Groundwater resources

Question 1

What is the zone of aeration?

Answer 1

Rock or sediment that allows water to pass through it and has pore space that could store water.

Question 2

What is the zone of saturation?

Answer 2

Rock or sediment that can store water in its pore space and allow water to move through it.

Question 3

What is the water table?

Answer 3

The upper surface of the zone of saturation; the boundary between the zone of aeration and zone of saturation.

Question 4

What is an impermeable layer?

Answer 4

A layer of rock that does not allow fluids to flow through it; impermeable layers around porous and permeable rock can form good aquifers

Question 5

What is the recharge area of an aquifer?

Answer 5

Area on Earth’s surface that allows water to infiltrate into an aquifer.

Question 6

Why do urban aquifers recharge slower than rural aquifers?

Answer 6

Buildings and roads form an impermeable layer in the recharge area. Urban areas experience more surface runoff and evaporation.

Question 7

What type of rock is necessary for Karst to form?

Answer 7

Carbonate rocks and other soluble minerals

Question 8

How do caverns form?

Answer 8

Fractures and joints in carbonate rock allows water to dissolve the rock and enlarge the passages.

Question 9

How can water naturally form an acid that can dissolve rock?

Answer 9

Carbon dioxide in the air and soil reacts with water to form a weak carbonic acid.

Question 10

How does cavern formation change locations?

Answer 10

Surface stream erosion or changes in the recharge area can lower the water table and empty caverns. New cavern formation occurs at a lower level.

Question 11

How do sinkholes form?

Answer 11

Surface fractures widen to form bowl-shaped depressions, or pressure on unsupported caverns can cause surface land to fall into the cavern.

Question 12

Why is Karst topography an economic concern?

Answer 12

Millions of dollars are spend annually repairing buildings and roads that are damaged due to unstable ground conditions.

Question 13

What is a stalactite?

Answer 13

A growth of evaporate minerals that formed from flowing or dripping water and that hangs down from the ceiling of a cavern

Question 14

What is a stalagmite?

Answer 14

A growth of evaporate minerals that formed from flowing or dripping water and that rises from the floor of a cavern.

Question 15

Why is Karst Topography vulnerable to groundwater contamination?

Answer 15

Fractures and joints allow contaminants to easily enter groundwater systems without natural filtration.

Question 16

What are some sources of urban groundwater contaminants?

Answer 16

Runoff of road salt or leaking oil, industrial spills or air pollution, leaking underground storage tanks, waste disposal sites, and garden and lawn chemicals.

Question 17

What are some sources of rural groundwater contaminants?

Answer 17

Agricultural fertilizers and pesticides, animal waste, and leaking septic systems.

Question 18

What are two problems associated with aquifer contamination?

Answer 18

Contaminants can spread undetected throughout a large aquifer or connected aquifers. Aquifers are difficult and expensive to clean up.

Question 19

Why might a government abandon a well field?

Answer 19

The contamination is too extensive to clean. Withdrawals of water are much larger than natural recharge.

Question 20

Why might a government regulate activities in a recharge area?

Answer 20

Recharge areas are vulnerable to groundwater contamination. It is easier to prevent contamination than to clean it up.

Question 21

How do flood conditions form?

Answer 21

A flood is when the zone of aeration is filled with excess water and the water table is at the surface.

Question 22

What factors control the depth of the water table?

Answer 22

The amount of water removal, the amount of recharge, and the slope of the permeable rock that forms the aquifer.

Question 23

What is a spring?

Answer 23

A spring forms when the water table naturally at the surface.