GEO 100 Ground Water

Put these subsurface layers associated with ground water in the correct order.

1. Vadose zone 2. Water table 3. Phreatic zone

Rank the U.S. sectors listed by amount of fresh water withdrawn in billion of gallons per day in 2010, with the largest user on top.

1. thermoelectric power 2. Irrigation 3. Public supply 4. rural use

If someone told you that there were 10 ppb halite in your glass of drinking water, that would mean that for every billion grams of water, there are ______ grams of salt.

10

How much water is used each day in the United States on a per person average?

1130 gallons

Which type of aquifer will be more impacted when impermeable cover is placed over its recharge area?

A confined aquifer

What is an aquifer?

A geologic material that has enough water to act as a source, and the water easily flows through the material

Of the states listed, which three withdraw the least amount of water per day?

Alaska North Dakota Maine

Phreatic zone

All pore spaces are filled with water; also known as the saturated zone

Regardless of the process involved, water entering an aquifer is called ____________, whereas water exiting an aquifer is called _____________.

Blank 1: recharge Blank 2: discharge

Ground water flows from high hydraulic head to low hydraulic head, which is represented by the elevation of the ___________ table in unconfined aquifers and of the potentiometric ______________ in confined aquifers

Blank 1: water or groundwater Blank 2: surface

Which of the following states withdraws the most water per day?

California

Which state is allocated the most water in the lower basin of the Colorado River?

California

What is the name of the feature created at the groundwater surface when water is pumped from a well at a rate faster than can be naturally recharged?

Cone of depression

What type of aquifer is shown in this illustration?

Confined

Overall, which is the current trend for the High Plains aquifer?

Discharge exceeds recharge.

True or false: The main concern of the Colorado River Compact was the legal apportioning of water between the United States and Mexico.

False

What are the three primary geologic material properties that control both porosity and permeability?

How well grains fit together Mineral or rock fragment shape Range of grain sizes

After electric power generation, which U.S. sector accounts for the largest daily water withdrawal?

Irrigation

Of the sectors listed, which uses the highest percentage of ground water, as opposed to other sources, for its water supply?

Irrigation

Which of the following describes the Colorado River Compact?

It apportioned water to the seven states in the Colorado River drainage basin. It was adopted in 1922.

Which of the following accurately apply to the High Plains aquifer?

It is being overused. The water originated from Ice Age glacial melt recharge.

Which of the following are common characteristics of a perched water table?

It is often underlain by an aquitard. It is separate from the regional water table. It contains a relatively small amount of water.

Which of the following defines potentiometric surface?

It is the height to which water will rise (if allowed) in a confined aquifer.

Which of the following describe TDS?

It is used to express water quality. It is the sum concentration of all dissolved chemicals in a sample of water. It means "total dissolved solids."

How does ground water flow?

It sometimes flows into streams. It flows from high elevation to low elevation. It flows laterally.

Which part of the Colorado River basin is seeing a higher population growth and, therefore, will likely need more water in the future?

Lower Basin

The water of the Colorado River became so concentrated in dissolved minerals in the mid-twentieth century that a desalination plant was built to improve the quality of the water flowing into ______.

Mexico

Vadose zone

Pore spaces are filled with air and water; also known as the unsaturated zone

What happens when the recharge area of a confined aquifer is covered by impermeable material such as concrete?

Recharge decreases and less water is available.

The Colorado River Compact originally apportioned 7.5 million acre-feet to the seven U.S. states within its drainage basin and then later another 1.5 million acre-feet to Mexico. Scientists now believe this volume of water is no longer available. Why is there a difference between the original estimate of water available and the current estimate?

Reservoirs constructed after the compact have led to massive amounts of water lost to evaporation. The original estimates were based on inaccurate data taken during a wet period.

What type of water is best suited for improvement through water filtration?

Slightly saline ground water

Which two regions of the United States listed have the highest average annual precipitation?

Southeast Pacific Northwest

What is permeability?

The ease through which fluids flow through a material

Why is this an artesian groundwater system?

The ground water rises above the top of the aquifer.

Why does lowering of the water table often result in subsidence?

The pore water that added buoyancy is no longer there, and the aquifer materials become compacted.

Water table

The top of the saturated zone

Which of the following accurately describe how the water table can vary?

The water table changes height depending on the balance of water entering and leaving the system. The water table can come above the ground surface.

Why is water transferred from one drainage basin to another?

To provide water for areas that have a lot of people but not enough water

What type of aquifer is shown in this illustration?

Unconfined

Which of the following best describes groundwater flow depicted in the image?

Water flows from high to low elevations into the stream.

What is hard water?

Water that has a lot of dissolved calcium and magnesium

A subsurface material that has both high permeability and high porosity and serves as a source of ground water is called a(n) ___________.

aquifer

A rock or sediment that has low permeability, regardless of porosity, is a(n) ______.

aquitard

A rock that can hold a lot of water but does not allow for water to easily flow through it will be considered a(n) _________, not an aquifer.

aquitard

The Ogallala Aquifer is located in the ______ of the United States.

central plains

A(n) _________ aquifer is one that is overlain and underlain by aquitards, and the water within it is under pressure.

confined or artesian

The easiest way to improve any water supply is to practice __________ on many levels.

conservation

Within the majority of the High Plains aquifer area, _______ for agriculture exceeds groundwater recharge.

discharge

Total ________ solids, or TDS, is a way to express water quality.

dissolved

The ______ half of the United States has the highest annual precipitation.

eastern

The process of ______ from the numerous reservoirs located along the Colorado River has resulted in a reduction in both water quality and flow.

evaporation

Using a membrane to screen out undesirable dissolved minerals in water is called ______.

filtration

Water that contains a large amount of dissolved calcium and magnesium is described as ____________.

hard

The majority of freshwater use in the United States is associated with ______.

hydroelectric power plant operation

The purpose of a(n) ____________ transfer is to move water from one drainage basin to another in order to provide for a large population in an area that is naturally dry or arid.

interbasin

The watering of crops, which is known as ____________, is the sector that uses the highest percentage of ground water (as opposed to surface water) in the United States.

irrigation

A groundwater setting that is described as artesian is one that ______.

is a confined aquifer, and the water in the aquifer rises above the level of the aquifer

Water quality may be described in terms of ppm, which means how much of a substance exists in a(n) __________ parts of water. This measurement is commonly used with grams or milligrams.

million

Inaccurate streamflow measurements taken during an abnormally wet period were used in the early estimation of water available in the Colorado River and led to a(n) ______ of the water available to be apportioned.

overestimation

Separate from and above the regional water table, a(n) __________ water table usually contains only a small amount of ground water.

perched

The _________ of a material is a measure of how readily liquids pass through it.

permeability

The amount of open space in a material is its ___________, which is a measure of how water it can hold.

porosity

Saying that groundwater flow is influenced by differences in hydraulic head is the same as saying that the ______ energy of the water table influences flow.

potential

In a confined aquifer, geologist's describe the ______ surface rather than the height of the water table.

potentiometric

When overpumping of an aquifer in a coastal region occurs, __________ intrusion may result.

saltwater

Porosity and permeability are both controlled by the properties of the rock grains or fragments the geologic material is made from; these include grain ___________, grain size, and how well the grains fit together.

shape

The lowering of the land surface caused by the overwithdrawal of water in an aquifer is called _________.

subsidence

Water quality is based on ______.

the amount and type of impurity

Porosity is ______ and usually is measured as a percentage.

the amount of pore space in a geologic material a measure of how much fluid a material can hold

Saltwater intrusion occurs when ______.

the removal of fresh ground water draws saline water into a well

A quantity of water may contain a relatively large proportion of an impurity. The safety of the water then depends on the ______ of impurity.

type

A(n) __________ aquifer is directly open to infiltration from the surface.

unconfined

A(n) ___________ aquifer is directly open to infiltration from the surface.

unconfined

Taking shorter showers, fixing broken plumbing, and planting native vegetation are all ways to practice ___________ conservation.

water

The ________ table can be above or below the ground surface; it changes in elevation depending on recharge and discharge, and typically takes the shape of the topography above it.

water

Recharge is

water entering an aquifer through infiltration and migration.

Discharge is

water exiting an aquifer (i.e., entering a stream, lake, spring, or other aquifer).

A cone of depression forms when ______.

water is pumped from an unconfined aquifer at a rate that is faster than recharge