Climate change is increasing the competition for freshwater resources in the Zambezi River Basin, as CDKN's Miren Gutierrez reports.

The Zambezi River Basin is home to about 40 million people who depend on the river for fish, drinking water, agricultural irrigation, electricity production, mining, and other uses. Yet until recently, nobody had thought of examining how these competing uses might be impacted by climate change, and how this could affect some of the most important regional energy investments – hydropower plants on this shared river.

One of the challenges has been putting hydropower production in the river basin management equation, says Randall Spalding-Fecher, Project Research Director of ‘Climate Change and Upstream Development Impacts on New Hydropower Projects in the Zambezi’. This project was funded by CDKN and implemented from 2012 to 2014 by a consortium led by University of Cape Town’s Energy Research Centre, including Centre for Energy Environment Engineering Zambia, University of Zambia, University of Eduardo Mondlane, Pöyry, and OneWorld Sustainable Investments.

“While investment in power supply is catching up, the gap between electricity supply and demand in the region persists”, says Mr. Spalding-Fecher. “There is huge potential for Southern Africa to develop hydropower production as part of increasing supply, which has not kept up with population increases and economic growth. Electrification levels in many countries of the region are still some of the lowest in the world and power shortages frequently impair regional economies.”

“There are many hydropower plants in the pipeline, but the planning for these rarely considers climate change in any meaningful way and often ignores potential increases in upstream demand for other uses. Some of these plans are outdated; their designs were formulated based a historical climate that will be quite unlike the future climate", he adds. "Although there uncertainties in the absolute magnitude of changes, we know that there is the potential for dramatic changes in rainfall patterns in Southern Africa in the next 30 or 40 years, and these hydropower plants are  expensive, long-term commitments.”

Projected climate change, economic and urban development, and population changes are expected to have sweeping consequences in the Zambezi River Basin. That is why, in 2012, CDKN set out to develop a spatial water allocation model for the Zambezi River Basin that would include hydropower plants and other infrastructure vulnerable to climate change (e.g. irrigation).

The idea was to provide scientifically robust and integrated information and tools to allow policy-makers to make informed choices on how they might respond to the impacts of climate change, and how current development plans might need to change. The objective of this work was to assess how upstream changes in climate and irrigation demand would affect water availability for major downstream hydropower plants. The analysis covered major existing plants (including the Kariba dam, on the border between Zambia and Zimbabwe, and the Cahora Bassa dam, in Mozambique), extensions to existing plants, and major new plants (such as the Batoka Gorge dam, also on the Zambia–Zimbabwe border).

The analysis showed that some of these new investments are vulnerable to potential drying climate. Some new investments, such as Batoka Gorge, might struggle to produce their target output under either a wetting or drying climate.  For others, the combined effect of climate change and “prioritising irrigation demand in the upstream catchments could compromise hydropower output”, says a policy brief summarising the findings. “Over time, the combined effects of climate change and the competing uses accumulate, and these effects are more pronounced further downstream in the basin”, says Mr. Spalding-Fecher.

A final report looking at the water supply and demand scenarios warns that, ‘while future climate is subject to scientific uncertainty, the impact of irrigation is a policy uncertainty. This both because the level of irrigation investment is driven by political and economic priorities, but also because the priority given to irrigation demand versus hydropower demand for water is a political decision.’

The report offers scenarios testing the impact of different future climates and levels of irrigation development assuming that both hydropower is prioritised over irrigation, and the opposite. The reason for exploring these alternatives is not to arrive at a single ‘right’ answer, but to show the implications of different decisions and possible futures.

During this first phase of the project, CDKN sought to generate buy-in among stakeholders, including the Zambezi River Authority (ZRA), The Southern African Power Pool (SAPP), and the Zambezi Watercourse Commission (ZAMCOM), and SADC Energy, among others.

“But we knew this was not sufficient. This (first) phase looked at individual plants, but not at the entire power system”, says Spalding-Fecher. Phase 2 will address impacts on national and regional electricity grids, by “linking water modelling with a regional electricity model in a way that is sophisticated enough to include robust projections, but user-friendly for decision-makers”. With World Bank’s financial support, Mr. Spalding-Fecher and his team are leading this second phase.

Challenges ahead…

The Zambezi is the fourth-longest river in Africa, and its basin covers about 1.37 million square kilometres across eight countries: Angola, Botswana, Malawi, Mozambique, Namibia, Tanzania, Zambia, and Zimbabwe. Transboundary management of these shared water resources has been an ongoing challenge.

“Water management in the basin is especially difficult because countries have multiple and competing interests; inadequate basin-level institutional structures; institutional, legal, economic, and human resource constraints; poor data collection, poor communication; and inadequate training”, say Christine J. Kirchhoff and Jonathan W. Bulkley in a paper published in 2008.

In fact, one of the main challenges, according to Mr. Spalding-Fecher, is coordination. For example, so far the project has had ‘nointeraction’ with the African Ministers’ Council on Water (AMCOW) –formed in 2002. “There is a long way to go in terms of coordination both across sectors and between different levels of governance (e.g. regional, sub-regional, national, basin/sub-basin)”.

Mr. Spalding-Fecher groups the existing challenges into three categories: institutional, policy-related, and technical.

“More institutional dialogue and communication is needed across sectors and countries. For example, the energy people need to talk to food people, etc.”, he says. “There is some level of dialogue across most sectors, but the energy sector tends to be less connected to any of the others. We need to bridge that gap.” There is the challenge of enabling structures, and bilateral and multilateral agreements, and policy. And there is the need for technical analysis and decision support tools to inform those discussions. Until now, there was some data and modelling available, but “they were not integrated and user-friendly enough to support that work, and were often not in the public domain”.

The solutions need to work across sectors, but also across scales. Mr. Spalding-Fecher mentions one example: “One decision we had to make was whether to look at water use by mining across the entire basin or not. At a local level, it is big issue in the Northern Zambia, where copper is mined. But if you look downstream, the other flows are large enough that mining is unlikely to impact major downstream investments … There is a historic lack of coordination across sectors and across scales. You need to look at how you use regional agreements to facilitate the best choices at national and local levels.”

Image: Zambezi, courtesy Mags pics for everyone, flickr.com