Groundwater table and hydrochemistry of Kakinada coastal aquifer– A research report by National Institute of Hydrology

The report deals with groundwater table and hydrochemistry of the Kakinada coastal aquifer in East Godavari, Andhra Pradesh. As a part of the monitoring of groundwater levels and its quality in and around Kakinada town, the analysis of groundwater levels and its quality during the year 1996 is presented in the report. The flow of groundwater is controlled by the drainage of the area and a subdued replica of surface topography.

The influence of seawater was clearly observed on Total Dissolved Solids (TDS), Cl, Na and HCO₃ contents in the observation wells. According to the hardness classification, the study area falls under hard to very hard zone. The change in major anions and cations in the observation wells indicates mixing of shallow groundwater in the study area. Groundwater samples have been classified according to Stiff’s, Piper’s and US Salinity Laboratory Classification. The hydrochemical ratios of Mg/ Cl, Cl/ HCO₃ and Mg/Ca for each sample has been calculated. The SAR and per cent Na in each well indicated that the study area falls under medium hazard of sodium in the study area.

The TDS, HCO₃ and NO₃ contents exceeded the maximum desirable limits of the ISI (1983) drinking water standards. Detailed investigations are to be initiated to find the sources of nitrate pollution in the study area. The direction of groundwater flow is perpendicular to the sea coast. More studies are necessary to confirm the groundwater divide line in the area. 

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