EARTH SCIENCE | BIOSPHERE | ECOSYSTEMS | MARINE ECOSYSTEMS | ESTUARY
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Water level heights were measured every 5 minutes at five station locations in the 70km length Tamar estuary, Tasmania, for six months. Pressure loggers deployed in the water recorded total pressure and the inverse barometer effect was accounted for by two additional pressure loggers deployed above ground within 15km of a station. The data include barometric pressure, water temperature, and water level relative to Australian Height Datum (AHD83). The data captures tidal amplification and asymmetry between ebb and flood tides in the estuary for the purpose of a research project completed in 2018 by Karen Palmer. Based on the Tamar estuary model created for NRM North by BMT WBM Pty Ltd using TUFLOW FV (with permission), a new hydrodynamic model was created and calibrated with observed water levels. Different scenarios of sea level rise and bathymetry change were then simulated to model the effects on tidal amplitude and phase.
Policy and decision makers often seek guidance as to the benefits of conservation and repair of coastal seascapes, to justify and underpin any potential investments. Much is already known about the broad habitat and nursery values of seascapes among the science community, but there is also a need for estimation of clear and unambiguous market-based benefits that may arise from investment in repair. Recognising that this economic knowledge is imperfect for Australian seascapes, three case studies spanning tropical, subtropical and temperate environments explored the benefits in question. The case studies focus on saltmarsh habitats in particular, which have received very little investment in repair despite subtropical and temperate coastal saltmarsh listed as vulnerable ecological community under Australian Federal legislation. A subset of economically important species and conservative judgments were used to characterise the minimum potential economic benefit. For each of the case studies the conclusion was that while the biological information will remain imperfect, the business case for investment in the repair and conservation of coastal seascapes is compelling. We outline priorities for further research to make the business case more tangible to policy makers, stakeholders and the general public.
Two OneTemp HOBO pressure data loggers were installed at the Seaport Marina in central Launceston in June 2014 by Dr Ian Kidd, measuring water depth at 1-hr intervals as well as water temperature. Depth is calculated from temperature, total pressure, and barometric pressure, based on fresh water density. The height of the gauge relative to AHD was measured 23 March 2018 by Launceston City Council surveyor Leigh Cornwell, and a correction applied to the data to give water level in metres AHD. The gauge was installed for the purpose of Dr Kidd's PhD research into sediment transport processes in the upper Tamar, and remains open with data collected monthly by Karen Palmer (IMAS honours student). Both projects were supervised by Dr Andrew Fischer.
In collaboration with the Tasmanian State Emergency Service, water level monitoring instruments were installed to enable the collection of data in four estuaries identified as being vulnerable to coastal and compound flooding: Derwent Estuary, Huon Estuary, Georges Bay, and Macquarie Harbour. These instruments recorded fluctuations in water levels due to the combined influences of tide, river discharge, and weather events. The effects of the January 2022 Hunga Tonga-Hunga Ha’apai tsunami following a significant submarine volcanic explosion was also recorded in three out of the four estuaries. The datasets, comprising reduced water level observations, predicted water level, and residuals, are available from the IMAS Data Portal. Water level observations of varying duration were recorded between November 2020 – November 2022 for 14 sites in four Tasmanian estuaries. This work was undertaken by Karen Palmer as part of a PhD candidature at the University of Tasmania under the supervision of Dr Christopher Watson, Dr John Hunter, Assoc Prof Hannah Power (University of Newcastle), and Dr Rebecca Harris.