Full Text: Update On Water Levels At Lake Kariba

The Zambezi River Authority has given an update on the water levels at Lake Kariba.

We publish the update, the first of 2023, below;

Lusaka, 16^th February 2023 – The Zambezi River Authority (the Authority) hereby updates the public regarding the water situation in the Kariba Catchment and lake levels at the Kariba Dam. This is the first update for the year 2023.

Lake Levels Recorded at Kariba

It is worth noting that the lake level at Kariba, which had been in recession in the last quarter of 2022, has been rising steadily following the onset of rains on and around the lake and Zambezi River Upper Catchment.

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The year 2023 commenced with a low lake level of 475.61m or 0.83% of live storage available for power generation on 1^st January 2023. This was an increase from the lowest record of 475.60m (10cm above the Minimum Operating Level-MOL) recorded on 30^th December 2022.

 

From this lower lake level, the level now increased to 476.85m recorded today, 16^th February 2023 which translates to 6 Billion Cubic Meters (BCM) or 9.32% of stored usable water meant for power generation by the two utilities – ZESCO Limited and Zimbabwe Power Company (ZPC) at Kariba North Bank Power Station and Kariba South Power Station, respectively.

This level translates to a rise of 1.24m from the level recorded on 1^st January 2023. The current lake level of 476.85m, therefore, places the lake at 1.35 meters above the Minimum Operating Level (MOL) of 475.50m.

Hydrological and Climate Outlook 

According to the Africa Rainfall Climatology (ARC) Rainfall Estimator (RFE) of the Climate Prediction Center (CPC) of the United States of America, the Kariba Catchment can be said to have received normal rainfall over most parts of the Upper Catchment and normal to below normal over the larger part of the Lower Catchment during the last 90 days of the 2022/23 rainfall season (November 2022 to February 2023).

This outcome is in sync with the seasonal rainfall outlook prediction by both the CPC and the SADC Climate Services Centre’s 26^th Southern Africa Regional Outlook Forum (SARCOF-26) and the downscaled forecasts of the Meteorological Departments of Zambia and Zimbabwe, of normal to above normal rainfall over Southern Africa in general, and the Kariba Catchment in particular. This situation has resulted in generally average inflows into Lake Kariba during this period, which, coupled with the controlled power generation outflows, has been responsible for the increasing water levels at Kariba Dam.

The CPC rainfall outlook for the next 7 days indicates a 50% – 65% chance of receiving above normal rainfall over the whole of the Lower Catchment while the Upper Catchment is expected to receive below normal rainfall during the outlook period.

Zambezi River Flows as Monitored at Chavuma Gauging. 

Zambezi River flows monitored at Chavuma rose to 2,338 m³/s on 27^th January 2023 before receding and oscillating around 1,600 m³/s up today, 16^th February 2023 when they posted 1,538 m³/s. This is another recovery from 489m³/s recorded on 1^st January 2023. On 16^th February 2022, the river flows were lower at 1,192 m³/s. 

River flows at this hydrometric station are expected to keep rising to the end of the first quarter of 2023.

Zambezi River Flows as Monitored at Victoria Falls Gauging Station

The river flow recorded at the Victoria Falls on 1^st January 2023 was 502 m³/s. The level has since risen to 1,412 m³/s recorded today, 16^th February 2023. On the same date in 2022, the river flow was lower at 989 m³/s.

The flows are projected to continue rising and reach the peak in the second quarter of 2023.

Current Hydrological Situation and water utilisation 

The Authority highlights that whereas the Kariba Catchment has generally received the predicted rainfall amounts, it is noteworthy that a significant increase in the Kariba Dam water level will only start being recorded between April to June 2023 which is the period during which the waters from the Barotse Floodplains greatly influence water levels at Lake Kariba. Despite the reasonably good rainy season and in light of the expected peak lake inflows that will only be realized during the period indicated above, water allocation to the two power utilities will not be increased in the short term.

Commendably, both power utilities have adhered to the guidance from the Authority, that is, capping average generation at each of their respective power stations at 250MW in December 2022 and as recently reviewed upwards to the 350MW cap obtaining currently. This generation output will be maintained while the hydrological outlook at Kariba continues to be reviewed during the weekly Joint Technical Committee (JTC) meetings between the Authority and the two Kariba power generation utilities under the auspices of the Joint Technical Committee.

2023  Water Allocation for Power Generation operations at Kariba Dam

The Zambezi River Authority allocated 40 BCM of water to cater for power generation operations at Kariba for the year 2023. This allocation is being shared equally between ZESCO Limited and Zimbabwe Power Company (ZPC) for their respective power generation operations at Kariba. 

In partial fulfilment of its mandate, the Authority will continue to monitor the hydrological outlook in the Kariba catchment and where necessary, adjust this water allocation in an effort to sustain reservoir operations at Kariba.

The Zambezi River Authority is a Bi-National organization mandated to contribute to the economic, industrial, and social development of the Republics of Zambia and Zimbabwe by obtaining the greatest possible benefits from the natural advantages offered by the waters of the Zambezi River (between Zambia and Zimbabwe) through the most economical and effective means of providing water for generation of electricity and for other purposes which the Contracting States may decide upon.

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