NATIONAL GROUND-WATER RESOURCES ASSESSMENT PROGRAM FOR ETHIOPIA

About 26% of the population in Ethiopia have access to an adequate and safe water supply. As competing demands for water increase, ground water is needed to supplement surface-water sources. Regional ground-water data are scarce, and assessment of the coupled, ground- and surface-water systems is needed. To meet this need, a phased National Ground-Water Resources Assessment Program that uses expertise and data from all pertinent Ethiopian agencies, as well as expertise from the U.S. Geological Survey and the International Atomic Energy Agency, has been proposed for the country.

The hydrogeology, topography, and drought susceptibility of Ethiopia varies widely. Much of the western half of the country is characterized by volcanic highlands that receive abundant rainfall during the summer rainy season. Lowland areas, underlain by sedimentary and crystalline rocks in eastern and southern Ethiopia, receive little rainfall and are susceptible to drought. To accommodate this variability, 6 type areas have been selected for study, on the basis of hydrogeologic setting, data availability, and socio-economic requirements, during the first phase of the program. Within these type areas, subareas will be selected for intensive scientific study to better understand the processes that are critical for ground-water development. For example, isotopic analyses may be used to determine sources of water to lakes in the Rift Valley. Additional climatic stations and stream gages may be installed for the development of better water budgets to assess ground-water recharge and discharge. Geophysical methods will be applied to determine horizontal and vertical extent of aquifers and confining units. The knowledge gained in the type area studies will be transferred to other parts of Ethiopia with similar hydrogeology during later phases of the program.

Critical to the success of the program is the creation and maintenance of a national ground-water database and standardized data collection forms and procedures. The database will store information regarding well construction and production, springs, lithology, water quality, water levels, and hydraulic properties.