Bhangar

Geography glossary

Also called: Bangar, Old alluvium · Topic: Structure and Physiography of India: Himalayas, Plains, Peninsula, Coasts and Islands · NCERT: Class 10, Ch 1 "Resources and Development"; Class 11, Ch 2 "Structure and Physiography"

Meaning

Bhangar (also written bangar, and called old alluvium) is the older alluvium of the Northern Plain. It lies on raised terraces above the flood level of rivers. Floods do not reach it, so its soil is not renewed. It is less fertile than khadar and contains kankar, which are lime nodules.

It matters because it covers a large part of India's food-bowl plain. It is also a favourite Prelims topic: questions often test the bhangar–khadar contrast and the north-to-south order of the plain's zones.

Explanation

How bhangar forms (cause → process → result)

  • Alluvium is loose clay, silt, sand and gravel that rivers carry and drop.
  • Step 1: rivers build a plain.
  • In the Quaternary period (the last ~2.6 million years), Himalayan and Peninsular rivers filled the deep hollow (a foredeep) south of the Himalayas with sediment.

  • This sediment built the Indo-Ganga-Brahmaputra plain.

  • Step 2: the river cuts deeper.

  • Over time, a river cuts its bed lower.

  • Its old floodplain is left high and dry, like a step beside the river. This step is a terrace.

  • Step 3: the old land stops getting new silt.

  • Floods now stay in the lower land next to the river.

  • The raised terrace gets no fresh silt, so its soil stays old and is not renewed.

  • Result: a raised belt of old alluvium. This is the bhangar.

Main features

  • Age: older alluvium.
  • Position: terraces above the flood level, away from the active floodplain.
  • Kankar:
  • Kankar are lime nodules (small lumps of calcium carbonate) in the soil.

  • Lime in old, unflooded soil slowly gathers into these lumps over a long time.

  • Texture and fertility: the soil is coarser and less fertile than khadar.

Place in the plain's zones

  • Order from north to south: Shiwalik foothills → Bhabar → Tarai → Bhangar/Khadar → delta.
  • Bhangar and khadar lie side by side:
  • Bhangar is on the higher ground.
  • Khadar is on the low floodplain along the river.
Feature Bhangar Khadar
Age of alluvium Older Newer
Position Terraces above flood level Floodplains
Renewed by floods? No Yes, almost every year
Kankar Present Absent
Fertility Lower High

Where it occurs

  • The Northern Plain (Indo-Ganga-Brahmaputra plain): the wide, flat lowland between the Himalayas and the Peninsular Plateau.
  • It is about 3,200 km long and 150-300 km wide. It is wider in the west and narrower in the east.
  • It is only 50-150 m above sea level.

  • Its alluvium is up to 1,000-2,000 m thick.

  • Across its three parts (west to east):

  • Punjab-Haryana plain: the Satluj, Beas and Ravi, which are tributaries of the Indus.
  • Ganga plain: from Delhi to West Bengal. Rivers here include the Ganga, Yamuna, Ghaghara, Gandak, Kosi and Son.

  • Brahmaputra plain: the narrow valley in Assam.

  • Within the plain: bhangar is the higher land above flood level, south of the tarai belt. Khadar lies below it along the river channels.

  • Worldwide: old alluvial terraces form along large rivers wherever a river has cut below its old floodplain. "Bhangar" is the Indian name for this landform.

Don't confuse with

  • Khadar: newer alluvium on the floodplain. Floods renew it almost every year, so it is very fertile. It has no kankar. Bhangar is older, sits above flood level and has kankar.
  • Bhabar: a belt of coarse boulders, pebbles and gravel, 8-10 km wide, at the foot of the Shiwaliks. Streams sink and vanish into it. Bhangar is fine-to-coarse old alluvium much further south.
  • Tarai: a wet, marshy belt 10-20 km wide, just south of the bhabar. There, the streams that sank into the bhabar come back up. Bhangar is dry, raised terrace land.
  • Kankar vs bhangar: kankar is not a zone of the plain. It is the lime nodules found inside bhangar soil.

Prelims Hooks

  • North-to-south order: Shiwalik → Bhabar → Tarai → Bhangar → Khadar.
  • Kankar (lime nodules) is found in bhangar, not khadar. This is a common trap.
  • Bhangar = older alluvium on terraces above flood level. Khadar = newer alluvium on floodplains.
  • Which is more fertile? Khadar. Bhangar is less fertile because floods do not renew its soil.
  • The plain is built by three river systems: the Indus, Ganga and Brahmaputra. It formed in the Quaternary period by filling the foredeep left by the Tertiary Himalayan orogeny (mountain-building event).
  • Match: streams vanish → bhabar; streams re-emerge → tarai; kankar on raised terraces → bhangar; yearly fresh silt → khadar.

Mains Points

  • Farming differences within the plain (GS-I):
  • Bhangar soil is not renewed by floods. It is coarser and holds kankar, so it is less fertile than khadar.
  • So farming on bhangar depends more on irrigation and soil care. Khadar gets free fresh silt every year.

  • This explains why farm output can differ even inside India's "food bowl", which grows wheat, rice, sugarcane and jute.

  • Flood safety vs fertility trade-off (GS-I / GS-III, disasters):

  • Bhangar sits above flood level, so it is safer for settlements, roads and railways.
  • Khadar is more fertile but faces yearly floods, river avulsion (a river suddenly shifting to a new course; the Kosi is called the "Sorrow of Bihar") and waterlogging.

  • Good land-use planning keeps homes and buildings on raised bhangar terraces and treats khadar as flood-prone farmland.

  • Groundwater and land pressure (GS-III, resources):

  • The deep alluvium under the plain, including bhangar, holds rich groundwater.
  • Fertile flat land and good water supply support very dense population and intensive farming.
  • So bhangar areas need careful groundwater use to keep this farming going.

Related concepts

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Sources

  1. 1Class 10, Ch 1 "Resources and Development"; Class 11, Ch 2 "Structure and Physiography" (primary)