sub basement profiling on rivers

[goldenshamrock]

Good Day, have just joined and read few a few threads prior. I am interested to know of anyone's experiences or knowledge of using sonar, as an example for sub basement profiling of rivers. Basically to determine and pinpoint areas below the perceived river bottom that may have cavities, pockets, less dense material, faults and cracks. Primary interest is to more accurately identify these spots for potential catchment points for diamonds and possibly gold. River depths 5 to 20 feet. Sub basement depths wishing to explore up to another 20 feet below as initial assessment. All comments welcome.

Goldenshamrock

[Altra]

Hello Goldenshamrock,

I forgot to mention something in my other post. What I think you want is known as "Sub bottom profiling" not basement. Google it.
Not cheap here is an example
http://www.edgetech.com/subbottom.html

Regards Mark

[goldenshamrock]

Hi Mark,

Thank you. Yes sub bottom has more hits> like the portable version of the edgetech site. Have mailed inquiring as to its suitability for what I want to do and of course the all important price.

Goldenshamrock

[goldenshamrock]

Hi Mark,

Had feedback from edgetech; has all the bells and whistles, but with a price to match and way out of my league and definitely budget - 40K ex works. Have carefully reviewed as per your suggestion sometning along the lines of a good fishfinder. This will, as I see it, allow for a fairly good indication of how the bottom of rivers are and allow us to then prospect those places in first instance. Maybe a SD version with GPS will also come in handy. Note most promote for use on lakes and wonder if will be as effective and accurate on moderate flowing rivers, although their shalowness may offset. Thanks Again

Goldenshamrock

[Alec Collyer]

Sub Bottom profiling

Hi Mark,
The basic rule is, the lower the frequency the keeper you can look. A fishfinder at 50KHz will punch into wet sediment quite well, how far depends on many things such as depth of water you're sat in, and what the sediment is, compacted mud you won't get through, "fluid" sand can work quite well, I've seen ballast mounds from a wreck under 12 feet of waterlogged sand.with the underlying rock strata beneath, The transducer was on a kiddies plastic sledge dragged along the bottom and at 150KHz.
You could use a humminbird 981 or similar, which has GPS and photoshots recording onto an SD card, for replay later (see many earlier posts). Yours, Alec (UK)