Identifying recharge areas for the upstream portion aquifers of Awash Basin, Ethiopia

Abstract

Study area: The western and eastern flanks of Ethiopia's Awash and Abay Basins, respectively. Study focus: Identifying recharge zones of the main aquifers in the Upper Awash Basin, which are water resources targeted for long-term sustainable use. In this work, lithohydrostratigraphic concepts with fracture density, hydrogeochemical and stable isotopic insights were applied using information from 94 water-supply wells, 188 geoelectrical resistivity, 124 hydrochemistry, and 81 stable isotopic data sets. New hydrogeological insights of the area: The results illustrate that recharge of superficial deposits and Rift basalt aquifers is from modern precipitation and from nearby streams/rivers through fractures, which is exemplified by mixed CaHCO3 or CaMgHCO3 water types of low TDS (5), low RA (468 mg/l), low Ca/Na ratio (2.0), highly depleted isotopic signals, and low deuterium excess (<11) relative to the Local Meteoric Water Line. The results also reveal groundwater flux from the adjacent eastern flank of Abay Basin.

Keywords

• Aquifers
• Recharge area
• Groundwater chemistry
• Stable isotopes
• Part of the Upper Awash Basin
• Ethiopia