DEFINITION OF AQUIFER

Definition of aquifer Any body of permeable rock or regolith saturated

with water through which groundwater moves. The term

aquifer is usually reserved for rock or soil bodies that contain

economical quantities of water that are extractable by exist-

ing methods. The quality of an aquifer depends on two main

quantities, porosity and permeability. Porosity is a measure of

the total amount of open void space in the material. Permeability

is a term that refers to the ease at which a fluid can

move through the open pore spaces, and it depends in part

on the size, the shape, and how connected individual pore

spaces are in the material. Gravels and sandstone make good

aquifers, as do fractured rock bodies. Clay is so impermeable

that it makes bad aquifers or even aquicludes, which stop the

movement of water.

There are several main types of aquifers. In uniform, permeable

rock and soil masses, aquifers will form as a uniform

layer below the water table. In these simple situations, wells

fill with water simply because they intersect the water table.

However, the rocks below the surface are not always homogeneous

and uniform, which can result in a complex type of

water table known as a perched water table. This results

from discontinuous impermeable rock or soil bodies in the

subsurface, which create domed pockets of water at elevations

higher than the main water table, resting on top of the

impermeable layer.

When the upper boundary of the groundwater in an

aquifer is the water table, the aquifer is said to be unconfined.

In many regions, a saturated permeable layer, typically sandstone,

is confined between two impermeable beds, creating a

confined aquifer. In these systems, water only enters the system

in a small recharge area, and if this is in the mountains,

then the aquifer may be under considerable pressure. This is

known as an artesian system. Water that escapes the system

from the fracture or well reflects the pressure difference

between the elevation of the source area and the discharge

area (hydraulic gradient), and it rises above the aquifer as an

artesian spring, or artesian well. Some of these wells have

made fountains that have spewed water 200 feet (60 m) high.

See also FRACTURE ZONE AQUIFERS; GROUNDWATER.

Title Post:
Rating: 100% based on 99998 ratings. 99 user reviews.
Author:

Terimakasih sudah berkunjung di blog SELAPUTS, Jika ada kritik dan saran silahkan tinggalkan komentar