Chapter 5: Indian Physiography
5.1 Introduction to Indian Physiography
Physiography studies India’s physical landscape, divided into three major divisions: the Himalayas, the Indo-Gangetic Plains, and the Peninsular Plateau. Understanding these is critical for UPSC, PSC, and SSC exams, as they influence climate, agriculture, and settlement patterns.
UPSC Relevance: Questions often test physiographic divisions, their formation, and economic significance.
5.2 The Himalayan Mountains
- Formation: Result of the collision between the Indian Plate and Eurasian Plate (~50 million years ago), making them the youngest fold mountains.
- Divisions:
- Greater Himalayas (Himadri): Highest range, perennial snow (e.g., Mount Everest, Kanchenjunga ~8,586 m).
- Lesser Himalayas (Himachal): Middle range, hill stations (e.g., Shimla, Mussoorie).
- Shiwalik Range: Southernmost, foothill zone, prone to erosion.
- Trans-Himalayan Zone: Includes Karakoram and Ladakh ranges (e.g., K2 ~8,611 m).
- Regional Divisions: Western (Kashmir), Central (Himachal), Eastern (Arunachal).
- Significance:
- Climatic barrier: Blocks cold Central Asian winds, influences monsoon.
- Hydrological source: Origin of major rivers (Ganga, Indus, Brahmaputra).
- Biodiversity: Hosts unique flora/fauna (e.g., Himalayan tahr).
Prelims MCQ Trend: Match Himalayan ranges with peaks or passes (e.g., Nathu La = Sikkim).
Mains Angle: “Discuss the role of the Himalayas in shaping India’s climate and river systems.”
5.3 The Indo-Gangetic Plains
- Extent: Stretches from Punjab to Assam, ~2,400 km long, 150–300 km wide.
- Formation: Alluvial deposits from Himalayan rivers (Ganga, Indus, Brahmaputra).
- Sub-Divisions:
- Bhabar: Coarse sediments at Himalayan foothills.
- Terai: Marshy, fertile zone below Bhabar (e.g., Dudhwa National Park).
- Bangar: Older alluvium, less fertile.
- Khadar: Newer alluvium, highly fertile (e.g., Uttar Pradesh plains).
- Significance:
- Agriculture: “Granary of India” (Punjab-Haryana), supports rice, wheat.
- Population: Densest region, ~40% of India’s population.
- Urban Centers: Delhi, Kolkata, Patna.
Prelims Alert: Identify sub-divisions (e.g., Terai = marshy zone).
Mains Task: “Analyze the role of Indo-Gangetic Plains in India’s food security and urbanization.”
5.4 The Peninsular Plateau
- Extent: Largest physiographic division, ~43% of India’s land area, south of Indo-Gangetic Plains.
- Formation: Ancient, stable, part of Gondwana landmass.
- Sub-Divisions:
- Deccan Plateau: Volcanic basalt (Deccan Traps), black soil (Maharashtra, Telangana).
- Chota Nagpur Plateau: Mineral-rich (Jharkhand, coal, iron).
- Malwa Plateau: Black soil, agriculture (Madhya Pradesh).
- Central Highlands: Vindhya and Satpura ranges.
- Significance:
- Minerals: Chota Nagpur = “Mineral Storehouse” (coal, mica).
- Rivers: Narmada, Godavari, Krishna originate here.
- Forests: Tropical deciduous (teak, sal).
Prelims Favorite: Match plateaus with minerals or rivers.
Mains Angle: “Evaluate the economic significance of the Peninsular Plateau in India’s development.”
5.5 The Coastal Plains
- Western Coastal Plain: Narrow, between Western Ghats and Arabian Sea (Konkan, Malabar coasts).
- Ports: Mumbai, Cochin, Kandla.
- Fisheries: High productivity due to upwelling.
- Eastern Coastal Plain: Wider, between Eastern Ghats and Bay of Bengal (Coromandel, Northern Circars).
- Deltas: Ganga, Godavari, Krishna.
- Ports: Chennai, Vishakhapatnam.
- Significance: Trade, agriculture (rice), tourism (beaches).
Prelims Pick: Identify coastal features (e.g., Chilika Lake = Eastern Coast).
Mains Task: “Compare the economic roles of Western and Eastern Coastal Plains.”
5.6 The Indian Islands
- Andaman & Nicobar Islands: 572 islands, volcanic origin (Barren Island), coral reefs.
- Lakshadweep: 36 coral atolls, Arabian Sea, Kavaratti capital.
- Significance:
- Strategic: Maritime security, Exclusive Economic Zone (EEZ).
- Biodiversity: Coral reefs, dugongs.
UPSC Relevance: “Discuss the strategic and ecological importance of India’s islands.”
Chapter 6: Drainage Systems
6.1 Introduction to Drainage Systems
Drainage systems refer to the river networks and their tributaries, critical for irrigation, hydropower, and flood management in India.
UPSC Relevance: Questions focus on river origins, tributaries, and their socio-economic impact.
6.2 Classification of Indian Rivers
- Himalayan Rivers: Perennial, snow-fed, large discharge (e.g., Ganga, Indus, Brahmaputra).
- Features: Form large deltas, floodplains, meanders.
- Peninsular Rivers: Seasonal, rain-fed, smaller discharge (e.g., Godavari, Krishna).
- Features: Form estuaries (Narmada, Tapi), less meandering.
- Inland Rivers: Non-perennial, end in deserts (e.g., Luni, Ghaggar).
Prelims Alert: Classify rivers as Himalayan or Peninsular.
Mains Angle: “Compare Himalayan and Peninsular rivers in terms of flow and utility.”
6.3 Major River Systems
- Indus System:
- Origin: Mansarovar Lake, Tibet.
- Tributaries: Jhelum, Chenab, Ravi, Beas, Sutlej.
- States: Jammu & Kashmir, Punjab.
- Significance: Indus Water Treaty (1960) with Pakistan.
- Ganga System:
- Origin: Gangotri Glacier (Bhagirathi), Uttarakhand.
- Tributaries: Yamuna, Son, Kosi, Gandak, Ghaghara.
- Delta: Sundarbans (world’s largest).
- Significance: Supports 40% of India’s population, sacred river.
- Brahmaputra System:
- Origin: Yarlung Tsangpo, Tibet.
- Tributaries: Dibang, Lohit, Subansiri.
- States: Arunachal Pradesh, Assam.
- Significance: Flood-prone, forms Majuli island.
- Peninsular Rivers:
- Godavari: Origin in Trimbak, Maharashtra; “Dakshina Ganga.”
- Krishna: Origin in Mahabaleshwar, Maharashtra; Nagarjuna Sagar Dam.
- Kaveri: Origin in Brahmagiri Hills, Karnataka; disputes with Tamil Nadu.
- Narmada: Origin in Amarkantak, Madhya Pradesh; forms estuary.
- Tapi: Origin in Satpura Hills, Madhya Pradesh; west-flowing.
Prelims Favorite: Match rivers with origins or tributaries.
Mains Task: “Discuss the role of river systems in India’s agriculture and inter-state disputes.”
6.4 Dams and Their Significance
- Major Dams:
- Hirakud (Mahanadi, Odisha): Longest dam, flood control.
- Tehri (Bhagirathi, Uttarakhand): Highest dam, hydropower.
- Sardar Sarovar (Narmada, Gujarat): Irrigation, drinking water.
- Bhakra Nangal (Sutlej, Punjab): Green Revolution enabler.
- Issues: Displacement, environmental impact, inter-state conflicts (e.g., Kaveri dispute).
UPSC Angle: “Evaluate the socio-economic benefits and challenges of large dams in India.”
6.5 River Interlinking Project
- Objective: Transfer water from surplus to deficit basins (e.g., Ganga to Peninsular rivers).
- Components: Himalayan (14 links), Peninsular (16 links).
- Benefits: Irrigation, flood control, hydropower.
- Challenges: Ecological damage, displacement, high cost.
Mains Task: “Critically analyze the feasibility of India’s River Interlinking Project.”
6.6 Floods and Flood Management
- Flood-Prone Areas: Assam (Brahmaputra), Bihar (Kosi), West Bengal (Ganga).
- Causes: Heavy monsoon, deforestation, siltation.
- Management: Dams, embankments, National Flood Management Policy.
Prelims Alert: Identify flood-prone rivers.
Mains Angle: “Discuss the causes and management of floods in India’s river basins.”