Ground Water and or Fracture Locating using electromagnetics

[DavidMartin]

Hoping to learn what the general consensus is in regard to locating ground water and or fractures using electromagnetics. My back ground is mechanical but was exposed to the fundamentals of electromagnetics in school so I should be able to grasp the concepts. From internet reading I have come across transient electromagnetic sounding and seismoelectrical method. Both utilize a receiver that records the properties of a electromagnetic wave as it propogates through the ground.

http://www.frontiergeo.com/tem_sounding.html

http://www.epa.gov/esd/cmb/Geophysi...omagnetic_Methods/Seismoelectrical_Method.htm

Are there other methods, excluding dousing, and do any of the methods work?

Thanks,
David

 

[aeoliantexan]

I am not familiar with the methods described, but there are several other geophysical methods for mapping the soil and rock strata and discontinuities. These include seismic reflection, seismic refraction, electrical resistivity, ground-penetrating radar, and several others. If you want to map the preferential flow of groundwater, there is a firm called Willowstick that induces an AC current between two deep electrodes and measures the electromagnetic field at numerous points on a surface grid, then reduces and interprets the data with software. I was a skeptic, but the last project I saw did locate higher groundwater flow under a dam, and borings and piezometers confirmed their conclusions. Expert interpretation is needed for all these techniques.

 

[fattdad]

problem with near-surface water is the surface-water interaction rule. For public water supply, you'll likley need to filter. Water from deeper aquifers is less likely to be influence by surface water and more likley to be tap ready.

I think the best way to site a well is to drill the well where you want it to be ultimately located.

f-d

ípapß gordo ainÆt no madre flaca!

 

[DavidMartin]

there are several other geophysical methods for mapping the soil and rock strata and discontinuities. These include seismic reflection, seismic refraction, electrical resistivity, ground-penetrating radar, and several others.

Thank you for the input! I'll check them out.

If you want to map the preferential flow of groundwater, there is a firm called Willowstick that induces an AC current between two deep electrodes and measures the electromagnetic field at numerous points on a surface grid, then reduces and interprets the data with software. I was a skeptic, but the last project I saw did locate higher groundwater flow under a dam, and borings and piezometers confirmed their conclusions. Expert interpretation is needed for all these techniques.

Do you remember how deep the water was? I suspect all the methods mentioned are good tools in locating water but at what depth are they no longer effective? This is a question I would like to answer.

problem with near-surface water is the surface-water interaction rule. For public water supply, you'll likley need to filter. Water from deeper aquifers is less likely to be influence by surface water and more likley to be tap ready.

The wells in my area are between 300-600 ft.

I think the best way to site a well is to drill the well where you want it to be ultimately located.

Could you explain your reason why?