ASSESSMENT OF GROUNDWATER QUALITY IN TA N’GABU, CHIKWAWA
Abstract
Groundwater resources in some parts of the lower section of the Shire River valley, Malawi, are not potable for rural domestic water supply due to high salinity. Knowledge of spatial variation of water quality is essential in locating and sustaining usable water supplies. In this study, a comprehensive assessment of the quality of groundwater from the Malemia village has been conducted to determine salinity status of boreholes, assess the spatial variation of water salinity among the boreholes and show the relationship between the groundwater chemistry and the geology of the Malemia village in TA Ngabu. Groundwater samples were collected from four boreholes in Malemia Village and at each borehole two samples were collected. Then the samples were analysed for physical chemical parameters. The results were evaluated and compared with WHO and MBS water quality standards. Sodium and bicarbonate are dominant ions among cations and anions. EC, TDS, Chlorine, Carbonate, Bicarbonate, Calcium, Magnesium and Sodium exceeded the acceptable limits of WHO and MBS drinking water recommended guideline. The correlation matrix shows that physical- chemical parameter of the borehole water significantly affects the salinity in the area. On that note TA Ngabu has high salinity levels which is caused by rock-water interactions and evaporation-sedimentation processes as revealed by Gibbs diagram. The piper trilinear diagram shows that all groundwater samples are calcium magnesium bicarbonate type (Ca-(Mg)-HCO3) which are associated with high salinity. The studied results reveal that the groundwater in TA Ngabu is brackish and slight to moderate saline, this shows that salinity is an issue in the area as evidenced by people in the study area who abandoned the boreholes because of high salinity levels and opt for unprotected water sources for water supply. To respond to the salinity problems in the area: desalination water treatment methods should be employed, experienced and suitably qualified hydrogeologists should be employed for good borehole siting and management in areas of high salinity levels and finally monitoring programs should be put in place to frequently monitor the quality of the water being used by people in the TA Ngabu.
Research summary
Groundwater resources in some parts of the lower section of the Shire River valley, Malawi, are not potable for rural domestic water supply due to high salinity. In this study, a comprehensive assessment of the quality of groundwater from the Malemia village has been conducted to determine salinity status of boreholes, assess the spatial variation of water salinity among the boreholes and show the relationship between the groundwater chemistry and the geology of the Malemia village in TA Ngabu. The studied results reveal that the groundwater in TA Ngabu is brackish and slight to moderate saline, this shows that salinity is an issue in the area as evidenced by people in the study area who abandoned the boreholes because of high salinity levels and opt for unprotected water sources for water supply. To respond to the salinity problems in the area: desalination water treatment methods should be employed, experienced and suitably qualified hydrogeologists should be employed for good borehole siting and management in areas of high salinity levels and finally monitoring programs should be put in place to frequently monitor the quality of the water being used by people in the TA Ngabu.