A GIS-based assessment of spatial groundwater quality for drinking purposes in Asmara City, Eritrea

Abstract: Presently the water-supply problem in the Asmara area has reached to a critical level. Using a GIS-based method this study identifies the spatial variability of the groundwater quality in the Asmara Area which could be an alternative source. The results show that, the Total Dissolved Solids (TDS), Total Hardness (TH), Chloride (Cl^-), Nitrates (NO₃^-), Calcium (Ca), Magnesium (Mg), Sulphate (SO₄) and pH are 791.71, 569.12, 124.41, 64.46, 155.60, 46.64, 159.26 and 7.72 mg/L, respectively. Moreover, the zone map of the developed groundwater quality shows that the potable water without treatment covers about 35%, and the potable water in the absence of better alternate sources covers about 58% of the total area. The remaining, 7.04% of the total, falls under non-potable groundwater quality. The verification of the spatialanalysis demonstrates that the framework is the first one in Eritrea and could be used as a potential prediction for the assessment of the spatial groundwater quality in the countries with further verification results. Hence, the delineation of groundwater quality zones and establishment of a GIS-based database will easily help the decision makersto monitor and plan the utilization of the groundwater resources in the study area.

Keywords: Groundwater quality; physicochemical parameters; GIS spatial analysis; framework