TY - JOUR
T1 - The influence of grid shape and grid size on hydraulic river modelling performance
AU - Bomers, Anouk
AU - Schielen, Ralph Mathias Johannes
AU - Hulscher, Suzanne J.M.H.
N1 - Springer
Funding Information:
This research is supported by the Netherlands Organisation for Scientific Research (NWO, Project 14506) which is partly funded by the Ministry of Economic Affairs and Climate Policy. Furthermore, the research is supported by the Ministry of Infrastructure and Water Management and Deltares. This research has benefited from cooperation within the network of the Netherlands Centre for River Studies. The authors would like to thank the Dutch Ministry of Infrastructure for providing the data. Besides, the authors would like to thank Mrs. Becker and Mr. Van Dam from Deltares for their valuable insights. Finally, the authors would like to thank the two anonymous reviewers for their suggestions, which greatly improved the quality of the paper.
Publisher Copyright:
© 2019, The Author(s).
PY - 2019/10
Y1 - 2019/10
N2 - Grid shape (curvilinear/structured versus triangular/unstructured) and grid size affect model output. In this study structured, unstructured and hybrid grids with a high and low resolution were compared. As a case study, we use the Waal River (with main channel and floodplains). We studied simulated water levels using the six grids, considering equal main channel friction, which enabled to study the isolated effects of grid shape and size. The spread in simulated water levels was found to be rather large with a maximum deviation of 78 cm. Therefore, calibration was performed such that simulated water levels resembled measured water levels by adjusting the main channel friction. This enabled us to draw conclusions on the choice of optimal usage of the grids in engineering studies. Bathymetry accuracy and numerical friction, both as a result of grid resolution, and numerical viscosity as a result of grid shape play a vital role. The analysis shows that unstructured grids are affected most by the calibration which is reflected in the wide spreading of calibrated friction values. From the six grids studied, the hybrid grid with curvilinear grid cells in the main channel and triangular grid cells in the floodplain is recommended for hydraulic modelling since computation time is low, while model output shows sufficient accuracy.
AB - Grid shape (curvilinear/structured versus triangular/unstructured) and grid size affect model output. In this study structured, unstructured and hybrid grids with a high and low resolution were compared. As a case study, we use the Waal River (with main channel and floodplains). We studied simulated water levels using the six grids, considering equal main channel friction, which enabled to study the isolated effects of grid shape and size. The spread in simulated water levels was found to be rather large with a maximum deviation of 78 cm. Therefore, calibration was performed such that simulated water levels resembled measured water levels by adjusting the main channel friction. This enabled us to draw conclusions on the choice of optimal usage of the grids in engineering studies. Bathymetry accuracy and numerical friction, both as a result of grid resolution, and numerical viscosity as a result of grid shape play a vital role. The analysis shows that unstructured grids are affected most by the calibration which is reflected in the wide spreading of calibrated friction values. From the six grids studied, the hybrid grid with curvilinear grid cells in the main channel and triangular grid cells in the floodplain is recommended for hydraulic modelling since computation time is low, while model output shows sufficient accuracy.
KW - UT-Hybrid-D
U2 - 10.1007/s10652-019-09670-4
DO - 10.1007/s10652-019-09670-4
M3 - Article
SN - 1567-7419
VL - 19
SP - 1273
EP - 1294
JO - Environmental fluid mechanics
JF - Environmental fluid mechanics
IS - 5
ER -