Hydrochemistry And Stable Isotope Assessment Of Groundwater And Surface Water Bongo District, Upper East Region, Ghana

Abstract

The hydrogeochemical data of groundwater and surface water of Vea dam water of the Bongo District in the Upper East Region of Ghana were examined to determine the main factors controlling the groundwater chemistry and the resultant water type formed in order to determine the suitability of the water for different uses. Conventional graphical methods combined with multivariate statistical analysis are the main methods applied to groundwater and surface water hydrochemical and stable isotope ((δ2H and δ18O) data to identify the geochemical characteristics. Results from 25 groundwater and 20 surface water samples indicated that the concentrations of major ions were low. Based on total hardness and TDS, the groundwater ranged from moderately hard to hard and fell under fresh (TDS<1000 mg/l) water type. By comparing the chemical parameters of groundwater in the study with the WHO guidelines, groundwater was of excellent to good quality for domestic use except in certain locations where fluoride exceeded the permissible limit. Generally groundwater and surface water in the area were suitable for irrigation purposes based on the analysis of sodium absoption ratio, sodium percentage, sodium residue carbonate, permeability index, and magnesium harzard classifications. Conventional graphical plots of the hydrochemical data suggested that the dominant groundwater type was Ca-Mg-HCO3 water type which signified modern meteoric water recharge. Hierarchical cluster analysis (HCA) of the hydrochemical data, resulted in two clusters suggesting rock weathering and anthropogenic activities being the main processes controlling the water chemistry. On the basis of ratio the geochemical processes that control the hydrochemistry of groundwater types in the area were dissolution of carbonate, silicate mineral weathering and ion exchanges. The stable isotopic compositions suggested that there were no apparent hydraulic relationship between surface water and groundwater in the location. However, the result suggested that, both water system were recharged from local precipitation, indicating meteoric origin.