Why this matters now
Indo-Gangetic Plain is tested for: alluvial fill formed post-Himalayan upliftment (50-60 mya); ~7 lakh sq km; 4 sub-regions: Bhabar, Tarai, Bhangar, Khadar; 3 macro divisions: Punjab Plain (Indus), Ganga Plain (Ganga-Yamuna), Brahmaputra Plain; Doabs (interfluves between Punjab rivers); world’s most fertile alluvium; ~38% of India’s population; granary of India (Green Revolution); challenges: soil salinity, waterlogging, urbanisation, sub-surface water depletion.
4 Sub-regions
| Sub-region | Location | Features |
|---|---|---|
| BHABAR | Foot of Himalayas; 8-16 km wide strip | Coarse pebbles + gravel + boulders. Streams disappear underground. Tea, agricultural not. |
| TARAI | South of Bhabar; 15-30 km wide | Streams re-emerge as marshy + swampy; rich biodiversity. Includes Tarai forests + tiger reserves (Jim Corbett, Dudhwa). |
| BHANGAR | Older alluvium; upper terraces away from floodplain | Above flood level; high lime + sodium content (Reh, Kallar salt patches); needs irrigation. |
| KHADAR | Newer alluvium; floodplain | Renewed annually by floods; very fertile; sandy loam; supports rice + sugarcane + wheat. |
3 Macro Divisions
- Punjab Plain (Indus System Plain): West Punjab + Haryana. ~1,75,000 sq km. 5 Punjab Doabs: Bist Doab (Beas-Sutlej), Bari Doab (Beas-Ravi), Rachna Doab (Chenab-Ravi), Chaj Doab (Jhelum-Chenab), Sind Sagar Doab (Indus-Jhelum). Bhakra-Nangal + Indira Gandhi Canal irrigation.
- Ganga Plain: UP + Bihar + part Jharkhand + WB. ~3,75,000 sq km. Upper Ganga Plain (Haridwar-Allahabad), Middle Ganga Plain (Allahabad-Rajmahal), Lower Ganga Plain / Bengal Plain (Rajmahal-Bay of Bengal). Doabs in Ganga Plain: Ganga-Yamuna Doab; Rohilkhand Plain.
- Brahmaputra Plain (Assam Valley): Assam, parts Arunachal. ~70,000 sq km. Long narrow 720-km from Sadiya to Dhubri. Floods + erosion.
Agriculture + Demographics
- Green Revolution belt: Punjab + Haryana + W. UP. Wheat + rice basket. M.S. Swaminathan + Norman Borlaug 1960s-70s.
- Sugarcane: UP largest producer; sugar industries Kanpur Belt.
- Cotton: Punjab (now declining due to whitefly + bollworm).
- Tea: Brahmaputra Plain (Assam) + Tarai.
- Jute: Bengal Plain (Ganga Delta).
- Cropping intensity: ~150-200% (multiple crops/yr).
- Population: ~50+ crore (~38% of India); world’s most densely-populated plain.
- Cities: Delhi, Chandigarh, Amritsar, Lucknow, Kanpur, Allahabad, Patna, Kolkata, Guwahati.
Challenges: Soil salinity (Punjab-Haryana from over-irrigation), groundwater depletion (Punjab water table dropping 0.5-1 m/yr), Northern India winter pollution (stubble-burning trapped by Himalayan inversion), Khadar river-erosion (Kosi changing course Bihar).
UPSC angle
Know INDO-GANGETIC PLAIN — great alluvial plain northern India ~7 lakh sq km 21% India; 2400 km Punjab to Assam; formed by alluvium Indus+Ganga+Brahmaputra last 50-60 mya post-Himalayan uplift; 4 SUB-REGIONS NORTH-SOUTH: BHABAR (foot Himalayas 8-16 km strip, coarse pebbles+gravel+boulders, streams disappear underground), TARAI (south Bhabar 15-30 km, marshy+swampy biodiversity, Tarai forests + Jim Corbett + Dudhwa TR), BHANGAR (older alluvium upper terraces above flood level, high lime+sodium REH+KALLAR salt patches), KHADAR (newer alluvium floodplain renewed by floods very fertile sandy loam rice+sugarcane+wheat); 3 MACRO DIVISIONS: 1) PUNJAB PLAIN/INDUS SYSTEM PLAIN ~175000 sq km, 5 PUNJAB DOABS (BIST Doab Beas-Sutlej, BARI Doab Beas-Ravi, RACHNA Doab Chenab-Ravi, CHAJ Doab Jhelum-Chenab, SIND SAGAR Doab Indus-Jhelum), Bhakra-Nangal+Indira Gandhi Canal; 2) GANGA PLAIN ~375000 sq km UP+Bihar+Jharkhand+WB, Upper Ganga Plain Haridwar-Allahabad+Middle Allahabad-Rajmahal+Lower/Bengal Plain Rajmahal-Bay of Bengal, GANGA-YAMUNA DOAB + Rohilkhand Plain; 3) BRAHMAPUTRA PLAIN/ASSAM VALLEY ~70000 sq km, 720 km Sadiya-Dhubri; AGRICULTURE GREEN REVOLUTION belt Punjab+Haryana+W.UP (Swaminathan+Borlaug 1960-70s) wheat+rice basket, UP sugarcane largest (Kanpur Belt), cotton Punjab (now declining whitefly+bollworm), tea Brahmaputra+Tarai, jute Bengal Plain Ganga Delta; cropping intensity 150-200%; pop ~50+ cr ~38% India world’s most densely-populated plain; cities Delhi+Chandigarh+Amritsar+Lucknow+Kanpur+Allahabad+Patna+Kolkata+Guwahati; CHALLENGES soil salinity Punjab-Haryana over-irrigation, groundwater depletion Punjab 0.5-1 m/yr, winter pollution stubble-burning + Himalayan inversion, Khadar river-erosion Kosi changing course Bihar.
Frequently asked questions
What are the 4 sub-regions of the Indo-Gangetic Plain?
From Himalayas southward: Bhabar (coarse foothill pebbles), Tarai (marshy belt), Bhangar (older alluvium, high lime), Khadar (newer alluvium, very fertile floodplain).
What are the 5 Punjab Doabs?
Bist Doab (Beas-Sutlej), Bari Doab (Beas-Ravi), Rachna Doab (Chenab-Ravi), Chaj Doab (Jhelum-Chenab), Sind Sagar Doab (Indus-Jhelum). Punjab means “land of 5 rivers”.
What is Khadar?
Newer alluvium deposited annually by floods along riverbanks — very fertile, sandy loam, ideal for rice/sugarcane/wheat. The actual floodplain.
How is the Indo-Gangetic Plain India’s breadbasket?
The Green Revolution belt of Punjab + Haryana + W.UP produces most of India’s wheat + rice. Multiple cropping intensity 150-200%. ~38% of India’s population lives here.