Geography of India: Physiography, Climate, Soils, Agriculture, Industry and Transport
This domain is the heaviest factual block of the Karnataka II PUC syllabus: India's physiographic divisions, monsoon mechanism, soil and vegetation types, crop seasons, industrial location and the transport network. Questions usually ask you to match a feature with its cause or region.
Physiography and drainage
- Six divisions: the Himalaya (Himadri, Himachal, Shiwalik, plus Purvanchal), Northern Plains (Bhabar, Terai, Bhangar, Khadar), Peninsular Plateau (Central Highlands, Deccan Plateau, Western and Eastern Ghats), Indian Desert, Coastal Plains, and the island groups.
- Himalayan rivers are antecedent and perennial (Indus, Ganga, Brahmaputra); peninsular rivers are consequent and seasonal (Godavari, Krishna, Cauvery, Narmada, Tapi).
Monsoon climate
- Seasonal wind reversal results from the northward migration of the ITCZ, differential heating of land and sea, the Tibetan Plateau as a heat source, the tropical easterly jet and the Somali (cross-equatorial) jet.
- Southwest monsoon: June to September. Retreating northeast monsoon: October to December, which is why coastal Tamil Nadu's wet season is winter. Western disturbances bring winter rain to Punjab and Haryana.
Soils and vegetation
- ICAR groups: alluvial, black (regur, from Deccan basalt, ideal for cotton), red (crystalline rocks), laterite (leached under heavy rainfall), arid, forest, saline-alkali (reh) and peaty.
- Vegetation: tropical evergreen, semi-evergreen, moist and dry deciduous, thorn, montane and mangrove.
Agriculture, industry and transport
- Kharif - rice, jowar, bajra, cotton, groundnut, jute; rabi - wheat, gram, barley, mustard; zaid - melons and cucumber.
- Iron and steel: Jamshedpur (TISCO, 1907), Bhilai, Rourkela, Durgapur, Bokaro, Visakhapatnam, Salem, all tied to iron ore, coal, water and rail. Cotton textiles: Mumbai, Ahmedabad, Kanpur, Coimbatore.
- Golden Quadrilateral with north-south and east-west corridors; major ports include Kandla, JNPT, Visakhapatnam, Paradip, Chennai, Kochi and Mangaluru.
Worked example
A soil is clayey, black, self-ploughing, moisture-retentive and derived from Deccan basalt. Identify it and its best crop. Reasoning: basalt parent rock plus self-ploughing property indicates black (regur) soil; its high clay and moisture retention suit cotton.
Traps that cost marks
- Laterite versus red soil - laterite is leached, red soil is simply weathered crystalline rock.
- Bhangar (old, calcareous alluvium) versus Khadar (new, more fertile).
- Naming the southwest monsoon as Tamil Nadu's main rain source.