Conceptualization of the Process of Aquifer Recharge: A Combined Interpretation of Physico-Chemical, Isotopic, and Basic Basin Attributes

Aychluhim Debebe Damtew1, Stefan Wohnlich1
1 Angewandte Geologie, Ruhr-Universität Bochum

P 10.2 in Hydrogeologie arider Gebiete

This study is carried out in the southwestern part of the Main Ethiopian Rift Valley where over 90% of domestic and industrial water supplies are sourced from groundwater yet little is known about the sources and mechanisms of recharge that sustains this resource. Interpretations on physico-chemical properties and isotopic concentrations measured in water samples collected from springs, shallow and deep aquifers, cold, warm, and thermal waters, rivers, and lakes combined with some of the basic basin attributes that majorly influence on the process of aquifer recharge reveal the existence of four different mechanisms of recharge, and atmosphere-derived waters as major sources to replenish the different aquifer systems in the basin. Each of the objectively divided sections of the basin displays different mechanisms by which source waters transport to aquifer systems in the respective sections. Four major groundwater recharge characteristics are identified in the basin that includes structure-controlled and non-structure-controlled recharges. The other recharge characteristics particularly observed in the northern and northeastern parts of the study area take account of the amount of precipitation whereas, the shore aquifers in the southern-half of the basin seen to receive no recharge from the two major tectonic Lakes, rather the shallow aquifers in this zone are recharged in a diffuse mechanism via the unsaturated quaternary covers from atmosphere-derived waters and near-surface-ponded sources in a rather slow rate. A combined mechanism of diffuse and fracture-controlled recharge feeds the deeper aquifers in this shore section.  It could be concluded that these approach help unveil the different recharge mechanisms and sources in areas that are scantily researched and where hydrogeological and hydrological measurements are costly to acquire.



Letzte Änderung 24.03.2014