Which statement about artesian wells is true?

Which statement about artesian wells is true?

• A. They occur when groundwater is under natural pressure in a confined aquifer
• B. They rely on atmospheric pressure
• C. They require pumping to bring water to surface
• D. They cannot occur in regions with aquifers

Answer: (A)

Artesian wells occur when groundwater is under natural hydraulic pressure in a confined aquifer. This happens when water is trapped between impermeable layers, with recharge at a higher elevation. The incoming water pressurizes the aquifer, so when a well taps into it the pressure pushes the water up the casing, and it may rise above the ground surface without pumping. If the potentiometric surface is above ground level, you get a flowing artesian well. This isn’t about atmospheric pressure, and pumping isn’t needed to bring water to surface in a true artesian system. Artesian conditions also require a confined aquifer, so they can occur where such aquifers exist.

Artesian wells occur when groundwater is under natural hydraulic pressure in a confined aquifer. This happens when water is trapped between impermeable layers, with recharge at a higher elevation. The incoming water pressurizes the aquifer, so when a well taps into it the pressure pushes the water up the casing, and it may rise above the ground surface without pumping. If the potentiometric surface is above ground level, you get a flowing artesian well.

This isn’t about atmospheric pressure, and pumping isn’t needed to bring water to surface in a true artesian system. Artesian conditions also require a confined aquifer, so they can occur where such aquifers exist.