Groundwater, Contamination, and Coastal Processes

Vocabulary terms covering groundwater properties, hydraulic equations, contamination, geological mapping, coastal landforms, and environmental hazards.

Groundwater

Water stored below Earth’s surface in soil, sediment, and rock.

Aquifer

An underground reservoir that stores groundwater, typically composed of high porosity and permeability materials like sand, gravel, or sandstone.

Aquitard

A geological layer that stores some water but does not transmit it well.

Aquiclude

A material that does not store or transmit water.

Porosity

The amount of empty space in a material.

Permeability

A measure of how easily fluid can flow through a material; depends on the pores being connected.

Water table

The top of the saturated zone underground.

Hydraulic gradient

The ratio calculated as $ext{change in elevation} / ext{horizontal distance}$.

Velocity

The rate of movement calculated as $ext{distance} / ext{time}$.

Discharge

The volume of water flow calculated as $ext{area} imes ext{velocity}$.

Hydraulic conductivity

A measure of a material's ability to transmit fluid, calculated as $ext{velocity} / ext{slope}$.

Contamination plume

A spreading zone of pollution that originates from a single source and is most concentrated near that source.

Structure contours

Map lines that show equal elevation or depth underground.

Strike

A line connecting points of equal elevation on a structure contour map.

Dip

The direction water flows downward, which is always perpendicular to the strike.

Karst

A landscape formed by acidic water dissolving limestone, resulting in features like sinkholes, caves, and springs.

Leachate

Contaminated liquid produced from landfill waste that poses a threat to soil and groundwater.

Resistivity

Resistance to electric current; low levels of this property indicate the presence of contamination such as leachate.

Conductivity

The physical property that is the opposite of resistivity.

Depositional processes

Coastal processes that add sediment and build land, forming features like beaches, deltas, barrier islands, and reefs.

Erosional processes

Coastal processes that remove sediment and cause land to shrink, forming features like wave-cut cliffs, wave-cut platforms, and marine terraces.

Emergent coastlines

Coastlines that grow seaward.

Submergent coastlines

Coastlines that retreat landward.

Estuary

A coastal wetland where freshwater and saltwater mix.

Tidal flat

A wetland area covered by water at high tide and exposed at low tide.

Salt marsh

A flooded coastal grassland that helps store sediment and reduce wave energy.

Storm surge

A rise in sea level during storms caused by wind pushing water onshore, becoming most dangerous during high tide.