Significance of Offshore Aquifers

Syllabus: GS1/ Geography, GS3/ Environment

Context

• Scientists have confirmed the existence of a massive offshore freshwater aquifer beneath the Atlantic Ocean, stretching from New Jersey to Maine, marking the first systematic global expedition to drill for undersea groundwater.

What are Offshore Aquifers?

• Offshore aquifers are underground bodies of porous rock or sediment saturated with freshwater, located beneath the sea floor.
• They resemble land-based aquifers but remain submerged under shallow coastal waters, extending up to 90 km from the shoreline.
• A 2021 study in Environmental Research Letters estimated that nearly 1 million cubic kilometres of freshwater lie beneath the oceans, around 10% of Earth’s terrestrial groundwater reserves.
• Location: Confirmed and studied locations include the coasts of;
  • United States (Northeast Atlantic, California)
  • Australia (Perth Basin, Sydney Basin)
  • China (Yellow Sea, recently discovered large reserves)
  • South Africa (Cape Peninsula)
  • Europe (North Sea, Mediterranean).

How Do They Get Freshwater?

• Ice Age Hypothesis: During glacial periods, when sea levels were lower, rainfall infiltrated exposed land, gradually filling aquifers that are now under the ocean.
• Onshore Connection Hypothesis: Some offshore aquifers remain linked to land aquifers and receive freshwater recharge through groundwater flow.
• Cap Rock Protection: A clay-rich compacted layer seals the aquifers, preventing freshwater from mixing with surrounding seawater.

Why are Offshore Aquifers Significant?

• Addressing Global Water Crisis: According to the UN (2023), global freshwater demand will exceed supply by 40% by 2030. Offshore aquifers could act as strategic reserves.
• Climate Resilience: Rising global warming, changing rainfall patterns, and over-extraction of land aquifers have worsened water scarcity. Offshore aquifers offer an alternative to stressed terrestrial sources.
• Strategic Importance: For countries facing droughts and urban demand, offshore aquifers can reduce dependence on costly desalination or water imports.

Challenges in Extraction

• High Cost: Offshore drilling is technologically complex and expensive. The US northeast exploration cost $25 million.
• Engineering Difficulties: Designing wells under the seabed, ensuring transport of water onshore, and preventing seawater intrusion are major hurdles.
• Environmental Risks: Extraction could disturb marine ecosystems, alter pressure balances, or cause saltwater contamination.
  • If the water is ancient (from Ice Age recharge), it is a non-renewable resource and must be used cautiously.
• Governance Issues: Questions of ownership, coastal community rights, and international disputes over undersea water remain unresolved.

Way Ahead

• Framing International Law: The global community can develop a
• or other instruments to govern the equitable and sustainable use of offshore freshwater resources, preventing future conflicts.
• Integrated Water Management: Offshore aquifers can be viewed as a strategic part of a diversified water portfolio that includes conservation, wastewater recycling, and sustainable use of surface water.

Source: IE