- Title
- Characterising the tsunami hazard in estuaries: an examination of the influences of elevation, tide, morphology, and tsunami wave parameters
- Creator
- Wilson, Kaya Max
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2021
- Description
- Research Doctorate - Doctor of Philosophy (PhD)
- Description
- Tsunamis can cause devastation to coastal communities around the world with populations living at low elevation around estuaries especially exposed. This thesis characterises the tsunami hazard in estuaries by examining the influence of elevation, tide, morphology, and tsunami wave parameters and expands the evidence base used in the estimation and management of this potential threat. Overall, this thesis shows that there is some tolerance for bathymetric data uncertainty used in tsunami modelling in the order of 3-5 m with model results showing maximum runup uncertainty of 10-30% depending on estuary morphology. Results further show that within riverine estuaries, both estuary entrance dimensions and the presence of estuary channel constrictions show a disproportionately large influence on the tsunami hazard along the length of the estuary with significant channel constrictions causing an elevated tsunami hazard downstream and a reduced hazard upstream. Tsunami modelling of these channel constrictions is shown to be sensitive to changes in depth and therefore tide. This thesis demonstrates that the application of a static tide in tsunami modelling is only appropriate for use with channel constrictions at high tide but at other tide levels can be reliable for the open coast, estuary mouths, and 1-2 hours from tsunami arrival. Tsunamis occurring at high tide are more likely to cause inundation, however, findings within this thesis show that tsunamis coinciding with a low tide are more likely to cause higher maximum current speeds with the fastest current speeds occurring at the shallowest water depths with rare exceptions. Tsunami wave parameters are also considered and tsunami wave period is found to be of most concern when modelling tsunamis in small bays (<1 km in length) showing greater wave amplification for shorter wave periods. Conversely, large bays (>7 km in length) show greater wave amplification for longer wave periods. Such wave amplification within coastal bays can be significant especially in V-shaped bays where maximum water level amplification can result in maximum water levels 80% higher than adjacent locations. Due to the demonstrated amplification of the tsunami hazard, this thesis concludes that V-shaped bays should be considered a priority for tsunami estimation. New, simplified methods for tsunami estimation in riverine estuaries are presented which require only minimal input data and do not require access to complex tsunami modelling. These methods include attenuation rates and a tsunami estimation workflow which takes into account estuary dimensions and influential estuary channel features. This thesis shows that tsunami estimation using only estuary entrance and channel feature elevation data can provide maximum water level estimates within 110% of complex modelling results.
- Subject
- tsunami; estuaries; bay shapes; Australia; hazard; coastal hazard; tide; tsunami-tide; Sydney Harbour; Port Hacking; morphology
- Identifier
- http://hdl.handle.net/1959.13/1489103
- Identifier
- uon:52620
- Rights
- Copyright 2021 Kaya Max Wilson
- Language
- eng
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| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details Download | ATTACHMENT01 | Thesis | 32 MB | Adobe Acrobat PDF | View Details Download | ||
| View Details Download | ATTACHMENT02 | Abstract | 532 KB | Adobe Acrobat PDF | View Details Download |