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How can we still lack groundwater?
That 71% of the Earth's surface is covered by oceans is completely irrelevant to the issue of fresh groundwater depletion. Salty groundwater is useless for drinking or irrigating crops.
The issue at hand is the depletion of those underground reserves of fresh water. This depletion can result from natural or human causes. ...
18
Relatively important, depending on the basic principles of the modeling you are interested in, and to what extent you want to get yourself involved in it.
In many areas of computational geophysics, e.g. atmospheric, oceanic, hydrological modeling etc., there are modelers, modelers, and modelers. First group of modelers get model output from somebody else, ...
16
This is a really complex problem and would require a really detailed explanation about atmospheric circulation, meteorology and hydrology.
The short answer to your question is that water is going somewhere else. If you look at the studies about moisture recycling, among the others van der Ent et al 2014 or 2010, you can see that the precipitation that ...
14
A "true subterranean ocean" would suggest a vast amount of liquid water in the mantle. This is most probably not present, for which there are a number of clues.
First of all, when looking at the temperature (~2000K) and pressure (~20GPa) in the transition zone and look at a phase diagram for water it is clear water can't exist as a liquid even ...
14
In my opinion, there is no such thing as water veins as described in this article, but, it is a fact that there is water circulation underground.
In the natural environment, water can either circulate in porous mediums (like within the small spaces between sand grains in sandy soils) or as underground streams. There is also the concept of the water table ...
14
You're making a mistake, at least for the second case:
In the second case, the water ends up as rain, presumably within a few hundred kilometers of the evaporation point.
You cannot model a dry region (or indeed any region on earth) as a closed system for hydrological purposes. When water evaporates in a dry climate, it transports much farther than a ...
13
Is it possible that the recent droughts are signs of epic crust failure?
No. Even though your 5 points do not make much sense, I'll try to answer it anyway.
There are no continental plates. There are lithospheric plates, consisting of both continental crust and oceanic crust. While it is true that arches in construction (buildings and bridges) are held "up"...
11
This is a large glacier calving event. Calving occur at the front of the glacier, probably a very wet (and likely warm based) glacier where a considerable amount of water is flowing out of the system (thus from the glacier to the sea). The amount of water is important as it can accelerate the ice flow speed on the valley floor, enabling the breaking of big ...
10
Water in liquid state always takes the fastest route to lower altitude. All rainwater would flow vertically down to the groundwater surface if not the permeability was limited by the material properties.
The permeability controls how fast water infiltrate and penetrate the material. For example, can surface runoff water flow on top of a hard road coating, ...
10
We pump it out. Open and closed pit mines usually have pumping installations to get the water out.
Look up Mine dewatering on Wikipedia.
There have also been numerous accidents in the past where mines were flooded (YouTube: Turkey mining accident: 18 workers trapped after underground water floods mine), and when left alone many abandoned mines will fill up ...
9
To answer this question, I'll back up a bit and first talk about what happens to rain as it flow to streams then about what happens when streams dry up.
When it rains, some of the rain hits the ground or trees/plants and is evaporated before it flows away from where it hits and before it sinks into the soil very far. Some enters the soil but is taken up by ...
8
Well B is a normal water table well, which will have a relatively steep, tight, local, and deep 'cone of depression'. Well A doesn't have a 'cone of depression' - it has a 'cone of depressurization', which has an entirely different physical configuration. That is, wide and shallow. So the drawdown in well B will fall rapidly, whilst there isn't really a ...
7
Terminology
The term "average" isn't a specific term. Are you talking daily average or annual average? The question "What is the average?" begs the question of "Across what timeframe?"
To explain that point, let's look at a chart:
This is the groundwater level of a well in Georgia (US). The "Average" for this well in December 2003 would be 176.9 ...
7
As far as I know, there’s no one definitive pedo-transfer function (PTF) but there have been several studies that train functions against multi-site databases, rather than just deriving site-specific functions. These PTFs typically define soil moisture-conductivity-suction relationships based on silt, sand and clay fractions from which you can read off ...
7
Groundwater consists mostly of water, obviously.
Usually, "minerals" in water (for example in bottled water) are actually not minerals but rather dissolved ions. Strictly speaking, minerals are solids. Fluoride, then, is also a "mineral", and actually a dissolved ion.
Groundwater usually begin their life as precipitation: rain, melting snow, etc. These are ...
7
Groundwater is stored in the porosity of rocks, that is space between clasts or cracks. Larger cavities, e.g. karsts, is usually only a minor contribution to ground water reservoirs and are only common in limestone.
The Great Artesian Basin aquifer is made up of Mesozoic sandstone. It is covered by impermeable rocks that allow pressure to build up within ...
7
The age of groundwater can vary over a large span. The moment a drop of rain enters the ground it becomes groundwater and when it reaches the groundwater table, the water starts to flow towards a lower hydrostatic level, usually towards the sea, a river or a lake. If you have a well, you'll pump up water to lower the hydrostatic level near the well, so that ...
7
GPS units require a clear view of the sky to fix their position. Because unlike radio signals used for communications, once the GPS signal have bounced in a wall becomes useless for computing the receiver's position. Therefore, the GPS would loss fix shortly after entering the pothole.
The studies made in the area that determined the point at which the ...
6
As your question involves environmental law, the correct answer to this question will be based on whichever country or agency would be in charge of providing a permit; as you already noted, commercial considerations will probably end up with doing the minimum requirement. Delving into local law or contacting the appropriate agency will probably provide you ...
6
According to this pdf: Physikalische Grundlagen der Klimaarchive Eis und Grundwasser (mostly German - some English) all methods to determine the age of groundwater bodies older than ~60 years are radiometric:
39Ar: 30 yr - 2000 yr
14C: 1,000 yr - 30,000 yr
36Cl: 100,000 yr - 1,000,000 yr
81Kr: 100,000 yr - 1,000,000 yr
40Ar: 100,000 yr - >10,000,000 yr
4He: ...
6
Like many things in Earth Science, the answer is, "It depends."
In this case it depends on the composition of the soil and the contaminant you are talking about. Climate, particularly the amount of precipitation, can also have an effect.
Septic systems are primarily designed to promote aerobic conditions and aerobic bacteria to degrade organic compounds ...
6
The red line or piezometric line is the level to which the water wants to rise - if it were allowed to reach hydrostatic equilibrium. Artesian conditions are anywhere where a confined aquifer sits below the hydraulic head level (the level to which the water wants to rise).
In this case the water is confined and cannot reach the water table even though it ...
5
Klanomath is technically correct regarding natural radionuclides, although in practical terms it is only radiocarbon and 36-Cl that are used to date water. Tritium, from atom bomb tests in the 1950s and 1960s used to be used, but the concentration has now decayed to levels indistinguishable from background. In some parts of the world other radionuclides such ...
5
as for constituents in groundwater this pub may help, or at least point to additional information.
as for is it safe to drink - according to [estimated water use] http://water.usgs.gov/edu/wups.html, approximately 34% of all public supply water comes from the ground.
5
The other thing to be mindful about is near surface water or moisture in soil resulting from a high water table, poor soil drainage or a leaking water pipe. Such moisture can lead to rising damp in buildings. This can bring with it salts from the ground that get left stone, bricks and mortar which can lead to deterioration of the structure of the building.
...
5
Groundwater ages vary enormously across the globe and with depth: from hours in parts of Florida and areas with Karstic geology, to tens of thousands of years in the American breadbasket, all the way to several billion years as was recently discovered in Canada. Remember that some of this groudwater may be perfectly drinkable, while by far, most of it will ...
5
An Inverted or Perched water table is a water table that is above the main or regional water table in an unconfined aquifer. The perched water table is generally above a layer of low permeability material such as clay. In the image below, notice that there is an "inverted" water table along bottom of the perched water table.
4
It is definitely possible to completely drain an aquifer. However, as the potentiometric surface (water level) in the aquifer drops, extraction of water becomes less economical, but the perceived value of the water increases. It is possible to apply "unconventional" drilling techniques like directional drilling and fracking to extract groundwater. You could ...
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