Indian Physical Geography

Physiographic divisions, drainage systems, climate, and natural vegetation of India.

Author

Geography Team

Welcome to the Indian Physical Geography module.

Physiographic Divisions of India

Warning📘 Syllabus Coverage
Syllabus Topic Details
NEP-2020 Unit I — Physiography divisions of India
UGC NET Major Physiographic Regions and their Characteristics

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NoteKey Concepts
  • The Great Himalayas: Young fold mountains. Trans-Himalaya, Greater (Himadri), Lesser (Himachal), Outer (Shiwaliks), Northeast hills (Purvanchal). Influence on climate and rivers.
  • The Northern Plains: Formed by Indus, Ganga, Brahmaputra systems. Bhabar, Terai, Bangar, Khadar (soil zones). Extremely fertile and agriculturally productive.
  • The Peninsular Plateau: Oldest stable landmass (Gondwana). Central Highlands (Malwa, Chotanagpur) and Deccan Plateau. Flanked by Western and Eastern Ghats.
    • Palghat Gap (Palakkad Gap): Located between the Nilgiri Hills and Anaimalai Hills.
    • Mawsynram: The place with the highest recorded rainfall in the world, located in the Khasi Hills.
  • The Great Indian Desert (Thar): Arid region, Luni river, shifting dunes (barchans).
  • The Coastal Plains: Western Coast (narrow, submerged - Konkan, Malabar) vs. Eastern Coast (broad, emergent - Coromandel, Northern Circars).
    • Thalghat: A major pass located in the state of Maharashtra.
    • Tropic of Cancer: Passes through eight Indian states including Rajasthan, Madhya Pradesh, Chhattisgarh, and West Bengal.
    • Indian Sundarban Region: Eroding in the southern sea-facing section with little change or accreting in the northern interior section.
  • The Islands: Andaman & Nicobar (volcanic/tectonic origin) and Lakshadweep (coral origin).
    • Ten Degree Channel: Separates the Andaman Islands (Little Andaman) from the Nicobar Islands (Car Nicobar).
  • Syntaxial Bends: The Himalayan mountain range exhibits two major syntaxial bends — the Western (near the Indus gorge) and the Eastern (near the Tsangpo/Zangbo gorge).
  • Kashmir Valley: A large intermontane valley located between the Pir Panjal Range and the Zaskar Range.
  • **Fluvial Indicators:*
    • Pebble Stratum: Usually associated with a fast-flowing river.
  • Geological Evolution Chronology: (i) Northward movement of Indian plate → (ii) Deccan plateau hotspot volcanism → (iii) Collision of Indian plate with Eurasian plate → (iv) Formation of Narmada fault system.
  • Impact Structures: Ramgarh (Rajasthan), Dhala (MP), and Lonar Lake (Maharashtra) — a unique basaltic rock crater lake formed by a meteorite impact.
  • Mineral Reserves: The correct ranking of states with the largest Manganese reserves is Odisha > Karnataka > Madhya Pradesh > Maharashtra.

Drainage Systems of India

Warning📘 Syllabus Coverage
Syllabus Topic Details
NEP-2020 Unit I — Himalayan and Peninsular rivers, watershed and interlinking
UGC NET Drainage System (Himalayan and Peninsular)

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NoteKey Concepts
  • Himalayan Rivers: Antecedent, perennial (snow and rain-fed), youth stage (gorges, rapids), shifting courses (e.g., Kosi). Examples: Indus, Ganga, Brahmaputra systems.
    • Brahmaputra Basin: Covers parts of China (Tibet), India, Bhutan, and Bangladesh.
  • Peninsular Rivers: Consequent, seasonal (rain-fed), mature stage (broad valleys, graded profiles). Flow largely west to east (Mahanadi, Godavari, Krishna, Cauvery) forming deltas, except Narmada and Tapi (flowing west in rift valleys forming estuaries).
  • **River Origins (Himachal Pradesh):*
    • Beas: Originates from Beas Kund near the Rohtang Pass.
    • Ravi: Originates from the Kullu Hills (near Rohtang Pass).
    • Chenab: Formed by the confluence of the Chandra and Bhaga rivers at Tandi.
    • Mahanadi: Does not originate from the Himalayas.
    • Decreasing length: Godavari > Krishna > Mahanadi > Kaveri.
  • Water Divides: The Great Water Divide separating Arabian Sea drainage (23%) from Bay of Bengal drainage (77%).
  • River Basin Percentages: (of total geographical area of India)
    • Ganga: 25.2%
    • Godavari: 9.5%
    • Krishna: 7.9%
    • Mahanadi: 4.3%
  • **National Waterways (NW):*
    • NW 1: Allahabad to Haldia (Ganga-Bhagirathi-Hooghly system).
    • NW 2: Sadiya to Dhubri (Brahmaputra river).
    • NW 3: Kottapuram to Kollam (West Coast Canal).
    • NW 4: Kakinada to Pondicherry (Godavari-Krishna-Canals).
  • Interlinking of Rivers (NRLP): Proposal to transfer water from surplus (Himalayan/Brahmaputra) to deficit basins (Peninsular). Ecological and geopolitical concerns.
  • India-WRIS: Refers to the Water Resources Information System.
  • Watershed Management: Integrated conservation of soil, water, and biomass within a hydrological unit to prevent degradation.

Climate and Mechanism of Indian Monsoon

Warning📘 Syllabus Coverage
Syllabus Topic Details
NEP-2020 Unit I — Climatic classification, Mechanism of Indian monsoon
UGC NET Climate: Seasonal Characteristics, Climatic Divisions, Indian Monsoon

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NoteKey Concepts
  • Characteristics: Tropical Monsoon climate. Four seasons: Winter, Pre-Monsoon (Summer), Southwest Monsoon, Post-Monsoon (Retreating).
  • Monsoon Mechanism:
    • Thermal Concept (Halley): Differential heating of land and sea.
    • Dynamic Concept (Flohn): Shifting of the ITCZ northward over the Ganga plain.
    • Jet Stream Theory (Yin): Sub-Tropical Westerly Jet moving north of Himalayas allowing Tropical Easterly Jet to establish, triggering the onset. Jet streams also influence glacier melting in the Himalayas (when the polar jet stream moves northward, it brings warm air to the region accelerating glacier melt).
    • Oceanic Factors: El Niño (negative impact), Indian Ocean Dipole (Positive IOD enhances rainfall).
  • Climatic Classifications: Koeppen (Amw, Aw, BShw, Cwg), Trewartha.
  • Western Disturbances: Cyclonic storms from the Mediterranean bringing winter rain to NW India (crucial for Rabi crops).
  • **Local Storms:*
    • NORWESTER: Also known as Kal Baisakhi, these are the most common summer storms in Bengal, Assam, and Odisha.
  • **Extreme Weather:*
    • Cloudburst (IMD definition): Rainfall of \(\ge\) 10 cm in one hour.

Soils and Natural Vegetation

Warning📘 Syllabus Coverage
Syllabus Topic Details
NEP-2020 Unit I — Soils: distribution and characteristics; Unit II — Biosphere reserves
UGC NET Types and Distribution of Natural Resources: Soil, Vegetation

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NoteKey Concepts
  • Major Soil Types (ICAR):
    • Alluvial: Most widespread, fertile (Khadar/Bangar), transported by rivers.
    • Black (Regur): Deccan trap region, clayey, high moisture retention, ideal for cotton.
    • Red & Yellow: Crystalline rocks, iron-rich, poor in humus/NPK.
    • Laterite: Formed by leaching in high temp/rainfall areas (Western Ghats), poor fertility, used for brick-making.
    • Arid, Forest, Saline/Alkaline, Peaty soils.
  • Natural Vegetation:
    • Tropical Evergreen (Western Ghats, NE), Tropical Deciduous (Monsoon forests, most widespread - Sal, Teak), Thorn Forests (NW), Montane Forests (Himalayas - altitudinal zonation), Mangroves (Sundarbans).
  • Conservation: Social forestry, Joint Forest Management (JFM), Biosphere Reserves, National Parks.
  • Environmental Social Movements: Notable movements and their leadership include the Chipko Movement (Sunderlal Bahuguna), Narmada Bachao Andolan (Medha Patkar), Bishnoi Movement (Amrita Devi), and the Jharkhand Movement (R. M. Munda).

Natural Disasters in India

Warning📘 Syllabus Coverage
Syllabus Topic Details
UGC NET Natural Disasters in India (Earthquake, Drought, Flood, Cyclone, Tsunami)

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NoteKey Concepts
  • Earthquakes: Himalayan belt, North-East, and Gujarat (High seismic zones IV and V due to tectonic collision).
  • Floods: Brahmaputra, Ganga, Kosi (Bihar), Mahanadi basins. Caused by heavy monsoon, poor drainage, deforestation in upper catchments.
  • Droughts: Chronically drought-prone areas in Rajasthan, Rayalaseema, Vidarbha, Bundelkhand. Erratic monsoon rainfall.
  • Cyclones: Bay of Bengal highly prone (Odisha, Andhra, West Bengal coasts) during pre and post-monsoon seasons. Storm surges cause massive destruction.
  • Tsunami: Vulnerability of eastern coast and A&N islands (2004 Indian Ocean Tsunami).
  • Management: NDMA, SDMA framework, early warning systems, shifting focus from relief to mitigation and preparedness.

Quick Reference

Key Scholars — Indian Physical Geography

Contributors and Their Contributions (NET Notes — Pulakesh Pradhan)

Scholar Key Contribution
Sydney Burrard Longitudinal division of the Himalayas (Punjab, Kumaon, Nepal, Assam)
O.H.K. Spate India and Pakistan: A General and Regional Geography; comprehensive regionalization
R.L. Singh India: A Regional Geography; detailed physiographic classification
Voelcker and Leather Early scientific land and soil classification in India
S.P. Ray Chaudhry ICAR 1963 soil classification (Seven groups, later expanded to ten)
S.K. Chatterjee Key geographer in NATMO (1957) soil and thematic mapping

Notes compiled by Pulakesh Pradhan — Indian Physical Geography (NET)

Indian Physical Geography Quick Reference

Key Concepts

Concept Details
Himalayan Orogeny Collision of Indian and Eurasian plates.
Peninsular Plateau Oldest landmass, part of Gondwanaland.
Indian Monsoon Mechanism Thermal concept (Halley), Dynamic concept (Flohn), Jet Stream (Yin).
Drainage Systems Himalayan (Antecedent) vs Peninsular (Superimposed).

Notes compiled by Geography Team