water table

The upper level of this saturated layer of an unconfined aquifer is called the water table or phreatic surface. Below the water table, where in general all pore spaces are saturated with water, is the phreatic zone. Substrate with low porosity that permits limited transmission of groundwater is known as an aquitard.

The upper limit of the saturated zone may be thought of as the water table (it is shown as a dashed line on the diagram below). The zone above the water table, where pore spaces contain both air and water, is known as the unsaturated zone.

Confined aquifers have a layer of impenetrable rock or clay above them, while unconfined aquifers lie below a permeable layer of soil. Many different types of sediments and rocks can form aquifers, including gravel, sandstone, conglomerates, and fractured limestone.

Aquifers must be both permeable and porous and include such rock types as sandstone, conglomerate, fractured limestone and unconsolidated sand and gravel. Fractured volcanic rocks such as columnar basalts also make good aquifers.

San Diego Formation, an aquifer used for public water supply in San Diego County, California and Los Angeles, California. Turlock Basin, underlies the San Joaquin River in the San Joaquin Valley of central California. One of the largest aquifers in the Western United States.

A confined aquifer is an aquifer below the land surface that is saturated with water. A water-table–or unconfined–aquifer is an aquifer whose upper water surface (water table) is at atmospheric pressure, and thus is able to rise and fall.

Ogallala Aquifer

The ground penetrating radar (GPR) system is used for underground water detection. GPR is a promising technology to detect and identify aquifer water or nonmetallic mines. One of the most serious components for the performance of GPR is the antenna system.

Aquifers Overview Unlike surface water, which is mostly found in the northern and eastern parts of the state, aquifers are widely distributed throughout California. Additionally, they are also often found in places where freshwater is most needed, for instance, in the Central Valley and Los Angeles.

An aquifuge is an absolutely impermeable unit that will not transmit any water. An aquiclude is a formation that has very low hydraulic conductivity and hardly transmits water. See also Wikipedia.

The granite is much less permeable than the other materials, and so is an aquitard in this context.

Clay is the most porous sediment but is the least permeable. Clay usually acts as an aquitard, impeding the flow of water. Gravel and sand are both porous and permeable, making them good aquifer materials. Gravel has the highest permeability.

Permeability defines how easily a fluid flows through a porous material. Materials with a high permeability allow easy flow, while materials with a low permeability resist flow.

Earth Science Mid Term Review Vocabulary

Clay

When the distance between particles is getting smaller, the liquid (water) has no place to go and have to go up. That means capillarity increase as particle sizes decreases.