Improving the safety of Kariba Dam
© 2013 EPFL
Heavy seasonal rains in the Zambezi catchment feeding Lake Kariba, on the border between Zimbabwe and Zambia, have repeatedly forced authorities to open the gates of the spillway to prevent the Kariba Dam from uncontrolled overtopping.
The excess water gushes out of the orifices as high-velocity jets with such force that, over time, it has gnawed a hole over 80 meters deep into the riverbed, threatening to undermine the dam’s foundations if left unchecked. Thanks to their reputation accrued over the past decades in studying the process of rock scour at civil hydraulic structures, ENAC’s Hydraulic Constructions Laboratory was mandated to find a solution to attenuate the destructive scouring of the Kariba riverbed. Professor Anton Schleiss and his team used a hybrid numerical and physical modeling approach to test and validate a solution, which they have submitted to the Zambezi River Authority. The solution proposed involves reshaping of the geometry of the scour hole in the downstream direction to reduce pressure fluctuations of the impacting jets and achieve stable conditions without scouring.