on some dhors.

Rajasthan Plain

• Rajasthan plain occupied by Thar or the Great Indian Desert.
• This plain is an wave like plain whose average elevation is about 325 m.
• The desert region is called Marusthali and forms a greater part of the Marwar plain.
• Geologically it is a part of the Peninsular Plateau.
• It has a few outcrops of gneisses, schists and granites.
• Rajasthan plain is only at the surface that it looks like an aggradation plain.
• In general, the eastern part of the Marusthali is rocky while its western part is covered by shifting sand dunes
• Eastern part of the Thar Desert up to the Aravali Range is a semi-arid plain known as Rajasthan Bagar.
• It is drained by a number of short seasonal streams originating from the Aravali.
• Luni is an important seasonal stream
• The tract north of the Luni is known as thali or sandy plain.
• North of the Luni, there is inland drainage having several saline lakes.
• Sambhar, Didwana, Degana, Kuchaman are some of the important lakes in the Rajasthan plain.
• The largest is the Sambhar lake near Jaipur.

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Punjab-Haryana Plain

• Punjab-Haryana plain  is formed by five important rivers of Indus system.
• The plain is primarily made up of ‘doabs’ – the land between two rivers.
• Punjab means “The Land of Five Rivers” referring to the following rivers: the Jhelum, Chenab, Ravi, Sutlej, and Beas.
• The eastern boundary of Punjab Haryana plain is marked by subsurface Delhi-Aravali ridge.
• Northern part of this plain near Shiwalik hills has been intensively eroded by numerous streams called Chos landform.
• The only river between the Yamuna and the Satluj is the Ghaggar.
• The Ghaggar is considered to be the present day Successor of the legendary Saraswati River.
• The Punjab-Haryana Plains may be divided into
  • Bari Doab between the Beas and Ravi
  • Bist Doab between the Beas and Satluj
  • Malwa Plain the central part of the region
  • Hariyana–Bhiwani Bagar in the southern and south-eastern parts of the region.

Gangetic Plains

• Ganga PIain lie between the Yamuna catchment in the west to the Bangladesh border in the east.
• The Ganga along with its large number of tributaries originating in the Himalayans
• Those rives have brought large quantities of alluvium from the mountains and deposited it here to build this extensive plain.
• The peninsular rivers such as Chambal, Betwa, Ken, Son, etc. joining the Ganga river system.
• General slope of the entire plain is to the east and south east.
• Rivers flow sluggishly in the lower sections of Ganges.
• As a result the area is marked by local prominences such as levees, bluffs, oxbow lakes, marshes, ravines, etc.
• Almost all the rivers keep on shifting their courses making this area prone to frequent floods.
• The Kosi river is very notorious in this respect. It has long been called the ‘Sorrow of Bihar’.

Upper Gangetic Plain

• It includes the Ganga–Yatnuna doab, Rohilkhand Division and parts of the Agra Division.
• The catchment area of the Yamuna river makes its western boundary
• In addition to Ganga and the Yamuna, it is traversed by the Kali and Sharda rivers.
• A unique feature of the Upper Gangetic Plain is the presence of Bhur

Middle Gangetic Plain

• It includes central and eastern Uttar Pradesh, and the Bihar Plains up to Muzaffarpur and Patna.
• It has thick alluvial deposits with less Kankar formation.

Lower Gangetic Plain

• Lower Gangetic Plain extends from Patna in the west, the foot of Darjeeling Himalaya in the north to the Bay of Bengal in the south.
• It is bordered by Assam and Bangladesh in the cast and the Chotanagpur Plateau in the west.
• In the lower part of the Lower Ganga Plain is Sundarban delta.
• The plain has a monotonous surface.
• The Lower Gangetic Plain is the divider between between Rajmahal Hills of Peninsular India and the Meghalaya Plateau
• It formed by subsequent sedimentation by the Ganga and the Brahmaputra rivers.

Rahr Plain

• It lying to the east of the Chotanagpur Plateau, it is a part of the Lower Gangetic Plains.
• Drained by the Damodar and Subarnarekha river.
• It covered by the lateritic-alluvium soils
• Soil erosion is the main problem of the Rahr plain region.
• Rice, maize and pulses are the main crops here.

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Ganga-Brahmaputra Delta or Sundarban Delta

• Ganga-Brahmaputra Delta or Ganges delta is the largest delta in the world.
• The Ganga river divides itself into several channels in the delta area.
• Ganges delta is studded with a large number of estuaries, mud flats, mangrove swamps, sandbanks, islands and forelands.
• Large part of the coastal delta is a part of Sundarban delta and  covered by tidal forests.
• Sundarban is the largest mangrove swamp in the world.
• Sundarhan gets its name from the Sundari tree (Heritiera fomes) which grows well in marshland.
• Mangrove forest covers an area of about 10,000 km² 
• In West Bengal, they extend over 4,260 km² across South 24 and North 24 Pargana district.
• East India Company appointed William Dampier and Hodges to survey and identify the boundaries of the Sundarbans forest in 1764.
• Sundarban enlisted as UNESCO World Heritage Sites in 1987 for it’s biodiversity.
• In 2019, it has been designated as a Ramsar site.
• It is considered as a World Network of Biosphere Reserve from 2001.

Brahmaputra Plain

• Brahmaputra plain is also known as Assam Valley.
• Most of the Brahmaputra valley is situated in Assam.
• Its western boundary is formed by the Indo-Bangladesh border as well as the boundary of the lower Ganga Plain.
• Its eastern boundary is formed by Purvanchal hills.
• Tributaries of the Brahmaputra river coming from the north form a number of alluvial fans.
• Tributaries branch out in many channels giving birth to river meandering leading to formation of bill and ox-bow lakes.
• There are large marshy tracts in this area.
• Manas, Kaziranga, Orang National Parks are located in this area.
• The alluvial fans formed by the coarse alluvial debris have led to the formation of terai or semi-terai conditions with dense forest
• Brahmaputra plains have numerous islands.
• Majuli (area 930 sq km) is the largest river island of the world and country’s first river island district.

Significance of the Northern Plains of India

• Northern plains of india is one fourth of the land of the country, hosts half of the Indian population.
• Fertile alluvial soils, flat surface, slow moving perennial rivers and favorable climate facilitate intense agricultural activity.
• Use of irrigation has made Punjab, Haryana and western part of Uttar Pradesh the granary of India (Prairies- granaries of the world).
• The entire Indo-Gangetic plain except the Thar Desert, has a close network of roads and railways.
• Indo-Gangetic plain has led to large scale industrialization and urbanization.
• There are many religious places along the banks of the sacred rivers like the Ganga and the Yamuna.
• Those are very dear to Hindus.
• Here flourished the religions of Budha and Mahavira and movements of Bhakti and Sufism

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