Water Resources

UPSC frequently extracts quantitative baselines from this section, such as India's 4% share of global precipitation and its global per capita water availability rank (133rd). It sets up the concept of water stress based on the Falkenmark indicator (threshold of 1,000 cubic meters per capita per year). Candidates should skip general descriptions of water pollution but pay close attention to industrial-urban demand spikes and groundwater overdraft statistics. A common trap is assuming that India's water crisis is solely physical, whereas the NCERT emphasizes qualitative scarcity driven by unequal distribution and over-exploitation.

This section outlines the transition from historical water-management structures (e.g., Sringaverapura, Bhopal Lake, Hauz Khas) to modern multi-purpose projects. It provides details on major river systems (Sardar Sarovar on Narmada, Hirakud on Mahanadi, Bhakra-Nangal on Satluj-Beas) and discusses ecological consequences like reservoir-induced seismicity, soil salinization, and sedimentation. It is essential for mapping interstate river disputes (e.g., Krishna-Godavari dispute involving Maharashtra, Karnataka, Andhra Pradesh). Focus on institutional conflicts, environmental impacts, and civic movements like Narmada Bachao Andolan. Skip generic benefits of dams.

Extremely high-yield for traditional water conservation techniques, which UPSC tests regularly. Candidates must memorize the exact geographical distribution of localized technologies: Guls/Kuls (Western Himalayas), Khadins/Johads (Rajasthan), Tankas (semi-arid Rajasthan), and Bamboo Drip Irrigation (Meghalaya). Focus on structural details, such as how Tankas are built inside houses and connected to rooftop pipes. Watch out for traps where UPSC matches traditional systems to incorrect states or ecological zones. Pay close attention to Tamil Nadu's legal milestone as the first state to mandate rooftop rainwater harvesting.