Macrotidal coastal environments are characterised by complex patterns of sediment transport that have been poorly documented in the international literature. Of particular environmental concern is the transport of sediment from tropical coastal catchments, through estuaries and into coral reef environments. Consequently, knowledge of the distribution of benthic environments, and transport pathways of both fine and coarse sediment is required for the effective management of this issue. The Great Barrier Reef (GBR) is located on the continental shelf adjacent to the coast of tropical northeastern Australia. The GBR comprises an outer coral-dominated environment that encloses a large lagoon dominated by catchment-derived sediments. Keppel Bay is a macrotidal environment that represents the interface of the large catchment of the Fitzroy River with the southern GBR lagoon. We classified the benthic sediments of Keppel Bay into five distinct facies based on the statistical analysis of physical and geochemical sediment data and modelled seabed shear stress (the influence of waves and tidal currents). Multibeam sonar was employed to determine bedload sediment transport directions as indicated by bedform geometry, and to identify areas of sediment accumulation and erosion. Our findings suggest that much of the catchment-derived fine sediment accumulates in the mouth of the Fitzroy River. Outer Keppel Bay is dominated by relict palaeochannels, and the shoreward transport of sediment from the continental shelf. The Fitzroy River-Keppel Bay system provides a useful facies model for a seasonal, sediment-starved macrotidal depositional setting in which bedrock configuration and relict features dominate geomorphology, and restrict processes of modern sediment accumulation.

Map for ITR tourist ministerial brief showing leases, coastal waters, and reefs in Ningaloo area. Not for public distribution.

A tsunami can build a fan as it exits a breach through a natural or man-made embankment. In south-central Chile, such fans formed where the 1960 Chilean tsunami and its predecessors cut through beach ridges several meters high. Today the scours hold groundwater-fed ponds that bisect the ridges. Fans beside such ponds provide stratigraphic evidence for repeated tsunamis and for changes in erosion and sedimentation during the tsunami of 1960. In our best-studied example, 2 km from the sea, the 1960 tsunami built a sandy fan that tapers landward from a maximum thickness of 60 cm. At distances 10-50 m from the landward edge of the pond, the sand is faintly laminated and is rich in pebble- and cobble-size clasts that were probably derived from the fill of a pre-existing scour pond. Above the highest of these clasts the sand contains three distinctly laminated intervals. In the lowest of these intervals the laminae are parallel; in the middle they form ripple-drift cross-sets that record landward-directed flow; and a capping unit the laminae are again parallel. The tsunami's second wave, which eyewitnesses describe as far greater than the first, may account for most of this erosion and deposition kilometers from the sea. Scour-pond fans may provide valuable clues to the occurrence and size of past tsunamis because the scours can be detected by remote sensing and because the associated fans can produce long-lasting sedimentary records of tsunami flow.

This report was compiled and written to summarise the four-year (2008 to 2012) 'Sustainable management of coastal groundwater resources' project. This project was funded by the National Water Commission's (NWC) Raising National Water Standards Program. Geoscience Australia was a key project partner, and worked closely with collaborators from Ecoseal, Arche Consulting, GHD, Kempsey Shire Council and the NSW Department of Primary Industries (Office of Water). The summary report was published under the National Water Commission's 'Waterlines' series. This executive summary document is supported by related publications that deal with the following topics: 1. hydrogeology, monitoring and hydrochemistry; 2. development of a groundwater flow and transport model for the Macleay Sands Aquifer; 3. mapping and risk assessment of groundwater-dependent ecosystems (GDEs); 4. development and application of early warning indicators to assess the condition of groundwater resources; and 5. socioeconomic assessment and cost-benefit analysis, The key project objective was to develop an integrated approach for managing the availability and quality of coastal groundwater resources so that coastal aquifers do not become overallocated, depleted or degraded as a consequence of increasing demand from rapidly expanding urban centres such as South West Rocks. The second objective was to combine groundwater and seawater intrusion modelling tools, assessment of groundwater dependent ecosystems (GDEs), and a framework for applying indicators and cost–benefit analysis to support the long-term management of coastal sand aquifers. These methodologies can then be applied to similar coastal sand dune aquifers along the North Coast of New South Wales and help ensure that any new groundwater sources are developed sustainably, with minimal impact on GDEs such as coastal dune vegetation communities. The study will help improve management of groundwater resources in coastal dune aquifers in the Mid North Coast region and, potentially, other coastal communities reliant on coastal dune systems for water supplies.

The ratio of benthic silicate (SiO4 or DSi1) vs carbon dioxide (CO2) fluxes at 299/341 (87%) sites in 10 Australian estuaries was 0.15 to 0.19 (r2=0.8), indicating diatoms 2,3 as the major type of organic material (OM) being degraded in the sediments . Diatoms contributed 33% of the degradable OM at the remaining 42 (13%) sites. Diatomaceous phytoplankton was thus central to nutrient cycling in these estuaries. Dam-induced DSi depletion in coastal waters, a cause of toxic non-silicious algal blooms is now a global problem1. Our investigation indicated that DSi has another and potentially important global role in nutrient cycling in coastal waterways, also prompting a new DSi-dependent nutrient cycling model. The Si-opal inclusion (frustule) in living diatoms confers a density that causes rapid settling to the sediments4 where denitrification recycles N2 to an atmospheric sink, in this way lowering internal N cycling and preventing eutrophication5. Also, DSi is recycled quantitatively to the water column, participating in repeated cycles of diatom productivity. The silicate-diatom-sediment nexus is thus sustained and the N-loss processes of denitrification and burial are sustained.

Tracking changes in the canopy density of mangroves, Digital Earth Australia (DEA) Mangrove Canopy Cover reveals how these extraordinary trees may be responding to sea level rise, severe tropical cyclones, drought, climatic cycles, changing temperatures and large storm events. Mangroves provide a diverse array of ecosystem services but these are impacted upon by both natural and anthropogenic drivers of change. In Australia, mangroves are protected by law and hence the natural drivers predominate. It is important to know the extent and canopy density of mangroves in Australia so that we can measure how mangroves are responding to sea level rise, severe tropical cyclones and climatic cycles. This product provides valuable information about the extent and canopy density of mangroves for each year between 1987 and 2018 for the entire Australian coastline. The canopy cover classes are: - 20-50% (pale green) - 50-80% (mid green) - 80-100% (dark green) The product consists of a sequence (one per year) of 30 m resolution maps that are generated by analysing the Landsat fractional cover developed by the Joint Remote Sensing Research Program and the Global Mangrove Watch layers developed by the Japanese Aerospace Exploration Agency. This product is the result of a collaboration between Geoscience Australia, the University of Aberyswyth, CSIRO, the Joint Remote Sensing Research Program and the Terrestrial Ecosystem Research Network.

The coastal zone is arguably the most difficult geographical region to capture as data because of its dynamic nature. Yet, coastal geomorphology is fundamental data required in studies of the potential impacts of climate change. Anthropogenic and natural structural features are commonly mapped individually, with their inherent specific purposes and constraints, and subsequently overlain to provide map products. This coastal geomorphic mapping project centered on a major coastal metropolitan area between Lake Illawarra and Newcastle, NSW, has in contrast classified both anthropogenic and natural geomorphological features within the one dataset to improve inundation modelling. Desktop mapping was undertaken using the Australian National Coastal Geomorphic (Polygon) Classification being developed by Geoscience Australia and supported by the Department of Climate Change. Polygons were identified from 50cm and 1m aerial imagery. These data were utilized in parallel with previous maps including for example 1:25K Quaternary surface geology, acid sulphate soil risk maps as well as 1:100K bedrock geology polygon maps. Polygons were created to capture data from the inner shelf/subtidal zone to the 10 m contour and include fluvial environments because of the probability of marine inundation of freshwater zones. Field validation was done as each desktop mapping section was near completion. This map has innovatively incorporated anthropogenic structures as geomorphological features because we are concerned with the present and future geomorphic function rather than the past. Upon completion it will form part of the National Coastal Geomorphic Map of Australia, also being developed by Geoscience Australia and utilized in conjunction with Smartline.

<div>The A1 poster incorporates 4 images of Australia taken from space by Earth observing satellites. The accompanying text briefly introduces sensors and the bands within the electromagnetic spectrum. The images include examples of both true and false colour and the diverse range of applications of satellite images such as tracking visible changes to the Earth’s surface like crop growth, bushfires, coastal changes and floods. Scientists, land and emergency managers use satellite images to analyse vegetation, surface water or human activities as well as evaluate natural&nbsp;hazards.</div>

This record contains processed and topographically corrected Ground Penetrating Radar (GPR) data (.segy, .bmp), and a summary shapefile collected on fieldwork at Adelaide Metropolitan Beaches, South Australia for the Bushfire and Natural Hazards CRC Project, Resilience to Clustered Disaster Events on the Coast - Storm Surge. The data was collected from 16-19 February 2015 using a MALA ProEx GPR system with a 250 MHz shielded antennae. The aim of the field work was to identify and define a minimum thickness for the beach and dune systems, and where possible depth to any identifiable competent substrate (e.g. bedrock) or pre-Holocene surface which may influence the erosion potential of incident wave energy. Surface elevation data was co-acquired and used to topographically correct the GPR profiles. This dataset is published with the permission of the CEO, Geoscience Australia.

Legacy product - no abstract available