In this article, we will discuss Physiographic Divisions of the Great Plains of India. So, let’s get started.
Physiographic Divisions of the Great Plains of India
The Great Plains of India are a remarkably homogeneous surface with an imperceptible slope. In fact, they are a featureless alluvial fertile plains formed mostly by the depositional process of the Himalayan and Vindhyan rivers. These rivers deposit enormous quantity of sediments along the foothills. Beyond the foothills, the rivers deposit the alluvium in their flood plains. The Northem Plains of India may be divided into the following sub-regions:
The Bhabar Plain
Location-lies to the south of the Shiwalik from west to east (jammu Division to Assam)
Its width is greater in the Western plains than in the eastern plains of Assam
Its width measures 8 to 15 km
Its width measures 8 to 15 km
Composition-Gravel and unasserted sediments deposited by the rivers descending from the Himalayan region and the Shiwaliks
Due to high porosity, small streams (chos and raos) disappear in this region and only big rivers flow over the surface in this tract
Unsuitable for crop cultivation
Big trees with large roots thrive in this region
Inhabitants are largely cattle keeping Gujjars
The Tarai Tract
Location-Lies south to the Bhabar tract and it is 15-30 km wide.
It is wider in the eastern parts of the Great Plains in Brahmaputra region due to high rainfall
It is a zone of excessive dampness, thick forests, rich wild life and infested with mosquitoes
Once a marshy zone of jungle and wild grass along the southern edge of the Shiwaliks, Tarai has been almost reclaimed for agriculture
In Uttarakhand, Uttar Pradesh, Haryana, Punjab, and Jammu Divisions (J&K) the Tarai forests have been cleared for cultivation of crops
Cultivated crops include sugarcane, rice, wheat, maize, oilseeds, pulses, fodder.
The Bhangar Plains
They represent the upland alluvial tracts of the Great Plains of India, formed by the older alluviums.
The Bhangar formations were deposited during the middle Pleistocene Period and it lies above the flood limits of the rivers.
Its soil is dark in colour, rich in humus content and productive. It contains concretions and nodules of impure calcium carbonate or ‘Kankar’.
In relatively drier areas, the Bhangar also exhibits small tracts of saline and alkaline
efflorescences known as ‘Reh’, ‘Kallar’ or Thur’.
Bhangar is generally a well-drained and most productive land of the Great Plains of India.
The Bhangar deposits have the fossils of elephants, horses, man, rhinoceros, hippopotamus, etc.
The Khadar Plains
The new alluvium tracts along the courses of the rivers are known as the ‘Khadar’ or ‘Bet lands.
Tracts are enriched by fresh deposits of silt every year during the rainy season.
Khadar land consists of sand, silt, clay and mud. Post-independence, this region has been brought under cultivation and devoted to sugarcane, rice, wheat, maize, oilseeds, legumes, and fodder crops.
The Khadar deposits have the fossils of living species like man, deer, oxen, buffaloes, horses, elephants, rhino, etc.
The deltaic plain is an extension of the Khadar land.
It covers about 1.9 lakh sq km of area in the lower reaches of the Ganga River.
It is an area of deposition as the river flows in this tract sluggishly.
The deltaic plain consists mainly of old mud, new mud and marsh.
In the delta region, the uplands are called ‘Chars’ while marshy areas are known as ‘Bils’.
The delta of Ganga being an active one is extending towards the Bay of Bengal.
Meso-regions of the Northern Plains of India
On the basis of geo-climatic and topographical characteristics, the Northern Plains of India may be divided into the following four meso-regions:
The Plains of Rajasthan;
The Punjab Haryana Plains;
The Ganga Plains; and
The Brahmaputra Plains.
The Plains of Rajasthan
They lie to the west of the Aravallis and include the Marusthali and the Bagar of Rajasthan. The
Rajasthan plains cover a total area of about 175,000 sq km. This plain has a general slope from north-east to south-west. In the lower reaches of the Luni river (Gujarat), this plain is only 20 m above sea level. A substantial part of this plain has been formed by the recession of the sea as is evidenced by the presence of salt water lakes (Sambhar, Degana, Didwana Kuchaman, Lunkaransar-Tal, and Pachpadra). The Sambhar Lake occupying an area of about 300 sq km during the rainy season lies about 65 km to the north-west of Jaipur city.
During the Permo-carboniferous Period, the greater part of the Rajasthan plain was under the
sea. It has several dry beds of rivers, like Saraswati and Drisdavati which indicate that the area
earlier was fertile. At present, Luni is the only flowing river which reaches the Arabian Sea through the marshes of the Rann of Kachchh. Its water is sweet in the upper reaches but turns brackish in the lower parts. North of the Luni, there is a large area of inland drainage.
At present, the greater part of the Rajasthan Plains are a desert covered with longitudinal and
transverse sand dunes and barchans (Barkhans). A large number of playa lakes occur in the basins. In the south-western parts of the Rajasthan plain, there are the alluvial tracts known as Rohi (fertile plains). In the north-eastern part they consist of dry beds of the Ghaggar known as the Ghaggar Plains.
The Punjab Haryana Plains
Stretching over an area of about 650 km from north-east to south-west and 300 km from west to east, the Punjab-Haryana Plain is an aggradational plain, deposited by the Satluj, Beas, and Ravi river. The height of the plains varies from 300 m in the north-near jammu and Kathua to 200 m in the south-east. In the east the Delhi Ridge separates it from the Gangetic Plain. The general direction of slope is from north-east to south-west and south. The main topographical features of the Punjab-Haryana Plains are bluffs, locally called as Dhaya, as high as three metres or more, and the Khadar belts known as Bet. The undulating topography south of the Shiwaliks is adversely affected by erosion, caused by the seasonal streams locally called as Chos. The south western parts, especially Hissar District is sandy, characterised by shifting sand-dunes. Satluj, Beas, and Ravi are the only perinneal rivers. Between the Satluj and the Yamuna, the Ghaggar (the ancient Saraswati) is a seasonal stream which passes through Ambala Cantt. Its course is about ten km wide and contains water only during the rainy season.
The Punjab-Haryana Plains may be divided into: (i) the Bari-Doab between the Beas and Ravi, (ii) the Bist Doab, between the Beas and Satluj), (iii) the Malwa Plain, the central part of the
region, and (iv) the Haryana-Bhiwani Bagar in the southern and south-eastern parts of the region.
The Ganga Plains
The Ganga Plains lie between the Yamuna catchment in the west to the Bangladesh border in the east. It is about 1400 km from west to east and has an average width of 300 km from north
to south. The general gradient of the plain is about 15 cm per km from north-west to south-east. The maximum height of this plain is found to the north of Saharanpur (276 m) followed by Roorkee (274 m), Agra (169 m), Kanpur (125 m), Allahabad (98 m), Patna (53 m), Kolkata (6 m), and Sagar Island only 3 m above sea level.
The main topographical variations in the plains include, Bhabar, Tarai, Bhangar, Khadar, river
bluffs (levees), abandoned courses, Khols, dead-channels, Bills, Tals, and badlands. The Ganga
Plains can be subdivided into the following sub-regions:
(a) The Upper Ganga Plain
The Upper Ganga Plain includes the Ganga-Yamuna Doab, Rohilkhand Division, and parts of the Agra Division. The catchment area of the Yamuna river makes its western boundary, Shiwaliks in the north and 125 m contour in the south. The elevation of the Upper Ganga Plain varies between 100 m to about 300 m. In addition to Ganga and the Yamuna, it is traversed by the Kali and Sharda rivers. A unique feature of the Upper Ganga Plain is the presence of Bhur (undulating, aeolian sandy deposits). Devoted to sugarcane, rice, wheat, maize, pulses, mustard, fodder, vegetables and orchards, it is one of the most productive plains of India in which the Green Revolution is a big success.
(b) The Middle Ganga Plain
Sprawling over an area of about 144,400 sq km, the Middle Ganga Plain includes central and eastern Uttar Pradesh, and the Bihar Plains up to Muzaffarpur and Patna. In the north, it is bounded by the Shiwaliks along the Indo-Nepal border. It has thick alluvial deposits with less Kankar formation. The region is homogeneous and featureless where monotony is broken by river levees, bluffs, ox-bow lakes, Dhus, Tals, Jala and Chaurs (marshy lands). Being a low gradient plain, the rivers often change their courses in this region. Gandak and Kosi are the main left hand tributaries, while the Son is an important right hand tributary of the Ganga in the Middle Ganga Plain.
(c) The Lower Ganga Plain (Area 80,970 sq km)
The Lower Ganga 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 east 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 eastern part of the plain is drained by the Tista, Jaldhakia, Sankosh joining the Brahmaputra, and the western part by the Mahananda, Ajay, and Damodar. In the extreme south-west, Kasai and Subarnarekha are the main rivers. The general slope of this plain is towards south and south-east.
The Lower Ganga Plain has been formed by the downwarping of a part of the Peninsular
India between Rajmahal Hills and the Meghalaya Plateau and subsequent sedimentation by the
Ganga and the Brahmaputra rivers. The plain has a monotonous surface dissected frequently by the channels of the main streams and their tributaries.
Ralır Plain: Lying to the east of the Chotanagpur Plateau, it is a part of the Lower Gangetic Plains. Drained by the Damodar and Subarnarekha, it is covered by the lateritic-alluvium soils. Soil erosion is the main problem of the Rahr plain. Rice, maize and pulses are the main crops of the Rahr plain.
Sundarbans: The largest mangrove swamp in the world, the Sundarbans, or the beautiful forest,
gets its name from the Sundari tree which grows well in marshland. It is home to the Royal Tiger
The Brahmaputra Plain
Stretching over an area of about 56,275 sq km, it is the eastern part of the Great Plains of India. It is about 720 km long and about 80 km wide. The region is surrounded by high mountains on all sides, except on the west. it is a depositional plain. The general altitude of the Brahmaputra plain varies between 130 m in the east to only 30 m in the west. The Assam Valley is characterised by a steep slop along its northern margin but the southern side has a gradual fall from the Meghalaya Plateau. The whole length of the plain is traversed by the Brahmaputra. Due to the low gradient, the Brahmaputra is a highly braided river having numerous islands. Majuli (area 930 sq km) is the largest river island of India and the second largest in the world after the Marajo Island of the Amazon River. The valley of Brahmaputra also has a number of isolated hillocks on both flanks of the Brahmaputra River. It is one of the most productive plains of India in which rice and jute are the main crops.
There is a marked difference between the physiography of the north and the south banks of the Brahmaputra river. The northern tributaries descending from the Arunachal and Assam Hills froma series of alluvial fans which coalesce and obstruct the courses of the tributaries forcing them to from meanders and adopt paralled course along the main stream, Brahmaputra. Consequently, there are numerous levees along the north bank. This has led to the formation of Bils, ox-bow lakes, marshy tracts, and Tarai lands with dense forest cover. The southern bank of the Brahmaputra is less uneven and less wide. Moreover, the tributaries in the southern part are considerably larger.
Here, Dhansiri and Kapili, through their headward erosion have almost isolated the Mikir and Rengma hills from the Meghalaya Plateau.
The valley of Assam may be divided into (i) the Upper Assam and (ii) the Lower Assam. These are demarcated along 94° East longitude. The Upper Assam Valley includes the districts of Lakhimpur, Dibrugarh, Jorhat, and Sibsagar, and the Tezpur Tehsil of Darrang District. It is a monotonous plain except for the low hill ranges along the southern and south-eastern border. The Lower Assam Valley consists of Nagaon, Dhubri, Goalpara, Barpete, Kamrup, Nalbari, Kokrajhar, and parts of the Darrang District. This region does not posses monotonous physiographic characteristics since its landscape is interspersed with the spurs of Meghalaya Plateau. Here, the right bank tributaries from a trellis pattern of drainage, while the left bank tributaries exhibit the dendritic pattern. Swamps and marshes are numerous in the northern region of the Lower Brahmaputra Valley.
The Brahmaputra: It is one of the great rivers of the world. Flowing eastward to the north of the Himalaya in Tibet (China), it turns sharply south and passes through Assam before entering Bangladesh. The river valley has fertile alluvial plain which is conducive to growing rice and jute. It is also famous for its tea and the two national parks at Kaziranga and Manas.