Talk:Aquifer

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[edit] Depth of Aquifers

I was hoping to find some estimates or commonish values for how deep some of these huge aquifers are ... or how deep the aquifer by my place in Nowhereville, USA might be. 500 feet? 5000 feet? 5 miles? I can't any answer to this with a google search, either... cheater 04:38, 28 March 2006 (UTC)

[edit] Capillary saturation issue

The capillary fringe can be un-saturated on a water content basis. This is an important distinction for modelling processes which depend on gas exchange/diffusion rates, such as in support of biological remediation. In a compacted fill this is not an important distinction, but in a natural setting with medium to fine textured soils, it can be. The exception would be in highly ordered materials and in coarse material where the capillary fringe would be on the order of a millimeter.

Water rises into the capillary fringe due to surface tension but it normally cannot achieve 100% occupancy in the void space in the medium available to it. Due to variaton in pore size, saturation (on a water content basis) is not typically achieved throughout the observed capillary fringe. Stated another way, when one observes the fringe moistened by capillary action above the level of free water, one is not observing saturated conditions throughout the material on a water content basis. Saturation is only occuring in the smallest pore spaces within the moistened fringe. Significant air content in the void portion is present and increases with distance above the free water depth.

Supporting references:

  • Capillary Fringe: that zone of soil immediately above the water table (see Capillary Fringe) that acts like a sponge sucking water up from the underlying water table and retaining this water somewhat tenaciously. Soil pores act like capillary tubes. The smaller the soil pore, the greater is the rise of water within the soil pore. The pores within a soil matrix are typically composed of numerous pore sizes. At the base of the capillary fringe most if not all of the soil pores are completely filled with water. At the top of the capillary fringe, only the smallest soil pores are filled with water. Therefore, the water content of the capillary fringe decreases with increasing distance above the water table. The size of the diameter of the soil pore defines the capillary rise of the water column. It is possible that soils can be completely saturated with water, yet the water table is some number of feet below this point of complete saturation. The water table is defined by that point in the soil column where water is free to move; therefore, it is not tenaciously bound within the soil pores. The water table is physically determined by the level to which ground water flows into a porous pipe which has a diameter large enough so that capillary forces from this pipe cannot complicate the determination of the top of the water table.
  • In those soils where the vertical thickness of the capillary fringe at least equals the depth to the water table, then the capillary fringe can behave as a wick, wicking the waters originating from the water table to soil surface where it can be evaporated to the atmosphere.

from http://www.earthdrx.org/definitions.html

  • Capillary fringe: A zone in the soil just above the plane of zero gauge pressure that remains saturated or almost saturated with water. The extent can be inferred from the retentivity profile and depends upon the size-distribution of pores.

from http://www.soils.org/sssagloss/search.html

  • capillary fringe—The zone above the water table and below the boundary of saturation where the soil is saturated but at pressures less than atmospheric (i.e., under tension). A new equivalent term gaining acceptance is tension saturated zone.

from http://amsglossary.allenpress.com/glossary/browse?s=c&p=6

Paleorthid 04:02, 12 September 2005 (UTC)

[edit] Too technical

This article needs to be made more accessible. I pulled it up when I wondered, "what is an aquifer?" Having read the article, I'm still not sure. Let's take the first paragraph of the main body:

This diagram indicates typical flow directions in a cross-sectional view of a simple confined/unconfined aquifer system (two aquifers with one aquitard between them, surrounded by aquiclude) which is in contact with a stream (typical in humid regions). The water table and unsaturated zone are also illustrated.

Yikes! Aquitard? Aquiclude? Flow directions? Unsaturated zone? Some (but not all) of these terms are defined later on, but you need to at least give the five-word subclause definition the first time you refer to a technical term.

This article made my head spin, and I'm a technician in training and profession. --TreyHarris 19:57, 28 December 2005 (UTC)

  • 15-Oct-2007: Done (2 years later). I have added prior definitions of aquitard/aquiclude (other terms are linked), and I overlayed "(aquitard)" on the diagram, narrowed to allow more non-technical text to be added, while splitting sentences into simpler phrasing. Those changes follow the comments detailed above. I am removing the {technical}-tag at top, which did not simplify this article during the past 2 years. -Wikid77 08:54, 15 October 2007 (UTC)

[edit] Water Mining

Just wanted to point to the new article Water Mining that allows for a detailed discussion of over-pulling above recharge rates. 75.6.148.210 06:02, 29 September 2006 (UTC)

over pulling??? what kind of terminology is that? --kris 16:41, 29 September 2006 (UTC)