Indexing the Groundwater Quality Index for human consumption (GWQI_HC) for urban coastal aquifer assessment

About 40% of the world’s population live in coastline, where the groundwater is one of the most important source of water for human drinking purpose. However, many natural and anthropogenic activities can affect the groundwater potability. The present paper is aimed at indexing the groundwater quality index for human consumption (GWQI_HC) for an accurate assessment of urban coastal aquifers suitability for drinking purpose. A bibliographic review of 50 groundwater quality index studies and a Delphi method form were accomplished to find the parameters to be indexed in the GWQI_HC. The parameters most used in the sampled articles formed the GWQI_HC_B and the parameters most indicated by the groundwater experts who answered the Delphi method formed the GWQI_HC_D. These indexes were applied using a data set of groundwater samples collected from the study area Tamoios district, Rio de Janeiro. The results showed that the GWQI_HC_D was indexed with more parameters that influenced the suitability of groundwater for drinking purpose. The GWQI_HC_D was indexed with parameters more important for human health and its ratings were on average 6.2% more stringent than the GWQI_HC_B ratings. Therefore, it is recommended that the GWQI_HC applied in urban coastal regions be indexed with the parameters indicated in this study by the Delphi method (NO₃⁻, Mn, Fe⁺², TDS, total coliforms, electric conductivity, pH, Cl⁻, Al, Na⁺², Ca⁺², and F⁻).