Spatiotemporal variation of shallow groundwater quality in selected parts of Kitui County, Kenya

Abstract

Many people living in dry areas of Kenya rely on groundwater for household and livelihood purposes. Notably, the demand for water has been on the rise due to population increase, livelihood diversification, among others. The resultant activities have had an effect on the quality of water, a situation aggravated by factors like deforestation, agricultural activities, and others. Natural pollutants, such as the weathering of rocks, minerals, also affect the water quality. In the current study, samples were collected from randomly selected 30 shallow wells during both the wet and dry seasons and analysed using a portable laboratory kit. Of concern were turbidity, pH, electrical conductivity, calcium, aluminium, magnesium, chloride, sulphates, nitrates, total dissolved solids, fluoride, zinc, calcium carbonate, and salinity. The results were compared with the prescribed water quality standards. From the results, all tested parameters other than turbidity, nitrates and sulphates complied with the recommended quality requirements. The research, therefore, concluded that the shallow groundwater sources in the study area are generally suitable for human consumption except for the shallow well water points which contain high levels of sulphates, nitrates and turbidity. The study found significant spatial variation (p≤0.05) in the physical and chemical characteristics of shallow groundwater resources in the areas, which were attributed to geologic materials and human activities carried out in the study area. Further, statistically significant temporal variations (p≤0.05) were observed in the shallow groundwater for both the wet and dry seasons. The study results also revealed a significant statistical association (p≤ 0.05) between the water quality parameters in the studied areas, which implies that the parameters have a similar source of origin in the environment. Based on the findings, the study proposes training programs for farmers on the sustainable application of quantities of farm inputs in crop production. Regular monitoring of groundwater is necessary to allow the taking of preventive and remedial measures.