Flooding tailwater levels for NSW coastal entrances

E Watterson, E., You, B., Baldock, T., Callaghan, D. and Nielsen, P. (2013). Flooding tailwater levels for NSW coastal entrances. In: 22nd NSW Coastal Conference, Port Macquarie, NSW, Australia, (1-12). 12-15 November, 2013.

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Name Description MIMEType Size Downloads
Author E Watterson, E.
You, B.
Baldock, T.
Callaghan, D.
Nielsen, P.
Title of paper Flooding tailwater levels for NSW coastal entrances
Conference name 22nd NSW Coastal Conference
Conference location Port Macquarie, NSW, Australia
Conference dates 12-15 November, 2013
Place of Publication Coffs Harbour, NSW, Australia
Publisher East Coast Conferences
Publication Year 2013
Sub-type Fully published paper
Start page 1
End page 12
Total pages 12
Language eng
Formatted Abstract/Summary
Ocean water levels often differ from expected tidal predictions. Such differences, referred to as tidal residual, are caused by a range of meteorological and oceanographic conditions. Tide and tidal residuals can influence the level of flood risk in tidal waterways.

This study examined 88 water level records from a network of coastal NSW gauges. Some sites have collected data since the 1980’s and the average record length of all sites is just under 20 years. A full range of NSW coastal environments was considered from the open ocean to small creeks. A range of techniques were used to examine contributions of key metocean drivers to water level variation, including; tide, storm surge, wave setup and coastal trapped waves. Additional data sets, such as; 20 coastal weather stations; 20 streamflow gauges and 7 offshore waver rider buoys were examine in regard to driving influences on coastal water levels.

Tidal and residual water levels are independent for open ocean locations but not for locations within tidal waterways. Gauges located just inside river entrances deviate significantly and systematically from true ocean levels. While in the past this difference was attributed to wave setup, the findings of this investigation support the current understanding that only very shallow entrances (< 2 m) are susceptible to significant wave setup.

This study presents methods to calculate dynamic tailwater levels based on true open ocean locations for use as tailwater conditions of coastal flood models and design curves that can be used to estimate extreme residual return interval values. These combined can be used to determine dynamic tailwater levels for NSW tidal waterways.

Investigations of metocean drivers presented in this study provide an explanation for much of the variability in non-tidal water level variations. However, some variation and the physical processes responsible remains unclear and poorly understood.
Q-Index Code EX
Q-Index Status Provisional Code
Institutional Status UQ

Document type: Conference Paper
Collection: School of Civil Engineering Publications
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Created: Tue, 21 Jan 2014, 14:10:32 EST by Julie Hunter on behalf of School of Civil Engineering