Aquifer

• Water abstraction


  The extraction of water from rivers or groundwater aquifers
• Aquifer


  A body of rock or sediment that stores groundwater and allows the flow of groundwater.
• Features of Aquifers


  - porosity: space in the rock

  - permeability: measure the ease as which water flows through rock

  - associated geological structures: rock below being impermeable and rock above being permeable
• Aquifer recharge


  the input process of water percollating the aquifer
• When were most aquifers recharged?

  During the ice age 10,000-20,000 years ago
• Ancient aquifers


  -often saline

  -can cause soil salinisation

  -killing crops
• Over-exploited aquifers


  -changes in surface hydrology

  -ecological impacts

  -saltwater incursion

  -subsidence

  -reduced supplies
• saltwater incursion


  Movement of saline water into freshwater aquifers due to water tables lowering, reducing pressure and pulling seawater into Aquifer
• Examples of over-exploited aquifers


  -> high plains aquifers

  -> North China Plain

  -> Malta
• Subsidence


  the sinking of regions of the Earth's crust to lower elevations
• Primary threats to aquifers


  -over exploitation

  -pollution

  Driven by intense and poorly managed farming