Modelling lowland reservoir sedimentation conditions and the potential environmental consequences of dam removal: Wloclawek Reservoir, Vistula River, Poland

摘要

The decommissioning of dams has been discussed on an international scale in the context of the economic, social, and environmental costs of maintaining aging infrastructure. While dams can provide extensive benefits such as water management, power generation, and flood control, their environmental impacts can be detrimental, and much remains to be characterized. In Poland, there is growing concern about the future of the Wloclawek Dam and Reservoir, located on the Vistula River 110 km northwest of Warsaw. One of Poland's largest reservoirs, it has a volume of 408 million m~3 and an area of 70.4 km~2. This study explores the sediment transport and silting rates for the reservoir using a CCHE2D model and parameters including: channel width, average velocity, average depth, and Froude numbers at the cross-sections of the reservoir. The study findings provide a better understanding of the sedimentary conditions, and permit a precise delineation of three different zones in the reservoir: riverine, transitional, and lacustrine. The potential consequences of dam removal have been modelled and indicate that dramatic changes in hydraulic parameters will result, and a new 22.7 km~2 flood plain may form, which corresponds to 33% of the current reservoir area.