Abstract
A simple induced polarization method in time domain measurement is apllied to the investigation for ground water. The procedure in di-pole di-pole array is to measure the electric value (Vp) between the poles after 2.5 s electrical current (I) and to measure the electric value (Vs) 0.5 m/s just after current cut. Using the measured values, an apparent resistance ratio, a percentage of induced polarization and a percentage of possible charge are calculated.
(1) (3)
(2) (4)
where,
ρ: apparent resistance ratio (Ω·M),
M: percentage of induced polarization (%)
MA: percentage of possible charge (at the depth shallower than 100 m from surface),
MB: percentage of possible charge (at the depth deeper than 100 m from surface),
a: distance between the poles (m),
n: coefficient of isolation,
Vp: potential differece between potencial poles (mV),
Vs: potential differece between potencial poles at 0.5 m/s just after current cut (mV),
I: electric current in earth (mA).
The area and amount of the hidden ground water can be inspected by utilizing apparent resistivity, polarization ratio chargeability more acculately than the ordinal method using only the p value. Describing the principle and method of measurement, this paper shows the efficiency of the proposed procedure for the ground water investigation with the survey at five different geological condition.
