Groundwater Quality Assessment of Shallow Coastal Aquifer in Guntur District of Andhra Pradesh

In the year 2021, a survey was conducted in the coastal mandals of Guntur district, Andhra Pradesh, to determine the quality of irrigated groundwater. A total of 29 representative samples were collected along with GPS locations. The water samples were tested for a variety of chemical characteristics, including: pH, EC, Ca+2, Mg+2, Na+ , K+; CO3-2, HCO3-, Cl- and SO4-2. The pH, EC, SAR and RSC in groundwater ranged from 6.9-8.2, 0.6-9.2 (dSm-1), 1.75-17.59 (mmol l-1)1/2, -35-7.8 (me l-1). The concentration of cations viz., Ca+2, Mg+2, Na+ and K+ varied from 0.4-21.8, 1.2-20, 2.22-47.7 and 0.02-0.87 me l-1 with mean values of 8.51, 8.10, 19.30 and 0.23 me l-1 respectively. Concentration of anions viz., CO3-2, HCO3-, Cl- and SO4-2 varied from 0-0.8, 2.6-16.6, 2.0-52.0 and 0.4-21.8 me l-1 with an average values of 0.27, 7.19, 18.70 and 2.70 me l-1 respectively. The relative abundance of ions for most of the water samples were Na+ > Ca+2 > Mg+2 > K+ for cations and Cl- > HCO3- > SO4-2 > CO3- for anions. According to CSSRI classification of irrigation water, 41.38, 17.24, 24.13, 13.80, 0.0, 0.0 and 3.45 per cent samples were good, marginally saline, Saline, High SAR Saline, marginally alkaline, alkali and highly alkali, respectively. Spatial variability maps of pH, EC, SAR, RSC and groundwater quality of the study area were developed.