A season-wise estimation of total dissolved solids from electrical conductance and silica in ground waters of upper Gunjanaeru River basin, Kadapa district, Andhra Pradesh

摘要

In order to establish season-wise relationship between total dissolved solids (TDS), electrical conductance (EC) and silica (SiO_2) in upper Gunjaneru River basin, Kadapa district, Andhra Pradesh, a study has been made by collecting 51 and 46 ground water samples during post-monsoon and pre-monsoon season, respectively. TDS, EC and silica are some of the ground-water quality parameters measured in a laboratory generally. EC and silica measurements are made quickly and are less costly than TDS measurement. The results indicate that 99.7% and 99.8% of the variability in TDS could be ascribed to the variable EC and SiO_2 concentrations and the rest by some other unaccounted variables in the post-monsoon and pre-monsoon season, respectively. Inclusion of SiO_2 concentration in the regression models produces, for individual samples, a lower per cent difference between measured and estimated TDS for both seasons. However, on the average the inclusion of SiO_2 in regression models reduced the mean difference 0.09% for the post-monsoon season and 0.11% for the pre-monsoon. From regression analysis it is found that the multiple regression model did not improve the predictability of TDS values over the linear regression model for both post-monsoon and pre-monsoon seasons. TDS can be estimated from either EC or EC and SiO_2 by these regression models within the acceptable limit of error. This is due to the low content of SiO_2 in the groundwater samples in shale aquifers of the study area.