© Photographer: JEKESAI NJIKIZANA/AFP Flood gates on the Kariba Dam wall between Zimbabwe and Zambia open ceremonially on February 20, 2015 after the two neighbors signed $294 million in deals with international investors. T

(Bloomberg) --

The Kariba dam has plunged to its lowest level since 1996, raising further risks to the hydropower plants that Zimbabwe and Zambia depend on for nearly half of their power.

Water levels at the world’s largest man-made freshwater reservoir that straddles the two countries, fell to 10% of usable storage, according to data posted on the Zambezi River Authority’s website. That’s the least since 1996 and worse than the 11% recorded during a drought in 2016.

Large parts of Zambia and Zimbabwe are experiencing the worst drought in at least four decades, forcing the nations to cut generation from Kariba after water flows fell sharply in the Zambezi river that feeds it. Each country has implemented power cuts lasting as long as 18 hours a day as a result.

The two nations’ economies have suffered. Zambia’s will grow by less than 2% this year, the lowest in more than two decades, while Zimbabwe’s economy will contract by 7.1%, according to the International Monetary Fund.

Seasonal rains, which usually fall from October through April aren’t off to a good start, even as the volume of water tumbling over Victoria Falls rose to 252 cubic meters per second by Monday. While that’s more than double the lows reached in November, it’s only slightly better than 234 cubic meters measured this time last year, which ended up being one of the worst seasons on record.

The flows at Victoria Falls are a good indication of how much water is entering Kariba as there aren’t any major tributaries before the Zambezi reaches the dam about 125 kilometers (78 miles) to the east. Outflows from Kariba’s turbines were 987 cubic meters per second on Dec. 8, nearly quadruple the amount of water flowing into the dam.

Zambia’s meteorological department forecasts normal to better-than-normal rain for the current season, but international forecasters including the South African Weather Service predict less-than-normal precipitation for much of the region.

(Updates with impact on economies in fourth paragraph)

--With assistance from Taonga Clifford Mitimingi.

To contact the reporter on this story: Matthew Hill in Maputo at mhill58@bloomberg.net

To contact the editors responsible for this story: Gordon Bell at gbell16@bloomberg.net, Alastair Reed

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