Identification of groundwater type and recharge estimation through hydrochemical analyis: A case study in ayanalem well field, Northern Ethiopia

The study focused on groundwater type identification and groundwater recharge estimation through hydro chemical analysis in Aynalem well field Northern Ethiopia. Aynalem wellfield is the main source of water for domestic water supply of Mekele town, capital of Tigray regional state. From the hydro chemical data analysis, there exist at least two classes of water types in Aynalem catchment. Ca-HCO₃ dominated water type at the upper catchment and Ca-SO₄ dominated water type at the lower western extreme of the catchment are present with a clear evolutionary trend between the two types. The groundwater in the area is pumped with little consideration to groundwater recharge and effects of climatic forcing on the recharge. The main recharge mechanism considered was direct recharge from rainfall. Annual recharge of 30–40 mm (4.5–6% of the average annual rainfall) is estimated by applying the Chloride mass balance method.