Groundwater

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Groundwater Noun

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[ground-waw-ter]

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Groundwater

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Freshwater found below Earth's surface that occupies the cracks and spaces in soil, sand, and rock formations.

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Example: This diagram shows a cross-section of the earth where groundwater is stored in underground layers of rock and soil called aquifers.

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Infiltration Noun

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[in-fil-trey-shuhn]

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Infiltration

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The process by which water on the ground surface seeps down and enters the soil and underlying rock layers.

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Example: Rain (precipitation) soaks into the ground, a process called infiltration. More water infiltrates porous soil than non-porous soil, eventually reaching the water table.

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Porosity Noun

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[paw-ros-i-tee]

Back

Porosity

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A measure of the empty spaces, or pores, within a material, which determines its capacity to hold water.

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Example: This diagram shows that porosity is the empty space, or pores, found between individual rock grains, which is where groundwater can be stored.

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Permeable Adjective

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[pur-mee-uh-buhl]

Back

Permeable

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A quality of a material, such as rock or soil, that allows fluids like water to pass through it.

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Example: This diagram shows how permeable pavement allows water to pass through its layers (pavers, gravel, stone) to reach the soil, demonstrating a permeable surface.

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Impermeable Adjective

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[im-pur-mee-uh-buhl]

Back

Impermeable

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A quality of a material that prevents the passage of fluids, such as water, through its structure.

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Example: This diagram shows how a layer of impermeable clay stops water from passing through, trapping it underground in a confined aquifer.

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Unsaturated Layer Noun

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[uhn-sach-uh-rey-tid ley-er]

Back

Unsaturated Layer

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The portion of subsurface above the water table where pores in soil and rock are not completely filled with water.

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Example: This diagram shows the ground layer above the water table, called the unsaturated layer, where spaces between soil particles hold both air and water.

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Saturated Layer Noun

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[sach-uh-rey-tid ley-er]

Back

Saturated Layer

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The subsurface area of permeable rock or soil where all pores and fractures are completely filled with groundwater.

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Example: This diagram shows a cross-section of the ground where the lower layer of porous rock is completely filled, or saturated, with groundwater.

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Water Table Noun

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[waw-ter tey-buhl]

Back

Water Table

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The upper surface of the saturated layer of groundwater, below which the ground is completely saturated with water.

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Example: This diagram shows a cross-section of the ground, where the 'Water Table' is the upper boundary of the area completely saturated with groundwater (the aquifer).

Front

Aquifer Noun

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[ak-wi-fer]

Back

Aquifer

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A body of porous and permeable rock or sediment that is saturated with groundwater and can transmit it.

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Example: This diagram shows an aquifer is an underground layer of rock or sediment that holds groundwater, located beneath the water table and above impermeable rock.

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Capillary Action Noun

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[kap-uh-ler-ee ak-shuhn]

Back

Capillary Action

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The movement of water within the narrow spaces of a porous material, often acting against the force of gravity.

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Example: This diagram shows how water climbs up a narrow tube (capillary attraction), similar to how groundwater moves up through small spaces in soil.