Geophysical Expression for Groundwater Quality in Part of Chittoor District, Andhra Pradesh, India - Management of Natural Resources in a Changing Environment - page 56

the quantitative relation shows almost direct relation of both the parameters. The
correlation coeficient r 2 is 0.2853 which amounts to 53 %.
The above mentioned qualitative and quantitative relationship between longitu-
dinal unit conductance ( S ) and hydrochemical parameters of Cl, SAR, EC, TDS, Ca,
Na, NO 3 illustrate significant relationship between the geophysical parameter, lon-
gitudinal unit conductance and various hydrochemical parameters.
The correlation can be improved to further levels of better significance if the
geophysical data is collected exactly at the same spot from where the water samples
were collected from bore wells for chemical quality analysis. However, in the pres-
ent studies the correlation coefficients for the various parameters are all above 60 %,
hence it is possible to estimate the chemical quality parameter by just carrying out
simple Vertical Electrical Soundings (VES) at many sites and by conducting water
quality analysis at few sites.
Geophysical surveys can be conducted in short field seasons and are appreciably
cost effective compared to the expenditure in detailed water quality analysis in any
study area. The qualitative and quantitative results shown in the correlation patterns
and correlation graphs clearly illustrate the geophysical expression of water
quality.
Conclusions
In the contour map the parameters of S and TDS have shown significant direct rela-
tion, the correlation coefficient r 2 is 0.5274 which amounts to 73 %. In the eastern
region the contours of high longitudinal unit conductance match well with contours
of higher values of total hardness. Similarly in the western region low values of
contours of S match significantly with lower values of contours of total hardness.
The correlation coeficient r 2 is 0.4025 which amounts to 64 %. Contours showing
higher values of Na match remarkably with contours showing higher values longi-
tudinal unit conductance in space. The correlation coefficient of r 2 is 0.3236 which
amounts to 57 %. High level contours of longitudinal unit conductance match well
with high level contours of calcium and vice-versa. Hence, there is direct qualitative
relationship between S and calcium, the correlation coefficient r 2 is 0.3709 and
shows significant quantitative relationship between S and calcium which amounts to
61 %. Specific conductance increases with increase in the values of S and vice-
versa. The correlation coefficient r 2 which is 0.4294 amounts to 66 % which is sig-
nificant. There is a complete match between the patterns of contours S and Cl. The
qualitative relation of the S and chloride is almost direct. The correlation coefficient
r 2 is 0.4688 which amounts to 68 %. The qualitative and quantitative relationship
between longitudinal unit conductance ( S ) and hydrochemical parameters of Cl,
SAR, EC, TDS, Ca, Na and NO 3 illustrate significant relationship.
In present study the correlation coefficients for the various parameters are all
above 60 %, hence it is possible to estimate the chemical quality parameter by just
carrying out simple vertical electrical soundings (VES) at many sites and by con-