GIS-based evaluation of shallow aquifer vulnerability to pollution using DRASTIC model: a case study on Abakaliki, southeastern, Nigeria

Groundwater is prone and most vulnerable to pollution from several human-mediated activities. Several measures have been taken to appraise the vulnerability of groundwater in order to manage it effectively. The current study uses the DRASTIC framework in a geographic information system (GIS) platform to evaluate groundwater vulnerability. For this study, a total of seven hydrogeological factors were investigated, and the resulting groundwater vulnerability map was created using an overlay weighted process and the DRASTIC index, which is divided into three vulnerable groups (high, moderate, and low). In the south and eastern provinces of the study area like Aghameghu, Obeagu, Ezzeagu, Ndiechi, Obusia Amachi, Odagateda, Okpuitumo Umuhu, Ugbuloke, and Ofe Iyioku, high groundwater contamination is been ascertained. The water quality indicators—nitrate and TDS—were adopted to validate the model, with a precision of 75% and 70%, correspondingly. GIS application of the DRASTIC model was proven to be an effective technique for evaluating the groundwater vulnerability in urban and semi-urban environments. This map can be used primarily for groundwater preservation and planning in a given area, as well as a necessary backdrop for management and land use decisions.