Drainage

Story hook

In May 2002, then Prime Minister Atal Bihari Vajpayee announced something audacious: the Interlinking of Rivers project, a proposal to weld India's 4,500-odd rivers into one giant plumbing network. The idea was that the water-surplus Brahmaputra and Ganga could be piped southward to refill the water-deficient Cauvery and Krishna. The estimated cost: ₹5.6 lakh crore (later revised upward to over ₹11 lakh crore). The map of proposed canals looked less like geography and more like an electrical circuit diagram — 30 separate links, 14 Himalayan and 16 peninsular, crossing 1,000 km of terrain.

Two decades later, only one link — Ken-Betwa — has finally broken ground in December 2024 after years of legal battles. Why so slow? Because rivers are not pipes. They are living ecosystems carrying silt, fish, and political memory. Tamil Nadu and Karnataka have been at war over the Cauvery since the 1892 agreement between the Madras Presidency and the Princely State of Mysore. The Indus Waters Treaty 1960 survived three wars between India and Pakistan but is now under stress. The Brahmaputra, called Tsangpo in Tibet, is being dammed by China at Medog (the world's largest hydropower project, planned 60 GW) — and India worries that water can be weaponized.

Rivers shaped Indian civilization. The Harappans lived along the Indus and the now-vanished Saraswati. The Vedic culture expanded along the Saraswati-Drishadvati. The Magadhan empires grew on the Ganga. Madurai prospered on the Vaigai. Today's India gets ~80% of its drinking water and 86% of its irrigation from surface and groundwater connected to these river systems. Understanding drainage means understanding the geological foundations of food security, energy, geopolitics, and disasters.

Why this matters for UPSC

Drainage is asked every Prelims as a factual paper (origins, tributaries, dams, tribunals) and once every two Mains cycles as an analytical paper (interlinking, transboundary disputes, glacial retreat, floods). The 2023 Mains asked about trans-Himalayan rivers and 2024 Prelims tested Cauvery basin states. Expect 1-2 questions every Prelims year.