<p><a href="http://www.teamhydrosource.com/about_us/index.asp">Hydrosource Associates</a> (no personal relation) claims to use the following:</p>

<blockquote>
  <p>HSA’s use of geophysical instruments and methods includes seismic, electrical resistivity, ground penetrating radar, electromagnetic, magnetic, gravimetric, self-potential, and magnetotelluric.</p>
</blockquote>

<p>Since you're looking for a list, you could investigate each of those technologies above.</p>

<p>However, the one instrument not mentioned above and the most high recommended method is simply <a href="http://www.kgs.ku.edu/Publications/PIC/pic23.html">using geological maps</a>.</p>

CC BY-SA 3.0
2014-05-07T12:24:50.297Z
Just to give an answer to this question...
Richard
CC BY-SA 3.0
2014-05-07T12:27:09.077Z
Thanks. What's self-potential here?
Deer Hunter
CC BY-SA 3.0
2014-05-07T12:31:24.473Z
@DeerHunter [Spontaneous potential on Wikipedia](http://en.wikipedia.org/wiki/Spontaneous_potential).  Basically checking the difference (electric potential difference) between the ground surface and the bottom of the hole.
Richard
CC BY-SA 3.0
2014-05-07T12:24:33.293Z
2014-05-07T12:24:33.293Z
Richard
<p>I'm not an ideal person to answer this, but that's never stopped me before, so here goes! :)  I've helped several hydrologists with the geophysical side of things at various points, but I'm not in any form or fashion a hydrologist myself.  My father did the government permitting for residential water wells and septic systems where I grew up, though, so I've seen a bit of things from both the academic side and the practical side.</p>

<p>For locating the average residential water supply well, gephysical methods are basically never used.  They're just too expensive compared to drilling the well.  </p>

<hr>

<p>However, for making detailed hydrological models, geophysical methods (particularly ground penetrating radar (GPR)) get used quite a bit.  In fact, there's a whole field called "hydrogeophysics" that deals with imaging in near-subsurface environments.  </p>

<p>These methods don't get applied for locating a single well. They get applied to build detailed 3D models to constrain things like contaminant transport.  </p>

<p>If you need to know how groundwater is flowing in 3D, then you need a more detailed image of the subsurface than you do to locate a single water well.  GPR is the most commonly used method, but I've seen almost every sort of geophysical data used in some cases (basically where it's already been collected and is freely available).</p>

<p>Basically, the bigger the budget, the more fancy tools can get thrown at the problem. :)  </p>

CC BY-SA 3.0
2014-05-07T14:01:03.623Z
2014-05-07T14:01:03.623Z
Joe Kington
<p>From what @Richard and @JoeKington said in their answers,
it seems that the usual way of finding water is through a
<a href="http://www.britannica.com/EBchecked/topic/278885/hydrological-map">hydrological map</a>.</p>

<p>However, for the sake of completeness, I'll include here a bit about
what geophysical methods <strong>could</strong> be used to find water.
I'll not comment on the practical issue of cost-benefit as that was nicely explained by @JoeKington in his answer.</p>

<p>That said,
any geophysical method is only able to detect a <strong>contrast</strong> of a physical
property.
For example, seismic methods are sensitive to variations in seismic wave
velocity, electric and electromagnetic methods are sensitive to
resistivity/conductivity, gravimetry is sensitive to density variations, etc.
So for any geophysical method to detect water, there has to be a contrast in
the physical property between the water level and the surrounding rocks/soil.</p>

<p>Knowing this we can already rule out
<a href="http://en.wikipedia.org/wiki/Gravimetry">gravimetry</a> and
<a href="http://en.wikipedia.org/wiki/Magnetic_survey_%28archaeology%29">magnetometry</a>
because there
is no significant density/magnetization contrast when we reach the water level.
These methods can give you an idea of the regional geologic setting, and that
can help you find water. But detecting water directly? Probably not.</p>

<p>The presence of water does have an impact on the electrical conductivity but
that is usually not very large unless the water is salty, which I'm guessing
you wouldn't want to drink.
Methods like
<a href="http://en.wikipedia.org/wiki/Ground-penetrating_radar">GPR</a>
and
<a href="http://www.epa.gov/nerlesd1/cmb/GeophysicsWebsite/pages/reference/methods/Surface_Geophysical_Methods/Electrical_Methods/">electrical resistivity
methods</a>
could map the depth of the water layer, but this effect might be masked depending on the soil type (clay might have very low resistivity and that makes "seeing" what is beneath very difficult).</p>

<p>Seismic wave velocity is usually affected by the presence of water in the
soil.
If all you want is the depth of the water level, then
shallow <a href="http://en.wikipedia.org/wiki/Seismic_refraction">seismic refraction</a> might be a good method for that.
Acquisition is relatively cheap and the data are easy process (usually just simple trigonometry).</p>

<p>Most of these methods will not tell you for sure if the water is there or if it
is drinkable.
However, they can give a bit more insight to complement the hydrological information.</p>

CC BY-SA 3.0
2014-05-07T14:21:03.197Z
2014-05-07T14:21:03.197Z
Leo Uieda
<p>How can one detect (preferably artesian) aquifers nowadays that a lot of sensors are available? Should I use ground-penetrating radars, neutron detectors, or any other advanced devices? Can seismic imaging be used to characterize the extent of the aquifers?</p>

CC BY-SA 3.0
2014-05-06T12:18:06.957Z
Are you looking for a list of possible solutions or the best technology available?  Are you trying to find a way to accomplish this or is this a theoretical question?  If it is a specific region, there may be high quality aquifer maps available.  Or you could try coat hangers.  :P
Richard
CC BY-SA 3.0
2014-05-06T12:20:23.443Z
@Richard - Already used a coat hanger of mine. Did not strike water. Am interested in the state-of-the-art technology.
Deer Hunter
CC BY-SA 3.0
2014-05-06T12:22:28.770Z
Also of interest for Martian water prospecting ;p
Deer Hunter
CC BY-SA 3.0
2014-05-06T12:36:41.327Z
OK, so you're interested in actually drilling a well.  That helps.  It means you're not interested in [possible technologies](http://www.jpl.nasa.gov/news/news.php?release=2011-290) as much as actual results.  (As an aside, [coat hangers are unreliable](http://en.wikipedia.org/wiki/Dowsing#Scientific_appraisal).)  I'm just clarifying the question.  I don't have any good answers, but there are [some companies](http://www.findwellwater.com/) out there that specialize in this sort of thing.
Richard
CC BY-SA 3.0
2014-05-06T15:27:01.900Z
Appears that the question might really be "How accurate & reliable are electro-seismic surveys in modeling of groundwater flow systems?"
blunders
CC BY-SA 3.0
2014-05-06T15:31:32.930Z
@blunders - not really, that's too narrow an interpretation.
Deer Hunter
CC BY-SA 3.0
2014-05-06T15:57:51.783Z
Meaning you don't have a "real life" problem, but are interested in the topic, right?
blunders
CC BY-SA 3.0
2014-05-06T18:50:55.530Z
Finding water is easy. Just go down far enough anywhere.  What you want is a fresh water aquifer with a high enough permeability to support a well.  Geophysical methods aren't terribly relevant for this (or rather, they can be in some cases, but there's no need spend that much). You'd be much better off asking a local hydrologist. Surface mapping is far more useful than geophysical methods for most near-surface aquifers. It's mostly just a matter of knowing which regional aquifers are present and what depths they're at in your exact area. (There are exceptions, of course, though.)
Joe Kington
CC BY-SA 3.0
2014-05-06T22:01:59.117Z
+1 @JoeKington: Great points, though get the feeling that that the OP's "interest for Martian water prospecting" is the real reason behind the question, not drilling a well locally; as such, it's off-topic in my opinion.
blunders
CC BY-SA 3.0
2014-05-07T11:24:17.280Z
@Joe but isn't the depth of the aquifers mapped by geophysical methods (not rhetorical)? If knowing the local depth is all you need (and maybe you have some instruments lying around) a quick geophysical study could help.
Leo Uieda
CC BY-SA 3.0
2014-05-07T12:59:06.317Z
@LeoUieda - Usually not.  Reflection seismic, etc are rarely used for hydrology.  Mapping the depth of the aquifers is done through correlations with other wells in the region and standard surface mapping techniques.  Compared to drilling a shallow water well (low thousands of $), geophysical methods are usually quite expensive.  (A big exception is GPR, but I've only seen it used in hydrology to map very shallow unconfined aquifers. They're typically not what you're targeting for drinking water.)
Joe Kington
<geophysics><hydrology><remote-sensing>
What geophysical instruments should I use to detect water without drilling?
Deer Hunter
# What geophysical instruments should I use to detect water without drilling?

(Asked by: username_0 on 2014-05-06)

How can one detect (preferably artesian) aquifers nowadays that a lot of sensors are available? Should I use ground-penetrating radars, neutron detectors, or any other advanced devices? Can seismic imaging be used to characterize the extent of the aquifers?

**Tags:** geophysics, hydrology, remote-sensing

> **Comments:**
> **username_1**: Are you looking for a list of possible solutions or the best technology available?  Are you trying to find a way to accomplish this or is this a theoretical question?  If it is a specific region, there may be high quality aquifer maps available.  Or you could try coat hangers.  :P  
> **username_0**: @username_1 - Already used a coat hanger of mine. Did not strike water. Am interested in the state-of-the-art technology.  
> **username_0**: Also of interest for Martian water prospecting ;p  
> **username_1**: OK, so you're interested in actually drilling a well.  That helps.  It means you're not interested in [possible technologies](http://www.jpl.nasa.gov/news/news.php?release=2011-290) as much as actual results.  (As an aside, [coat hangers are unreliable](http://en.wikipedia.org/wiki/Dowsing#Scientific_appraisal).)  I'm just clarifying the question.  I don't have any good answers, but there are [some companies](http://www.findwellwater.com/) out there that specialize in this sort of thing.  
> **username_2**: Appears that the question might really be "How accurate & reliable are electro-seismic surveys in modeling of groundwater flow systems?"  
> **username_0**: @username_2 - not really, that's too narrow an interpretation.  
> **username_2**: Meaning you don't have a "real life" problem, but are interested in the topic, right?  
> **username_3**: Finding water is easy. Just go down far enough anywhere.  What you want is a fresh water aquifer with a high enough permeability to support a well.  Geophysical methods aren't terribly relevant for this (or rather, they can be in some cases, but there's no need spend that much). You'd be much better off asking a local hydrologist. Surface mapping is far more useful than geophysical methods for most near-surface aquifers. It's mostly just a matter of knowing which regional aquifers are present and what depths they're at in your exact area. (There are exceptions, of course, though.)  
> **username_2**: +1 @username_3: Great points, though get the feeling that that the OP's "interest for Martian water prospecting" is the real reason behind the question, not drilling a well locally; as such, it's off-topic in my opinion.  
> **username_4**: @Joe but isn't the depth of the aquifers mapped by geophysical methods (not rhetorical)? If knowing the local depth is all you need (and maybe you have some instruments lying around) a quick geophysical study could help.  
> **username_3**: @username_4 - Usually not.  Reflection seismic, etc are rarely used for hydrology.  Mapping the depth of the aquifers is done through correlations with other wells in the region and standard surface mapping techniques.  Compared to drilling a shallow water well (low thousands of $), geophysical methods are usually quite expensive.  (A big exception is GPR, but I've only seen it used in hydrology to map very shallow unconfined aquifers. They're typically not what you're targeting for drinking water.)  

---

## 3 answers

### Answer by username_4 on 2014-05-07. Score: 7 | Accepted answer

From what @username_1 and @username_3 said in their answers,
it seems that the usual way of finding water is through a
[hydrological map](http://www.britannica.com/EBchecked/topic/278885/hydrological-map).

However, for the sake of completeness, I'll include here a bit about
what geophysical methods **could** be used to find water.
I'll not comment on the practical issue of cost-benefit as that was nicely explained by @username_3 in his answer.

That said,
any geophysical method is only able to detect a **contrast** of a physical
property.
For example, seismic methods are sensitive to variations in seismic wave
velocity, electric and electromagnetic methods are sensitive to
resistivity/conductivity, gravimetry is sensitive to density variations, etc.
So for any geophysical method to detect water, there has to be a contrast in
the physical property between the water level and the surrounding rocks/soil.

Knowing this we can already rule out
[gravimetry](http://en.wikipedia.org/wiki/Gravimetry) and
[magnetometry](http://en.wikipedia.org/wiki/Magnetic_survey_%28archaeology%29)
because there
is no significant density/magnetization contrast when we reach the water level.
These methods can give you an idea of the regional geologic setting, and that
can help you find water. But detecting water directly? Probably not.

The presence of water does have an impact on the electrical conductivity but
that is usually not very large unless the water is salty, which I'm guessing
you wouldn't want to drink.
Methods like
[GPR](http://en.wikipedia.org/wiki/Ground-penetrating_radar)
and
[electrical resistivity
methods](http://www.epa.gov/nerlesd1/cmb/GeophysicsWebsite/pages/reference/methods/Surface_Geophysical_Methods/Electrical_Methods/)
could map the depth of the water layer, but this effect might be masked depending on the soil type (clay might have very low resistivity and that makes "seeing" what is beneath very difficult).

Seismic wave velocity is usually affected by the presence of water in the
soil.
If all you want is the depth of the water level, then
shallow [seismic refraction](http://en.wikipedia.org/wiki/Seismic_refraction) might be a good method for that.
Acquisition is relatively cheap and the data are easy process (usually just simple trigonometry).

Most of these methods will not tell you for sure if the water is there or if it
is drinkable.
However, they can give a bit more insight to complement the hydrological information.


---

### Answer by username_1 on 2014-05-07. Score: 6

[Hydrosource Associates](http://www.teamhydrosource.com/about_us/index.asp) (no personal relation) claims to use the following:

> HSA’s use of geophysical instruments and methods includes seismic, electrical resistivity, ground penetrating radar, electromagnetic, magnetic, gravimetric, self-potential, and magnetotelluric.

Since you're looking for a list, you could investigate each of those technologies above.

However, the one instrument not mentioned above and the most high recommended method is simply [using geological maps](http://www.kgs.ku.edu/Publications/PIC/pic23.html).

> **Comments:**
> **username_1**: Just to give an answer to this question...  
> **username_0**: Thanks. What's self-potential here?  
> **username_1**: @username_0 [Spontaneous potential on Wikipedia](http://en.wikipedia.org/wiki/Spontaneous_potential).  Basically checking the difference (electric potential difference) between the ground surface and the bottom of the hole.  

---

### Answer by username_3 on 2014-05-07. Score: 4

I'm not an ideal person to answer this, but that's never stopped me before, so here goes! :) I've helped several hydrologists with the geophysical side of things at various points, but I'm not in any form or fashion a hydrologist myself. My father did the government permitting for residential water wells and septic systems where I grew up, though, so I've seen a bit of things from both the academic side and the practical side.

For locating the average residential water supply well, gephysical methods are basically never used. They're just too expensive compared to drilling the well.

---

However, for making detailed hydrological models, geophysical methods (particularly ground penetrating radar (GPR)) get used quite a bit. In fact, there's a whole field called "hydrogeophysics" that deals with imaging in near-subsurface environments.

These methods don't get applied for locating a single well. They get applied to build detailed 3D models to constrain things like contaminant transport.

If you need to know how groundwater is flowing in 3D, then you need a more detailed image of the subsurface than you do to locate a single water well. GPR is the most commonly used method, but I've seen almost every sort of geophysical data used in some cases (basically where it's already been collected and is freely available).

Basically, the bigger the budget, the more fancy tools can get thrown at the problem. :)


---

