Ground Water Systems

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 karst topographyc. identification of groundwater zones

including the water table, zone of saturation, and zone of aeration;

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

Objective

1. Describe underground water sources (such as aquifers and springs).

2. Explain how geologic processes such as erosion and human activities such as waste disposal can pollute water supplies.

3. Describe point source (e.g. sewers, waste pipes) and non-point source (e.g. sanitary landfills, runoff of pesticides) water pollution.

Enduring Understanding

Weathering, erosion, and deposition are interrelated processes that form a cycle of forces that wear down and build up the Earth’s surface.

Water is continuously passed through the hydrologic cycle.

Fresh water is necessary for survival and most human activities.

Ground Water Systems

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

Ground Water Systems

The average length of time that groundwater remains underground is several hundred years.

Ground Water Systems

Groundwater can return to the surface at places where the water table intersects Earth’s surface

Ground Water Systems

Springs emerge where an aquifer and aquiclude come in contact at the surface

Ground Water Systems

Limestone and sandstone formations, sand and gravel are common aquifers

Ground Water Systems

Clay and shale layers are aquicludes

Ground Water Systems

Many of the lakes in Karst regions such as Florida are flooded sinkholes that are fed by springs

Ground Water Systems

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

Ground Water Systems

Geysers are explosive hot springs that erupt at regular intervals

Ground Water Systems

Old Faithful, located in Yellowstone National Park in Wyoming is a famous geyser

http://www.nps.gov/yell/photosmultimedia/yellowstonelive.htm

Wells

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

Wells

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

Wells

Simple wells are dug below the water table into the zone of saturation

Wells

Cone of depression is a lowering of the water table around the head of a well

Wells

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

Wells

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

Wells

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

Confined Aquifers

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

Confined Aquifers

Artesian wells contain water under pressure between two aquicludes

Confined Aquifers

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

Water Quality

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

Water Quality

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

Water Quality

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

Water Quality

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

Water Quality

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

Water Quality

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

Water Quality

Chemicals in solution cannot be filtered by the fine-grained sediments

Water Quality

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

Water Quality

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