India: Physical Environment and Drainage
Domain 6: India - Physical Environment and Drainage
This domain tests India's major relief divisions and how drainage reflects structure and climate. Questions ask you to locate features, compare Himalayan and peninsular rivers, and explain drainage patterns.
Core rules
- Physiography: the Himalayas (young fold mountains), the Northern Plains (alluvial fill by Indus, Ganga and Brahmaputra), the Peninsular Plateau (old, stable block with tabular hills and rift valleys), the Coastal Plains (eastern wider with deltas; western narrow with estuaries), and the islands.
- Himalayan rivers: perennial, fed by snowmelt and monsoon rain; deep gorges and antecedent drainage; large silt load; deltas in the east.
- Peninsular rivers: largely rain-fed and seasonal; broader, shallower valleys; fixed courses; many flow east into the Bay of Bengal, while Narmada and Tapi flow west through rift valleys.
- Patterns: dendritic (tree-like), radial (from a dome), trellis (folded rocks), centripetal (inward to a basin).
Worked example
A river rises near Amarkantak, flows west through a narrow rift valley between the Vindhya and Satpura ranges, and enters the Arabian Sea through an estuary. The clues - Amarkantak, westward flow, rift valley, estuary - identify the Narmada. Reasoning: peninsular west-flowing rivers occupy fault troughs and carry less silt, so they form estuaries rather than large deltas.
Traps
Do not call the Northern Plains a plateau. Do not say all peninsular rivers are perennial. Do not place the Narmada in the Ganga system. Do not confuse a delta (deposition at a mouth) with an estuary (drowned river mouth scoured by tides).