Groundwater mapping en IWRM in Borena and Jimma Zones in Ethiopia
In the past, many wells drilled in the area of this project were unsuccessful or gave less yield than expected. This was due to lack of proper hydrogeological and geophysical investigations. Acacia Water delivers (shallow) groundwater mapping and Integrated Water Resources Management (IWRM) services as part of a REACH programme. This approach contributes to more successful drillings.
This project focusses on Health-Nutrition-Wash nexus, specifically in the Zones Jimma and Borena (Oromia Region), to grow access to water for local communities, in and around schools at remote areas in Ethiopia. Its implementation is supervised by Engender Health and Amref Health Africa.
Both NGOs aim to strengthen the position of women and children in schools. Within the global research programme REACH, Improving Water Security for the Poor, collaborations are established around this shared goal by delivering world-class science that transforms policy and practice.
The local programme in Ethiopia is financed by the Embassy of the Kingdom of the Netherlands (EKN) to Ethiopia.
Shallow aquifers as a source for clean and safe water
Delivering clean and safe water by utilizing shallow aquifers as a source, is the aim of this project. The study areas are located in Oromia, the country’s largest state comprising approximately 32% of the land. The goal of the project is to drill 2 boreholes for Borena Zone and 10 for Jimma Zone, which were selected through the studies. By now 10 wells are drilled in Jimma, and 2 in Borena.
The story of a single water well drilling
Borena Zone on the south, bordering Kenya, has a landscape of very distinct sceneries. The western part is characterized by volcanic ridges transitioning into plains towards the south. The Zone’s capital, Yabello, is quite different, located at a crystalline basement rock. However, most of Borena Zone is covered by arid to semi-arid vegetation, particularly shrubs, due to its semi-arid climate.
Annual rainfall averages between 600 and 900 mm, with two short rainy seasons: March to May and September to November. However, Borena frequently faces extensive droughts. Last year, 2023, a devastating drought displaced a significant number of pastoralists and caused widespread livestock deaths.
The sites that were selected for the drilling and construction are Dambela Aba Chana and Chabi site. At Dambela Aba Chana, the site situated approximately 27 km east of Yabello, is a high-priority target and was found suitable for shallow well drilling and construction of a water well.
Despite reaching a depth of 51 meters, the borehole was considered too shallow in Ethiopian water well drilling experience. The drilling encountered crystalline basement (metamorphic) rock, which is common throughout the Borena zone and prevents deeper drilling. However, there are some scientific reasons, why this borehole is still considered special.
Identifying optimal (shallow) aquifer locations
In the past, many wells drilled in this area were unsuccessful or gave less yield than expected. This was due to the lack of proper hydrogeological and geophysical investigations.
Acacia Water prioritizes a scientific approach. And procedures to classifying the hydrogeological strata and overall groundwater potential of the area. We do so by Groundwater Mapping.
Groundwater Mapping allows for the identification of optimal shallow aquifer locations, with the potential for exceeding yield expectations, at the most arid and drought affected parts of the country.
The cutting samples of rocks that were collected during the drilling work, serve as crucial verification for the geological, hydrogeological, and geophysical studies.
This comprehensive approach ensures data accuracy and transparency.
Long lasting impact
Beyond the immediate commercial benefit, this type of explorative consulting work establishes a valuable knowledge resource for future endeavors. The data and findings are incorporated in a final report and can be used as input for similar projects or research studies. Thus, promoting long-term knowledge availability and sharing of expertise.
The final outcome: the well at Dembela Aba Chana of Borena delivers a remarkable flow rate exceeding 10 liters per second while maintaining an acceptable salinity range for water scares areas.
This unique geological setting significantly influences the chemistry and quality of the aquifer in comparison to the Dambela Aba Chana site. From the pumping test operation result, the well at Chabi delivered 4 liters per second for a continues 36 hours with optimum drawdown.
The other one is Chabi site at western part of Borena zone. At this area the unique geological setting significantly influences the chemistry and quality of the aquifer in comparison to the Dambela Aba Chana site. From the pumping test operation result, the well at Chabi delivered 4 liters per second for a continues 36 hours with optimum drawdown.
