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Case Study of Flood Profile Hydraulic Modeling Uncertainty
Estimating flood profiles using hydrological inputs and hydraulic modelling is a central component of floodplain mapping studies. Flood profile estimates are subject to several sources of uncertainty, the evaluation of which should be included in any floodplain mapping study. There is knowledge uncertainty in the model and its parameterization, and natural variability in the river system in time and space. In Canada, uncertainty is typically addressed by adding freeboard to design flood profiles. However, freeboard standards may not adequately address uncertainty, and might lead to a false perception of additional safety levels. This case study presents a flood profile uncertainty analysis of the Riverbottom Road reach of the Cowichan River, located on Vancouver Island. The overall results of the uncertainty analysis were used as a defensible basis for design freeboard selection in the 2020 floodplain maps. Geomorphic uncertainty informed the maps’ recommended review frequencies and other triggers for future floodplain mapping updates. The analysis identified spatial variability in uncertainty. Incised and confined sub-reaches displayed the highest uncertainty, while reaches with wide unconstrained floodplain areas displayed the lowest uncertainty. This result has implications for dike infrastructure resiliency and freeboard selection in the face of future climate change uncertainty.
Case Study of Flood Profile Hydraulic Modeling Uncertainty
Estimating flood profiles using hydrological inputs and hydraulic modelling is a central component of floodplain mapping studies. Flood profile estimates are subject to several sources of uncertainty, the evaluation of which should be included in any floodplain mapping study. There is knowledge uncertainty in the model and its parameterization, and natural variability in the river system in time and space. In Canada, uncertainty is typically addressed by adding freeboard to design flood profiles. However, freeboard standards may not adequately address uncertainty, and might lead to a false perception of additional safety levels. This case study presents a flood profile uncertainty analysis of the Riverbottom Road reach of the Cowichan River, located on Vancouver Island. The overall results of the uncertainty analysis were used as a defensible basis for design freeboard selection in the 2020 floodplain maps. Geomorphic uncertainty informed the maps’ recommended review frequencies and other triggers for future floodplain mapping updates. The analysis identified spatial variability in uncertainty. Incised and confined sub-reaches displayed the highest uncertainty, while reaches with wide unconstrained floodplain areas displayed the lowest uncertainty. This result has implications for dike infrastructure resiliency and freeboard selection in the face of future climate change uncertainty.
Case Study of Flood Profile Hydraulic Modeling Uncertainty
Lecture Notes in Civil Engineering
Walbridge, Scott (editor) / Nik-Bakht, Mazdak (editor) / Ng, Kelvin Tsun Wai (editor) / Shome, Manas (editor) / Alam, M. Shahria (editor) / El Damatty, Ashraf (editor) / Lovegrove, Gordon (editor) / Valsangkar, Nathan A. (author) / McLean, David G. (author)
Canadian Society of Civil Engineering Annual Conference ; 2021
Proceedings of the Canadian Society of Civil Engineering Annual Conference 2021 ; Chapter: 16 ; 183-195
2022-06-03
13 pages
Article/Chapter (Book)
Electronic Resource
English
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