Hydrogeochemical characterization of groundwater in mountainous catchment and its suitability for drinking purposes in Irob, Tigray, Northern Ethiopia

Abstract

The primary source of drinking water in Ethiopia's semi-arid mountainous regions is groundwater. The present study aims to assess the hydrogeochemical characteristics of low-grade basement rocks dominated by mountainous catchments. Moreover, it examines the suitability of the groundwater quality for drinking purposes in Irob, Tigray, northern Ethiopia. However, relatively little is known about the water chemistry and groundwater quality of the resources in the area. Fifteen samples of groundwater were collected and examined for ions according to standard procedures. The outcomes were assessed against the World Health Organization (WHO) requirements for water drinking quality. To identify the source of dissolved ions and the process involved, graphic interpretations were applied. The results show that Ca–Mg–SO4–HCO3 and Ca–SO4–HCO3 were the dominant water types. Gibbs plots and ionic ratios reveal that silicate weathering, carbonate dissolution and ion exchange control water chemistry. Furthermore, the findings reveal that 60, 80, 46.67, 46.67, 60, 6.67, 60 and 53.33% of samples are above the safe limits of the WHO for hardness, alkalinity, total dissolved solids, electrical conductivity, calcium (Ca2+), potassium (K+), bicarbonate (HCO3-) and sulfate (SO42-), respectively. Consequently, the groundwater quality assessment demonstrates that the water sources in lower parts of the catchment are unsuitable for drinking.