Author(s): Paolo Ronco; Giacomo Fasolato; Giampaolo Di Silvio
Linked Author(s): Giampaolo Di Silvio
Keywords: Sediment transport; Linear transport; Long term morphodynamics; Data uncertainty; Reservoir sedimentation
Abstract: The Cahora Bassa reservoir, located in the Southern Africa continent on the Lower Zambezi River, is quite large (capacity of 72, 500 106 m3) but interested by an heavy sediment input. The river downstream the dam is likely to be strongly affected by the presence of the impoundment, possibly down to the delta. Two different morphodynamic models (a uniformflow model, STE. RI. MOR., and a steady-flow model, PLA. RI. MOR. ) have been compared for studying the long-term evolution of the Lower Zambezi, with and without the presence of the dam. The linearized waterflow and sediment transport equations have been analytically solved under the hypothesis of quasi-equilibrium conditions. This solution permits to reconstruct the river bathymetry from the planimetric data, the only ones available for the Zambezi River. The same solution, moreover, allows to incorporate in the STE. RI. MOR. model an approximate form of the non-uniform flow. The numerical simulations show that all models provide very similar results, no matter the non-uniform effects and the space-resolution adopted in the models. By contrast, the results depend substantially on the sediment input from the upper Zambezi and from the tributaries.