I am planning to do 2D resistivity surveys to demarcate paleochannel network.
You need to contact some earth scientists working in sedimentary geology.
My advice would be to make sure your 2D profiles are long enough to capture the edges and banks of the paleochannels. Next, think about the type of sediments comprising the paleochannels. For example, in slower moving waters, you would expect finer grained sediments, which have a tendency to hold water more easily, which in turn would be of lower resistivity. Lastly, make sure to collect many lines that would provide enough context for characterizing the subsurface. That is where we have been the most successful.
Besides Dale's tips I you advice to adopt a multiscale approach carrying out several profiles sampling, along the same line, with different electrode spacings. Without a priori information the best practice is to perform the acquisition along a grid of lines. This approach could guarantee the reconstruction of more resolved electrical stratigraphies and to resolve thin layers which could characterize the paleochannel. The long scale acquisitions would allow the preliminar location of paleochannel area (better the corresponding anomaly area where it could be placed) and short scale its characterization.
You can try to use resistivity and IP together. IP will guide you to differentiate between clay or other material base on the chargeability value.
Dear Imran,
You have received some good advice already. Dales tips are valuable if only resistivity measurements can be made. Also, understanding the expected electrical signature of the paleochannels is a very important first step. The suggestion for a multi-scale approach is also very important. In fact, I would recommend you to either consider aerial photography/remote sensing or electromagnetic induction (EMI) measurements in order to find the most suitable locations to study the paleochannels in more detail using ERT. This could provide you with the necessary spatial context for the otherwise spatially sparse ERT transects.
Best Regards,
Sander
We had good success with GPR. There are several papers and posters in my or Jamie Pringle's researchgate listings.
I agree with Robin. GPR use can give good results for this.
You please talk to Prof. Rajiv Sinha , Department of Earth Sciences of your IIT, Kanpur.
Dear imran,
you recived very important comments, i need to add u must read the geological history of the area under project , so u can make an idea about its trends, widths, depths, and sediments in/out . Then u can make a suitable array to catch them. The best array design which keep the relation between objects dismmeter and depth and electrod spacing, finally you make the trend of 2D array crossing the trend of channel.
I hope you successful work
Dear imran,
you recived very important comments, i need to add u must read the geological history of the area under project , so u can make an idea about its trends, widths, depths, and sediments in/out . Then u can make a suitable array to catch them. The best array design which keep the relation between objects dismmeter and depth and electrod spacing, finally you make the trend of 2D array crossing the trend of channel.
I hope you successful work
Hi Imran,
Dale and Roberto gave you good tips. You can also had to your survey a different method, like seismic reflection or, not so good for the final result, seismic refraction.
Dear Imran,
We are using GPR technique to identify ancient paths on semi-arid river floodplains. It gives excellent results if the processes and the characteristics of sediments allows an armour layer to develop.
Irman, can you give an update to imaging your paleochannel network? Was ERT, EMI, or GPR the most successful?
If it very shallow the tool is GPR
If it is deeper the tool is ERT
If it deepest the tool is Microgravity
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