Hydrogeophysics - Science topic

I have some articles in this topic

https://www.researchgate.net/publication/324851262_Application_of_geoelectrical_measurements_for_detecting_the_ground-water_seepage_in_clay_quarry_at_Helwan_southeastern_Cairo_Egypt?_sg=3AjghFTdxwbDiJmCOwI9rITm_KlcnfiLYNdo7gUTcuMFxYwblBBlIt1YV28u_iU16HWICsnTvyCXxJB5_rd0g-yvoySoK9aYnAAYxTbP.7Bg0n5zaXTbyxUtIZI8s8zqDLkkztHgf_y2I60a-gt74cg4URDx0pXj6b5d7iCpS3uR5H4sGH-GKkmayybanuQ

Please, see the attached file

I think that article answer your question

Do not depend on Resistivity tables. There are numerous factors affecting resisitivity as porosity, permeability, size of grains, fabric, packing, sorting, depth, diagenesis......etc. Each area has its specific resistivity.

Pelase check this instrument https://www.campbellsci.com/tdr100 and this article:

Thank you for your answer, Guopeng. Hence, our experience is different and it would be interesting to explain way. I think that, apart of soil humidity, it is important to consider soil deeper layers, at least up to 100cm, or the presence of rock in case of shallower soils.

You need a focussing module in ENVI SArscape which will cost you. Better use Sentinel (open source).

To All who provided answers and insight to my question above: thank you. Your suggestions are entirely sensible and valid, and clearly come from good knowledge of relevant disciplines, and from experience. I apologise for my delay in replying. Our concern at the time was the seemingly random recommendations and 'geophysical survey' results we had received. But then we discovered a company who had previously drilled several boreholes in the area without success. Even though I suspect they did not use any advanced techniques to identify the locations, this did not bode well for our project, which had enough for a single drilling effort only. But the village in question does have access to a surface waterhole in a shallow ground depression, so I think this was the most obvious way to address their water security needs - even though it needs treatment. Many thanks again - I just thought I would give you feedback on how it turned out. Kind regards.

Hi Yue,

Perhaps a spatial TDR or a frequency dependent dielectric approach might help. We have used the dielectric methods to determine the state variables (moisture content, porosity etc.) of soils along side concentration of suspended solids in aq. solutions in the recent past. You have rightly pointed that pore fluid salinity impacts the TDR traces, but this can be taken care of either by modifying the sensor or by applying an semi-empirical approach.

Prof. Alexander Scheuermann at UQ would be the one nearby to have an expert opinion.

Kind regards,

Partha

Thanks, Tomas and Anthony, for the answers. I found that Karstified carbonates are excellent heat trapps when covered (sealed) by loose sediments with lower thermal conductivty. This is enhanced if the sedimentary cover is a coal which has the lowerest thermal conductivity.  

Hi Kehinde

Hope the following link and papers will be helpful for you.

Dear Andrea,

Different forms of Henry's law are discussed in the technical literature. 

The table depicted in the following link lists some of Henry's law and constant. The table reveals that a certain change in the solvent (water) has a significant effect on Henry's constant as expected when the values of TDS and TOC are relatively high in water. 

It should also be noted the Henry's law is a limiting law that only applies for dilute solutions. The range of concentrations in which it applies becomes narrower the more the system diverges from ideal behavior. Roughly speaking, that is the more chemically different the solute is from the solvent.

It also only applies for solutions where the solvent does not react chemically with the gas being dissolved. A common example of a gas that does react with the solvent is carbon dioxide (CO2), which rapidly forms hydrated carbon dioxide and then carbonic acid (H2CO3) with water.

Hoping this will contribute to the discussion on this topic,

Rafik

Hi Jarrett! Thanks for sharing the story. I would rather call it an act of bravery we won't venture in now :-D

Dear David, actually i thought about that possibility initially. But if you have a look at Hansen's link (and Jarett's story)...you might think otherwise. Perhaps (wind driven) shore-ward thrusting of broken fragments of ice cover appears best to explain these ice blocks. Enechelon blocks, mostly dip towards the lake. Any thermally induced (faults etc) event won't perhaps produce such polarity in the arrangement of these ice blocks.

Your question is difficult to answer because it lacks detail. Over what period was the change in water quality observed?  How many samples did you collect to observe the change in ratio.  How deep is the well and what is the length of the screened interval?

The most common hydrochemical facies for confined aquifers are composed of Na-Cl and Na-HCO3 water types. Semiconfined aquifers will tend to have Na-SO4 and Ca-Mg-SO4 water  types.   Layered aquifers bounded by effective confining layers will have differing composition because naturally occurring vertical mixing is restricted.  In such situations, a  well with an long screened interval or open hole interval will allow aquifer fluids to become mixed in the well bore environment. The mixing ratio among samples collected can change for any number of reasons that typically are related to environmental conditions such as poor grout bonding, pump use, or biofouling.  If an increase in EC is positively correlated to an increase in Na/Cl ratio, it usually means that fluids in the well are derived from more than one aquifer source and that the mixing ratio in the water will be susceptible to change.  A piper diagram will help you identify the end-member compositions of the mixtures, when sample data points fall on a linear trend. 

As with all geophysical questions, it all depends.  Questions like how deep are you imaging, what equipment are you using, are you doing 1D VES or 2D profiles, will influence the answer on array type.

Typically, I stay away from the dipole-dipole array.  Granted, it does have a high resolution, but it generally is noisier.   If you are imaging down to +1000m, you are pretty much forced to use it based on logistics.

For most of our work, we like Schlumberger array for shallow targets and Wenner array for deeper targets.  I used to do exclusively pole-pole based on depth of investigation and low noise, but the resolution at the the bottom of the profile is much lower and the Wenner array has just as good noise characteristics.

There has been a lot of work on developing 'optimized' arrays that maximizes the model resolution of the subsurface.  Check out the latest works by Loke and Paul Wilkinson - fascinating stuff.  But, to get command files developed for multi-channel acquisition systems, such as the SuperSting R8, can be a challenge.

The best method is using 2D or 3D resistivity imaging ,and study the changes in resistivity values in vertical and horizontal directions.

From my point of view the different is that a pore pressure transducer can measure positive and negative pore water pressure, that means saturated (e.g. Groundwater) and unsaturated conditions (e.g. drying porous media). Tensiometers are mainly developed to measure the soil suction, tension, matrix potential...  only at unsaturated conditions.

When reaction is intensive and considerable absorption or dissolution take place within the time frame of the studied problem, it's require to take into account geometrical properties change e.g. change in reactive surface area, change in permeability and porosity, by solving coupled solid mass conservation equation in addition to the ADRE and fluid conservation equation.

I agree with colleague Rainer Blum  that using global geoid undulation as a complementary information for groundwater geophysical exploration is very limited to reconnaissance studies on a very large scale. This is not useful as normally, groundwater exploration or contamination studies is done on a very local scale basis. In addition to that,  popular geoelectrical methods (VES, HRP, 2D and 3D earth resistivity imaging, .......etc) are better methods for groundwater problems.

Yes, specially in the triggering of mass movements (falls, slides or mixed movements).

At the TU Bergakademie Freiberg in Germany a Scientific Diving Center is doing Excursions to the mediterranean sea. Gas sampling under water (up to 40m) at geothermal active regions close to the island Panare (Italy ) is one of their work.

They developed a device to measure the gas volume and the temperature of fumaroles. They also analyse the gas composition.

You can contact them under: http://tu-freiberg.de/sdc/team ( merkel@geo.tu-freiberg.de or Gerald.Barth@sdc.tu-freiberg.de )

We used UAS with thermal cameras for rhinoceros location (http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0083873).

Hope it helps, good luck

Dear Sachin, groundwater moved in 3D where other components as relative water density of different groundwater flows and artificial inlfuence (as extraction) need to be incorporated, Please, visit the page below where important references and other related information are available, suludos,jjoel carrillor  

Dear Christian,

You provide too little information for informed comment, so I make only one: ammonium ion in groundwater comes from the anoxic degradation of organic matter.

Concentrations up to 8 mg/L NH4+ are common in shallow groundwater (< 50 mbgl) of the Bengal Basin (see first attached). Boron, if that is what you mean by 'Bor' can derive from deep brines, salt-water intrusion (unlikely in your geological setting?), deep continental salts, or from ion-exchange (see second attached).

Sorry the URL above has a character appended that makes it not work. Try this one

You can check this

Dear Abebe,

please find the source of an interesting thesis by Hedi Feibel on MHP in Ethiopia including estimation of mph potential:

in wet season with higher rainfall and discharge, there is a greater chance for alkali and alkali earth elements to be washed and transported in aqueous solutions. In fact the main reason is the ionic potential of these elements which makes them to form dissolved hydroxides soluble in water. You may refer to Introduction to geochemistry by Krauskopf and Bird (1995) or other textbooks on geochemistry for further information.

The question is interesting and as said Ludovit due to the complexity of the question we could conclude that is without answer. This question has many similarity with another that I have found in Q&A regarding the seismic "When are seismic boundaries the same as geologic boundaries?" You can read my answer to that to have my general idea to attempt an answer.

In your question you use the term "calibrating" that could have a different meaning in terms of geophysical interpretation and of geological interpretation.

For me the "calibration" not is the "the geological interpretation", as well as the two interpretative levels, geophysical and geological, are complementar but should be not confused.

Electrical resistivity method gives a resistivity-stratigraphy (resistivity model) that is the result of a geophysical acquisition , processing, and model reconstruction procedures. In general the resolution and errors of the reconstructed resitivity stratigraphy, should be taken in to account when we pass to geological interpretation.

In general these procedures applied to the "real resistivity stratigraphy" constitute a smoothing, or generate an averaged stratigraphy which is dependent also by the local etherogeneity and layer morphology of the "real layers" (see the complexity claims in the Ludovit answer). In other words the geophysical resitivity stratigraphy is a local averaged model of the real resistivity stratigraphy. It depends of our experimetal procedure (spacing, measurement errors, software inversion etc.)

The geo-stratigraphy obtained from boreholes data generally have a resolution and error different with respect geophysical resitivity stratigraphy, generally higher resolutions and lesser errors in the layer definition (reconstruction). For this reason, the geophysical model, several time, does not fit the borehole data but generally constitutes a raw but useful interpolation of the geologic data.

So if we have only the geologic stratigraphy, the "calibration" of geophysical stratigraphy, in strict sense, is not possible but we can attempt an interpretation of geophysical results in geologic sense.

In my opinion a method (unfortunately to expensive) to calibrate the resitivity stratigraphy or the resitivity model is to acquire resistivity logs during the core drilling, or alternately to perform laboratory resistivity measurements on the drilled cores.

If are available these data, you can compare the borehole data with geologic stratigraphy and you can extract several degree of correlations, and averages, in order to construct an interpretative model, in terms of the resistivity layer boundary and of the facies resistivity, that we can use to construct a conceptual model for the interpretation of the indirect surface results, resitivity stratigraphy obtained with VES, ERT tomography procedures. This could be a standard of calibration but I said before is expensive. For oil research this is a standard. The "while drilling" technology have reached a high degree of development for this reason: to calibrate and to interpretate the results of seismic and other geophysical surveys. Neverthless this is not exaustive for a complete calibration but is surely better in terms of the mining risk reduction.

Unfortunately, now, the funding for water resource research and water protection are not comparable with the oil exploration, but probably when the water resource will become “the transparent gold” like “the black gold” for oil this will be the standard.

I think any text book in groundwater can help you in this issue. See the following link to the book,

This is just example, however, there are lots of books that can help and available for free on the net.

Kind regards,

Amro

Take a look at Applied hydrogeology in page that explains some kinds o springs. it is possible to have hot springs without a heat source. groundwater can be heated by geothemal grade and, depending on geological structures, it may flow up without losing the heat acquired.

Please, here is the new meeting for 2013:

Dear Colleagues,

We hope to see you at the NMR session at SAGEEP in Denver next spring. Please note that the deadline for abstracts has been extended until December 14 (nine days away). We are on track to have this be one of the biggest sessions at the meeting again, and are looking forward to receiving contributions from those of you who have not yet submitted. Keep in mind, the are only short abstracts; extended abstracts are optional.

Best Regards,

Elliot Grunewald

and Kristina Keating