UPSC Prelims — Indian Geography and Environment
Why This Chapter Matters
Geography and Environment together give 20-30 questions in UPSC Prelims. Physical geography of India, climate, rivers, and environment-ecology overlap significantly with current affairs.
Indian Geography
Physical Features
The Himalayas (Fold Mountains):
Three parallel ranges:
Passes: Zoji La (J&K, NH-1), Rohtang (HP), Shipki La (HP-Tibet), Nathu La (Sikkim-China), Bomdi La (Arunachal).
Northern Plains (3200km long, 150-300km wide):
Most fertile, most populated. Formed by Indus, Ganga, Brahmaputra river systems.
Bhabar: narrow belt near Himalayan foothills, permeable, rivers disappear.
Terai: swampy, marshy, forests. South of Bhabar.
Bhangar: older alluvium, above flood level. Contains Kankar (calcium carbonate nodules).
Khadar: newer alluvium, in flood plains. More fertile than Bhangar.
Peninsular Plateau:
Oldest and most stable landmass. Ancient crystalline rocks.
Deccan Plateau: basaltic lava (Deccan Traps — volcanic eruptions ~65 million years ago). Black/Regur soil excellent for cotton.
Western Ghats (Sahyadri): continuous range along west coast. Highest peak: Anamudi (2695m — South India's highest). UNESCO World Heritage Site (biodiversity hotspot).
Eastern Ghats: discontinuous, cut by rivers. Lower than Western Ghats. Highest: Jindhagada (1690m).
Coastal Plains:
Malabar Coast (West): Kerala-Karnataka-Goa. Backwaters (Vembanad Lake), lagoons, estuaries. Receives SW monsoon heavily.
Coromandel Coast (East): Tamil Nadu. Deltaic. Receives NE monsoon (Oct-Dec).
Islands:
Andaman & Nicobar: Bay of Bengal. 572 islands. Coral reefs. Active volcano: Barren Island. Narcondam (dormant). Duncan Passage separates South Andaman from Little Andaman. 10-degree Channel separates A&N from Indonesia.
Lakshadweep: Arabian Sea. 36 islands (only 10 inhabited). Coral atolls. Smallest UT. Kavaratti is capital.
Rivers
Himalayan Rivers (Perennial — snow-fed + rain-fed):
Indus: Originates in Tibet (Mansarovar lake area), flows through Ladakh, enters Pakistan. Total length 3180km. Tributaries in India: Jhelum, Chenab, Ravi, Beas, Sutlej (all go to Pakistan after 1960 Indus Water Treaty).
Ganga: Gangotri glacier → Bhagirathi joins Alaknanda at Devprayag = Ganga. Major tributaries: Yamuna, Ghaghra, Gandak, Kosi (from Nepal), Son (from Peninsular India). Length 2525km in India (total 2700km including Bangladesh). Empties into Bay of Bengal — forms world's largest delta (Sundarbans) shared with Bangladesh.
Brahmaputra: Originates in Tibet (Kailash range as Tsangpo), enters India at Arunachal (as Dihang/Siang), becomes Brahmaputra in Assam. Joins Ganga in Bangladesh (as Jamuna). One of few rivers with braided channels.
Peninsular Rivers (Rain-fed, seasonal, west to east mostly):
Godavari: "Ganga of South." Longest peninsular river (1465km). Nashik to Bay of Bengal.
Krishna: Mahabaleshwar to Bay of Bengal.
Kaveri: Brahmagiri hills to Bay of Bengal. "Ganga of South" also used.
Mahanadi: Chhattisgarh to Bay of Bengal. Hirakud Dam (world's longest earthen dam).
Narmada: Amarkantak plateau → flows WEST → Arabian Sea. Exceptional east-west flowing river on Peninsular plateau.
Tapi (Tapti): Satpura → flows west → Arabian Sea. Another east-west flowing river.
Luni: Rajasthan. Flows into Rann of Kutch. Saline in lower reaches.
Climate
Tropical Monsoon climate — defined by monsoon winds.
Monsoon:
SW Monsoon (June-September): Moisture-laden winds from Indian Ocean. Hits Western Ghats → heavy rainfall on windward side. Leeward side (Deccan) gets rain shadow — drier.
Bay of Bengal branch: enters Northeast India, Bengal, moves west along Gangetic plain.
Arabian Sea branch: hits Western Ghats (Kerala June 1 — official onset date).
Seasonal cycle:
Winter (Nov-Feb): Cold in north, pleasant in south.
Hot weather (Mar-May): Dry, very hot in interior. "Loo" — hot dry wind in north India.
SW Monsoon (June-Sep): Main rainy season. 75% of India's annual rainfall.
Retreating monsoon (Oct-Nov): Withdraws from north first. NE monsoon brings rain to Tamil Nadu coast.
Rainfall extremes:
Wettest: Mawsynram (11872mm annually), Meghalaya — also world record.
Driest: Leh, Ladakh.
Most rainy days: Agumbe (Karnataka).
Tamil Nadu gets rain in winter (Oct-Dec) from NE monsoon.
Climate types (Koppen) in India:
Humid tropical (Kerala, coastal): Af/Am | Hot desert (Rajasthan): BWh
Semi-arid (Deccan, interior): BSh | Humid subtropical (north plains): Cwa
Alpine (Himalayas): ET/EF
Soils (Quick Reference)
Alluvial: Most widespread, Indo-Gangetic plains, river valleys. Most productive. Rice, wheat, sugarcane.
Black/Regur: Deccan trap, Maharashtra, MP, Gujarat. Cotton. Self-ploughing.
Red/Yellow: Iron oxide, East and South India. Low fertility.
Laterite: Leached, Western Ghats, NE hills, Odisha. Tea, coffee, cashew.
Desert/Arid: Rajasthan. Sandy, dry.
Saline/Alkaline: Waterlogged areas, coastal areas. Usar in UP.
Peaty/Organic: Sundarbans, Kerala backwaters.
Forest: Mountain slopes.
Environment and Ecology
Key Concepts
Food chain vs Food web:
Food chain: linear (grass→grasshopper→frog→snake→eagle)
Food web: interconnected network of food chains (more realistic, more stable)
Trophic levels and 10% law:
Only 10% of energy transferred to next level.
More trophic levels = more energy loss = less efficient.
Biodiversity types:
Genetic: variation within species.
Species: number of species in an area.
Ecosystem: variety of ecosystems.
India's biodiversity:
2.4% of world's land → 7-8% of world's species.
12 mega-diverse countries (most biodiversity). India is 8th largest in land.
17,000+ plant species, 90,000+ animal species.
Protected Area Network:
National Parks: Human habitation prohibited. Boundary fixed by legislation. No pastoral/grazing.
Wildlife Sanctuaries: Restricted human activity. Boundary by notification.
Biosphere Reserves: Large areas, multiple use. Buffer zone + core zone + transition zone.
Tiger Reserves: Under Project Tiger (1973). 54 tiger reserves currently.
Elephant Reserves: 33 reserves.
Key ecosystems:
Mangroves: Coastal, saline-tolerant trees. Largest: Sundarbans (India+Bangladesh). Others: Bhitarkanika (Odisha), Pichavaram (Tamil Nadu).
Coral reefs: Lakshadweep (best in India), Andaman-Nicobar, Gulf of Mannar, Gulf of Kutch.
Wetlands: 75+ Ramsar sites in India. Important: Chilika Lake (Odisha — largest coastal lagoon), Wular Lake (J&K — largest freshwater lake), Loktak Lake (Manipur — only floating island ecosystem — Phumdis).
Environmental Laws (India):
1972: Wildlife Protection Act (Schedule I = highest protection)
1974: Water (Prevention and Control of Pollution) Act
1980: Forest Conservation Act (requires Central approval for forest diversion)
1981: Air (Prevention and Control of Pollution) Act
1986: Environment Protection Act (umbrella act)
2002: Biological Diversity Act
International Conventions:
CITES (1975): Convention on International Trade in Endangered Species. Controls trade in wildlife.
Ramsar Convention (1971): Conservation of wetlands.
CBD (Convention on Biological Diversity, 1992): Signed at Rio Earth Summit. India ratified.
Paris Agreement (2015): Climate. Limit warming to 1.5-2°C. NDCs (Nationally Determined Contributions).
Montreal Protocol (1987): Ozone layer. Phase out CFCs.
Kyoto Protocol (1997): GHG reductions. Differentiated responsibilities.