Physical Geography of India

Location and size

• India lies between 8°4′N and 37°6′N latitude and 68°7′E and 97°25′E longitude.
• It is the 7th largest country, with 3.287 million km², or 2.4% of the world's land area.
• It has a land border of about 15,200 km and a coastline of about 7,500 km. Recent remeasurement puts the coastline at 11,098 km (2023–24).
• The Tropic of Cancer passes through 8 states: Gujarat, Rajasthan, MP, Chhattisgarh, Jharkhand, West Bengal, Tripura and Mizoram.
• Standard Meridian: 82°30′E, near Mirzapur and Prayagraj. IST = GMT + 5:30.

Physiographic divisions

1. The Himalayas
   • Three parallel ranges:
     • Himadri (Greater Himalaya), with Everest and Kanchenjunga;
     • Himachal (Lesser Himalaya), with hill stations such as Shimla and Mussoorie;
     • Shiwaliks (Outer Himalaya), with duns such as Dehradun.
   • Trans-Himalaya: the Karakoram (K2), Ladakh and Zaskar ranges.
   • Purvanchal (the eastern hills): the Patkai, Naga, Mizo and Garo–Khasi–Jaintia hills.
2. The Northern Plains
   • Formed by the Indus, Ganga and Brahmaputra.
   • Bhabar: a pebbly belt where streams sink underground.
   • Terai: marshy, where the streams re-emerge.
   • Bhangar: old alluvium, with kankar.
   • Khadar: new alluvium, flooded every year.
3. The Peninsular Plateau
   • The Central Highlands: the Aravalli (oldest fold mountains), Malwa, Bundelkhand and Chotanagpur (Jharkhand; rich in minerals).
   • The Deccan Plateau, made of basalt from the Deccan Traps.
   • The Western Ghats (Sahyadri) are continuous and higher. Anamudi (2,695 m) is the highest point of peninsular India.
   • The Eastern Ghats are broken by rivers.
4. The Thar Desert: in western Rajasthan.
5. The Coastal Plains
   • West coast: Konkan, Kannad and Malabar (with backwaters called kayals).
   • East coast: the Northern Circars and Coromandel; broad, with deltas.
6. The Islands
   • Andaman and Nicobar: volcanic and tectonic. Indira Point is India's southernmost point.
   • Lakshadweep: coral atolls.

Drainage

	Himalayan rivers	Peninsular rivers
Flow	Perennial (snow and rain)	Seasonal (rain-fed)
Valleys	Deep gorges (antecedent rivers)	Shallow, graded valleys
Course	Meandering, shifting in plains	Fixed courses
Examples	Indus, Ganga, Brahmaputra	Godavari, Krishna, Kaveri, Mahanadi, Narmada

Ganga system

• The Bhagirathi (from Gangotri) and Alaknanda join at Devprayag to form the Ganga.
• Left-bank tributaries: the Ramganga, Gomti, Ghaghara, Gandak, Burhi Gandak, Bagmati, Kosi and Mahananda. Most of these flow through Bihar.
• Right-bank tributaries: the Yamuna, Son (from Amarkantak), Punpun; the Damodar joins the Hooghly.
• The Ganga is about 2,525 km long. It is the National River (2008) and National Waterway 1 (Prayagraj to Haldia).

Brahmaputra

• Called the Tsangpo in Tibet, the Dihang/Siang in Arunachal Pradesh, and the Jamuna in Bangladesh.
• Majuli in it is a large river island.

Peninsular rivers

• East-flowing (form deltas):
  • the Mahanadi (Hirakud Dam);
  • the Godavari, the longest peninsular river, called the "Dakshin Ganga";
  • the Krishna;
  • the Kaveri.
• West-flowing (form estuaries):
  • the Narmada and Tapi, which flow through rift valleys;
  • the Mahi and Sabarmati.
• Jharkhand and Bengal rivers: the Damodar (once the "Sorrow of Bengal", controlled by the DVC, 1948), the Subarnarekha, the North Koel and the Barakar.

Climate: the monsoon

• India has a tropical monsoon climate.
• Mechanism:
  • differential heating of land and sea;
  • the northward shift of the ITCZ in summer;
  • the Tibetan Plateau heating up;
  • the easterly jet stream;
  • El Niño, La Niña and the IOD.
• South-west monsoon (June–September):
  • It gives about 75% of annual rainfall.
  • It has two branches, the Arabian Sea branch and the Bay of Bengal branch.
  • Normal onset over Kerala is 1 June, and it covers the whole country by 8 July.
  • It withdraws from mid-September.
• "Break" in the monsoon: dry spells when the monsoon trough moves to the Himalayan foothills.
• North-east monsoon (October–December): brings rain to Tamil Nadu and the Coromandel coast.
• Local winds:
  • Loo: a hot, dry wind over the north plains in May–June.
  • Mango showers: in Kerala and Karnataka.
  • Kalbaisakhi (Nor'westers): in Bengal, Odisha and Assam.
  • Western disturbances: bring winter rain that helps the rabi wheat crop.
• Rainfall extremes: Mawsynram and Cherrapunji (Meghalaya) are among the wettest places. Leh and Jaisalmer are among the driest.

Soils (ICAR classifies 8 main groups)

Soil	Where	Features and crops
Alluvial	Northern plains, deltas	Most widespread (about 40%); rich in potash; rice, wheat, sugarcane
Black (regur)	Deccan (Maharashtra, MP, Gujarat)	From basalt; holds moisture, self-ploughing; cotton
Red and yellow	Eastern Deccan, Chotanagpur, Odisha	Iron gives the red colour; low fertility; millets and pulses
Laterite	Western Ghats, Odisha, Chotanagpur, Meghalaya	Leached; good for cashew, tea, coffee
Arid / desert	Rajasthan	Sandy, saline
Saline / alkaline	Dry areas, Sundarbans	Reh and kallar
Peaty / marshy	Kerala, Sundarbans	High in organic matter
Forest / mountain	Himalayas	Varies with altitude

Soil erosion: ravines in the Chambal (badlands); sheet erosion in Chotanagpur.

Natural vegetation and forests

• Types of forest:
  • Tropical evergreen: the Western Ghats and north-east; more than 200 cm of rain.
  • Tropical deciduous (monsoon forests): the most widespread type. Sal grows in Jharkhand and teak in MP.
  • Thorn forests: in dry areas.
  • Montane forests.
  • Mangroves: the Sundarbans, the largest mangrove forest in the world.
• India State of Forest Report 2023:
  • Forest cover is about 21.76% of the country's area. With tree cover, the total is about 25.17%.
  • Madhya Pradesh has the largest forest area.
  • Mizoram has the highest percentage of forest cover.
  • Jharkhand has about 29.8% forest cover. Bihar has about 7.8%.
  • The National Forest Policy (1988) target is 33% of the area under forest or tree cover.

Exam tip: Draw the Ganga basin from memory with every tributary, marked left or right bank. BPSC and JPSC ask which rivers flow through which districts. Use the Bihar and Jharkhand geography units for the state detail.