Deck 19: A Hidden Reserve: Groundwater

Question 1

The porosity of vesicular basalt is about 30%;however,when water is poured on it,the water does not come out the other side.How is this possible?

A)The vesicles in basalt are filled with sediments and thus cannot hold water.
B)The vesicles in basalt are not connected,so it has no permeability.
C)The minerals in the basalt react chemically with the water to produce gases.
D)Vesicular basalt is similar to a sponge and will soak up all the water.

Answer 1

B

Question 2

The dissolution of rock produces ________.

A)primary porosity
B)primary permeability
C)secondary porosity
D)a reduction in primary porosity

Answer 2

C

Question 3

You have a choice to drill your water well into a shallower unconfined aquifer or a deeper confined aquifer.Drilling deeper will cost more money;however,you chose to drill into the confined aquifer.Why?

A)The confined aquifer will most likely have a higher water quality.
B)The confined aquifer will most likely have a higher permeability.
C)The confined aquifer will not be subject to overpumping.
D)The confined aquifer will contain more water.

Answer 3

A

Question 4

In unfractured,permeable rock and sediment,water molecules usually take a ________ path.

A)straight
B)wandering
C)circular
D)rectangular

Question 5

Material through which water readily flows is termed ________.

A)fluent
B)porous
C)permeable
D)fluid

Question 6

In the figure below,where would be the best place to locate a well that would supply the most water?

A)A
B)B
C)C
D)D

Question 7

Which list correctly orders the three types of subsurface water from shallowest to deepest?

A)groundwater,soil moisture,vadose zone water
B)soil moisture,groundwater,vadose zone water
C)groundwater,vadose zone water,soil moisture
D)soil moisture,vadose zone water,groundwater

Question 8

Rock or sediment between the water table and the land surface represents a(n)________.

A)aquitard
B)confined aquifer
C)unconfined aquifer
D)unsaturated zone

Question 9

An impermeable layer of rock or sediment is termed a(n)________ in hydrogeologic contexts.

A)aquitard
B)confined aquifer
C)unconfined aquifer
D)unsaturated zone

Question 10

Which statement best fits the figure below?

A)The oases formed next to or above permeable rock.The confined aquifer has low porosity and permeability.
B)The oases formed next to or above impermeable rock.The confined aquifer has high porosity and permeability.
C)The oases formed next to or above impermeable rock.The confined aquifer has low porosity and permeability.
D)The oases formed next to or above permeable rock.The confined aquifer has high porosity and permeability.

Question 11

A regular kitchen sponge has ________ porosity but ________ permeability.

A)high;high
B)low;high
C)high;low
D)no;high

Question 12

Groundwater ________.

A)does not affect the porosity of the rock and sediment through which it flows
B)uniformly increases porosity because of the dissolution of grains
C)uniformly decreases porosity because of the deposition of minerals into pores
D)may increase or decrease porosity through dissolution or deposition

Question 13

If a material is porous,it ________.

A)will be permeable as well
B)will be impermeable
C)may be permeable or impermeable
D)would not be permeable or impermeable

Question 14

If an intrusive igneous rock is unfractured,it serves as a(n)________ in local hydrogeology.

A)aquifer
B)aquitard
C)artesian well
D)perched aquifer

Question 15

The majority of liquid freshwater within Earth exists in ________.

A)lakes
B)rivers and streams
C)groundwater
D)atmospheric clouds

Question 16

The figure below shows the Ogallala and Dakota aquifers along with interlayered shale deposits.What likely occurred in the area to produce the alternating shale and sandstone layers?

A)metamorphism to produce shale
B)transgression and regression
C)intrusion of shale between sandstone
D)precipitation of clay into the shale layer

Question 17

If a material is highly permeable,it ________.

A)must be porous
B)cannot be porous
C)must be fractured
D)must either have substantial porosity or be fractured

Question 18

You have a choice to drill your water well into a more shallow unconfined aquifer or a deeper artesian aquifer.Drilling deeper will cost more money,however you chose to drill into the artesian aquifer.Why?

A)The artesian aquifer will have a higher permeability.
B)The artesian aquifer will not be subject to overpumping.
C)The artesian aquifer will flow on its own,without a pump.
D)The artesian aquifer will contain more water for your use.

Question 19

An aquifer can have ________ porosity and ________ permeability but not ________ porosity and ________ permeability.

A)low;high;high;no
B)high;no;low;high
C)no;no;high;high
D)high;no;no;no

Question 20

Imagine you have a layer of limestone with high porosity but low permeability.What can you do to increase its permeability to allow water to be pumped from the layer and used as a source of drinking water?

A)Add acid to the layer to dissolve the rock and create connections between the pores.
B)Drill down to the layer and set off explosives in the hole to fracture the rock.
C)Remove the overburden so that there will be less pressure trapping the water.
D)Increase the hydraulic conductivity by adding metals to the water.

Question 21

Land subsidence is likely when ________.

A)groundwater recharge occurs
B)the calcium and magnesium content of groundwater increases
C)the water table raises
D)discharge lowers the water table

Question 22

Any place where groundwater naturally flows out of Earth's surface is termed a(n)________.

A)artesian well
B)geyser
C)spring
D)recharge area

Question 23

Pumping vast quantities of water locally ________.

A)raises the local water table
B)lowers the local water table,forming a cone-shaped depression
C)lowers the local water table,forming a cylindrical depression
D)does not affect the water table

Question 24

During a particularly cold winter in Florida,the temperatures remained below freezing for several weeks.To avoid freeze damage to the crops,farmers used well water to continuously spray the crop and maintain a protective coating of ice around the crop.Shortly after this long cold snap,sinkholes began forming throughout the region.Were these events linked?

A)No;watering crops does not cause the formation of sinkholes.
B)No;sinkholes form in a karst landscape,which farmers cannot farm on.
C)Yes;the farmers removed too much water from the aquifers and induced subsidence.
D)Yes;the farmers added too much weight to the surface and induced subsidence.

Question 25

The hydraulic gradient in Darcy's Law is essentially the same as which of the following?

A)the slope of a line
B)the quadratic equation
C)a Pythagorean triangle
D)the area of a triangle

Question 26

Consult the figure below.Where is the hydraulic head the highest and why?

A)A,because there is more rock above it.
B)A,because there is more water above it.
C)B,because there is less rock above it.
D)B,because there is less water above it.

Question 27

The rate of groundwater flow per unit area through a body of rock or sediment depends ________.

A)only on the slope of the local water table
B)only on the porosity of the rock or sediment
C)on the slope of the water table and the porosity of the rock or sediment
D)on the slope of the water table and the permeability of the rock or sediment

Question 28

An artesian well is one that ________.

A)discharges groundwater at the ground surface without pumping
B)has its intake sited within the vadose zone of an unconfined aquifer
C)has its intake sited within the unsaturated zone of an unconfined aquifer
D)has its recharge area at an elevation below sea level

Question 29

Consult the figure below.If someone were to dump chemicals into a dry river,what would happen to those chemicals?

A)They would evaporate into the atmosphere and no longer be a danger.
B)They would remain in the soil but would not make it into the groundwater.
C)They would seep into the groundwater but flow away from the city's wells.
D)They would end up flowing with the groundwater toward the city's wells.

Question 30

You are performing a dye trace study in which you add some dye to a recharge area of the Norton Aquifer and monitor various wells drilled into the aquifer to watch for the dye to appear.You have determined that the discharge of groundwater in the Norton Aquifer is 7.5 ´ 10-⁷ m/s,and you are monitoring wells at distances of 0.5 m (Well A),2 m (Well B),and 100 m (Well C)from the recharge area.When do you expect the dye to appear at each well site?

A)Well A = ~7 days,Well B = ~30 days,and Well C = ~4 years
B)Well A = ~6 seconds,Well B = ~3 seconds,and Well C = ~133 seconds
C)Well A = ~1.5 ´ 10-6 seconds,Well B = ~3.75 ´ 10-7 seconds,and Well C = ~7.5 ´ 10-9 seconds
D)Well A = ~7 years,Well B = ~30 years,and Well C = ~4 years

Question 31

The elevation of the water table ________.

A)is a constant for a given area so long as the topography remains the same
B)may rise during times of drought and sink during rainy periods
C)may rise during rainy periods and sink during droughts
D)is completely unpredictable

Question 32

Rates of groundwater flow are ________ than stream flow because the water ________.

A)higher;can flow through large caverns
B)higher;does not have any obstacles to overcome
C)lower;contains dissolved ions that slow it down
D)lower;must make its way through tiny pore spaces

Question 33

You are attempting to calculate the discharge of groundwater in the Marshak Aquifer.The measured the height of the water table in Well A is 300 m and 175 m in Well B,and the wells are 15,000 m apart.The Marshak Aquifer is composed of fine-grained sandstone with a hydraulic conductivity of 3 ´ 10-⁵ m/s,and a cross-sectional area of 2 m².Calculate the discharge of the Marshak Aquifer.

A)0.5 ´ 10-7 m/s
B)6.0 ´ 105 m/s
C)5.0 ´ 105 m/s
D)5.0 ´ 10-7 m/s

Question 34

Consult the figure below.What will eventually happen to the Everglades if the people of Miami and Fort Myers do not stop using the water?

A)It will shift toward Lake Okeechobee.
B)It will eventually dry up and disappear.
C)It will shift to be closer to Fort Myers.
D)It will be replenished by recharge.

Question 35

As a rule,groundwater always flows from areas of ________.

A)greater elevation to those of lesser elevation
B)greater water pressure to those of lesser water pressure
C)greater hydraulic head to those of lesser hydraulic head
D)lower hydraulic head to those of greater hydraulic head

Question 36

Hard water results from relatively high concentrations of dissolved ________.

A)calcium and magnesium
B)francium and cesium
C)sodium
D)potassium

Question 37

You are drilling a water well when you hit water at a much more shallow level than you expected.What have you likely found?

A)an artesian aquifer
B)a perched aquifer
C)a natural spring
D)an aquiclude

Question 38

Why does an artesian well flow without pumping?

A)The water table is at the surface in an artesian aquifer.
B)The hydraulic head is very low in the aquifer.
C)The water in an unconfined aquifer is pressurized.
D)The water in a confined aquifer is pressurized.

Question 39

A periodic explosive eruption of steam and water from within the ground up through the surface is termed a(n)________.

A)artesian well
B)geyser
C)spring
D)recharge area

Question 40

You are testing the groundwater quality of an aquifer and find that it has high amounts of arsenic.What is the likely source?

A)The arsenic comes from the dissolved minerals in the aquifer rock.
B)The arsenic comes from the reaction of the water with your testing supplies.
C)The arsenic is being poured into the groundwater to poison the town.
D)The arsenic is not actually there;it does not show up in groundwater.

Question 41

The majority of large cave and karst systems have resulted from ________ etching into ________.

A)carbonic acid;limestone
B)ascorbic acid;dolostone
C)phosphoric acid;shale
D)sea water;rock salt

Question 42

For several generations,your family has lived on a farm with a water well.There has never been a problem with the water supply in the past;however,your well has now gone dry.There are several small farms nearby and a large and growing city 50 miles to the north.What can you conclude is the most likely reason for your well to become dry?

A)The farmers nearby have suddenly started using much more water than they used to.
B)The growth of minerals in pore spaces in the aquifer rock has decreased its permeability.
C)As the city grew larger,more wells were drilled and water was overpumped,thus lowering the water table.
D)The water has stopped infiltrating into the ground because of the overuse of pesticides.

Question 43

Sinkholes are a concern primarily for residents whose dwellings are constructed atop ________.

A)sandstone
B)shale
C)limestone
D)granite

Question 44

A(n)________ aquifer is more likely to be contaminated than a(n)________ aquifer.

A)confined;unconfined
B)unconfined;confined
C)artesian;surficial
D)sandstone;limestone

Question 45

Topography dominated by depressions formed by the collapse of caves is termed a ________.

A)valley and ridge province
B)karst landscape
C)horst and graben landscape
D)speleothem formation

Question 46

In addition to its immense size,what else is unusual about Carlsbad Caverns in southeastern New Mexico?

A)Geologists think the system was produced by sulfuric acid rather than carbonic acid.
B)The caverns are within a deposit of rock salt rather than limestone.
C)The caverns were formed within the span of just a few days in 1937.
D)Although there are conduits to the surface,the caverns do not host a population of bats.

Question 47

In many areas with karst terrain,people use sinkholes as places to dump garbage.What effect might this practice have on the groundwater supply?

A)None;sinkholes are not connected to groundwater sources.
B)It clogs the sinkholes so that water cannot percolate into the groundwater.
C)It could contaminate the groundwater in unconfined aquifers only.
D)It could contaminate the groundwater in any or all aquifers in the area.

Question 48

Imagine that some of the wells around a city have begun to show elevated levels of a toxic substance.Without knowing what the toxic substance is,how can you determine what the source of the chemicals might be?

A)Without knowing what the toxic chemical is,it would be impossible to pinpoint where the source is.
B)Determine if there are any chemical factories in the area and report them to the authorities.
C)Determine which wells show the chemicals and which do not and use that data to track the flow of the water.
D)Determine which well shows the highest concentration and determine the closest source to that well.

Question 49

The majority of caves are formed by the dissolution of bedrock ________.

A)above the water table
B)just below the water table
C)greater than 10 m below the water table
D)greater than 10 m above the water table

Question 50

Karst terrain could form in areas where the metamorphic rock ________ is prevalent because the rock contains the mineral ________.

A)marble;calcite
B)marble;quartz
C)quartzite;quartz
D)schist;calcite