Geology Reference
In-Depth Information
It may be necessary to mention that a parameter model derived either by
conventional or computer method may not be unique because of an inherent
limitation, namely the phenomenon of equivalence resulting in a range of
models fitting the same sounding curve. Another limitation is the simplified
assumption of horizontal, homogeneous and isotropic model layers, which is
never the case in nature. It is, therefore, very essential to gather the
hydrogeological knowledge of the area and correlate the sounding data
obtained near existing wells with lithology for a reliable interpretation.
Multi Electrode Resistivity 2-Dimensional Imaging (MER2DI)
The improvement of resistivity methods using multielectrode arrays has led
to an important development of electrical imaging for subsurface surveys
(Griffiths and Turnbull, 1985; Griffiths et al., 1990; Barker, 1992; Griffiths
and Barker, 1993). Such surveys are usually carried out using a large number
of electrodes, 24 or more, connected to a multi-core cable. A laptop micro-
computer together with an electronic switching unit is used to automatically
select the relevant four electrodes for each measurement. Apparent resistivity
measurements are recorded sequentially sweeping any quadruple (Current
and Potential Electrodes) within the multi-electrode array. MER2D data can
be interpreted with the help of RES2D inversion software and finally a true
Figure 3.
(a) Profile layout and (b) Comparison of different
arrays along Line A in Mohabatnagar.
