🌊 Drainage System
Rivers of India — Himalayan and Peninsular river systems.
🌊 India's River Systems
India's drainage system is divided into two major groups based on their origin and characteristics.
Himalayan Rivers (Perennial — flow all year):
Fed by glaciers AND monsoon rains. Carry large amount of silt. Create large fertile plains and deltas.
• Indus system: Indus, Jhelum, Chenab, Ravi, Beas, Sutlej (5 rivers give Punjab its name: "land of 5 rivers")
• Ganga system: Ganga, Yamuna, Ghaghra, Gandak, Kosi, Son, Chambal. Most important river system of India.
• Brahmaputra system: Brahmaputra (Tsangpo in Tibet, Jamuna in Bangladesh). Carries the highest water volume of any Indian river. Creates world's largest river island — Majuli (Assam).
Peninsular Rivers (Seasonal — depend on monsoon):
Flow in valleys, shallower. Drain into either Arabian Sea or Bay of Bengal.
• West-flowing: Narmada, Tapi (flow in rift valleys, no delta — form estuaries)
• East-flowing: Mahanadi, Godavari, Krishna, Kaveri (form large deltas in Bay of Bengal)
Most peninsular rivers flow east (toward Bay of Bengal) because the Western Ghats act as a watershed.
But Narmada and Tapi are exceptions — they flow westward into the Arabian Sea. Why?
• They flow through rift valleys (grabens) — formed by faulting/geological fractures
• The Vindhya and Satpura ranges are on either side of their valleys
• They do NOT form deltas — form estuaries (funnel-shaped mouths) instead
• Their valleys are some of India's most fertile agricultural land
• Chilika Lake (Odisha) — largest coastal lagoon in India, largest wintering ground for migratory birds in Asia
• Wular Lake (J&K) — largest freshwater lake in India
• Vembanad Lake (Kerala) — longest lake in India (~96km), Nehru Trophy Boat Race
• Loktak Lake (Manipur) — largest freshwater lake in NE India, floating phumdis (vegetation islands)
• Dal Lake (Kashmir) — famous for houseboats and shikaras
Major Rivers of India
AnimationHimalayan rivers are perennial — they flow all year. Peninsular rivers dry up in summer.
Compare River Systems
Interactive• Flow through gentle slopes over long distances → carry heavy sediment load
• Flow slowly when they reach the coastal plain → deposit sediment → build deltas
• Bay of Bengal is calmer than Arabian Sea → waves don't wash away deposits
West-flowing rivers (Narmada, Tapi):
• Flow through rift valleys — narrow and fast
• Hard rocky valley floors — rivers carry less sediment
• Reach the Arabian Sea quickly through a narrow mouth
• Strong tidal action at the coast sweeps away any sediment
• Form estuaries instead — funnel-shaped, tidal influence reaches inland
So the difference is: slope gradient + sediment load + coastal conditions = delta vs estuary.
Area: ~10,000 sq km (India + Bangladesh combined)
Importance:
• Biodiversity hotspot — home to the Royal Bengal Tiger, Irrawaddy dolphins, saltwater crocodiles, Olive Ridley sea turtles
• UNESCO World Heritage Site (Indian side declared 1987)
• Ramsar wetland (internationally protected wetland)
• Carbon sink — mangroves store enormous amounts of CO₂
• Coastal protection — mangroves absorb cyclone energy, protecting inland areas
• Sundarban tigers are unique — they swim between islands and have been known to attack fishermen
• Name comes from "Sundari tree" (Heritiera fomes), a dominant mangrove species