Use of 222Rn and δ18O-δ2H Isotopes in detecting the origin of water and in quantifying groundwater inflow rates in an alarmingly growing lake, Ethiopia

Authors: Seifu Kebede and Samson Zewdu

Lake Beseka, located within Ethiopia’s Awash Basin, has expanded from 2 km² to 50 km² over the last 60 years, causing serious engineering and socio-economic challenge (inundation of urban utilities, irrigation farms, railways and roads; ecological changes in the lake; and threatening water salinization for water users downstream). This study used Dual Radon (²²²Rn) and δ¹⁸O-δ²H isotopes to (a) detect the origin of water, (b) pinpoint groundwater inflow zones and (c) determine rates of groundwater inflows in an expanding lake in central Ethiopia.