A karst spring in Alabama flows over rocks from a wooded limestone slope.

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Preparing the 3D view

Preparing lighting and the first complete frame…

Model scale

Vertical ×20. well, grains and pore symbols enlarged. steady radial flow.

Q = 0 m³/day · boundary head 31.0 m · well head 31.00 m · drawdown 0.00 m.

How to read these results

Unconfined: blue marks the top of saturated pores. K = 10 m/day, fixed head at 500 m, well radius 0.2 m. Steady Thiem / Dupuit approximation. Set pumping above zero to follow inward flow tracers.

Groundwater

Locate water in connected pores and explain how pumping changes the water table and flow towards a well.

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Why it happens

Groundwater fills connected pores and fractures below the water table. Pumping lowers hydraulic head near a well, creating a gradient that draws water towards it.

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Groundwater emerges at a karst spring in Alabama. Water stored in connected pores and fractures can return to the surface as spring flow.

Try a comparison

Switch to Confined aquifer: the gold surface is pressure head, not a lake.

Reading the result

The steady-flow calculation holds the outer head fixed; it does not determine recharge, long-term depletion or sustainable abstraction.

A common misunderstanding

Groundwater usually occupies a single underground lake.

Most groundwater occupies connected pores and fractures in rock or sediment. In an unconfined aquifer, the water table marks the top of the saturated zone. In a confined aquifer, water in a well may rise above the aquifer because of pressure rather than an underground open lake.

Cases

Exam language

Water table

The upper surface of an unconfined groundwater body, below which connected pores are saturated. Its height changes with recharge and groundwater flow. In a confined aquifer, the level reached in a well represents pressure head rather than a free water table.

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USGS observation well in Stephen C. Foster State Park, Georgia. Instruments record groundwater levels; the water table itself lies beneath the surface.

Aquifer

A body of permeable rock or sediment that stores groundwater and allows useful amounts to flow through it. Water occupies connected pores or fractures; an aquifer is usually not an underground lake. Both storage space and connectivity matter.

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USGS principal aquifers of the United States, 2000. Colours identify aquifer systems; the map does not show water-table depth or whether a particular well is confined.

Aquitard

A layer of rock or sediment with low permeability that slows groundwater flow. It may confine an aquifer without being completely impermeable.

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London Clay forms the lower part of the Naze cliffs. Clay-rich beds commonly transmit groundwater slowly and can act as aquitards; the cliff exposes the material, while permeability is established by testing.

Cone of depression

A lowering of the water table or groundwater pressure surface around a pumping well. Water flows towards the well down this hydraulic gradient. The cone is a pattern in water levels, not an empty cone excavated in the rock.

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Groundwater hand pump at Perambalur, India. Abstraction removes water from an aquifer; pumping may lower the water level around a well, which is measured below ground.

Recharge

The addition of water to an aquifer, usually as infiltrated rainfall or surface water percolates downwards. Recharge may take time and vary strongly by season and geology. It is not identical to all rainfall falling on the land above.

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Stream Passage Pot, Ingleborough, North Yorkshire. This entrance belongs to the Gaping Gill karst drainage system, where surface water enters underground passages.

Spring line

A line of springs where groundwater emerges along a geological or topographic boundary, often where permeable rock meets less permeable material. Its position reflects underground flow paths and can help explain the location of settlements.

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Groundwater emerges at a karst spring in Alabama. Water stored in connected pores and fractures can return to the surface as spring flow.

Confined aquifer

A saturated permeable layer bounded above by a low-permeability layer. Water in a well rises to its pressure level, which may or may not reach the ground surface.

Tracer progress0.40Boundary head31.0 mPump0 m³/day