Influence of dam operation on water resources management under different scenarios in the Zambezi River Basin considering environmental objectives and hydropower: Communication 56 (Laboratoire de constructions hydrauliques, Ecole polytechnique fédérale de Lausanne)

The hydropower potential in Africa is only very few exploited. The large rivers like Zambezi River still have considerable possibilities for installing further hydropower projects including the creation of reservoirs by large dams. The main African watersheds comprise also very vulnerable biotopes as wetlands, floodplains and deltas. This is exactly the case for the Zambezi river basin with its precious Barotse, Lukanga and Kafue flats as well as its large delta region. The question is how operation of the existing hydropower plants and reservoirs would have to be adapted in order to ensure environmental flows able to maintain the essential functionalities of the biotopes. Furthermore new projects should be designed in a way to mitigate as much as possible the negative effects or even to improve the present state. With her research project Mrs Dr. Théodora Cohen-Liechti was confronted with this challenge. In order to give an answer to the mentioned questions, she had to develop a hydraulic-hydrological model in a very a large river basin under data scarcity, which was never done in such a detailed degree before, namely for a daily time step. Furthermore the model comprises all relevant hydraulic structures and schemes as well as vulnerable floodplains. For the latter a new sub-model based on a reservoir approach was specifically developed. Mrs Cohen-Liechti studied by the help of the hydrological model numerous scenarios combining different levels of environmental requirements as well as several future hydropower developments. The analysis showed in principal that a reasonable compromise between energy production and environmental sustainability could be reached. Finally with the comprehensive hydraulic-hydrological model of the Zambezi River including new planned hydropower projects as well as extensions of existing power plants, the impact of climate change on the energy production was analyzed.

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