Groundwater suitability estimation for sustainable drinking water supply and food production in a semi-urban area of south India: A special focus on risk evaluation for making healthy society

• Groundwater of the study region is high to very high saline and low alkaline in nature. • Around 53% of the total area has good quality groundwater for drinking water supply. • Southeast part has poor groundwater quality due to less recharge from surface water bodies. • Nearly 82% of the groundwater samples possess health risks for infants in the study region. The main objective of the present investigation is to estimate groundwater suitability for sustainable drinking water supply and food production in a semi-urban area of south India with a focus on risk assessment for making healthy society. As urbanization and industrialization make the water unfit for water supply and crop rising in most parts of the world this study is very much significant for the fast growing Edappadi region in the southern part of India. A total of sixty-nine groundwater samples were obtained during May 2019 (summer season) and analyzed for Total Dissolved Solids (TDS), Electrical Conductivity (EC), pH, potassium (K + ), magnesium (Mg 2+ ), sodium (Na + ), calcium (Ca 2+ ), bicarbonate (HCO 3 − ), nitrate (NO 3 − ), sulphate (SO 4 2- ), chloride (Cl − ), and fluoride (F − ). Fluoride and nitrate ranged from 0.38 to 3.23 mg/L and 12 to 136 mg/L with an average of 1.7 mg/L and 62 mg/L, respectively. About 36 % of samples occupying 80.74 km 2 area surpass the allowable limit of fluoride (1.5 mg/L). Similarly, 42 % of samples occupying 98.75 km 2 area surpass the allowable limit of nitrate as per WHO and BIS standards (45 mg/L). Correlation studies point out that groundwater contamination is happening due to manmade activities. The Improved Water Quality Index (IWQI) suggested that about 57% of groundwater samples can be used for drinking utility. The alkalinity of groundwater is within the suitable level for crops but groundwater salinity is high to very high in most of the areas. The Total Hazard Index (THI) showed that 72%, 59%, 33% and 29% and 86%, 77%, 51% and 43% of groundwater samples are within the non-carcinogenic health risk category based on fluoride and nitrate contents, respectively, for infants, children, teens, and adults. This study will help the decision and policymakers such as municipal corporation, pollution control board, public works department, water supply and drainage boards, agricultural and public health departments, etc., to use appropriate groundwater resources for providing safe drinking water supply and food production from crops. The findings of this study can aid in the development of appropriate management strategies by the above government departments for ensuring safe water supply and health protection measures for inhabitants.