Performance of a Schlumberger Sounding Near Keg Lake on Campus

1469 Words Jan 31st, 2018 6 Pages
Forward model the DC resistivity sounding to produce an earth model.

Method:

The survey was carried out at Keg Lake on Curtin University grounds as shown in the map below: Figure 1: Keg Lake Curtin University, Google Maps.

Equipment Used

12V Battery Inverter Transmitter – turn AC to DC Porous Pots – potential electrodes [M&N in Figure 2] -Pair chosen in accordance to minimal potential level between the two Star Pickets – current electrodes [A&B in Figure 2]
-Provide maximum surface area for contact with ground Measuring Tapes Wire/ Cable/ Clips

The sounding survey was performed using a Schlumberger array. Two measuring tapes were rolled out in opposite directions from a fixed centre point, to ensure accurate measurements of both the voltage and current electrode spacing’s.

The Schlumberger layout can be seen below:

Figure 2: Schlumberger Array, www.nature.com

The electrode spacing’s chosen for the survey is related to the depth of investigation. Our area of interest in subsurface was the water table, so an educated estimate of its depth was required to decide on an appropriate maximum depth. To do this we used a comparison from the ground level we stood on, to the currently dry lake next to us and decided it would be located at around 5-10m deep. This being said a maximum depth of around 20m would be sufficient. With this total in…