The main focus of this study is to evaluate the groundwater quality through drinking water quality index and regression analysis in semi-arid region and the results are examined with reference to the drinking water quality standards laid down by WHO. Water quality index (WQI) was determined from fourteen physicochemical parameters like pH, EC, TDS, total hardness, total alkalinity, sodium, potassium, calcium, magnesium, chloride, bromide, nitrate, sulphate and fluoride. The drinking water quality index values range from 32.8 - 442.4, indicating three categories i.e. poor, very poor and unfit, which are inappropriate for drinking. Regarding correlation analysis results, EC, TDS, TH, Na + , Mg 2+ , Ca 2+ and Cl − shows high correlation. Most of the parameters are more or less correlated with each other, regression relations have the same correlation coefficients and pH, Na + , EC, TDS, Mg 2+ , Ca 2+ , Cl − , SO 4 2− , CO 3 2− , TH were significantly positively correlated (R>0.9), indicate the increase in the pollution load.

The present investigation revealsthe quality of Dam water for public consumption to determine the Dam water of Shajapur town. Physico-chemical parameters of Dam water were monitored during the study period. The parameters investigated were pH, TDS, Alkalinity, Total Hardness, Chlorides, Magnesium, Fluoride, Nitrates, Dissolve Oxygen and COD. Results obtained from the study revealed that quality of Dam water during study season is well within the permissible limit and the Dam water is safe for drinking or fit for human consumption.

This study is conducted in the Precambrian granitic terrain, to demonstrate the presence of the multi-aquifer system and examine the inter-communications between them. Distinct hydrochemical characters of the groundwater from shallow (~ 100 m) and deep (~ 400 m) wells, signifies their independent and unconnected nature initially. Hydrochemistry of deep groundwater is approximately constant (either Ca-Na-Cl or Ca-Na-Cl-SO4 type of water) during January 2015 to June 2016. Repeated carbon-14 measurements during the same period show the 14C activity of about 35 to 85 pMC (residence time about 3 to 8 ky BP). However, as a result of excess rainfall during 2016, hydrochemical facies of deep groundwater changed initially to Na-Ca-SO4-Cl and subsequently stabilised at Ca-Na-HCO3-Cl type with a drastic reduction in Cl and increased HCO3 and NO3 concentrations, while the 14C activity turned out to be to 100 pMC (modern age). These changes are attributed to ingression of fresh water into the deep aquifer, after paleo-groundwater depleted due to prolonged drought conditions along with the over-exploitation of limited potential deep aquifer. These drought and over-exploitation situations potentially improved the migration potential of fresh water to the deep aquifer and led to enhancing the groundwater recharge during the excess rainfall years. This brings a new perspective to the hydrogeological dynamics between shallow and deep groundwater. A conceptual model is proposed to explain the observed phenomenon. This study also suggests that, under climate driven drought conditions, deep aquifers could act as emergent groundwater resource to meet the water demands amid population growth.