Veterinary

Ascertaining the source of major dissolved solute and recharge mechanism of groundwater in the Golina River Basin, Northern Ethiopia

Hindeya Gebru^1,2*, Tesfamichael Gebreyohannes², and Ermias Hagos^2
1 Department of Earth Sciences, Samara University, Samara, Ethiopia
² School of Earth Sciences, Mekelle University, Mekelle, Ethiopia
*Corresponding author: hindualem@gmail.com 

This study uses major ions and stable water isotopes to understand the solute acquisition, origin, and recharge mechanisms of groundwater of the alluvial deposits (sand and gravels) and weathered and fractured volcanic rocks aquifers in the Golina River Basin (GRB), Ethiopia. The results of the hydrogeochemistry indicates that the solutes of the groundwater are dominantly acquiring by the natural weathering of Ca²⁺ and M^g2+-rich silicate minerals. The study suggest that groundwater preferentially flow through the basalts and little through the acidic rocks which determine the four groundwater facies (Ca²⁺–HCO₃^-, Mg²⁺–HCO₃^-, Ca²⁺–Mg²⁺–HCO₃^-, and Na⁺–HCO₃^-) in the area. Further, there is an ion exchange between groundwater and its host environment during the movement process, creating disequilibrium within the aquifer. Based on the similarity of their hydrochemical properties, the groundwater in the area is grouped into four major groups and four subgroups. The stable water isotopes results suggest that seasonal variances in the slope and intercepts of the local meteoric water line (LMWL) is associated with changes in meteorology and moisture sources, which underlie the subtle variations in δ¹⁸O and δ²H in precipitation over time and space. The seasonal local meteoric water lines of the Golina River Basin were obtained; resulting δ²H = 7.3±4.4δ¹⁸O +8.8±1 for wet season precipitations (months between June and September) and δ²H = 4.5±3.5δ¹⁸O +11.6±1.1 for dry season precipitations (months between October to May). The study further reveals that groundwater exhibits lower slope (5.1±2) and lower intercept (5.6±0.77) than LMWL and that of GMWL, indicating the evaporation of infiltrating meteoric waters before it joining the aquifer system. Therefore, the present study finds that groundwater is recharged from direct infiltration of the precipitation and recharged from the nearby mountainous regions on west and east of the basin.

Keywords: Solute source, groundwater recharge, stable water isotopes, Golina River Basin