consequences of aquifer oversue

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  • Consequences of aquifer overuse
    • Reduced supplies
      • if the extraction rate exceeds recharge rate = volume of water available reduced for future use
      • unsustainable use of aqifer carried on for many years before problems became obvious, so human activities that relied on it may have to stop
    • Subsidence
      • water that is no longer present in interstitial spaces in rock cannot support rock particles so compacted by weight above
      • casues subsidence at surface causing serious damage to buildings and pipelines
    • Changes in surface hydrology
      • many rivers, lakes and marshes fed by groundwater flowing out of aquifer springs
      • if groundwater is overexploited then the water table will be lowered and flow from the springs will decline
      • because of flow of water into wetlands has declined they may dry up
    • Ecological impacts
      • if water table is lowered then plants that have higher water requirments will die/become less abundant as fail to compete with plants which have lower requirments for water
      • other species may be affected even though dont rely on water directly but depend on species that need water e.g. for food
    • Saltwater incursion
      • 1). in coastal areas water table higher than sea level
      • 2). as rainwater percolates down to aquifer water flows sideways and out into sea
      • 3). seawards flow of freshwater prevents sea water from flowing into aquifer
      • 4). if aquifer overexploited then seawater flows sideways into aquifer replacing freshwater
      • 5). salt makes aquifer water unsuitable for irrigation as it could kill crops by osmotic dehydration
    • Seawater
      • Desalination of seawater is very energy intensive + expensive so only used in countries where seawater is available bu lack of freshwater supplies

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