What is the difference between a confined and an unconfined (water-table) aquifer? — @USGS

Groundwater movement via the USGS

Click here to read the FAQ from the USGS:

A confined aquifer is an aquifer below the land surface that is saturated with water. Layers of impermeable material are both above and below the aquifer, causing it to be under pressure so that when the aquifer is penetrated by a well, the water will rise above the top of the aquifer.

A water-table–or unconfined–aquifer is an aquifer whose upper water surface (water table) is at atmospheric pressure, and thus is able to rise and fall. Water-table aquifers are usually closer to the Earth’s surface than confined aquifers are, and as such are impacted by drought conditions sooner than confined aquifers.

Learn more:

  • Aquifers and Groundwater
  • Aquifer Basics
  • Credit: National Atlas of the U.S.

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