By Walter Nyamukondiwa
Lake Kariba will reach its full mark next year, Zambezi River Authority (ZRA) experts predicted yesterday.
With almost 11 metres to go before the lake is full, and with evaporation losses and the rationed allocations for the power stations, it is exceptionally improbable that the lake could fill this year despite the high inflows from the upper catchment that are now reaching Kariba, ZRA hydrologist Engineer Pherry Mwiinga has said.
Rainfall in the upper catchment, southeast Angola and northwest Zambia, did fulfil projections on the forecast of the Southern African Regional Climate Outlook Forum for the 2019-2020 season and run-off from these areas has been flowing into the lake.
There were very low inflows recorded between October and December because of poorer rains in northwest Zimbabwe and parts of southern Zambia.
Those poor inflows caused the ZRA to initially predict a longer period for the lake to fill, a prediction now being revised as the Angolan flood water finally arrives. Even in normal years, the upper catchment supplies the bulk of the Kariba water, and this year almost all.
Engineer Mwiinga now expects 55,5 billion cubic metres of water to flow into Lake Kariba this year to add to the 10,5 billion cubic metres of “usable water” already in the lake.
The water usable for the power stations is the top 13m of a full lake and while there is still a lot of water below the minimum retention level that water is below the intakes to the power stations.
“Our forecast indicates we may receive up to 55 billion cubic metres as inflows this year.
“That, plus current storage, should give us about 65,5 billion cubic meters. However, take out losses to evaporation at approximately 25 percent of this storage, this leaves us with 49,1 billion cubic metres,” he said. The Herald