introduction to groundwater

fossil water

The residence time of water in a groundwater aquifer can be from minutes to thousands of years. Groundwater is often called fossil water because it has remained in the ground for so long, often since the end of the ice ages. A diagram of groundwater flow through aquifers showing residence times. Deeper aquifers typically contain older "fossil water." Click image to the left or use the URL below. URL:



Groundwater resides in aquifers, porous rock and sediment with water in between. Water is attracted to the soil particles, and capillary action, which describes how water moves through porous media, moves water from wet soil to dry areas. Aquifers are found at different depths. Some are just below the surface and some are found much deeper below the land surface. A region may have more than one aquifer beneath it and even most deserts are above aquifers. The source region for an aquifer beneath a desert is likely to be far away, perhaps in a mountainous area.


The amount of water that is available to enter groundwater in a region, called recharge, is influenced by the local climate, the slope of the land, the type of rock found at the surface, the vegetation cover, land use in the area, and water retention, which is the amount of water that remains in the ground. More water goes into the ground where there is a lot of rain, flat land, porous rock, exposed soil, and where water is not already filling the soil and rock.

instructional diagrams

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the amount of water that is available to enter groundwater in a region is this.

a) capillary action

b) discharge

c) well water

-->  d) recharge

water moves through pores from wet soil to dry areas by

a) recharge

b) solvency

-->  c) capillary action

d) aquifericity

unconfined aquifers are open to the surface.

-->  a) true

b) false

which is an example of a discharge area?

a) water table

-->  b) stream

c) well

d) none of these

if a shallow well runs dry, a deeper well will likely tap another aquifer.

-->  a) true

b) false

when did most fossil water enter its aquifer?

-->  a) around the end of the ice ages.

b) during the ice ages.

c) during the time of the dinosaurs.

d) at the time massive amounts of water were first formed on earth.

are there aquifers in desert areas?

a) no, it is too dry.

b) yes, they are found near the surface just as in wet areas.

-->  c) yes, but only deep ones.

d) no, aquifers are in mountainous areas.

most groundwater has been in an aquifer for millennia.

a) true

-->  b) false

access to groundwater can only be gotten from wells.

c) true

d) false

diagram questions

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