Assessment of groundwater quality in hard rock aquifer of central Telangana state for drinking and agriculture purposes

Abstract Quality assessment of groundwater for drinking and irrigation was evaluated in parts of Nalgonda district of Telangana state, India. The overall groundwater quality and the suitability to drinking and irrigation were evaluated by hydrochemical analysis of 78 groundwater samples. The water quality parameters were compared with that of the limits set by World Health Organisation (WHO) and Bureau of Indian Standards (BIS). Groundwater is found to be contaminated by fluoride and nitrate ions. The water quality indices (WQI) suggest that during pre-monsoon, 72.5% samples are suitable for drinking while 86.8% are suitable during post-monsoon. Indicators like sodium absorption ratio (SAR), electrical conductivity (EC), percent of sodium (Na %), residual sodium carbonate (RSC), permeability index (PI), magnesium ratio (MR), residual sodium bicarbonate (RSBC), salinity hazard (SH), potential salinity (PS), soluble sodium percentage (SSP), and magnesium ratio (MR) were estimated for assessing the irrigation suitability of the groundwater samples. Wilcox, United States Salinity Laboratory diagrams (USSL diagram) and Doneen’s chart infer that most of the samples are suitable for irrigation purpose and the suitability improves during post-monsoon. The geochemical evolution of the groundwater was also studied using Piper’s and Chadha’s diagrams. The major facies found in groundwater are Na–Mg–HCO3–Cl, Na–Mg–HCO3, Na–HCO3, Mg–Ca–HCO3, Mg–Na–HCO3 and Na–Cl. Rock-water interaction, ion exchange and evaporite dissolution were found to be the major geochemical processes governing the groundwater chemistry