Drinking and irrigation quality and pollution assessments of the groundwater resources from Alappuzha in Kerala (India) through an integrated approach using WQI and GIS

Groundwater in coastal areas, with surging population and growing settlements, is constantly at risk of pollution. Alappuzha is one of the most well-developed coastal districts in the southwestern Indian state of Kerala and employing various physico-chemical parameters (pH, EC, TDS, alkalinity, hardness, and contents of sodium, potassium, calcium, magnesium, carbonate, bicarbonate, chloride, sulphate, nitrate, and fluoride), this study aims to evaluate the drinking and irrigation water qualities of its groundwater resources and present their spatial distributions using the GIS platform. In the moderately hard to very hard groundwater of Ca-Mg-SO4 type, the ions dominate with order Ca > Na > Mg > K and HCO3 > Cl > SO4 > CO3 > F. The water quality index (WQI) values (0.85-144, avg., 26.77) established the suitability of drinking water, revealing 53 % and 45 % of samples are lies under the categories of excellent and good, respectively. Only 2 % of the sample are in extremely poor water category. SAR, RSC, Na%, PI, KR and MH indices established that almost all of the groundwater can be used for agriculture, and the samples from northern coast showed vulnerability to contamination.