Geophysical Expression for Groundwater Quality in Part of Chittoor District, Andhra Pradesh, India - Management of Natural Resources in a Changing Environment - page 39

areas, the method is cumbersome, time-consuming and expensive. Quicker,
cost-effective techniques of analysis of groundwater quality can be achieved by
comparing and correlating primary hydrogeochemical parameters with an easily
obtainable geophysical parameter. This study reveals the significant relationship
between geophysical parameter and hydrogeochemical ions, i.e., longitudinal unit
conductance ( S ) and Ca, Na, Cl, NO 3 , SAR, EC, total hardness, TDS.
Methodology
Vertical electrical soundings carried out at 28 locations are shown in Fig. 2 . The
vertical electrical sounding data used in the present study are subjected to refine-
ment of the interpretations through the use of the software package Resist 87. The
computed values of apparent resistance ˁ, layer thickness ( h ) and longitudinal unit
conductance ( S ) are given in Table 1 . The interpreted curves of few soundings are
shown in Fig. 3 . Longitudinal unit conductance ( S ) is the sum of the ratios of thick-
ness ( h ) of different layers to their corresponding resistivities. In the present study,
S is the sum of S 1 + S 2 , where S 1 is ratio of thickness and resistivity of 1st layer, i.e.
h 1 /ˁ 1 , while S 2 = h 2 /ˁ 2 of 2nd layer.
Fig. 2 Location of geophysical soundings