Geology Chapter 17

Complete the sentences below that describe the relationships between climate change causes and effects. Match the words in the left column to the appropriate blanks in the sentences on the right. Make certain each sentence is complete before submitting your answer. Note that some terms will remain unused.

1. Increased in the rate of evaporation due to climate change can lead to drought. 2. Although there was low precipitation during the 1930s Dust Bowl, it was the farming methods, rather than low precipitation, that caused the extreme drought. 3. Changes in the land, such as deforestation through "slash and burn" practices and wildfires following overgrazing, cause the ground to dry and lead to drought. 4. Decreased rate of precipitation due to climate change can lead to drought. 5. Changes in the land surface, such as more asphalt, can increase heat absorption, which can increase the rate of evaporation.

This image shows the gradient of the water table between Well A and Well B. Please note that the label for each well also displays the elevation of the water table in that well. Using the information present in the figure, calculate the hydraulic gradient of this cross section.

11.7 m/km

About how long have wastewater treatment plants been in existence?

120 years

What percentage of the Earth's total freshwater is in the form of groundwater?

30.1%

A typical rate of groundwater flow for many aquifers is approximately ________.

4 cm/day

What percentage of Earth's liquid freshwater is in the form of groundwater?

96%

In which situation does the cone of depression need to be taken into account?

A well for industrial purposes is drilled proximal to a smaller, domestic well.

What is permeability?

Ability to transmit water

Which of the following is not a factor that will influence infiltration of groundwater?

Acidity of precipitation

Which of the following accounts for the largest usage of groundwater in the United States?

Agriculture and irrigation

What is the difference between an aquifer and an aquitard?

An aquifer is a rather permeable rock, whereas an aquitard is an impermeable rock.

Match the word with the correct definition. Drag the terms on the left to the appropriate blanks on the right.

Aquitard−impermeable layer that prevents flow. Confined aquifer−rock or regolith that can store and transmit water but is contained between two impermeable layers. Unconfined aquifer−rock or regolith that can store and transmit water and receives its recharge directly from the atmosphere.

During a summer with little rainfall, your house on a hill slope experiences an interval during which your well runs dry. You have to borrow water from your neighbor who lives downslope from you. Why does your neighbor have water when you don't?

As the water table drops due to the lack of precipitation, it goes below the base of your well

Why might the ground subside after groundwater is pumped to the surface?

As water is withdrawn, the water pressure drops, and the sediment is left to support the weight on top of it. As a result, the sediment packs more closely together, causing the ground to subside.

Which of the following materials is most readily dissolved by water?

Calcite

Which acid, found in most groundwater, is responsible for most karst topography worldwide?

Carbonic

How does groundwater create caverns?

Caverns are created when acidic groundwater dissolves and carries away limestone over time.

Which of the following materials would make the best aquitard?

Clay

What happens after a geyser erupts?

Cool groundwater seeps back into the underground chambers, and the cycle starts again.

________ is a term used to describe how the water table around a well becomes lower as water is taken from the subsurface.

Drawdown

When water is pumped from a well, drawdown occurs. Which of the following is a true statement regarding drawdown?

Drawdown decreases with increasing distance from the well.

What is drawdown, and how does it relate to the cone of depression?

Drawdown is when the water table around a well is lowered because of water discharge. This depression in the water table is conical and is called a cone of depression.

The majority of groundwater occurs as underground rivers.

False

__________ are intermittent springs that eject columns of water and steam at various time intervals.

Geysers

Match the water feature with the correct definition.

Geyser−intermittent hot springs that periodically eject water into the air with great force. Spring−a natural outflow of water where the water table intersects the surface. Hot spring−water in a basin that is 6-9∘Cwarmer than the mean annual temperature of the location. Artesian well−water under pressure in a confined aquifer that will rise above the level of the aquifer.

In order for an aquifer to be useful for reliable water extraction, what kind of porosity and permeability should it have?

High porosity, high permeability

How will the water table respond when there is a drought?

How will the water table respond when there is a drought?

What force pushes groundwater from pore space to pore space when below the water table?

Hydraulic gradient

Which countries/regions outside the United States are famous for their geothermal activity?

Iceland, New Zealand, Japan, and Siberia

What significant problem might arise when groundwater is heavily pumped at a coastal site?

If the groundwater withdrawal exceeds recharge, the saltwater will become high enough to be drawn into the wells.

Which of the following uses the largest percentage of the Earth's groundwater?

Irrigation

California's Central Valley is an important agricultural area for U.S. fruit and vegetable production. Because of the semiarid climate there, farmers must irrigate their crops. Which environmental problem do you anticipate as a result?

Land subsidence

Assume that the irrigation well in the middle of this image was installed by a seed corn company and not by the farmers who own the local wells on either side. If irrigation were stopped immediately, would this localized lowering recover immediately? Why or why not?

No. The average aquifer has a groundwater flow rate of 4 cm/day.

Assume that chemical pollutants have been illegally dumped in the major river on the left side of this image. Will those pollutants infiltrate and contaminate any other bodies of water? If so, which ones?

None. The major river is a discharge point

What geologic process is responsible for warming the water at nonvolcanic locations such as Hot Springs National Park, Arkansas, and Warm Springs, Georgia?

Normal geothermal gradient as groundwater circulates at depth

Please contrast porosity and permeability.

Porosity is the percentage of the total volume of rock or sediment that consists of pore spaces, whereas permeability is the ability of a rock or sediment to transmit fluid.

________ is when groundwater is being replenished. ________ is when groundwater is flowing back toward the surface.

Recharge; Discharge

Which environmental issue most commonly affects groundwater aquifers in coastal or island areas?

Saltwater contamination

Which of the following materials would be the best natural filter, removing contaminants from groundwater over a long period of time?

Slightly clayey sand

The points on this figure mark the locations of groundwater observation wells. The numbers refer to the elevation of the water table above sea level. Using this information, determine the direction of groundwater flow in this region. Assume that the top of the figure is north.

Southwest

________ is the portion of groundwater that is retained as a film on particle and rock surfaces and in tiny openings in the subsurface.

Specific retention

What groundwater feature forms where the water table intersects with the Earth's surface, creating a natural outflow of groundwater?

Spring

How do stalactites and stalagmites form? Select both correct processes.

Stalactites form on the ceiling when water seeps through the ceiling and deposits calcite. Eventually a soda straw develops, which develops into a stalactite after many more depositions of calcite. Stalagmites form when calcite-rich water falls to the floor from the ceiling, splattering minute amounts of calcite on the floor. After many such depositions, a stalagmite begins to take shape.

Which of the following is an example of a speleothem?

Stalagmite

If gravity pulls infiltrating water downward, what force allows water to be pulled upward at the capillary fringe?

Surface tension

An agricultural company purchased a large tract of land adjacent to your property and built a group of large commercial greenhouses on it. This company uses a lot of water to keep the plants green and healthy. During a particularly dry summer, the amount of water available to your well starts to decrease. Since you are utilizing the same aquifer, what has this company done to the water supply?

The company has compromised the aquifer and is essentially mining the water from it.

Assume that chemical pollutants have been buried at Point Y. The heavy dashed arrow shows the path of infiltration the pollutants followed. Which other bodies of water will be contaminated by these pollutants?

The contamination is flowing below the aquitards, so none will be contaminated.

What prevents water at the bottom of the underground caverns from boiling at the normal surface temperature?

The pressure from the weight of overlying water causes the boiling point to increase

How does the water table change around a pumping water well?

The water table elevation decreases.

While on vacation, you visit a local Imax theater and see a movie about cave diving in the Yucatan Peninsula. In one of the caves, which is currently filled with water, you notice the divers swimming past some stalactites and stalagmites. If the water table is now above the level of the ceiling of the cave, what does the presence of the cave decorations indicate about past water table levels?

The water table was much lower, and the features were formed by water dripping from the ceiling into an air-filled chamber.

Which household function has the highest daily water consumption?

Toilets

Which of the following is an erosional feature?

Tower karst

Freshwater is less dense than saltwater.

True

Is the water table usually flat like the surface of a kitchen table, and why or why not?

Underground, the water table is shaped like a subdued replica of the land surface. Additionally, the water surfaces of rivers and lakes are the level of the water table.

What geologic process is responsible for the geothermal features in Yellowstone National Park?

Volcanic activity

What is porosity?

Volume of pore space in a material

How will the water table respond if it is a wet spring?

Water table will rise.

The ________ is the point in the subsurface where 100% of the pore spaces are filled with water.

Zone of Saturation

An artesian well must tap into ______.

a confined aquifer

Which of the following best describes the cone of depression?

a dimple in the water table surface due to water pumped faster than an aquifer can be replenished

Rock, such as shale or clay, or other unlithified sediment can produce layers that are well sorted, but do not allow water to move through them. Which of the following terms is most accurate for this type of layer?

an aquitard

You accidentally flush your cell phone. Where will it most likely be found at a wastewater treatment facility?

bar screen

Which of the following products of a wastewater treatment facility is often put on farm fields as a fertilizer?

biosolids

What does the Kanapaha Wastewater Treatment Facility use to disinfect the treated water?

chlorine

Which of the following diseases has been all but eliminated from the United States because of wastewater treatment plants?

cholera

Where does settling of solids occur at a wastewater treatment facility?

clarifier

Which of the following materials has the highest porosity?

clay

A(n) __________ acts as a conduit that brings heated water to the surface.

fault

Once overlying water heats to a sufficient temperature, it __________ and releases pressure on the water below.

flashes to steam

In terms of freshwater storage, groundwater is second only to which of the following sources?

glaciers

As a hydrogeologist looking for a source of water for a housing development, which of the following attributes would you look for in a layer of sediment or sedimentary rock? CHECK ALL THAT APPLY

high porosity. high permeability.

To be a gaining stream, the elevation of the water table must be ________ than that of the surface of the stream.

higher

The cone of depression __________ near a well.

increases the hydraulic gradient

To ensure a continuous supply of water, a well must do what?

penetrate well below the regional water table surface

Worldwide, the largest percentage of freshwater readily available to humans is stored in _______.

pore spaces between rocks and sediments

Which of the following can result from excessive pumping of groundwater? CHOOSE ALL THAT APPLY.

reversing the direction of flow in the aquifer subsidence saltwater contamination

When rain falls on land, what factors influence the amount of water that soaks in? Please select all that apply.

the amount of vegetation on the surface the nature of the surface material the intensity of rainfall the steepness of the slope

The quantity of groundwater that can be stored within sedimentary material is most directly controlled by which of the following parameters?

the porosity of the material

What is the cone of depression?

the shape that the water table takes on near a pumping well

It is always difficult to pump groundwater from _____.

the vadose zone

In a losing stream, _____.

the water table is lower than the stream surface

The majority of groundwater is stored within which of the following zones?

the zone of saturation

Which of the following zones is the location of the most biological activity?

the zone of soil moisture

Which of the following has the highest permeability?

unlithified sand

When will a cone of depression stop enlarging?

when the amount of water flowing toward the well equals the amount of water being pumped out of the well