NEXUS Gains
Limpopo and Incomati Basins
Background
The Incomati and Limpopo basins face extreme water stress due to high levels of water resources development. Increasing climate variability challenges the ability to balance the water requirements of multiple sectors. Frameworks for coordinating the use of water resources across borders exist but have not been fully harnessed.
The Incomati flows through Eswatini and South Africa into Mozambique. Around half of its water is extracted for human use, particularly for sugarcane production and processing; there is limited discharge from the basin. The Incomati also contains numerous dams and covers part of Kruger National Park. While a 2002 tripartite water allocation agreement exists, the agreement is interim and will soon be updated to better match available water resources and current water demands. The Incomati and Maputo Watercourse Commission (INMACOM) was formed in 2021 to promote cooperation between member states to ensure the equitable development, protection, and sustainable utilization of water resources.
The Shashe, shared by Botswana and Zimbabwe, is a sub-basin of the Limpopo River Basin. Although it receives relatively high annual rainfall for this region, precipitation is highly seasonal, rendering virtually all the basin’s rivers and streams ephemeral. Storing water during periods in which the rivers are dry, is thus key. Most good sites for large dams have been developed, however, and the degree to which green infrastructure options are integrated into storage planning is unclear. It is critical to support planning that draws on the full suite of storage options, from large dams to aquifers to soil moisture, to enhance water security in the basin.
NEXUS Gains’ work in this water-stressed region focuses on data collection, analysis, and modeling to understand more about water flow and storage, and how these impact – and are impacted by – water allocation policies, infrastructure planning, and climate change.
Although the Incomati and the Shashe span international borders, they cover relatively small areas, meaning that this work can have significant and practical impacts, particularly when effective platforms for transboundary collaboration have been established.
Our work
NEXUS Gains works in Botswana, Eswatini, Mozambique, South Africa, and Zimbabwe to foster climate resilient and equitable approaches to water resource use. The Initiative recognized the creation of INMACOM as an opportunity to improve water allocation and has created a modeling tool that can support decision making. Likewise, multi-stakeholder platforms (MSPs) build capacity in using the tool and foster transboundary collaboration in the Incomati. In the Shashe, research on integrated water storage – from gray to green – addresses the increasing climate variability and growing pressure on water resources and lays the foundations for the planning of more optimal storage mixes.
Work Package 1: Trade-off analyses and foresight methodologies
In the Incomati, NEXUS Gains has developed a model that can be used by INMACOM to support basin-wide decision making. The model was co-developed with the University of Manchester, based on their Python Water Resources (Pywr) tool, as well as with young professionals from the countries. Data has been collected and fed in, and the tool can model how much water is diverted to each sector and state, how much water remains available for future activities, and the potential downstream impacts of basin development activities.
Workshops held with stakeholders in the three countries focused on the development of the model, discussed the required data, and strengthened local capacity to use the tool. Modeling results that demonstrate the degree to which different sectoral needs can be satisfied according to different scenarios will be presented in future workshops, and representatives from each WEFE sectoral group will be able to discuss what satisfies the majority of preferences.
The model will enable greater foresight, and the ability to understand the many variables that influence flow. While the interim agreement defined annual minimum flow requirements, the new tool could enable monthly modeling, according to seasonal and climate variations, as well as population growth and increased economic activity. The model identifies synergies and trade-offs which will impact resource users throughout the catchment. Rather than the traditional approach of transboundary water division, it is hoped that the model will support decision makers to allocate the water in a more dynamic, equitable, and sustainable way.
Work Package 2: Water productivity and storage
In the Shashe Basin, NEXUS Gains supports broadening storage planning from gray infrastructure, such as conventional large dams, to both green and gray infrastructure for water storage. Included in the storage options under consideration are groundwater aquifers, large dams, sand dams, conventional small dams, and soil moisture.
NEXUS Gains carried out a storage assessment to capture the potential volume of water storage available in dams, groundwater, and soil, and a mapping exercise to identify potential storage options. It is hoped that this work will encourage a shift in the way water storage is planned. An integrated water storage workshop, with actors from across different levels within Botswana and Zimbabwe, as well as the Limpopo Watercourse Commission (LIMCOM), wrestled with results of initial assessments, discussed how to get integrated storage into planning, and identified opportunities for further research.
Work Package 4: Strengthening nexus governance
NEXUS Gains has begun to design a basin-level MSP in the Incomati Basin to complement its Pywr tool and encourage stakeholder engagement and feedback on the results. The MSP is envisioned to bring together actors from WEFE sectors, including sugar estates, small scale farmers, commercial irrigators, and Kruger National Park. Each of these will be impacted in some way by the modeling and resulting decisions regarding water storage, use, and allocation. The basin-wide MSP will serve as a conduit to channel stakeholder preferences through to INMACOM.
Work Package 5: Developing capacity for WEFE actors, including women leaders
NEXUS Gains completed a survey of WEFE Nexus teaching in several technical colleges and universities in South Africa. Intensive summer schools were run in partnership with the University of KwaZulu-Natal and the University of Delft to build participants’ understanding of the WEFE Nexus concept.
Contact
Jonathan Lautze, Research Group Leader: Integrated Management of Basins and Aquifers, IWMI
Email: j.lautze@cgiar.org
Find out more
Read about the Initiative’s work in other target basins: