Abstract
This study aims at hydrodynamic modelling of Bow River, which passes through the City of Calgary, Canada. Bow River has a mobile gravel bed. Erosion and deposition processes were exacerbated by a catastrophic flood in 2013. Channel banks were eroded at various locations, and large gravel bars formed, which could lead to water level changes and accordingly more flooding. This study investigates the performance of Delft3D-Flow and MIKE 21 FM to simulate the hydrodynamics of the river during the 2013 flood. MIKE 21FM employs unstructured triangular mesh while Delft3D-Flow model uses curvilinear structured grids. Performance of each model was evaluated by the available historical water levels. The results of this study demonstrated that, with approximately the same averaged grid resolution, MIKE 21 FM resulted in more accurate results with a higher computational cost compared to the Delft3DFlow model. It was shown that Delft3D-Flow model may require higher grid cell resolution to result in comparably same depth-averaged velocities throughout the study area. However, considering the balance between the computational cost and the accuracy of the results, both models were capable to adequately replicate the hydrodynamics of the river during the 2013 flood. Results of statistical KS and ANOVA test analysis showed that the model predictions were sensitive to the horizontal eddy viscosity and the Manning roughness. This confirms the necessity of an appropriate calibration of the generated numerical models. The findings of this study shed light on the Bow River flood modelling, which can guide flood management.
Highlights
Bow River is one of the major natural streams in Calgary, Canada that provides the local communities with valuable functions such as source for water supply, waste water receiving water, recreational purposes, etc
As it can be seen, both models show almost comparable water levels relative to the measured data, the results of MIKE21 FM seems to be closer to the measured water levels
MIKE21 FM led to the lower amount of error statistics of the water level simulation
Summary
Bow River is one of the major natural streams in Calgary, Canada that provides the local communities with valuable functions such as source for water supply, waste water receiving water, recreational purposes, etc. In order to study rivers in flood events, the unsteady state flow conditions should be simulated to consider the flood hydrographs. To this end, the shallow water flow equations, which are governed by law of conservation of mass and momentum, should be solved. The capability of these models in modelling extreme flood events in large rivers is sought This assesses the capability of the models in simulation of a flood hydrograph in an unsteady-state flow condition. It reveals the practicality and suitability of these models in river management.
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