MODELLING THE MORPHOLOGICAL RESPONSE OF AN EBB TIDAL DELTA TO STORM WAVE FORCING

Proceedings of the International Conference on Coastal Engineering

Mahnaz Sedigh²  Rodger Tomlinson¹  Amir Etemad-Shahidi³  Nick Cartwright³ 

[1] Griffith Centre for Coastal Management, Griffith University;Griffith University, Griffith Centre for Coastal Management;Griffith University

关键词: ebb-tidal delta;    coupled modelling;    sediment transport;   

DOI  :  10.9753/icce.v34.sediment.63

学科分类：建筑学

来源: Coastal Engineering Research Council

【 摘 要 】

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 CoupledModel 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’sresultsshow 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.

【 授权许可】

Unknown