groundwater depletion

subsidence

Lowering the water table may cause the ground surface to sink. Subsidence may occur beneath houses and other structures (Figure 1.4).

salt water intrusion

When coastal aquifers are overused, salt water from the ocean may enter the aquifer, contaminating the aquifer and making it less useful for drinking and irrigation. Salt water incursion is a problem in developed coastal regions, such as on Hawaii.

groundwater overuse

Some aquifers are overused; people pump out more water than is replaced. As the water is pumped out, the water table slowly falls, requiring wells to be dug deeper, which takes more money and energy. Wells may go completely dry if they are not deep enough to reach into the lowered water table. Other problems may stem from groundwater overuse. Subsidence and saltwater intrusion are two of them.

ogallala aquifer

The Ogallala Aquifer supplies about one-third of the irrigation water in the United States. The Ogallala Aquifer is widely used by people for municipal and agricultural needs. (Figure 1.2). The aquifer is found from 30 to 100 meters deep over an area of about 440,000 square kilometers! The water in the aquifer is mostly from the last ice age. About eight times more water is taken from the Ogallala Aquifer each year than is replenished. Much of the water is used for irrigation (Figure 1.3). Click image to the left or use the URL below. URL: Intense drought has reduced groundwater levels in the southern U.S., particularly in Texas and New Mexico.

textbook_image

instructional diagrams

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questions

wells may go completely dry if they are not deep enough to reach in a lowered water table.

-->  a) true

b) false

which of these regions has intense droughts and reduced groundwater levels?

a) northeast

b) pacific northwest

c) midwest

-->  d) south

this aquifer supplies one-third of the irrigation water in the united states.

a) hetch-hetchy

-->  b) ogallala

c) quabbin

d) none of the above

land in some places, like the san joaquin valley of california, has undergone subsidence, which is due to

a) too much farming.

b) the aging of the groundwater aquifer.

c) a change from drip irrigation to overhead sprinklers for irrigation.

-->  d) overpumping groundwater.

in coastal regions, when an aquifer gets low, this might happen.

a) a reduction in farming.

b) drought

-->  c) salt water intrusion

d) none of these.

when a water table decline, wells must be drilled deeper.

-->  a) true

b) false

groundwater is a stable supply of water and can never be depleted.

a) true

-->  b) false

the water in the ogallala aquifer is mostly from the last ice age.

-->  a) true

b) false

the dust bowl will not be repeated as long as we continue to

-->  a) pump water from the ogallala aquifer.

b) stop farming in that region.

c) only grow crops in wet years.

d) use pesticides and herbicides to make plants grow better.

diagram questions

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