Assessment of groundwater quality for irrigation in the Oda river basin, Ejisu-Besease, Ghana

Hydrochemical study is a useful tool to identify the suitability of groundwater for irrigation purpose. Groundwater samples were collected from fourteen piezometers from the various locations in the study area to assess the quality of groundwater for irrigation use. To achieve this objective, concentrations of physicochemical parameters were analysed and interpreted with different irrigation indexes like Sodium adsorption ratio (SAR), ECw, Percent sodium, Magnezium hazard and Kelly’s ratio. The various parameters estimated showed that electrical conductivity values ranged between186 to 638 µS/cm, TDS values were less than 500mg/l, SAR values varies from 0.34 to 0.86 meq/l, Na % values ranges from 20.55 % to 44.09 %, MH values ranged between 25.86 % to 55.29 % and KR varying between 0.13 and 0.44. The hydrochemical study of the area revealed that alkaline earths exceed alkalis and weak acids exceed strong acids in groundwater which presented a Ca-Mg-HCO3 groundwater type. Results from the groundwater chemistry of the boreholes plotted on the USSL diagram and the Wilcox diagram indicated that the groundwater is of good quality for irrigation. The study unraveled the mechanism controlling groundwater chemistry as the chemical weathering of rock-forming minerals and evaporation.