Location: Watershed Physical Processes ResearchTitle: Simulation of sediment transport due to dam removal and control of morphological changes
|DING, YAN - University Of Mississippi|
Submitted to: International Conference on Hydroscience and Engineering (ICHE)
Publication Type: Proceedings
Publication Acceptance Date: 7/5/2014
Publication Date: 9/28/2014
Citation: Ding, Y., Langendoen, E.J. 2014. Simulation of sediment transport due to dam removal and control of morphological changes. In: Proceedings of the International Conference on Hydroscience and Engineering (ICHE). Sep 28 - Oct 2,2014, Hamburg, Germany, pp. 1127-1135.
Interpretive Summary: Across the United States more than a thousand dams have been removed or are planned to be removed within the near future, often to improve in-stream habitat or due to decommissioning. Removal of a dam may cause significant erosion of the sediment stored within the former reservoir, which may adversely impact downstream aquatic habitat. Scientists at the USDA, ARS, National Sedimentation Laboratory and the University of Mississippi have developed the one-dimensional channel evolution computer models CONCEPTS and CCHE1D to assess the effects of dam removal and drawdown scenarios on reservoir sediment erosion, channel forming processes, and downstream sediment transport rates. CCHE1D was used to assess the long-term morphological response of the Sandy River, OR, to the removal of Marmot Dam. Simulation results showed a persistent erosion of the coarse-grained sediments from the reservoir over a 10-year period with the eroded sediments moving downstream in the form of a wave. CONCEPTS was used to study the sediment dynamics in the Kalamazoo River, MI, over a 37-year period after removal of the Plainwell and Otsego City dams. Removing the dams would increase sediment loads twelve fold by rapidly eroding the fine-grained sediments stored behind the Otsego City Dam. Further, a simulation-based optimization tool with multiple objectives and constraints was developed for finding the optimized sediment release and relocation during the process of dam-removal. Combining this optimization tool with models such as CCHE1D and CONCEPTS facilitates sediment management at the watershed scale, which can be used by federal and state agencies, such as the US Geological Survey, the US Bureau of Reclamation, the US Corps of Engineers, the Natural Resources Conservation Service and the US Environmental Protection Agency, or private industry to minimize the downstream impact of dam removal and duration of elevated sediment concentrations caused by sediment evacuated from the reservoir.
Technical Abstract: This paper presents two case studies of post dam removal sedimentation in the United States. Two different one-dimensional channel evolution simulation models were used: CCHE1D and CONCEPTS, respectively. The first case is the application of CCHE1D to assess the long-term (up to 10 years) morphological response to the removal of Marmot Dam in the Sandy River, Oregon. Simulation results showed a persistent erosion of sediments from the reservoir over the 10-year period; the eroded sediments travel downstream as a wave. Further, it was found that the runoff will greatly affect the rate of morphologic adjustment. The second case is a CONCEPTS study of the sediment dynamics over a 37- year period after removal of the Plainwell and Otsego City dams along the Kalamazoo River, Michigan. Removing the dams would increase sediment loads twelve fold by rapidly eroding the fine-grained sediments stored behind the Otsego City Dam. Finally, to minimize morphological changes in the river reaches downstream of the dam site, this paper also showed the benefits of applying a simulation-based optimization tool with multiple objectives and constraints for finding the optimized sediment release and relocation during the process of dam-removal. Combining the presented optimization tool with models such as CCHE1D and CONCEPTS should be extended to manage sediment at the watershed scale.