Evaluation of the Conflict Between Hydropower Generation and Flood Control in The Cahora Bassa Dam, Mozambique

F E Banze; R Ploszai; H D O A Fill
Conflicts often arise for reservoirs with multiple water uses, such as hydropower generation, irrigation, and flood control. While high levels are desired to store water that will be used during the dry season for hydropower generation, low levels in the reservoirs may reduce flood damage. As most hydropower reservoirs are not designed for flood control, the operational planning usually seeks to minimize this conflict with careful allocation of appropriate space in the reservoirs for flood control. The present study compares the benefits provided by a reservoir for flood control versus those of a reservoir for hydropower generation, using a case study at the Zambezi River at the Cahora Bassa dam in Mozambique, Africa. The evaluation of these benefits was made using Monte Carlo simulations with synthetic series of natural inflows. The synthetic series were generated using inflow statistics from 1955 to 2012 at the Cahora Bassa dam. The results indicate that the consideration of flood control spaces in the reservoir results in a reduction of dependable energy, which in turn relies upon the return period considered and the proposed maximum outflow. Considering a return period of 100 years for flood control and 50 years for hydropower generation, an energy loss was observed of: 4 average MW for an outflow restriction of 15,000 m3.s-1; 90 average MW for an outflow restriction of 10,000 m3.s-1; and 196 average MW for an outflow restriction of 8,000 m3.s-1. Therefore, as expected, there is an increase in energy loss for lower outflow restriction.
Hydropower Generation; Flood Control; Synthetic Flow Series Generation
Download | Back to Issue| Archive