Abstract:
The Vea catchment, mainly underlain by crystalline
basement rocks, is located in Northern Ghana.
Hydrogeochemical studies were carried out in this area
with the objective of identifying the geochemical processes
influencing water quality and suitability of surface and
groundwater for agricultural and domestic uses. Sixty-one
groundwater and four surface water samples were collected
from boreholes, dams and rivers and analysed for Ca2?,
Mg2?, Na?, K?, HCO3
-, Cl-, and SO4
2-, Fetot, PO43-,
Mntot, NH4
?, NO3
-, NO2
-. In addition, pH, total dissolved
solids, electrical conductivity, total hardness, turbidity,
colour, salinity and dissolved oxygen were analysed.
Chloro-alkaline indices 1 and 2, and characterization of
weathering processes suggest that the chemistry of
groundwater is dominated by the interaction between water
and rocks. Cation exchange and silicate weathering are the
dominant processes controlling the chemical composition
of the groundwater in the area studied. Mineral saturation
indices indicate the presence of at least three groups of
groundwater in the Vea catchment with respect to residence
time. The meteoric genesis index suggests that 86%
of the water samples belong to the shallow meteoric water
percolation type. The findings further suggest that the
groundwater and surface water in the basin studied are
mainly Ca–Mg–HCO3 water type, regardless of the geology. Compared to the water quality guidelines of
WHO, the study results on sodium absorption ratio, sodium
percentage, magnesium hazard, permeability index and
residual sodium carbonate indicate that groundwater and
surface water in the Vea catchment are generally suitable
for drinking and irrigation purposes.
