VERTICAL ELECTRIAL SOUNDING (VES)


Vertical electrical sounding is a geophysical method for investigation of a geological medium, the method is used on the estimation of the electrical conductivity or resistivity of the medium. The estimation is performed based on the measurement of voltage of electrical field induced by the distant grounded electrodes (current electrodes). The following methods are used to carry out experiment in vertical electrical sounding;
v Wenner array (2D)
v Schlumberger array (1D)
v Dipole-dipole array
v Square array
AIM
1.     To determine the potential difference and current passing.
2.     To know the depth of water level in an area of mapping and to know the aquifer level of an area.
3.      It also determines the type of soil that can be used for building structures in a certain area.
4.     To know the type of crops that will be grown in that area.
APPARATUS USED
1. Tetrameter 300
2. Cable (blue = current wire and white/red = potential wire)
3. 5 Electrodes
4. Hammer
5. Masking tape
C = Current electrode (AB)
P = Potential electrode (MN)
Midpoint: This is the stationary point where the two point of meter tap start.
Traverse: A strength line to enhance a work, or a direction o part the meter tap follows (different direction, right and left direction).
Tetrameter: The instrument that measures or gives reading in resistance. Resistance (R) =   1
                              V
The tetrameter machine has to read 4 times before taking the reading, this is because we place the sounding cycle at 4.

Schlumberger array:

Steps in the determination of Schlumberger Array
1.       Location of mapping.
2.       Take one electrode and make a stationary point with a meter tape.
3.       Connect the various cable to the current and potential.
4.       Test the tetrameter SAS 300 if it’s producing or taking reading.
5.       From the data given, we extend the current to different position while the potential remains.
6.       Records are taken after every point of current and potential.

FIELD WORK
Cricket court off UBA Bank
GPS READING: 4° 53° 52°N
                             6° 55° 9°E

To get the geometric factor (K)





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