Maputo — 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 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 lowest 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.

Seasonal rains, which usually fall from October to the end of April aren’t off to a good start, even as the volume of water tumbling over Victoria Falls, known locally as Mosi-oa-Tunya, rose to 252m3 per second by Monday. While that’s more than double the lows reached in November, it’s only slightly better than 234m3 measured this time in 2018, 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 125km to the east. Outflows from Kariba’s turbines were 987m3 per second on December 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 SA Weather Service predict, less-than-normal precipitation for much of the region.