A synoptic assessment of groundwater quality in high water-demand regions of coastal Andhra Pradesh, India

In this article, a coastal region of India having high water demand for irrigation supply was studied for its groundwater quality in temporal and spatial domains. The statistical tests (Shapiro–Wilk W and Anderson–Darling A) of the chemical data of over 100 groundwater samples of the study area indicate the non-parametric nature of the distribution. High concentrations of F− and NO3− ions above drinking water permissible limits were present in 12% and 28% of samples, respectively. Similarly, Cl– ion, and total hardness were higher while Ca2+, Mg2+, and Na+ ions were marginally higher compared to drinking water limits. Kruskal–Wallis (ANOVA) test results indicate that seasonal variations are not very significant among chemical species. Based on irrigation water quality indicators, groundwater samples fall under the excellent to doubtful category during premonsoon and permissible to unsuitable category during postmonsoon season. These inferences were verified by using the Entropy Water Quality Index (EWQI). The spatial contours of the EWQI values clearly suggest that the impact of anthropogenic activities on groundwater is greater in the northern parts of the study area. Optimizing fertilizer application and effluent treatment can improve the groundwater quality thereby achieving sustainable groundwater management in this region. HIGHLIGHTS Hydrochemistry of the groundwater suggests a high vulnerability to nitrate contamination in the northern parts.; Seasonal variations in water quality data infer that the premonsoon season is better than postmonsoon season.; Indicators representing the water quality for irrigation show that groundwater is in the excellent to doubtful category excepting magnesium hazard and Kelley's ratio.