Live water & dead water
A number of theories have emerged over the water levels at Lake Kariba and how this has affected power generation at the Kariba South Hydro Power Station. This is because on the surface, there seems to be a lot of water in the lake, hence, it is assumed that water for power generation is available, contrary to @officialzpc’s narrative of the situation.
The Zambezi River Authority website relates that on 8 July 2018 the lake was 86% full and on 8 July 2019, it was on 27%. This is because inflows into Lake Kariba that come from rivers and tributaries flowing from Zimbabwe, DRC & Zambia, were very low due to the drought which affected the region.
Water intakes direct water from the lake into the station for power generation. These intakes were designed at a certain depth, about 13 metres below the maximum water level. They were not located at the bottom in order to avoid ingress of mud which would clogg the generation facilities. This means that only a certain amount of Lake Kariba water is accessible for power generation, and this is known as live water. If the water levels go below the water intake pipes there is no way to access water for power generation, thus, water below the intakes is referred to as dead water because it is unusable for power generation.
The drop in water levels at Lake Kariba has necessitated a reduction of water allocation to @officialzpc and ZESCO, hence, reducing their generation capacities in an effort to ensure electricity generation till the next rainy season.
To manage the running of Lake Kariba and the Kariba Dam, Zambezi River Authority (ZRA), a corporate body was established by parallel legislations from the parliaments of Zimbabwe and Zambia to govern, manage and take care of Lake Kariba.