Spatial assessment of groundwater quality using CCME-WQI and hydrochemical indices: a case study from Talupula Mandal, Ananthapuramu district, South India

Fluoride contamination in groundwater is known from different villages of Talupula Mandal. In the present study in part of SoI toposheet no.57 J/8) of Ananthapuramu district, Andhra Pradesh, the magnitude and credible geogenic sources of the fluoride contamination in groundwater are studied. The present study carried out includes 30 groundwater samples covering an area of 442.89 sq km using (GIS) and (CCME-WQI) techniques. Problem is causally related to fluoride intoxication of human beings and animals through drinking waters. Well waters in the Talupula Mandal surrounded areas carry a high level of fluoride concentrations, much above the internationally decided safety limits. ‘Fluorosis’ is imminent as a result of prolonged intake of waters with more than 1 to 1.5 ppm of fluoride. Fluoride testing results of groundwater from borewell pump using fluoride test kit reveal that about 50% groundwater samples show fluoride concentration more than 4.0 mg/l, 30% samples show between 2.0 and 3.0 mg/l and 20% samples show fluoride concentration is 1–2 mg/l and above (BIS permissible limit: 1.5 mg/l). Agriculture indices are as follows: sodium percentage (Na%) was found between ranges (20.04–55.26), sodium absorption ratio varies from 0.86 to 3.91), Kelly's ratio (KR) varies from 0.22 to 1.16, residual sodium carbonate varies from − 4.12 to 20.66), permeability index (PI) varies from 39.00 to 82.28, magnesium hazard varies from 52.83 to 85.47, potential salinity varies from (0.71–3.15); results shown that the majority of the groundwater samples were suitable for irrigation uses. According to Gibbs’ ratio samples Gibbs ratio 1 (0.04–0.45) and Gibbs ratio 2 (0.44–0.81) fall in the rock dominance. Major ion compositions plotted on a Piper tri-linear diagram indicate that the water is of Ca-HCO3 type and is mixed Ca–Mg–Cl type. The present study indicates that the groundwater chemistry is mostly controlled by geogenic processes (weathering, dissolution and ion exchange) and some extent of anthropogenic activities.