Water Resources

• (a) Global Share: India possesses 2.45% of the world's geographical land area, accounts for 4% of global freshwater resources, but must sustain nearly 18% of the world's total human population.
• (b) Annual Precipitation: The total annual volume of precipitation from rainfall and snow is estimated at approximately 4,000 cubic kilometers ($\text{km}^3$).
• (c) Total Utilizable Surface Water: Out of total surface runoff of 1,869 $\text{km}^3$, only 690 $\text{km}^3$ (approx. 37%) can be physically utilized due to rugged relief and monsoon seasonal floods.
• (d) Replenishable Groundwater: The total annual replenishable groundwater potential of the country is estimated at 433 $\text{km}^3$.
Combined, India's total utilizable water resource is $690 + 433 = \mathbf{1,123\text{ km}^3}$.

• Sectoral Breakdown:
1. Agriculture: Consumes 89% of surface water and 92% of groundwater.
2. Domestic Sector: Accounts for 9% of surface water and 3% of groundwater.
3. Industrial Sector: Accounts for 2% of surface water and 5% of groundwater.
• Why Agriculture Dominates:
1. India has over 140 million hectares of net sown area feeding 1.4 billion people.
2. High-yielding crops introduced during the Green Revolution (Paddy, Wheat, Sugarcane) are water-guzzling crops that require heavy, frequent flood irrigation throughout their growth cycles.
3. Highly erratic, seasonal monsoon rainfall (restricted to only 3–4 months) makes intensive canal and tubewell irrigation essential for winter (Rabi) and summer (Zaid) crops.

• Over-exploited States: The states of Punjab, Haryana, Rajasthan, and Western Uttar Pradesh exhibit critical groundwater exploitation exceeding 100% of their annual replenishable recharge rate, caused by unregulated electric tubewell pumping.
• Two Lethal Chemical Toxicities:
1. Fluoride Contamination: Excessive drawdown of aquifers in Rajasthan and Gujarat dissolves fluoride-rich subterranean minerals, causing widespread dental and crippling skeletal fluorosis (bone deformities) among rural populations.
2. Arsenic Poisoning: Catastrophic over-pumping in the lower Ganga-Brahmaputra alluvial plains (West Bengal and Bihar) exposes underground iron pyrite strata to oxygen, releasing lethal, carcinogenic Arsenic into tubewell drinking water, causing skin melanosis and cancers.

• Watershed Management: The rational, integrated, and sustainable management, conservation, and judicious utilization of all natural surface and groundwater resources within a specific drainage basin or catchment area (watershed).
• Two Primary Objectives:
1. Conserving Soil & Water: Preventing surface runoff, soil erosion, and reservoir siltation through percolation tanks, contour bunding, check dams, and vegetative afforestation, thereby recharging groundwater aquifers.
2. Livelihood & Biomass Development: Enhancing the biomass production of the watershed to provide sustainable fuelwood, fodder for livestock, drinking water, and irrigation for rural farming communities.

1. Haryali: A flagship Central Government-sponsored watershed development project executed directly by village Gram Panchayats with local community participation to conserve water for drinking, irrigation, fisheries, and rural afforestation.
   2. Neeru-Meeru ("Water and You"): A statewide community watershed conservation program launched in Andhra Pradesh, which mobilized citizens to excavate thousands of percolation pits, contour trenches, and check dams to recharge local groundwater.
   3. Arvary Pani Sansad: A legendary grassroots initiative in Alwar, Rajasthan, where local villagers guided by Rajendra Singh constructed hundreds of traditional earthen check dams called Johads, successfully reviving five dead seasonal rivers (including the Arvari river) and turning a drought-parched desert green.

• Rainwater Harvesting: A low-cost, eco-friendly method of collecting, diverting, filtering, and storing precipitation runoff from rooftops, paved compounds, and natural land catchments for immediate domestic use or for direct artificial recharge into underground aquifers.
• Tamil Nadu's National Lead: Tamil Nadu was facing severe recurring droughts and critical groundwater depletion in Chennai. To solve this crisis, the Tamil Nadu government enacted a historic law making Rooftop Rainwater Harvesting compulsory for every single building structure in the entire state! No new building blueprint is approved without an inspected RWH system, leading to a dramatic recovery of Chennai's underground water tables.

The National Water Policy establishes a strategic framework for planning and conserving India's water resources:
1. Hierarchy of Allocation Priorities: Clearly mandates that Drinking Water is the number one supreme priority, followed by (2) Irrigation, (3) Hydro-power, (4) Navigation, and (5) Industrial/other commercial uses.
2. Conjunctive Water Use: Emphasizes simultaneous, balanced management of surface water and groundwater.
3. Pricing & Conservation: Recommends charging commercial users realistic water tariffs to deter industrial water pollution and encourage wastewater recycling and desalination.

• Concept of "Day Zero": The critical tipping point when a city's municipal reservoirs, piped water networks, and accessible underground groundwater aquifers are completely exhausted, forcing municipal taps to be turned off permanently and residents to queue for rationed emergency water delivered by tankers.
• Indian Context: Cities like Chennai (in 2019) and Bengaluru (in 2024) experienced near-Day Zero scenarios when prolonged summer heat, deficient monsoon rains, rapid concretization of lakes, and unregulated borewell extraction caused private and public borewells to run bone dry.