<div>The Abbot Point to Hydrographers Passage bathymetry survey was acquired for the Australian Hydrographic Office (AHO) onboard the RV Escape during the period 6 Oct 2020 – 16 Mar 2021. This was a contracted survey conducted for the Australian Hydrographic Office by iXblue Pty Ltd as part of the Hydroscheme Industry Partnership Program. The survey area encompases a section of Two-Way Route from Abbot Point through Hydrographers Passage QLD. Bathymetry data was acquired using a Kongsberg EM 2040, and processed using QPS QINSy. The dataset was then exported as a 30m resolution, 32 bit floating point GeoTIFF grid of the survey area.</div><div>This dataset is not to be used for navigational purposes.</div>

A mini-poster on GA's capability in tsunami hazard modelling.

A new methodology is proposed to estimate storm demand and dune recession by clustered and non-clustered events, to determine if the morphological response to storm clusters results in greater beach erosion than that from individual storms that have the same average recurrence interval (ARI) or return period. The method is tested using a numerical morphodynamic model that combines both cross-shore and longshore beach profile evolution processes, forced by a 2D wave transformation model, and is applied as an example within a 20 km long coastal cell at an erosion hotspot at Old Bar, NSW mid-north coast, Australia. Wave and water level data hindcast in previous modelling (Davies et al., 2017) were used to provide two thousand different synthetic wave and tide records of 100 years duration for input to a nested nearshore 2D SWAN model that provides wave conditions at the 12 m depth contour. An open-source shoreline evolution model was used with these wave conditions to model cross-shore and longshore beach profile evolution, and was calibrated and verified against long-term dune recession observations. After a 50 year model spin up, 50 years of storm demand (change in sub-aerial beach volume) and dune toe position were simulated and ranked to form natural estimators for the 50, 25, 16, 12.5 and 10 year return period of individual events, together with confidence limits. The storm demand analysis was then repeated to find the return period of clustered and non-clustered morphological events. Morphological clusters are defined here by considering the response of the beach, rather than the forcing, with a sensitivity analysis of the influence of different recovery thresholds between storms also investigated. The new analysis approach provides storm demand versus return period curves for the combined population of clustered and non-clustered events, as well as a curve for the total population of individual events. In this approach, non-clustered events can be interpreted as the response to isolated storms. For clustered and non-clustered morphological events the expected storm demand for a 50-year return period is approximately 25% greater than that for individual events. Alternatively, for clustered and non-clustered events the magnitude of the storm demand that occurs at a return period of 17 years is the same as that which occurs at a return period of 50 years for individual events. However, further analysis shows that for a 50-year return period, the expected storm demand for the population of non-clustered events is similar to that of the clustered events, although the size of the population of the latter is much greater. Hence, isolated storms can generate the same storm demand as storm clusters, but there is a much higher probability that a given storm demand is generated by a morphologically clustered event. Appeared online in Coastal Engineering Volume 168, September 2021.

In November, 2018 a workshop of experts sponsored by UNESCO’s Intergovernmental Oceanographic Commission was convened in Wellington, New Zealand. The meeting was organized by Working Group (WG) 1 of the Pacific Tsunami Warning System (PTWS). The meeting brought together fourteen experts from various disciplines and four different countries (New Zealand, Australia, USA and French Polynesia) and four observers from Pacific Island countries (Tonga, Fiji), with the objective of understanding the tsunami hazard posed by the Tonga-Kermadec trench, evaluating the current state of seismic and tsunami instrumentation in the region and assessing the level of readiness of at-risk populations. The meeting took place in the “Beehive” Annex to New Zealand’s Parliament building nearby the offices of the Ministry of Civil Defence and Emergency Management. The meeting was co-chaired by Mrs. Sarah-Jayne McCurrach (New Zealand) from the Ministry of Civil Defence and Emergency Management and Dr. Diego Arcas (USA) from NOAA’s Pacific Marine Environmental Laboratory. As one of the meeting objectives, the experts used their state-of-the-science knowledge of local tectonics to identify some of the potential, worst-case seismic scenarios for the Tonga-Kermadec trench. These scenarios were ranked as low, medium and high probability events by the same experts. While other non-seismic tsunamigenic scenarios were acknowledged, the level of uncertainty in the region, associated with the lack of instrumentation prevented the experts from identifying worse case scenarios for non-seismic sources. The present report synthesizes some of the findings of, and presents the seismic sources identified by the experts to pose the largest tsunami risk to nearby coastlines. In addition, workshop participants discussed existing gaps in scientific knowledge of local tectonics, including seismic and tsunami instrumentation of the trench and current level of tsunami readiness for at-risk populations, including real-time tsunami warnings. The results and conclusions of the meeting are presented in this report and some recommendations are summarized in the final section.

The NEAM Tsunami Hazard Model 2018 (NEAMTHM18) is a probabilistic hazard model for tsunamis generated by earthquakes. It covers the coastlines of the North-eastern Atlantic, the Mediterranean, and connected seas (NEAM). NEAMTHM18 was designed as a three-phase project. The first two phases were dedicated to the model development and hazard calculations, following a formalized decision-making process based on a multiple-expert protocol. The third phase was dedicated to documentation and dissemination. The hazard assessment workflow was structured in Steps and Levels. There are four Steps: Step-1) probabilistic earthquake model; Step-2) tsunami generation and modeling in deep water; Step-3) shoaling and inundation; Step-4) hazard aggregation and uncertainty quantification. Each Step includes a different number of Levels. Level-0 always describes the input data; the other Levels describe the intermediate results needed to proceed from one Step to another. Alternative datasets and models were considered in the implementation. The epistemic hazard uncertainty was quantified through an ensemble modeling technique accounting for alternative models’ weights and yielding a distribution of hazard curves represented by the mean and various percentiles. Hazard curves were calculated at 2,343 Points of Interest (POI) distributed at an average spacing of ∼20 km. Precalculated probability maps for five maximum inundation heights (MIH) and hazard intensity maps for five average return periods (ARP) were produced from hazard curves. In the entire NEAM Region, MIHs of several meters are rare but not impossible. Considering a 2% probability of exceedance in 50 years (ARP≈2,475 years), the POIs with MIH >5 m are fewer than 1% and are all in the Mediterranean on Libya, Egypt, Cyprus, and Greece coasts. In the North-East Atlantic, POIs with MIH >3 m are on the coasts of Mauritania and Gulf of Cadiz. Overall, 30% of the POIs have MIH >1 m. NEAMTHM18 results and documentation are available through the TSUMAPS-NEAM project website (http://www.tsumaps-neam.eu/), featuring an interactive web mapper. Although the NEAMTHM18 cannot substitute in-depth analyses at local scales, it represents the first action to start local and more detailed hazard and risk assessments and contributes to designing evacuation maps for tsunami early warning. Appeared online in Front. Earth Sci., 05 March 2021.

<div>The Approaches to Newcastle bathymetry survey was acquired for the Australian Hydrographic Office (AHO) onboard the MV Offshore Guardian during the period 4 Dec 2020 – 15 Jan 2021. This was a contracted survey conducted for the Australian Hydrographic Office by Guardian Geomatics as part of the Hydroscheme Industry Partnership Program. The survey area encompases an area east of Approaches to Newcastle NSW. Bathymetry data was acquired using a Kongsberg EM 2040-07, and processed using Caris Hips & Sips processing software. The dataset was then exported as a 30m resolution, 32 bit floating point GeoTIFF grid of the survey area.</div><div>This dataset is not to be used for navigational purposes.</div>

<p>The Intertidal Extents Model (ITEM v1.0) product is a national scale gridded dataset characterising the spatial extents of the exposed intertidal zone, at intervals of the observed tidal range. The current version utilises all Landsat observations (5, 7, and 8) for Australian coastal regions (excluding off-shore Territories) between 1987 and 2015 (inclusive). <p>The Intertidal Extents Model (ITEM v1.0) consists of three datasets derived from the Landsat NBAR data managed in the Australian Geoscience Data Cube (AGDC) for the period 1987 to 2015. <p>The Coastal Cells shapefile (ITEM_CoastalCells.shp) identifies the location and extents of the 221 one degree by one degree AGDC cells used in the product, covering the mainland and Tasmanian coastline of the continent (Figure 1). The shapefile also includes information on the lowest (LOT) and highest (HOT) observed tides for the cell, and hence the observed tidal range (HOT-LOT), based on tidal modelling for the time of acquisition of each of the corresponding Landsat tile observations in the cell. <p>Attributes: <p>AGDC Cell Identifier <p>Lowest Observed Tide (LOT) - The lowest modelled tidal offset based on the acquisition times of all observations in the cell. Relative to Mean Sea Level (MSL) (m) x 1000. <p>Highest Observed Tide (HOT) - The highest modelled tidal offset based on the acquisition times of all observations in the cell. Relative to Mean Sea Level (MSL) (m) x 1000.

<p><b>Please Note: ITEM v2.0 has now been published and can be accessed on the link provided</b> <p>Note: This is collection-level record. For access to individual data sets, please navigate to them using the hyperlinks on this page. The Intertidal Extents Model (ITEM v1.0) product is a national scale gridded dataset characterising the spatial extents of the exposed intertidal zone, at intervals of the observed tidal range. The current version utilises all Landsat observations (5, 7, and 8) for Australian coastal regions (excluding off-shore Territories) between 1987 and 2015 (inclusive). The Intertidal Extents Model (ITEM v1.0) consists of three datasets derived from the Landsat NBAR data managed in the Australian Geoscience Data Cube (AGDC) for the period 1987 to 2015.

The Intertidal Extents Model (ITEM v1.0) product is a national scale gridded dataset characterising the spatial extents of the exposed intertidal zone, at intervals of the observed tidal range. The current version utilises all Landsat observations (5, 7, and 8) for Australian coastal regions (excluding off-shore Territories) between 1987 and 2015 (inclusive). The Relative Extents Model (ITEM_REL_mosaic_1987_2015.tif) utilises the tidal information attributed to each tile observation to indicate the spatial extent of intertidal substratum exposed at each 10% percentile of the observed tidal range for the cell. Attributes: Single Band Integer Raster: 0 - Always water 1 - Exposed at lowest 0-10% of the observed tidal range 2 - Exposed at 10-20% of the observed tidal range 3 - Exposed at 20-30% of the observed tidal range 4 - Exposed at 30-40% of the observed tidal range 5 - Exposed at 40-50% of the observed tidal range 6 - Exposed at 50-60% of the observed tidal range 7 - Exposed at 60-70% of the observed tidal range 8 - Exposed at 70-80% of the observed tidal range 9 - Exposed at highest 80-100% of the observed tidal range (land) -999 - No Data

The Intertidal Extents Model (ITEM v1.0) product is a national scale gridded dataset characterising the spatial extents of the exposed intertidal zone, at intervals of the observed tidal range. The current version utilises all Landsat observations (5, 7, and 8) for Australian coastal regions (excluding off-shore Territories) between 1987 and 2015 (inclusive). The Intertidal Extents Model (ITEM v1.0) consists of three datasets derived from the Landsat NBAR data managed in the Australian Geoscience Data Cube (AGDC) for the period 1987 to 2015. The Confidence Layer (ITEM_CL_mosaic_1987_2015.tif) reflects the confidence level of the Relative Extents Model, based on the distribution of classification metrics within each of the 10% intervals of the tidal range. The layer should be used to filter region/pixels in the model where the derived spatial extents may be adversely affected by data and modelling errors. Note: The confidence layer should be utilised on a cell-by-cell basis. Standard deviation values within the confidence layer for a particular cell are not comparable to other cells within the model. Attributes: Single Band Integer Raster: 0 - Model is invalid. Indicates pixels where data quality and/or number of observations have resulted in no available observations in one or more of the percentile interval subsets. -32767 - No Data All other values - The pixel-based average of the NDWI standard deviations calculated independently for each 10% percentile interval of the observed tidal range (x 1000).