This report provides a description of the activities completed during the Outer Darwin Harbour Mapping Survey, from 28 May and 23 June 2015 on the RV Solander (Survey GA0351/SOL6187). This survey was a collaboration between Geoscience Australia (GA), the Australian Institute of Marine Science (AIMS) and Department of Land Resource Management (Northern Territory Government) and the first of four surveys in the Darwin Harbour Seabed Habitat Mapping Program. This 4 year program (2014-2018) aims to improve knowledge of the marine environments in the Darwin and Bynoe Harbour regions by collating and collecting baseline information and developing thematic habitat maps that will underpin future marine resource management decisions. The program was made possible through funds provided by the INPEX-led Ichthys LNG Project to Northern Territory Government Department of Land Resource Management, and co-investment from Geoscience Australia and Australian Institute of Marine Science. The specific objectives of the Outer Darwin Harbour Marine Survey GA0351/SOL6187 were to: 1. Obtain high resolution geophysical (bathymetry) data for outer Darwin Harbour, including Shoal Bay; 2. Characterise substrates (acoustic backscatter properties, grainsize, sediment chemistry) for outer Darwin Harbour, including Shoal Bay; and 3. Collect tidal data for the survey area. Data acquired during the survey included: 720 km2 multibeam sonar bathymetry and acoustic backscatter; 96 sampling stations collecting seabed sediments, underwater photography and video imagery and oceanographic information including tidal data and 54 sound velocity profiles.

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 service contains the Australian Coastal Geomorphology Landform Type Classifications, used to support a national coastal risk assessment. It describes the location and extent of landform types identifiable at scales between 1:250,000 and 1:25,000. It describes the landform types present in either erosional or dispositional environments.

Bathymetry is the study and mapping of the sea floor. It involves obtaining measurements of the depth of the ocean and is the equivalent to mapping topography on land. Bathymetric data is collected in multiple ways: 1. Satellite data can be used to produce maps showing general features over a large area at low resolution. Satellite altimetry measures the height of the ocean surface. If there are hills/mountains on the sea floor, the gravitational pull around that area will be greater and hence the sea surface will bulge. This measurement can be used to show where the seafloor is higher, and this can be used to produce maps showing general features over a large area at low resolution. 2. Single beam echosounders produce a single line of depth points directly under the equipment. These measurements are usually made while a vessel is moving to identify general sea floor patterns and/or schools of fish. 3. Equipment that captures swathes of data by acquiring multiple depth points in each area, such as multibeam echosounders (or swath echosounders) and airborne laser measurements (LADS). These datasets are very high resolution, with data down to better than one metre accuracy. This bathymetry dataset is a collection of singlebeam data sourced from seismic navigation lines, multibeam data, satellite and LADS data acquired by GA and by other government and non-government agencies.

Fresh groundwater stored in Australian coastal aquifers is an important resource for humans and the natural environment. Many Australian coastal aquifers are vulnerable to seawater intrusion (SWI)—the landward encroachment of sea water into coastal aquifers—which can significantly degrade water quality and reduce freshwater availability. The increasing demands for fresh water in coastal areas and the anticipated impacts of climate change (such as sea-level rise and variations in rainfall recharge) may result in increases in the incidence and severity of SWI. Comprehensive investigations of SWI are relatively uncommon and the extent of monitoring and investigations specific to SWI are highly variable across the nation. In response to the threat posed by SWI, Geoscience Australia and the National Centre for Groundwater Research and Training, in collaboration with state and territory water agencies, undertook a national-scale assessment of the vulnerability of coastal aquifers to SWI. This assessment identified the coastal groundwater resources that are most vulnerable to SWI, including future consequences of over-extraction, sea-level rise, and recharge–discharge variations associated with climate change. The study focused on assessing the vulnerability of coastal aquifers to the landward migration of the freshwater–saltwater interface, rather than surface waterbodies.

The service contains the Australian Coastal Geomorphology Environments, used to support a national coastal risk assessment. It describes the location and extent primary geomorphological environments (both dispositional and erosional) present along the Australia coast and the processes acting on the features within.

The service contains the Australian Coastal Geomorphology Landform Subtype Classifications, used to support a national coastal risk assessment. It describes the location and extent of landform subtypes identifiable at scales between 1:25,000 and 1:10,000. It also provides further detail to the Landform Type, with particular reference to feature stability (e.g. dune types) and mobility (e.g. channel types).

The service contains the Australian Coastal Geomorphology Environments, used to support a national coastal risk assessment. It describes the location and extent primary geomorphological environments (both dispositional and erosional) present along the Australia coast and the processes acting on the features within.

The service contains the Australian Coastal Geomorphology Environments, used to support a national coastal risk assessment. It describes the location and extent primary geomorphological environments (both dispositional and erosional) present along the Australia coast and the processes acting on the features within.

Winds, waves and tides associated with storms are capable of causing severe damage to coastal property and infrastructure. Locations that are prone to erosion and inundation first require an accurate assessment of risk before deciding the most cost effective mitigation option. This research aims to produce probabilistic assessments of the coastal erosion and inundation risks associated with storms, particularly for coincident or clustered events, thereby helping to strengthen the resilience of coastal communities. Coastal erosion and inundation hazard is modelled in this study by simulations of realistic storm condition forcing (waves and tides) through a morphodynamic model to calculate return periods for maximum extent of shoreline retreat. This approach of characterizing erosion response return periods is superior to the assumption that the most energetic storm causes maximum erosion. This methodology is demonstrated for beaches in metropolitan Adelaide and at Old Bar, NSW. These sites were selected to test the methodology for a span of geographic conditions in terms of storm climate and deep-water wave exposure, working towards developing this method into a transportable framework applicable to other coastal areas. Desktop and field assessments of each site were conducted to document geomorphic and sediment characteristics to inform shoreline modelling. Having established the historical framework at each location, multivariate statistical analysis of wave (buoy or hindcast models) and tides for peak storm events has allowed for the synthesis of realistic future conditions. This complex sequencing of cycling between accretion and erosion incorporating cross-shore and alongshore sediment transport has been estimated using a probabilistic shoreline translation model. Here, model outputs coupled with a scaled exposure analysis, will describe the damage to coastal infrastructure for the two case study sites. This information can then be used to inform coastal management strategies. Presented at the Australasia's emergency management and public safety conference AFAC17