Ground Water

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 topography

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

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

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

4. Locate the region of karst topography in Virginia as the Valley & Ridge Province where limestone/dolomite is common.

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

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

The Hydrosphere

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

The Hydrosphere

97% of the hydrosphere in contained in the oceans

The Hydrosphere

The 3% contained by landmasses is mostly fresh water

The Hydrosphere

2.15% of that fresh water is locked in ice caps and glaciers

The Hydrosphere

Most of the remaining fresh water is stored underground

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.

Groundwater Movement and

Storage

Infiltration is the process by which precipitation enters the ground and becomes groundwater

Groundwater Movement and

Storage

Porosity is the percentage of pore space in a material

Groundwater Movement and

Storage

Well-sorted sand has a porosity of about 30%

Groundwater Movement and

Storage

Permeability is the ability of a material to let water pass through it and depends on how well connected the pores are

Groundwater Movement and

Storage

Sandstone, limestone and well-fractured bedrock is very permeable

Groundwater Movement and

Storage

Silt, clay and shale are impermeable

http://techalive.mtu.edu/meec/module06/Permeability.htm

Groundwater Movement and

Storage

Zone of Saturation is the depth at which groundwater completely fillsall the pores of a material

Groundwater Movement and

Storage

Water Table is the upper boundary of the zone of saturation

Groundwater Movement and

Storage

Aquifer is a permeable layerthrough which groundwater flows

Groundwater Movement and

Storage

Aquiclude is an impermeable barrier to groundwater flow

Groundwater Erosion

Most groundwater contains carbonic acid that forms when carbon dioxide dissolves in water and combines in water molecules. The slightly acidic groundwaterattacks certain rocks

Groundwater Erosion

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

Groundwater Erosion

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

Groundwater Erosion

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

Groundwater Erosion

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

Groundwater Erosion

Dripstone columns are formed when stalactites and stalagmites grow together

Karst Topography Limestone regions

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

Karst Topography

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

Click on link

Karst Topography

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

Karst Topography

Sinkholes are common in Florida, and Texas

Karst Topography

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

Ground Water Systems