Groundwater quality assessment for safe drinking water and irrigation purposes in Malda district, Eastern India

Groundwater quality assessment is a very useful approach for assessing water quality and it provides an understanding of the suitability of groundwater for various purposes, especially in drinking water. The prime objective of this study was to analyse the groundwater quality for drinking and irrigation purposes of Malda district of West Bengal, India. In this study, 83 wells were used for groundwater quality assessment. Piper diagram shows that NaCl, (Na + –K + ), HCO 3- are the dominant hydrochemical factors of groundwater in this region. The correlation values show that Na + and EC are highly correlated with Ca 2+ and TH, Mg 2+ and TH. WQI method was used to estimate the drinking water quality, which shows that approximately 50 percent of wells are in excellent categories, but high concentrations of few ions create poor quality drinking water on some sites. About 14 percent of well sites fall into the poor WQI categories. Various indices such as SAR, %Na, MAR, PI, CAI-I, KR has been analyzed to understand the groundwater suitability for irrigation purposes. According to SAR value, 87.95% wells were excellent for irrigation, but on the other hand 48.19% of wells were under doubtful category in % Na calculation; also some indices such as MAR, PI, CAI-I have a high value showing the inadequacy of groundwater for irrigation purposes. According to the USSL diagram 31% of the wells were under the C3S1 category, which isof high salinity and low alkalinity. Therefore, this water quality can be used for irrigation purposes of high salt tolerance plants. Wilcox’s diagram indicates that 34.94% wells fall under very doubtful quality for irrigation purposes.