Modelling the morphological response of an ebb tidal delta to storm wave forcing

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Author(s)
Sedigh, M
Tomlinson, R
Etemad-Shahidi, A
Cartwright, N
Year published
2014
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The Nerang river outlet - located on the Australian east coast - was stabilised with two entrance jetties in 1986. The
entrance, now known as the Gold Coast Seaway, has been the subject of growing concern about the ongoing growth
of the ebb tidal delta. Historical analysis of surveying data confirmed the gradual growth of ebb tidal delta, although a
sand bypassing system was implemented upstream when the entrance was stabilised. The dredging of the Seaway ebb
delta is inevitable to keep the navigation channel open and safe. However, the dredging operation is both time and
budget consuming and therefore having a more accurate ...
View more >The Nerang river outlet - located on the Australian east coast - was stabilised with two entrance jetties in 1986. The entrance, now known as the Gold Coast Seaway, has been the subject of growing concern about the ongoing growth of the ebb tidal delta. Historical analysis of surveying data confirmed the gradual growth of ebb tidal delta, although a sand bypassing system was implemented upstream when the entrance was stabilised. The dredging of the Seaway ebb delta is inevitable to keep the navigation channel open and safe. However, the dredging operation is both time and budget consuming and therefore having a more accurate model which can predict the pattern of morphological changes precisely seems essential. A coupled wave, flow and sediment transport model was developed using MIKE 21 Coupled Model to investigate the sediment transport pattern mainly in the area of the ebb-tidal delta and its linkage with littoral drift in the adjacent open coast. The hydrodynamics of the model were calibrated and verified against current measurements inside the Seaway and offshore wave data obtained from the Gold Coast Wave Rider Buoy. The pattern of the simulated morphological changes was qualitatively similar to that of the observations, and the model’s results show that the storm waves forcing govern the growth of the ebb-tidal delta, and also leads to severe bathymetry changes along the adjacent ocean beaches. The model was found to underestimated the volume of sediment transport in the domain and so further model sensitivity analysis is ongoing in an effort to reach to a quantitatively calibrated morphological model.
View less >
View more >The Nerang river outlet - located on the Australian east coast - was stabilised with two entrance jetties in 1986. The entrance, now known as the Gold Coast Seaway, has been the subject of growing concern about the ongoing growth of the ebb tidal delta. Historical analysis of surveying data confirmed the gradual growth of ebb tidal delta, although a sand bypassing system was implemented upstream when the entrance was stabilised. The dredging of the Seaway ebb delta is inevitable to keep the navigation channel open and safe. However, the dredging operation is both time and budget consuming and therefore having a more accurate model which can predict the pattern of morphological changes precisely seems essential. A coupled wave, flow and sediment transport model was developed using MIKE 21 Coupled Model to investigate the sediment transport pattern mainly in the area of the ebb-tidal delta and its linkage with littoral drift in the adjacent open coast. The hydrodynamics of the model were calibrated and verified against current measurements inside the Seaway and offshore wave data obtained from the Gold Coast Wave Rider Buoy. The pattern of the simulated morphological changes was qualitatively similar to that of the observations, and the model’s results show that the storm waves forcing govern the growth of the ebb-tidal delta, and also leads to severe bathymetry changes along the adjacent ocean beaches. The model was found to underestimated the volume of sediment transport in the domain and so further model sensitivity analysis is ongoing in an effort to reach to a quantitatively calibrated morphological model.
View less >
Conference Title
Proceedings of the Coastal Engineering Conference
Volume
2014-January
Copyright Statement
© The Author(s) 2014. This is an Open Access article distributed under the terms of the Creative Commons Attribution 4.0 International (http://creativecommons.org/licenses/by/4.0/) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Subject
Water resources engineering