Notes on Groundwater Resources and Management

Introduction to the Hydrological Cycle

• Groundwater is one of the most important resources on Earth's surface
• Lecture covers:
  • Overview of water availability on Earth
  • Important terminologies
  • Status of per capita water availability in India
  • Government initiatives for groundwater management

Understanding Groundwater

• Groundwater: Water stored in rocks, sand, soil, etc. within the Earth's surface.
• Aquifer: The structure that holds groundwater, formed by rocks or soils with small pore spaces.
• Saturated Zone: The area where aquifers are filled with water, also referred to as the saturated zone.
• Water Table: The upper level of the groundwater saturation within the aquifer, varies in depth.

Types of Aquifers

• Shallow Aquifers: Water table is near the surface (few meters down).
• Deep Aquifers: Water table is at greater depths (hundreds of feet down).
• Depth of groundwater is unevenly distributed in different aquifers.

Aquifer Composition

• Aquifers typically consist of:
  • Gravel
  • Sand
  • Sandstone
  • Fractured Rock (e.g., Limestone)
• Groundwater in sedimentary rocks is often abundant due to good porosity and storage capacity.
• Groundwater in metamorphic rocks is less abundant, found in fractures and lineaments.

Groundwater Flow

• Groundwater flow is influenced by the size of pore spaces in the soil.
• Groundwater generally follows gravity and can move from one aquifer to another.
• Seasonal variations (e.g., monsoon) can affect groundwater levels, causing them to rise or fall.

Pollution of Groundwater

• Pollution Sources:
  • Permeable materials above aquifers allowing pollutants to seep in.
  • Landfills, septic tanks, leaky underground storage, and agricultural runoff contribute to pollution.
• Groundwater pollution compromises its safety for drinking and other uses.

Distribution of Water on Earth

• 97% Salt Water (oceans/seas)
• 3% Fresh Water:
  • 68.7% in ice caps and glaciers
  • 0.3% in surface water (rivers, lakes, ponds)
  • 30.1% as groundwater
• Groundwater is a critical resource for drinking and agriculture.

Water Resources in India

• India has 0.4% of the world's water area but 17.1% of the world's population.
• Per capita water availability in India is ranked 132.
• Water quality ranking is 122.
• Increasing population leads to decreasing per capita water availability.

Issues with Groundwater Management

• Overuse Problems:
  • Groundwater depletion
  • Lowering of water tables due to excessive pumping
  • Increased costs for deeper water extraction
  • Reduced surface water supplies

Government Initiatives

• Water management is primarily a state responsibility, but supported by the central government.
• Jal Shakti Abhiyan: A campaign for water conservation and security.
• Ghar Ghar Jal Mission: Aims to provide potable water to rural households by 2024.
• National perspective plans for transferring water from surplus to deficit areas.

Conclusion

• Groundwater management is crucial for sustainability and meeting the needs of the population.
• Awareness and conservation efforts are necessary to ensure the longevity of groundwater resources.