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

Abstract

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. The chemical results indicate high concentrations of F− and NO3- ions were present in 12 and 28% of samples above drinking water permissible limits. Similarly, Cl– ion, and TH were higher while Ca2+, Mg2+, and Na+ ions were marginally higher as 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 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) computed by Shannon's entropy technique. 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.