The Kamuza barrage on Shire River at Liwonde, Malawi. Photo: World Bank
A huge crowd of demonstrators was around the Mangochi district council (Southern Malawi) on the morning of May 28, 2024, and the next day “Nations Newspaper” (that has a good coverage in Malawi) put in a piece with the title “Open Kamuzu Barrage, We are not Hippos !!”
The Kamuzu barrage (an artificial barrier across a river) was upgraded in 2018 with World Bank IDA financing and the objective to optimize hydropower generation and irrigation requirements downstream on the Shire River, and to better manage Lake Malawi water levels so that overflows and their damage are reduced. River Shire is the only outlet for water from the lake and the barrage is constructed across the river at Liwonde.
At a time when Malawi grapples with consecutive droughts and is projected to get reduced precipitation, the rising water levels of Lake Malawi are raising eyebrows and causing concern. Lake Malawi, the second largest lake in Africa by volume, is part of the Lake Malawi-Shire River System, and is crucial for Malawi's socio-economic development as 98% of Malawi’s electricity generation and irrigation depend on Lake Malawi outflows into the Shire River.
Lake Malawi overflows drop into the Shire River and sustain the flow of the river during the dry season, supporting the country’s hydropower plants. Lake levels depend on rainfall over the lake and runoff from mountainous regions in Tanzania, Malawi, and Mozambique. The critical water level of the lake, after which water will stop flowing out to the river, is called the Lake Malawi Outflow Threshold (LMOT) and is approximately 471.5 meters above sea level (masl). Below 471.5 masl the outflow to the Shire reduces to zero because of a sill near Mangochi. The lake water levels can be, and are, regulated at the barrage, but within a limited range, a margin of 2.22m (between 473.5 masl -475.72 masl). Below the lake water level of 473.5 masl and above 475.72 masl the barrage cannot regulate the water level.
The Kamuzu Barrage was built in 1965 and upgraded in 2018 (with support from the World Bank) to raise the maximum regulated water level by 40 cm and was essential in safeguarding operational integrity and longevity. Managed by the National Water Resources Authority (NWRA), the barrage is operated using the Kamuzu Barrage Operation Model (KABOM), which provides scenarios for water releases based on lake water levels and water demand downstream. The barrage is a very small faucet for a very large basin; it cannot stabilize the lake levels alone and when it does, it does very slowly and indirectly.
| The Hydrology of Lake Malawi in Simple Terms (the analogy) Lake Malawi's water levels result from a simple balance of inputs and outputs: River Inflow (29 km³/year) + Rainfall (39 km³/year) = Evaporation (57 km³/year) + River Outflow (12 km³/year). The lake's volume is 7,725 km³, and any water entering it stays for an average of 110 years. The Faucet: Rising lake levels are mainly due to river inflows and rainfall variations, not the outlet. Climate trends show shorter, intense rainy seasons, increasing runoff into the lake rather than soaking into the soil. The Bath: The lake’s large size and relatively small inflows and outflows mean that changes in water levels are slow and cumulative. The Drain and Its Plug: The river accounts for 17% of the lake's outflow, the barrage affecting just part of this flow. The barrage raises average minimum water level, slightly slowing the decrease in lake levels. However, it has minimal impact on high water levels, which are primarily due to natural variations. |
This year, Lake Malawi has experienced a significant increase in water levels, surpassing observations in the past decade. Levels exceeded historical averages, peaking at 476.38 masl (April 21-25, 2024). NWRA should have released 900 m³ per second according to the KABOM, but instead it released steadily, reaching 1010 m³ (May 11, 2024) stabilizing the water level around 476.19 masl, below the 477 masl threshold set in Malawi’s zoning regulation.
The rising water levels caused significant damage to livelihoods and property in low-lying areas, displacing more than 1,200 families. There was lots of misinformation and misunderstanding about how the barrage works, including about the amount of water it releases under such scenarios. This led to some members of the community mistakenly concluding that the barrage was the source of rising water levels in the lake.
I suppose it is essential to consider what happened, what could have been done differently, missed opportunities, and the way forward. Addressing the rising water levels of Lake Malawi requires a multi-faceted approach to ensure sustainable development and disaster resilience. Key topics that I propose to be considered should include:
- updating the KABOM
- reinforcing and strengthening the operational and regulatory framework
- clarifying the mechanisms to enforce the 477 masl mark
- having a clear communication strategy that is inclusive of all stakeholders.
I think a critical rethink of Malawi's approach to water resources management and restoration of its degraded land is overdue and we must tackle this to ensure the resilience and economic growth of the country.
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