Environmental Engineering Reference
In-Depth Information
Conclusions
Hydrochemical analysis shows that the groundwater in the study area is slightly
alkaline in nature. Based on the total dissolved solids, groundwater samples for both
the seasons are in the freshwater (<1,000 mg/l) category and all groundwater evalu-
ated is therefore suitable for drinking and irrigation purposes. Majority of ground-
water is hard in nature in both the seasons. Among the nine groundwater samples
analyzed in the study area, 22 % of samples have high fluoride content than the
maximum permissible limit (1.5 mg/l). The occurrence of the high fluoride concen-
tration in some of the wells is attributed to the dissolution of micacious minerals that
are associated with the mica schist formations. The hydrochemistry of cationic
dominance pattern is in the order of Na
+
>Ca
2+
> Mg
2+
> K
+
in pre- and post-mon-
soonseasons.TheanionicdominancepatternsisintheorderofHCO
3
−
>Cl
−
>SO
4
2
−
> F
−
>PO
4
3−
inpre-monsoonandHCO
3
−
>SO
4
2−
>Cl
−
> F
−
>PO
4
3−
in post-monsoon.
The hydrochemical types can be classified into three major groups such as Ca
2+
-
Na
+
-HCO
3
−
(average TDS value is around 310 mg/l), Na
+
-Ca
2+
-HCO
3
−
(average
TDS value is around 430 mg/l) and Na
+
-Ca
2+
-Cl
−
types (average TDS value is
around 870 mg/l). Ca
2+
-Na
+
-HCO
3
−
type of water is dominated in post-monsoon,
whereas Na
+
-Ca
2+
-HCO
3
−
type water is dominated in pre-monsoon, it may be attrib-
uted to the ion-exchange process. Based on Base Exchange Indices, 89 % and 11 %
of samples are Na
+
-HCO
3
−
type and Na
+
-SO
4
2−
type waters, respectively and major-
ity of the groundwater samples are shallow meteoric genesis in both the seasons.
Variation study of saturation indices reveals that all groundwater samples are under-
saturated with respect to anhydrite, gypsum, dolomite, halite, magnesite and siderite
minerals, and supersaturated with goethite mineral in both the seasons. As per the
SAR and RSC classification, all samples belong to good to excellent category in
post-monsoon,whereas44%inpre-monsoon(asperRSC)aredoubtfulcategoryin
the study area.
Acknowledgements
The authors are thankful to the SES, Jawaharlal Nehru University for pro-
viding research facilities and University Engineering Department, JNU for providing groundwater
samples and bore well information.
References
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