PLAINS OF INDIA

The Great Plains 

  • This is a transition zone between northern mountains and peninsular uplands in the south.
  • It is formed by the depositional work of three major river systems viz., the Indus, the Ganga and the Brahamaputra. Hence also known as Indo-Gan-getic-Bralunaputra plain.
  • This is the largest alluvial tract of the world extending for a length of 3200 km from mouth of Indus to mouth of Ganga of which Indian sector comprises 2400 km.
  • Its width decreases eastwards.
  • It covers a total area of 7.8km^{2} lakh .
  • This plain is characterised by extremely low gradient. 

Geomorphology of the Plains 

  • The Bihar is a narrow belt running in east west direction along the foot of Shivalik. Most of the streams sink and flow underground.
  • The Tarai is a wide marshy tract in the south of Bhabar running parallel to it. It is characterised by the re-emergence of underground streams of the Bhabar belt. It is a zone of excessive dampness, thick forest, rich wildlife and malarial climate.
  • Bangar plain is made up of old alluvial soil of the rivers and lies above flood limit of the plains. The alluviam is of dark colour and often impregnated with calcareous concreations known as Kanker.
  • Khadar Plains is the younger alluviam of flood plains called the Khadar or BET in Punjab. A new layer of alluviam is deposited by river flood almost every year, confined to the vicinity of the present channels.

Regional Division of the Great Plains 

The Rajasthan Plain

  • This includes Marusthali and Rajasthan Bagar areas.
  • The Great Indian Desert or That desert covers the western extremity of the great plains in western Rajasthan.
  • The eastern part of the Marusthali is rocky while its western part is covered by shifting sand dunes locally known as Dharian.
  • The eastern part of Thar desert upto Aravali range is a semi arid plain called Rajasthan Bagar.
  • The patches of fertile tracks in Bagar are called 'rohi'.
  • Luni salt river is the only living river in the arid plain which is originated from Annasagar and is last in the Runn of Kachchh.
  • The tract north of Luni is known as Thali or Sandy plain.
  • A part of the plain has also been formed by the recession of the sea as is evidenced by the occurrence of several salt water lakes e.g. Sambhar, Degana, Kuchamau, Pachpadra, Didwara, Lun Karransar.
  • The Rajasthan plain has several dry beds of rivers (Saraswati and Drusdvati).

Punjab or Haryana Belt 

  • To the east and northeast of That desert is Punjab-Haryana Plain.
  • Its eastern boundary is formed by Yamuna river.
  • It is characterised by flat, narrow strips of low lying flood plains known as beds, formed by shifting of river courses.
  • This plain formed by deposits of five rivers is called Doab.
  • From east to west these Doabs are: 
    Bist - between Bcas and Satluj 
    Bari - between fleas and Ravi 
    Rachna - between Ravi and Chenab 
    Chaj - between Chenab and Jhelum 
    Sindinagar - between Indus and Jhelum-Chenab.
  • Rivers in this plain have caused for themselves broad flood plains of Khadar flauked by bleeffs, locally called Dhaya.
  • The northern part of this plain adjoining the Shivalik has been eroded by numerous streams called Chos. 

The Ganga Plain 

  • This is the largest-unit of the great plains stretching from Delhi to Kolkata in the straits of Uttar Pradesh, Bihar and West Bengal.
  • Phygiegraphically this plain can be sub-divided into following three divi-sions:

I. Upper Ganges Plain 
This part is bordered by the Yamuna in the west and 100 m contour line (Alla-habad-Faizabad railway line) in the east. The upper Ganga plain can be divided into three micro units.

(a) Ganga-Yamuna Doab: Between the river Ganga and Yamuna forming the largest Doab, it comprises three sections. Upper Doab—Haridwar to Aligarh, Middle Doab—Aligarh to Kanpur, Lower Doab—:Kanpur to Al-lahabad
(b) Rohelkhand Plain: East of Ganga-Yamuna Doab, it lies entirely in UP and drained by Ramganga, Gomti and Sarda rivers.
(c) Awadh Plains: Eastward of Rohelkhand plain drained by Ghagra.

II. Middle Ganga Plain 
It occupies eastern UP and Bihar plains. Its eastern boundary corresponds to the Bihar-Bengal border. This is a very low plain, no part of which exceeds 150 m in elevation and alluviam deposits have less concur formations. Besides Ganga, Gomti, Ghagra, Rapti, Gandak, Kosi (in the north) and Son (in the south) are other important rivers. It has two parts : north Bihar plain and south Bihar plain (west of Rajmahal hills). A long line of Marshes, along Chhapra are known as Chaurs. On its outward side occur vast lowlands called Jala near Patna and Tal near Mokama. 

III. Lower Ganga Plain 
It extends from the eastern margin of the Chhotanagpur plateau in the west to the border of Bangladesh and Assam in the east. Most of these plain is perceived as Deltaic. This plain can be sub-divided into :

(a) North Bengal Plain: Its eastern part is drained by rivers joining Brah-maputra (Tista, Sankosh) and western part by the tributaries of Ganga (Mahananda, Ajay, Damodar) etc. Further southward lies the older delta of the Ganga which has been eroded into terraces known as Barind plain.
(b) Bengal Basin (Delta Proper): The heavily forested sundarbans in south and the cast Bhagirathi plain in the north offer contrasting features.
(c) Rarh Plain: Low land to the west of Bhagirathi. It comprises Birbhum, Asansol Rarh, Bankurah and Midnapur Rarh. IV Brahmaputra Plain (Assam valley) This is the eastern most part of the great plains. These plains extend from Sadiya in the east to Dhubri near Bangladesh border in the west. The region is surrounded by high mountains from all sides except on the west. Majuli is the largest river island in the world. The light bank tributaries of Brahmaputra from trellis pattern while left bank tributaries from Dendraitic pattern.

IV. Brabmaputra Plain (Assam valley) 
This is the eastern most pan of the great plains. These plains extend from Sadiya in the cast to Dhubri near Bangladesh border in the west. The region is surrounded by high mountains from all sides except on the west, Majuli is the largest river island in the world. The right bank tributaries of Brahmaputra from trellis pattern while left bank tributaries from Dendraitic pattern.