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Morphodynamic Modelling to Evaluate Flood Hazard Mitigation Strategies

Author(s): Parna Parsapour-Moghaddam, Colin Rennie, Jonathan Slaney

Linked Author(s): Colin Rennie

Keywords: Flood hazard-Morphodynamic numerical model-Gravel bar removal- Flood resiliency-River protection;

Abstract: Central to flood mitigation measurement is the need to understand a river’s morphodynamic characteristics. The spatio-temporal distribution of sediment transport throughout a river impacts river transportation capacity and flow resistance, and thus has important consequences for flood hazard. Gravel bar removal has been employed as an effective flood mitigation strategy. However, at the same time, it can disturb the river’s ecological stability. The present study employs a numerical model to simulate sediment mobilization of the Bow River, which passes through the city of Calgary, Canada. In 2013, the river experienced a catastrophic flood which led to inundation of the downtown core and low-lying areas. Sediment deposition during the flood event resulted in generation of new mid-channel bars. The flood resiliency action plan has identified removal of newly formed gravel bars for flood and erosion management, prior to the growth and development of riparian forests. The present study employs Delft3D to investigate the impact of gravel bar lowering on future flood risk and fluvial habitat. The developed model was calibrated using the measured ADCP data. Detailed channel bathymetry of the river was surveyed prior to and after the flood event; the observed morphodynamic change during the flood is used to validate the numerical model. Calibrated and validated numerical model is then employed to study the impact of gravel bed removal on the future flood hazard. The results of this study could have important implications for the proposed flood mitigation strategies and river protection.

DOI: https://doi.org/10.3850/38WC092019-1083

Year: 2019

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