Looking at the graph for Kariba water levels below it would appear that something happened in December 2014 or January 2015 increasing the draw down by about 0.75m per month (opening of the new Zambian station?). This means that the extra draw down since January will be in the region of 7.5m beginning November and 8.25m beginning of December. If you put that on the graph the lake will be at minimum operating level sometime in November 2015. So the generators will have to be switched off until January/February when we can expect inflows again. With inflows over previous draw downs averaging 0.5m per month from beginning January to end June it seems that whatever increased the draw down is unsustainable.
If whatever caused this extra draw down is stopped immediately we might just make it to the next inflows in January with about a metre to spare.