Introduction

• India has 4% of the world’s renewable water resources but supports 18% of the global population.
• Average annual precipitation: 4,000 BCM, the main freshwater source.

Water Resources Classification

• Natural Sources: Surface water, groundwater, subsurface river flow, frozen water.
• Artificial Sources: Treated wastewater, desalinated seawater.

Availability and Potential of Water Resources in India

Surface Water Resources

• 10,360 rivers and tributaries (>1.6 km length).
• Annual river basin flow: ~1,869 km³ (37% usable due to seasonal variability).
• Major contributors: Ganga, Brahmaputra, Barak rivers (cover <1/3 land but hold 60% of surface water).

Groundwater Resources

• Total replenishable groundwater: ~432 km³.
• Ganga-Brahmaputra basins hold 46% of replenishable resources.
• Heavy reliance: 50% irrigated land and 20 million tube wells depend on groundwater.

Water Bodies

Lagoons and Lakes

• Prominent in Kerala, Odisha, West Bengal.
• Usage: Irrigation (brackish water for paddy, coconuts), fishing.

Dams and Rivers

• ~5,000 major/medium dams, barrages.
• Storage capacity: 170 BCM; key for irrigation and groundwater recharge.

Usage of Water

• Irrigation: 78% of water use.
• Household Sector: 6% (80% from groundwater).
• Industrial Sector: 5%.

 Per Capita Water Availability

• Thresholds:
  • Water stressed: <1,700 m³/person/year.
  • Scarcity: <1,000 m³/person/year.
• Declining Trends:
  • 1951: 5,200 m³/person.
  • 2010: 1,588 m³/person.
  • Projected for 2050: 1,191 m³/person.

 Water Pollution and Scarcity

• Pollution: 70% of surface water polluted (agriculture, industry, urban runoff).
• Scarcity Issues:
  • Groundwater overuse in rural areas.
  • Women walk 200m–5 km daily for water in 54% of rural households (2012).