<abstract xmlns="http://www.w3.org/1999/xhtml"><p>Shallow-water models are standard for simulating flow in river systems during floods, including in the near-field of sudden changes in the topography, where vertical flow contraction occurs such as in case of channel overbanking, side spillways or levee overtopping. In the case of stagnant inundation and for frontal flow, the flow configurations are close to the flow over a broad-crested weir with the trapezoidal profile in the flow direction (i.e. inclined upstream and downstream slopes). In this study, results of shallow-water numerical modelling were compared with seven sets of previous experimental observations of flow over a frontal broad-crested weir, to assess the effect of vertical contraction and surface roughness on the accuracy of the computational results. Three different upstream slopes of the broad-crested weir (V:H = 1:<italic>Z</italic><sub>1</sub> = 1:1, 1:2, 1:3) and three roughness scenarios were tested. The results indicate that, for smooth surface, numerical simulations overestimate by about 2 to 5% the weir discharge coefficient. In case of a rough surface, the difference between computations and observations reach up to 10%, for high relative roughness. When taking into account mentioned the differences, the shallow-water model may be applied for a range of engineering purposes.</p></abstract>

Shallow-water models are standard for simulating flow in river systems during floods, including in the near-field of sudden changes in the topography, where vertical flow contraction occurs such as in case of channel overbanking, side spillways or levee overtopping. In the case of stagnant inundation and for frontal flow, the flow configurations are close to the flow over a broad-crested weir with the trapezoidal profile in the flow direction (i.e. inclined upstream and downstream slopes). In this study, results of shallow-water numerical modelling were compared with seven sets of previous experimental observations of flow over a frontal broad-crested weir, to assess the effect of vertical contraction and surface roughness on the accuracy of the computational results. Three different upstream slopes of the broad-crested weir (V:H = 1:Z1 = 1:1, 1:2, 1:3) and three roughness scenarios were tested. The results indicate that, for smooth surface, numerical simulations overestimate by about 2 to 5% the weir discharge coefficient. In case of a rough surface, the difference between computations and observations reach up to 10%, for high relative roughness. When taking into account mentioned the differences, the shallow-water model may be applied for a range of engineering purposes.

Performance of a shallow-water model for simulating flow over trapezoidal broad-crested weirs

Hydraulics in Environmental and Civil Engineering (HECE), Research unit Urban & Environmental Engineering

Journal of Hydrology and Hydromechanics

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Shallow-water models are standard for simulating flow in river systems during floods, including in the near-field of sudden changes in the topography, where...

Performance of a shallow-water model for simulating flow over trapezoidal broad-crested weirs

Published Online: Nov 15, 2019

Page range: 322 - 328

Received: Jan 08, 2019

Accepted: Mar 19, 2019

DOI: https://doi.org/10.2478/johh-2019-0014

Keywords
Discharge coefficient, Frontal broad-crested weir, Shallow flow modelling, Rough weir crest

© 2019 Jaromír Říha et al., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Performance of a shallow-water model for simulating flow over trapezoidal broad-crested weirs

Published Online: Nov 15, 2019

Page range: 322 - 328

Received: Jan 08, 2019

Accepted: Mar 19, 2019

DOI: https://doi.org/10.2478/johh-2019-0014

KeywordsDischarge coefficient, Frontal broad-crested weir, Shallow flow modelling, Rough weir crest

© 2019 Jaromír Říha et al., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Keywords
Discharge coefficient, Frontal broad-crested weir, Shallow flow modelling, Rough weir crest