Assessment of Groundwater Quality Status by using Hydrochemical and GIS approach for the feasible study of Coastal Reservoirs

Groundwater qualities of coastal aquifers in the Netravati and Gurapura catchment of Dakshina Kannada district Karnataka have been extensively monitored in post-monsoon seasons in 2021 and Pre-Monsoon 2022 to assess their suitability for domestic and drinking uses in four regions. Thirty-two groundwater samples were analysed for various physicochemical parameters such as GWL, pH, Oxidation Reduction Potential (ORP), Electrical Conductivity (EC), Total Hardness (TH), Dissolved Oxygen (DO), Total Dissolved solids (TDS), Temperature, Calcium (Ca), Magnesium (Mg), Chloride (Cl), Sodium (Na), Potassium (K), Sulphate (SO 4 ) and Carbonate and Bicarbonate. Most of these parameters fall under the permissible limits of BIS and WHO standards. Using hydrochemistry and the GIS method, the current study aims to evaluate the quality of groundwater (well water samples) in the Netravati river basin. The quality of the groundwater, indicates that coastal aquifers have gained prominence over the past ten years as a result of the using global demand for groundwater. According to the findings of the study, groundwater depletion and the rising seawater level are the primary factors that contribute to the saline condition of coastal wells during the pre-monsoon period. The study demonstrates that groundwater levels have been trending downward for some time. Seawater intrusion appears to be the main problem in the study area's coastal region, according to the study. The water quality index (WQI) results show that the quality of well water samples during the pre-monsoon session is much worse than during the post-monsoon session due to fresh rainwater during the post-monsoon session raises the groundwater level and increases the water's physical and chemical parameters. Based on the recommendations of the Hortons water quality index, groundwater quality is divided into four categories: excellent water quality (90-100), good water quality (71-90), poor water quality (51-70), and bad water quality (31-51).