Applications of δ2H and δ18O to Understand the Groundwater System in the Raya Valley, Northern Ethiopia

The study area is located in the northern part of Ethiopia, Horn of Africa. It is Bounded by NW Ethiopian plateau in the west and Afar rift to the east. The study area is intermountain with volcanic rock and the graben is covered with thick sediments. The average elevation for the highland is 2200 m a.s.l, where as average elevation for the central graben and eastern highland is 1600m a.s.l. Bimodal rainfall pattern is observed in the study area. The western highland is classified as humid and the central graben is semiarid climatic condition based on UNESCO, 1979. Primary data collected during the field work includes Rainfall samples, Lake Sample, Deep well samples, Hand dug well samples, and others. Systematic sampling of water for Isotopic analysis. Secondary Isotopic data is adopted from previous study Mamo, 2007. All samples were analysed by Liquid Water Isotope analyser for oxygen-18 and deuterium in the Isotope Hydrology Laboratory of Addis Ababa University.