Drainage System of India

India's drainage for UPSC: Himalayan and Peninsular river systems — Indus, Ganga, Brahmaputra, east- and west-flowing rivers, patterns, river linking.

SyllabusGS I · Geographical features and their location — changes in critical geographical features (including water-bodies and ice-caps); physical geography of India

India’s rivers are its oldest infrastructure. They carried the sediment that built the Northern Plains, they decide where cities, canals and dams sit, and they are at the centre of inter-State and international water disputes.

What UPSC asks

Prelims: origins and tributaries (which river rises where, which is a right- or left-bank tributary), rivers flowing through rift valleys, the Panch Prayag, river islands, drainage patterns, and which rivers form deltas versus estuaries. Map-based questions on rivers and the States they cross are common.
Mains (GS I and GS III): contrast between Himalayan and Peninsular rivers, floods and glacial lake outburst floods, river interlinking, and water-sharing treaties.

Key sub-topics

Sub-topic	Core idea
Himalayan vs Peninsular rivers	Perennial, antecedent, meandering vs seasonal, graded, fixed courses
Indus system	Five Punjab rivers; Indus Waters Treaty, 1960
Ganga system	Bhagirathi + Alaknanda at Devprayag; largest basin in India
Brahmaputra system	Tsangpo → Siang/Dihang → Brahmaputra → Jamuna
Peninsular rivers	East-flowing deltas; west-flowing Narmada and Tapi in rift valleys
Drainage patterns	Dendritic, radial, trellis, centripetal
River linking	National Perspective Plan (1980); Ken–Betwa link

Begin with the core page on Himalayan and Peninsular rivers, then use the quick revision sheet and practice questions.