Groundwater and Its Movement

Study Notes

Groundwater is water found underground in the cracks and spaces in soil, sand and rock.
A region completely filled with water is called the zone of saturation.
The upper boundary of the zone of saturation is the water table.
The depth of the water table varies based on precipitation and other weather conditions.
Above the water table is the zone of aeration, where materials are moist but not saturated with water.
Water moves through the ground due to permeability, the ability of a material to let water pass through.
An aquifer is a permeable layer of subsurface material that's saturated with water.
Impermeable layers are called aquicludes; they block groundwater flow.

Springs are areas where groundwater emerges naturally from the ground.
Springs can form at the edges of valleys, perched water tables, along fault lines, and underground pathways.
Hot springs emerge from sources that are hotter than the average annual temperature.
Geysers are eruptive hot springs that occur when water is superheated and vaporizes, building up pressure and resulting in eruptions.

Wells are holes dug or drilled into the ground to reach an aquifer.
Water-table wells are the simplest type, and the water level in the well matches the water table level.
Artesian wells tap into pressurized water in a confined aquifer.

Pollution can enter groundwater through runoff, infiltration, or direct contamination.
Sometimes polluted groundwater must be pumped out for treatment.
Humans should be aware of how their actions impact the groundwater system.

Groundwater is slightly acidic due to carbonic acid.
This acidity can dissolve limestone over time.
Caves are underground openings formed by dissolving rock by the action of groundwater.
Sinkholes form when caves collapse.