Public Section Preview
Key Points at a Glance
Use this section as the fast recall sheet for India's drainage systems, river basins, drainage patterns, and high-yield PYQ facts.
Two Broad Drainage Types
- Himalayan rivers - perennial, glacier+snow fed, antecedent drainage
- Peninsular rivers - seasonal/rain-fed, consequent drainage following plateau slopes
- The two regimes are separated by the Indo-Gangetic trough
- Classification is the foundation for all river questions in the exam
Ganga - India's Longest River
- Length: 2,525 km; drains the largest basin - 8.6 lakh sq km (26% of India)
- Rises from Gangotri glacier (Gaumukh) at 3,892 m in Uttarakhand
- India's national river (declared 2008)
- Declared national river status: 2008; Namami Gange programme: Rs 20,000 crore
Indus - Longest in the System
- Pakistan's national river, but originates in Tibet (near Mansarovar Lake)
- Passes through Ladakh (India) before entering Pakistan; total length 3,180 km
- India's share: ~1,114 km; regulated by Indus Waters Treaty (1960)
- Indus Gorge depth: ~5,200 m - deeper than the Grand Canyon
Brahmaputra - World Records
- Originates as Tsangpo in Tibet; enters India through Arunachal Pradesh (Dibang Valley)
- Flows 918 km in India before entering Bangladesh as Jamuna
- Forms the world's largest river island - Majuli (880 sq km) in Assam
- Annual discharge ~585 BCM - 3rd highest in Asia
Antecedent Drainage and Himalayan Gorges
- Himalayan rivers are older than the mountains - they cut through rising ranges
- This creates spectacular gorges: Indus Gorge (5,200 m deep)
- Brahmaputra's Yarlung Tsangpo Canyon: 5,382 m deep - world's deepest
- Antecedent rivers: Indus, Sutlej, Brahmaputra
Godavari - Dakshin Ganga
- India's longest peninsular river: 1,465 km
- Rises from Trimbakeshwar (Nashik, Maharashtra); called "Dakshin Ganga"
- Drains 3.13 lakh sq km - 2nd largest peninsular basin
- States covered: Maharashtra, Telangana, AP, Chhattisgarh, Odisha
Krishna River - PYQ 2023 Focus
- Length: 1,400 km; originates from Mahabaleshwar (Western Ghats, Maharashtra)
- PYQ 2023 asked for 8 tributaries: Bhima, Tungabhadra, Malprabha, Ghataprabha, Koyna, Musi, Muneru, Yerla
- Tungabhadra is the largest Krishna tributary; Hampi (UNESCO) is on its banks
- Nagarjunasagar Dam on Krishna - one of India's largest dams
Narmada and Tapi - West-Flowing Exceptions
- Both flow westward into the Arabian Sea through rift valleys (grabens)
- Unlike other peninsular rivers flowing east toward Bay of Bengal
- Narmada: 1,312 km (originates Amarkantak, MP); no delta - forms estuary
- Tapi: 724 km (originates Satpura range, MP; enters sea at Surat)
Five Drainage Patterns in India
- Dendritic - tree-like, most common; Ganga system, uniform substrate
- Trellis - right-angle tributaries; Peninsular rivers crossing parallel ridges
- Radial - rivers radiate from a central point; Amarkantak (Narmada, Son, Mahanadi)
- Centripetal - flow toward a basin; Loktak Lake, Sambhar Lake
- Parallel - rivers in plains; Punjab rivers (Ravi, Beas, Sutlej)
Kaveri River - South India's Granary
- Originates from Brahmagiri Hills (Kodagu, Karnataka) at 1,341 m; length 800 km
- Major tributaries: Hemavati, Arkavati, Shimsha, Harangi, Kabini (left); Lakshmantirtha (right)
- Forms Shivanasamudra Falls (98 m) - India's 2nd largest waterfall
- Cauvery water dispute (Karnataka vs Tamil Nadu): SC final order February 2018
Interlinking of Rivers (ILR) Project
- National Perspective Plan: 30 river links (16 peninsular + 14 Himalayan)
- Goal: transfer water from surplus basins to deficit regions
- Estimated cost: Rs 5.60 lakh crore
- Ken-Betwa Link - first approved (2021); Rs 44,605 crore; passes through Panna Tiger Reserve
River Basin Coverage - Key Data
- Ganga: 26% | Indus: 11.5% | Godavari: 9.5% | Krishna: 8%
- Brahmaputra: 5.9% | Mahanadi: 4.3% | Narmada: 2.9%
- Kaveri: 1.9% | Tapi: 1.6%
- Total utilizable water in India: ~1,123 BCM out of 1,869 BCM annual discharge