- Title
- Coastal lake tidal range amplifies sea-level threat in Lake Macquarie, Australia
- Creator
- Palmer, Karen; Harris, Rebecca M.; Watson, Christopher S.; Hunter, John R.; Power, Hannah E.
- Relation
- Australasian Coasts & Ports 2021 Conference. Proceedings of the Australasian Coasts and Ports 2021 (online 30 November - 03 December, 2021) p. 745-751
- Relation
- https://search.informit.org/doi/10.3316/informit.261670094596344
- Publisher
- New Zealand Coastal Society
- Resource Type
- conference paper
- Date
- 2022
- Description
- Understanding the contributions of sea-level and tidal range to total water levels is important for accurate assessments of future inundation risk. This is particularly critical in estuaries where low-lying development often becomes vulnerable to inundation with only small changes in water levels. Lake Macquarie is a large, microtidal coastal lake on the eastern coast of Australia. Increasing tidal range has been observed since water level records began in 1986 and has been attributed to morphological adjustment to entrance training that occurred in the late 1800s. Within tidal basins, the tidal range (the mean height between low and high water levels) is influenced by many variables including entrance conditions, basin geometry, river flow, and the tidal range at the ocean boundary. Increasing water depths in shallow, dissipative tidal basins like Lake Macquarie are linked to reduced attenuation, thus rising sea-level is another possible driver for increasing tidal range. Multi-decadal time series from the NSW coastal data network were analysed at five tidally influenced water level monitoring sites in Lake Macquarie. The annual mean high water (MHW) and mean low water (MLW) datums were calculated from primary harmonic constituents (Z0 and M2) and compared with arithmetic means of the peaks and troughs identified from time series analysis for the semidiurnal MHW/MLW and the diurnal mean higher high water (MHHW) and mean lower low water (MLLW). All five sites show increasing trends in mean water level, with the highest rate of increase observed at the Swansea Channel entrance. The tidal range between MHHW and MLLW appears to be stable at the entrance but increasing within the lake by 1.5-1.7 mm/yr. This trend exemplifies tidal amplification as a serious contributor to higher water levels and potentially increased inundation in low lying areas.
- Subject
- tidal range; sea-level rise; coastal lake; tidal basin; estuary
- Identifier
- http://hdl.handle.net/1959.13/1493637
- Identifier
- uon:53609
- Identifier
- ISBN:9780473647056
- Language
- eng
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