Water managers in Africa’s Limpopo and Blue Nile basins are embracing a diversity of storage solutions to benefit people and ecosystems.
Implementing diverse water storage solutions is a cost-effective way of enhancing water security in semi-arid catchments. An integrated storage approach advocated by the CGIAR Initiative on NEXUS Gains is finding favor with water resource managers in transboundary basins, where local storage decisions can have far-reaching basin-wide impacts. Using NEXUS Gains research, managers are able to opt for ‘green’ water storage options as sustainable alternatives to large ‘gray’ infrastructure. The successful application of this approach in two catchments – located in different regions of Africa – demonstrates its potential for larger-scale implementation.
In many of NEXUS Gains’ focus river basins, providing a reliable, year-round water supply is a considerable challenge. Water planners and communities must contend with recurring droughts, seasonal rainfall fluctuations, and land degradation – issue that are exacerbated by climate change and population growth. While large-scale dams and reservoirs are vital infrastructure in some areas, their construction and operation can often have negative impacts on aquatic ecosystems and local communities.
NEXUS Gains has developed a more integrated approach, guided by research in the water–energy–food–ecosystems (WEFE) nexus. Under the Initiative, researchers investigated and promoted diverse water storage solutions for semi-arid regions. Interventions such as small ponds, sand dams, and managed aquifer recharge, operate at a local scale, but in combination they represent sustainable ways to ensure long-term water supply without causing ecological harm.
By assessing the merits of various small-scale water storage solutions – and providing water resource managers with tools, guidelines, training, and facilitation – NEXUS Gains has contributed to strengthening water security in basins that experience complex WEFE challenges. The challenges are especially severe in water-stressed regions of Africa, where the Initiative has collaborated with researchers, water managers, and rural communities in key watersheds.
Two of these watersheds are the Shashe Catchment, a sub-basin of the Limpopo Basin shared by Zimbabwe and Botswana, and the Tana-Beles Catchment, a sub-basin of the upper Blue Nile Basin in Ethiopia. Both regions experience significant seasonal rainfall variation, and over recent decades droughts have become more intense and widespread. Local communities stand to gain a great deal from the approaches promoted by NEXUS Gains – particularly in areas where integrated water storage assessments have never been conducted before, including the entire Tana-Beles Catchment.
NEXUS Gains has worked closely with government departments, water authorities, meteorological offices, watercourse commissions, environmental protection authorities, and research institutions in both catchment countries. At a workshop organized in Zimbabwe by the International Water Management Institute (IWMI) and Dabane, participants showed strong interest in ‘green’ water storage options like sand dams, which are low-cost, effective structures that conserve underground water in the beds of seasonal rivers. Sergio Sitoe, executive secretary of the Limpopo Watercourse Commission, noted the importance of an integrated view: “In terms of the sand dam responding to the community’s needs, it helps a lot. However, there is a need for further investigations to address issues related to river hydrology – upstream and downstream implications, as well as ecological and social impacts, including groundwater-dependent ecosystems.”
“The NEXUS Gains program has provided critical evidence on the contributions of sand dams and other storage types to enable their integration into planning so that water scarcity can be better addressed in the Shashe Catchment.”
Sergio Sitoe, Executive Secretary of the Limpopo Watercourse Commission
Eng. Gilbert Mawere, director of Zimbabwe’s Department of Water Resource Development and Utilization, expressed his appreciation of the research. “The evidence generated from the research on water storage in Shashe Catchment has provided us with critical insights to transform water accessibility and management in our communities,” he said.
In Ethiopia, a similar workshop focused on integrating gray and green water storage solutions efficiently. Debebe Deferso, integrated water resources management lead executive officer at the Ministry of Water and Energy, said, “by providing estimates of water storage in all storage options, this work has supported our future planning toward integrated water storage.” Ayelign Mesafint, deputy head of the Amhara Region Irrigation and Lowland Area Development, also expressed enthusiasm: “I gained insightful knowledge on integrated water storage options and am committed to applying the evidence and experiences in my bureau’s regular work of irrigation dam planning and management, like research and design, operational plan development, and water release exercises.”
The enthusiasm of highly motivated decision-makers in both the Shashe and Tana-Beles catchments represents a significant step toward securing a more water-secure future for these regions. The widespread adoption of this diversified water storage approach, applied across catchments thousands of kilometers apart, underscores its transformative potential. Across Africa, diverse water storage innovations are ready to be taken up by collaborative efforts, integrating them into policy and planning, to build a more sustainable, resilient future.
Header image: Stakeholders attending the Shashe Catchment water storage workshop in October 2024. Photo by Bukiwe M. Sibanda.