Prior to my Iceland fieldwork earlier this year, I put together a simple spreadsheet to input my Vertical Electrical Sounding (VES) resistivity data into whilst in the field. VES for me is a tried and test back to basics geophysical technique. I needed a vertical profile through my fields sites to gain insight into how thick the ground ice is and how thick the sediment cover was above it. Logistically and economically collecting VES data to augment the previous year’s conductivity dataset was a good solution.
The VES system used in this case was the Megger DET4TD2 configured using a wenner array. The acquisition is fairly simple; insert the 4 probes at equal spacings with a constant centre point, click measure, record/write down the resistance, increase the spacing, click measure, record the resistance, “wash, rinse, repeat”.
Traditionally I have always just written the data down in my yellow notebook, and transcribed them when back in the office. The transcribed data is then run through software such as IPI2Win or R-VES for those of you who like to dabble in R.
I made this fairly simple spreadsheet to allow me to visualise the data in the field and ground truth (e.g. collect data over a ground ice exposure). I’ve made the spreadsheet available to download, it works particularly well on a phone or tablet in the field especially if you link excel to cloud storage such as google drive, Then you can’t lose your data.
It’s very simple to use, you will need Excel on your phone/tablet.
- Email the spreadsheet to the device.
- Open the spreadsheet using the excel app.
- Save the spreadsheet with your fieldsite name.
- Copy the template sheet and rename with the site number
- Insert probes at spacings p values represent where on the tape to insert each probe (tweak these if you want different spacings/depths).
- If needed water the probed with saline water.
- Click measure
- Enter the resistance given by the Megger DET4TD2 into the grey column next to the appropriate spacing.
- Move the probes and repeat steps 5-8 until you have finished collecting data at that point.
- As you enter data you will see it plot on the log graphs below, you can use these to identify changes in subsurface materials.
Busy day today in Leeds. I presented the results from my baseline survey in Iceland to the NSGG Postgraduate Research Symposium and was featured in a poster about geophysical survey with a mausoleum.
I was pleased with how my presentation went and if I didn’t pronounce Skeiðarárjökull right it was very close and sounded vaguely Icelandic. I received lots of good feedback and the other presentations stimulated some interesting discussion about a range of topics.
Unfortunately I missed a few of the presentations after lunch, but I did manage to squeeze in a quick meeting with George from Coptrz to discuss latest drone technologies (particularly thermal imaging and multi spectral cameras) and how they could be incorporated into my dead ice project, taking into account the need to transport the equipment by plane (LiPo batteries and planes don’t mix well).
I look forward to seeing how the other participants project a progress in the future, and would like to thank all involved for organising the event.
The first of the 3D models have been uploaded for viewing. These models were created using information collected using Emlid Reach RS GNSS, DJI Phantom 4 and Geonics EM-31.
Today I gave my first guest lecture at Keele University. The lecture provided an overview of the many ways in which geophysical data can be georeferenced, and the associated accuracies for each method. This included GNSS, Total Stations, Structure from Motion (SfM), Lidar, through to mobile mapping systems.
I felt that the lecture was well recived with a good level of student interaction via mentimeter.
I have safely returned from a successful eight day field trip to Skeiðarárjökull, Iceland to carry out the baseline survey alongside my wife and willing field assistant Sam Davenward. Despite the exceptionally changeable March weather we managed to install permanent control at six localities, carry out UAV flights for Structure from Motion (SfM) photogrammetry and acquire EM-31 conductivity data for each site.
It was great to physically experience the environment I have been learning about for my Literature review and to be able to appreciate the scale of the Ice buried in the subsurface at Skeiðarárjökull.
Thanks to my field assistant (Sam Davenward), supervisors (Dr Richard Waller and Dr Alex Nobajas) and the Skaftafell Rangers for there help and support in relation to this initial fieldtrip, and I look forward to the next season.
It is forbidden to fly drones within Skaftafel National Park without permission from the park rangers. A research permit was granted prior to fieldwork being conducted.