C. Identification of Groundwater Zones Including the Water Table, , and Zone of ;

Unit 7 Day 6

Groundwater

VA SOL

SOL 9 The student will investigate and understand how freshwater resources are influenced by geological processes and the activities of humans. Key concepts include

b. development of topography

c. identification of groundwater zones including the water table, , and zone of ;

e. dependence on freshwater resources and the effects of human usage on water quality;

Objective

1. Interpret a simple groundwater diagram showing the zone of aeration, the zone of saturation, the water table, and an .

2. Describe underground water sources (such as aquifers and ).

3. Explain the development of karst topography to include key terminology: joint, cavern, , carbonation, stalactite, and stalagmite.

4. Locate the region of karst topography in Virginia as the Valley & RidgeProvince where /dolomite is common.

Ground Water

If you drill a hole deep enough an .you will find water. Even in the ! Groundwater is present everywhere, but is only a small fraction of the Earth’s water supply.

The Hydrosphere

 is the water on and in Earth’s crust.

 of the hydrosphere in contained in the .

Thecontained by landmasses is mostly

 of that fresh water is locked in ice caps and

Most of the remaining fresh water is stored .

Groundwater Movement and Storage

As the Water Cycle runs much of the precipitation that falls on land becomes groundwater. From there it will begin a journey back to the ocean again.

is the process by which precipitation enters the ground and

is the percentage of in a material

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Well-sorted sand has a porosity of about 30%

 is the ability of a material tothrough it and depends on how well connected the pores are

Sandstone, limestone and well-fractured bedrock is very permeable

 are

 is the depth at which groundwater completely of a material

 is the of the zone of saturation

is a through which groundwater flows

Aquiclude is an impermeable barrier to groundwater flow

Groundwater Erosion

Most groundwater contains that forms when carbon dioxide dissolves in water and combines in water molecules. The attacks certain rocks

Carbonate rocks such as limestone that consist mostly of CaCO3 are susceptible to acid dissolution

 are natural underground openings that connect to the surface and are formed when groundwater dissolves limestone

 are dripstone formations that form slowly on the top of cavesas water drips slowly leaving a tiny deposit of CaCO3 that accumulates over time

are mound-shaped dripstone deposits that form underneath the stalactites.

Dripstone columns are formed when stalactites and stalagmites grow together

Karst Topography

Limestone regions that have , sinks, and sinking streams are said to have topography named after a limestone region in Croatia where these features are especially well-developed.

About 10% of the Earths surface and 15% of the United States is this type

 is a depression in the ground caused by the collapse of a cave

Sinkholes are common in Florida, and Texas

Virginia has an extensive cave system that extends through the that can be visited and explored quite easily

Ground Water Systems

Ground Water Systems

Groundwater moves slowly but continuously through on its journey back to the oceans.

The average length of time that groundwater remains underground is .

Groundwater can return to the surface at places where the Earth’s surface

 emerge where an aquifer and Aquiclude come in contact at the surface

 and sandstone , sand and gravel are common aquifers

Clay and shale layers are Aquiclude

Many of the lakes in such as Florida are flooded sinkholes that are fed by .

 have water temperatures higher than the human body and are common in the western United States where the subsurface is still hot from recent

 are that erupt at regular intervals

, located in YellowstoneNational Park in Wyoming is a famous geyser



Wells

Many homes in Norfolk use well water for lawns, utility, and even drinking water

Well is a hole dug or drilled into the ground to reach a of groundwater

Simple wells are dug below the water table into the

 is a lowering of the water table around the head of a well

is the difference between the original water table level and the level in the pumped well

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is when precipitation and runoff is added back to the zone of saturation

If recharge does not keep pace with drawdown the wells in an area will go

Confined Aquifers

Water table aquifers are unprotected and . Confined aquifers are sandwiched between aquicludes that form barriers that prevent pollutants from reaching the ground water

 contain water between two aquicludes

The is caused by the recharge areas being at a higher elevation

Water Quality

 Earth’s most precious . Because of its natural filtering and availability groundwater is the main source of this vital need.

Many geologic processes such as erosion can have harmful effects on our freshwater supplies

is the sinking of land elevation when too much groundwater is removed

In coastal areas such as Norfolk the freshwater supplies and makes well water undrinkable

It is also believed that a near the mouth of the Chesapeake Bay 35 million years ago contaminated the aquifer by in the seawater into the parent bedrock

Industrial and harmful chemical wastes from improperly constructed or maintained dumpsites (or ) can contaminate groundwater for many miles around the source

 in solution by the fine-grained sediments

It is important to realize that protecting our water supply is of vital importance.

It is our responsibility to be aware of how human activities affect our resources and act (and vote) accordingly!