Physico-chemical evaluation of groundwater along the coast of the Central Region, Ghana

Abstract

Groundwater, as a source of water supply, plays an important role in the socio-economic development of most communities worldwide. However, its potability in most coastal communities is often threatened by seawater intrusion. This study employed a combination of methods including the World Health Organization (WHO) guideline values, water quality index (WQI), ionic ratios, sodium adsorption ratio (SAR), percent sodium (%Na), permeability index (PI) and electrical conductivity (EC) to assess the quality of groundwater in some coastal communities of the Central Region of Ghana, for domestic and irrigation purposes. Physico-chemical data from sixty-nine (69) boreholes in the communities were acquired for the study; NaCl (43%), MgHCO3(20%) and mixed CaMgCl (20%) were found to be the dominant water types in the groundwater of the study area. About 61% of the communities had excellent to good groundwater quality for domestic use per WHO guideline values and WQI analyses whereas 43% had suitable groundwater to support plant growth and crop yield based on the PI, SAR, %Na, and EC analyses. However, there were elevated concentrations of the major ions close to the sea, and the ionic ratios revealed that seawater intrusion may be the cause of the high salinity in the groundwater of most communities in the area. This study has delineated areas in the communities with poor groundwater quality that may have to be avoided in the development of the resource for water supply.