Indo-Gangetic plains: Geography, Facts, Divisions and Importance

The Indo-Gangetic plains or the Great Plains are large alluvial plains dominated by three main rivers, the Indus, Ganges, and Brahmaputra. The great plains of India run parallel to the Himalayas, from Jammu and Kashmir in the west to Assam in the east, and drain most of northern and eastern India. The plains stretch 2400 kilometers from west to east and encompass an area of 700,000 km².

The major rivers in this region are the Ganges, Indus, and Brahmaputra along with their main tributaries–Yamuna, Chambal, Gomti, Ghaghara, Kosi, Sutlej, Ravi, Beas, Chenab, and Teesta—as well as the rivers of the Ganges Delta, such as the Meghna. The Great plain is home to nearly 1/7 of the world’s population. It is bound on the north by the abruptly rising Himalayas, which feed its numerous rivers and are the source of the fertile alluvium deposited across the region by the two river systems. The southern edge of the plain is marked by the Vindhya- and Satpura Range, and the Chhota Nagpur Plateau. On the west rises the Iranian Plateau.The Great Plains of India consists largely of alluvial deposits brought down by the rivers originating in the Himalayan and the peninsular region. The exact depth of alluvium has not yet been fully determined.  As per recent estimates the average depth of alluvium in the southern side of the plain (north of Bundelkhand) varies between 1300 to 1400 meters, while towards the Shivaliks, the depth of alluvium increases.  The maximum depth of alluvium has been recorded in Haryana near Ambala and Yamunanagar.

Divisions of Great Plain

Great plains are generally classified into four divisions:

Bhabar belt

Bhabar belt is adjacent to the foothills of the Himalayas and consists of boulders and pebbles which have been carried down by the river streams. As the porosity of this belt is very high, the streams flow underground. The Bhabar is generally narrow about 7–15 km wide. Bhabar is wider in the western plains in comparison to the eastern plans of Assam. The porosity of Bhabar is so high that most of the narrow streams get disappeared in this belt only and some of them go underground. This is also one reason that it is not suitable for crops and only big trees are able to survive.

Thus, Bhabar belt is a narrow belt that is located above the Terai belt, also sometimes known as Himalayan foothills. It is made up of porous and rocky soils that get made of the debris washed down from the higher ranges.  Streams disappear in this belt.

Terai belt

The Terai belt lies next to the Bhabar region and is composed of newer alluvium. The underground streams reappear in this region. The region is excessively moist and thickly forested. It also receives heavy rainfall throughout the year and is populated with a variety of wildlife. The Terai tract lies south of the Bhabar belt. The tract is marshy and lots of mosquitoes thrive there. The Terai belt is wider in eastern side especially in the Brahmaputra valley. The high rainfall, newer alluvium makes it excessive damp and lots of forests are found here. This implies that Terai belt is rich in biodiversity. Over the period of time, the forests have been cleared in various states such as Uttarakhand, Uttar Pradesh, Haryana, Punjab, and Jammu Divisions for cultivation of crops. Terai belt is known for the good cultivation of sugar-cane, rice, wheat, maize, oilseeds, pulses, and fodder.

Bhangar belt

This is the largest part of the Northern Plains made up of old alluvium and forms the alluvial terrace of the flood plains. The soil in this region consists of calcareous deposits called kankar. The Bangar or Bhangar belt consists of older alluvium. In the Gangetic plains, it has a low upland covered by Laterite deposits. The Bhangar formations were deposited during the middle Pleistocene Period. The Bhangar land lies above the flood limits of the rivers. The older alluvium soil is dark in colour, rich in humus content and productive.  Bhangar is generally a well drained and the most productive land of the Great Plains of India.

Khadar belt

The Khadar belt lies in lowland areas after the Bhangar belt. It is made up of fresh newer alluvium which is deposited by the rivers flowing down the plain. The Khadar tracts are enriched by fresh deposits of silt every year during the rainy season. The Khadar land consists of sand, silt, clay and mud. After Independence, most of the Khadar land has been brought under cultivation and devoted to sugarcane, rice, wheat, maize, oilseeds. legumes, and fodder crops.

Delta Plains

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 ‘Char’ while marshy areas are known as ‘Bili. The delta of Ganga being an active one, is extending towards the Bay of Bengal.

Importance of Great Plains

The Indo-Gangetic belt is the world’s most extensive expanse of uninterrupted alluvium formed by the deposition of silt by the numerous rivers. The plains are flat and mostly treeless, making it conducive for irrigation through canals. The area is also rich in ground water sources. The plains are the world’s most intensely farmed areas. The main crops grown are rice and wheat, which are grown in rotation. Others include maize, sugarcane and cotton.

The Indo-Gangetic plains rank among the world’s most densely populated areas. The Great Plains of India are covered with one of the most productive soils of the world. Its soils have the capacity to grow any crop of the tropical and temperate regions. The plains are often termed as the ‘Granary of India’. Most of the rivers traversing the Northern Plains of India are perennial in nature. A number of canals have been carved out of these rivers which make agriculture more remunerative and sustainable. The water table is high and suitable for tube well irrigation. The gentle gradient makes it navigable over long distances.