Learning with Kevin: Educational Resource Blog
  • Home
  • Contact Us

Artesian Wells

8/13/2013

0 Comments

 
An Aquifer often lies on top of a layer of less permeable rock. This stops or slows the downward flow of groundwater and helps to separate the water in this aquifer from flow in other aquifers that may be underneath it. And unlike water in rivers or streams, groundwater is under hydrostatic pressure that is greater than atmospheric pressure. Thus it can flow upwards, as well as downwards or sideways, just like water in the plumbing system of a house.

This is especially important when an aquifer dips beneath another layer that is much less permeable. As usual, rainwater fills up the aquifer and water flows out from it where it meets the surface. Below the impermeable layer, water is trapped in the aquifer, which is said to be confined. The water presses on the less-permeable confining layers above and below it.

If one drills a borehole into a confined aquifer, water will rise up the borehole until the column of water is enough to balance the pressure in the aquifer. Most major aquifers have a confined portion, where the aquifer is covered by impermeable rock layers and an unconfined portion, where the aquifer covered simply by soil or river or glacial deposits. Rainwater enters the aquifer through the unconfined part.

If many boreholes are drilled into the aquifer and found the level of water in all of them, it could be imagined a surface made by joining all the individual levels. In the unconfined part of the aquifer this surface would be the water table. It separates the saturated part of the aquifer from the unsaturated zone above it. But in the confined part of the aquifer, the spaces between mineral grains, every pore in fact, is filled with water: there is no unsaturated zone. Here the surface is an imaginary one called the pressure surface, or potentiometric surface. It passes through the confining layer somewhere above the aquifer.

If the unconfined part of the aquifer is beneath high ground, and the confined part beneath low ground, then the potentiometric surface may be above ground level. If a borehole is drilled into the aquifer the groundwater will be under sufficient pressure to overflow from the borehole. Such a borehole is called artesian well. But the borehole must go deep enough to reach the aquifer, even if this means drilling far below the potentiometric surface. Otherwise it will yield little or no water from the impermeable confining layer.

In many parts of world, the availability of water form artesian wells makes agriculture possible.
0 Comments

Your comment will be posted after it is approved.


Leave a Reply.

    Author

    Kevin is an enthusiastic writer who writes and shares interesting blogs. So stay tuned to the blog and learn with Kevin.

    Categories

    All
    About Kevin
    Education
    For Parents
    Free Resources
    Learning With Fun
    Mobile Learning
    Online Learning
    Students

    Tweets by @Learningwithkev

    Archives

    December 2021
    November 2019
    August 2019
    July 2019
    June 2019
    February 2019
    December 2018
    June 2018
    March 2018
    November 2017
    October 2017
    September 2017
    January 2017
    November 2016
    August 2016
    April 2016
    March 2016
    December 2015
    November 2015
    October 2015
    September 2015
    August 2015
    July 2015
    June 2015
    May 2015
    April 2015
    March 2015
    February 2015
    January 2015
    November 2014
    October 2014
    September 2014
    August 2014
    July 2014
    June 2014
    May 2014
    April 2014
    March 2014
    February 2014
    January 2014
    December 2013
    November 2013
    October 2013
    September 2013
    August 2013
    July 2013

    RSS Feed

Powered by Create your own unique website with customizable templates.
© Copyright 2011 learning with kevin. All Rights Reserved.