Note: This chapter was removed from the NCERT curriculum in the 2022 rationalization. It is retained here because water resources, water scarcity, groundwater depletion, and water conservation are among the most important topics in UPSC GS1 (geography), GS2 (welfare schemes), and GS3 (environment).

Why this chapter matters for UPSC: Water — its cycle, scarcity, conservation, and governance — is consistently one of UPSC's most tested environmental topics. India faces severe water stress, groundwater depletion, and inter-state water disputes. This chapter's fundamentals directly connect to Jal Jeevan Mission, National Water Policy, and river basin management.

PART 1 — Quick Reference Tables

The Water Cycle

Process Description Driven By
Evaporation Water from oceans/lakes/rivers → water vapour Solar heat
Transpiration Water from plants → water vapour (through stomata) Solar heat
Evapotranspiration Combined evaporation + transpiration Solar heat; measured in agriculture
Condensation Water vapour → tiny droplets → clouds Cooling of air at altitude
Precipitation Water falls as rain, snow, hail, sleet Gravity
Surface runoff Rain flows over land → rivers → ocean Gravity
Infiltration Water seeps into soil → recharges groundwater Gravity + soil permeability

India's Water Resources — Key Data

Resource India's Status
Annual average rainfall ~1,170 mm (varies enormously: Cherrapunji ~11,000 mm; Jaisalmer ~200 mm)
Total freshwater resources ~1,869 BCM (Billion Cubic Metres) per year
Utilizable water resources ~1,123 BCM
Groundwater 433 BCM utilisable; ~62% used for irrigation
Major rivers 12 major river systems; 7 interstate river disputes
Per capita water availability ~1,486 m³/year (2021) — below 1,700 m³ = water stress threshold

PART 2 — Detailed Notes

States of Water

Key Term

Three states of water:

  • Solid (ice): Below 0°C; water molecules in fixed lattice; less dense than liquid water (ice floats — crucial for aquatic life in cold climates)
  • Liquid (water): 0°C to 100°C at standard pressure; molecules flow freely
  • Gas (water vapour/steam): Above 100°C (boiling point at sea level); at lower altitudes (reduced pressure), water boils at lower temperatures (mountain cooking problem)

Why ice floats: Water is densest at 4°C — unique property. Below 4°C, ice expands as it crystallises. This is why ice floats, and why ponds freeze from the top down (not bottom up) — allowing fish to survive under the ice layer in winter.

India's Water Crisis

UPSC Connect

UPSC GS1 + GS3 — Water scarcity:

India faces a complex water crisis — the paradox being that India has 4% of world's freshwater but 18% of world's population.

Types of water scarcity:

  • Physical scarcity: Not enough water (Rajasthan, Kutch, parts of Marathwada)
  • Economic scarcity: Water exists but infrastructure to access it is lacking (parts of Northeast)

Groundwater crisis:

  • India extracts more groundwater than any other country (~250 BCM/year)
  • Over-extraction for irrigation (especially for water-intensive crops like rice and sugarcane in water-scarce regions — Punjab's groundwater depletion is severe)
  • CGWB (Central Ground Water Board): 67% of India's blocks show some level of groundwater stress
  • Water table dropping by 0.5–2 metres per year in many parts of Punjab, Haryana, Rajasthan, UP

Policy responses:

  • National Water Policy 2012: Prioritises drinking water > agriculture > industry; advocates integrated water resource management
  • Jal Shakti Ministry (2019): Merged Water Resources and Drinking Water ministries; single authority for water management
  • Jal Jeevan Mission (2019): Tap water to every household; ~78% connected as of early 2025
  • PM Krishi Sinchayee Yojana (PMKSY): "Har Khet Ko Pani" (water to every field) + "More Crop Per Drop" (micro-irrigation)
  • Pradhan Mantri Jal Sanchay (PMJS): Water conservation
  • Atal Bhujal Yojana (ABY): Groundwater management in 7 water-stressed states (UP, MP, Rajasthan, Maharashtra, Haryana, Gujarat, Karnataka)

Inter-state water disputes (major):

  • Cauvery: Karnataka vs Tamil Nadu (Cauvery Water Disputes Tribunal)
  • Krishna: AP, Telangana, Karnataka, Maharashtra
  • Mahadayi: Goa, Karnataka, Maharashtra
  • Ravi-Beas: Punjab, Haryana, Rajasthan

Rainwater Harvesting

Explainer

Rainwater harvesting: Collecting and storing rainwater for later use — on rooftops (rooftop harvesting), in check dams, tanks, and percolation pits.

Traditional Indian water harvesting systems:

  • Johad (Rajasthan): Community ponds for cattle and humans; revived by Rajendra Singh ("Waterman of India")
  • Kund (Rajasthan): Underground cisterns for rainwater storage
  • Stepwells (Vav/Baoli): Gujarat and Rajasthan; historical water storage + temperature regulation + social space (Rani ki Vav, Patan, Gujarat = UNESCO WHS)
  • Ahar-Pyne (Bihar): Traditional irrigation channels
  • Phad (Maharashtra): Community irrigation system
  • Zabo (Nagaland): Integrated land-water management
  • Kul (Himachal Pradesh): Diversion channels from glacial streams

Policy: Several state governments mandate rooftop rainwater harvesting for new buildings (Maharashtra, Tamil Nadu, Delhi). CGWB promotes Rainwater Harvesting Scheme.

Bangalore's solution: After severe water crisis (~2019), Bangalore implemented large-scale lake rejuvenation and rainwater harvesting — important case study.

PART 3 — Frameworks

Water–Food–Energy Nexus

A critical framework for UPSC Mains:

Component Link
Water Required for food production (70% of water use is irrigation)
Food Growing more food requires more water; some crops (rice, sugarcane) very water-intensive
Energy Pumping groundwater requires electricity; hydropower requires water; thermal power needs cooling water
Conflict Energy policy (more hydropower dams) affects water availability; agriculture policy (subsidised power → over-pumping groundwater) affects water tables

Exam Strategy

Prelims traps:

  • India's per capita water availability is below the 1,700 m³/year water stress threshold (2021 data: ~1,486 m³)
  • India is the largest groundwater extractor in the world (NOT China or USA)
  • Rani ki Vav (Patan, Gujarat): UNESCO World Heritage stepwell — example of traditional water harvesting
  • Rajendra Singh = "Waterman of India"; revived Johad in Rajasthan; Ramon Magsaysay Award winner
  • Cauvery River: Originates in Karnataka (Talakaveri, Coorg) → flows through Tamil Nadu → Bay of Bengal; NOT originates in Tamil Nadu

Previous Year Questions

Prelims:

  1. Which of the following is the correct order of water allocation priority under India's National Water Policy 2012?
    (a) Drinking water > Agriculture > Industry
    (b) Agriculture > Drinking water > Industry
    (c) Industry > Agriculture > Drinking water
    (d) Drinking water > Industry > Agriculture

  2. "Johad" is a traditional water harvesting system associated with:
    (a) Rajasthan
    (b) Gujarat
    (c) Kerala
    (d) Assam

  3. The Atal Bhujal Yojana focuses on:
    (a) Construction of dams
    (b) Groundwater management in water-stressed states
    (c) River linking project
    (d) Drinking water supply in urban areas

Mains:

  1. India faces both floods and droughts simultaneously. Critically examine the paradox and suggest solutions through integrated water resource management. (GS3, 15 marks)

  2. Traditional water harvesting systems of India have a lesson for modern water management. Discuss with examples from different regions. (GS3, 10 marks)