Similar to land aquifers, offshore aquifers are bodies of rock or sediment which contain freshwater but are located beneath the sea floor.
Key Features of Offshore Aquifers
- Extent: Such aquifers have been found across the globe off the coasts of Australia, China, North America, South Africa.
- Offshore aquifers can extend up to 90 kilometres off the coast and are believed to contain a million cubic kilometres of freshwater – about 10% of all terrestrial fresh groundwater.
- Freshwater Preservation: A cap rock layer, built from compacted clay-rich sediment, over the aquifers may have prevented freshwater from mixing with salt water in the ocean.
- Formation: There are generally two theories:
- Ice Age Hypothesis: During past ice ages, rainwater seeped into land areas that are now covered by the ocean.
- Connection Hypothesis: Offshore aquifers could be connected to onshore aquifers,which regularly supply them with water after rainfall.
- Significance: Potential untapped source of freshwater, especially for water-stressed regions and potential buffers during climate change induced droughts and erratic rainfall.
- According to 2023 UN Report, global freshwater demand is predicted to exceed supply by 40% by 2030.
- Challenges: High extraction cost, technical barriers, ecological risks on ocean ecosystem including marine life, governance issues etc.
