Aquifers and Groundwater

Groundwater

Where is Groundwater Found?

What is Groundwater?

• Free water that occurs deep below the surface

• Found in the "pore spaces" betweens gains of sediment or sedimentary rock.

• May also accumulate in the fractures of impermeable rock.

• Soluble rock like limestone, may dissolve and water occurs in subterranean caves.

Multiple Choice

Which of these is not a place in which groundwater accumulates?

• Subterranean limestone caves

• pore spaces of sedimentary rock

• hollow spaces between minerals in granite

• Interconnected fractures in rock

How Does Groundwater Accumulate?

• When rain or snow melts it can seep into the subsurface through the unsaturated zone and be trapped in the saturated zone.

• The upper boundary of the saturated zone is known as the water table.

• If the water table intersects the surface it can form a lake, stream, swamp or spring.

Multiple Choice

Groundwater results from the infiltration of rain and snowmelt into the subsurface.

• True

• False

Multiple Choice

The upper limit of groundwater is referred to as the

• unsaturated zone

• saturated zone

• water table

Porosity

• Refers to the the amount of open space within a rock or sediment that can hold water.

• Rounded sediment has greater porosity than angular sediment.

• Sedimentary rocks, like shale and sandstone, tend to have high porosity

• Whereas metamorphic & igneous rocks , like granite and gneiss, tend to have lower porosity.

Permeability

• is a measure of the ability of a material to transmit a fluid.

• Is related to the size and interconnectedness of the pore spaces.

• higher porosity leads to high permeability.

• fractures can also increase permeability.

• Highly compacted clay particles reduce it's permeability.

• conglomerate rock and sandstone are two examples of high-permeability rocks.

Multiple Choice

A measure of how much water a rock can hold

• porosity

• permeability

Multiple Choice

Sediment grain shape influences porosity in that ____ shape has greater porosity.

• rounded

• angular

Multiple Choice

Igneous and metamorphic rocks tend to have high porosity.

• True

• False

Multiple Choice

Which of these settings produces the lowest permeability?

• rocks with many interconnected fractures

• highly compacted clay particles

• loosely cemented gravel and sand

Multiple Select

Check the two rocks that have high permeability and allows water to accumulate in large quantities as groundwater.

• granite

• sandstone

• conglomerate

• shale