Geochemical Analysis of the Groundwater Quality along the Vrishabhavathi River Basin

Aim: The current study aims at assessing the groundwater quality along the Vrishabhavathi river basin for various water quality variables.

Study Design: Conventional Titrimetric and Spectrophotometric methods were employed to estimate the different water quality variables which are briefly explained in the methodology.

Place and Duration of Study: During the monsoon June 2015 the groundwater along the Vrishabhavathi river basin, Bengaluru, Karnataka, India were sampled for the present investigation.

Methodology: Water quality variables such as Temperature, pH, Electrical Conductivity and Total dissolved solids were estimated in the field using portable apparatus. Total Hardness, Cl-, HCO3-, Ca++ and Mg++ were estimated by titremetry. Na+ and K+ were estimated using Flame photometry. SO42- and F- were estimated using Turbidimetry and SPADNS method [Spectrophotometry]. Pb and Cr were estimated using Atomic Absorption Spectrophotometry. The standard guidelines of APHA [1998] were used for the entire analysis. Descriptive statistics and Correlation study has been done using SPSS 22 and Minitab 14.

Results: The detailed study of all the water quality variables is discussed in detail in the paper. LSI calculation indicates that majorly 53% of the water samples are classified under the class ‘D’ [Slightly scale forming and corrosive] and 40% of the water samples fall under the group ‘E’ [Scale forming but non-corrosive]. Piper trilinear plot reveals that majorly Ca++ and Mg++ are the dominant cations and HCO3- and Cl- are the dominant anions. Statistical measures such as Mean, SD, SE of sample means, coefficients of Skewness and Kurtosis have been computed using the statistical package to assess the characteristics of the selected water quality variables. Further, 95% confidence intervals have been obtained for the true means of these variables and water quality variables crossing the permissible limits of WHO [1993] have been identified using these confidence limits. Correlation study has been done to estimate the significance of the linear relationship between the pairs of variables at a given level of significance and thereby the set of water quality variables which are interlinked have been identified.

Conclusion: The water quality variables which have/have the tendency to cross the permissible limits set by WHO [1993] have been identified using the confidence intervals.

Through the Piper plot and LSI calculation, we can conclude that the groundwater samples are alkaline in nature and are not suitable for consumption.