Seasonal variations in groundwater quality in Twifo Praso, Ghana.

Abstract

The quality of groundwater from Twifo Praso town in the Twifo Atti-Morkwa District of Central region of Ghana was analysed from January 2023 to June 2023. A total of twenty groundwater samples were collected from boreholes and wells for both the dry and wet seasons. The samples were analysed for the physicochemical parameters such as temperature, pH, turbidity, conductivity, total dissolved solids, chloride, calcium, hardness and some selected anions PO4 3-, NO3 -, SO4 2-. Three heavy metals (Cd, Fe and Pb) and faecal coliforms levels were also determined. The results were compared to WHO acceptable limits and parameters such as TDS, PO4 3-, NO3 -, SO4 2-, chloride and K were all found to be within the permissible limits. The faecal coliforms ranged between not detected to 106 Cfu/mL. Student-t-test analysis was used to compare the parameters determined in the dry season and the wet season. The t-test results showed that there were statistically no significant differences in the parameters such as pH, electrical conductivity, TDS, calcium, TSS, sulphate, potassium, and coliform during the dry and wet seasons with p-values higher than 0.05. However, parameters such as chloride, turbidity, phosphate, nitrate and total hardness indicated statistically significant differences in the dry and wet seasons with p-values lower than 0.05. Cadmium was detected in only one of the samples (B1) which was within the WHO permissible limit of 0.003 mg/L. The concentrations of iron were all within the WHO permissible limit except for the sample B1 which was above the WHO permissible limit. A very alarming observation the study found was that, all the 10 samples of groundwater studied recorded lead concentration greater than 0.0015 mg/L which are above the WHO acceptable limit. The water quality index was the main criteria used to establish the quality of the water. Water Quality Indices were calculated for the dry and wet seasons using the weighted arithmetic water quality index (WAWQI). Ten parameters were used to calculate the WQI for both the dry and wet seasons. The WQI value of 105.38 was recorded for the wet season whereas, during the dry season WQI value of 68.72 was recorded. The water quality indices indicated that the groundwater in the study area ranged from poor in the dry season to undesirable for drinking in the wet season. The water quality indices, therefore indicated that the groundwater in the study area, Twifo Praso were unsafe for drinking.