Want to know what the Australian coastline may look like in 2100? This BETA version of Coastal Risk Australia (CRA) has been opened for public consultation to show you what the Australian coast may look like in 2100. It is an interactive map tool designed to communicate coastal inundation associated with sea level rise to the year 2100. Using Google Earth Engine technology, CRA allows you to investigate the extent of coastal inundation using the latest 3D models of the Australian coastline. Data have been captured using airborne LiDAR technology to create detailed digital elevation models (DEMs), which are then combined with ‘bucket-fill’ inundation modelling to create the map-based visualisations. How It Works Inundation = Sea Level Rise Scenarios (Low, Medium and High) + High Tide + Water-Land (MSL-AHD) Offset The inundation height for each area is computed using the above calculation. The default high tide level for each area is computed using the mean value of the virtual tide gauges hidden within the default view. To read more on the virtual tide gauges check the Guide, or to see them click on the tide gauges under the Layers panel. Sea Level Rise Scenarios CRA allows users to investigate projected 2100 sea level rise scenarios for their locality. These scenarios are based on findings from the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report, and are expressed in terms of Representative Concentration Pathways (RCPs). The RCPs have become a standard way for discussing future emission scenarios. Below are three sea level rise scenarios which have been used in CRA. The values below have been obtained from the IPCC Fifth Assessment Report, Climate Change 2013: The Physical Science Basis, Chapter 13 Sea Level Rise, Table 13.5 Median Values and Likely Ranges for Projections of Global Mean Sea Level Rise. The low scenario considers sea level rise in the context of a global agreement which would bring about dramatic reductions in global emissions. This low scenario, termed RCP 2.6, has a median sea level rise of 0.44 metres by 2100. The medium scenario considers sea level rise where global emissions stabilise after 2100. This medium scenario aligns approximately to RCP 4.5 and RCP 6.0, which have median sea level rises of 0.53 metres and 0.55 metres respectively by 2100. In CRA we have combined these scenarios for simplicity, and used the mean value of 0.54 metres. The high scenario is in line with recent global emissions and observations of sea level rise. This high scenario aligns to RCP 8.5, which has a median sea level rise of 0.74 metres by 2100. Tides, Tide Gauges and Virtual Tide Gauges People overwhelmingly want to know whether the tide will affect them. This means that a high tide needs to be used in addition to the sea level rise scenario to give an estimate of the of inundation extent. So in addition to the sea level rise scenarios, CRA uses a network of “virtual tide gauges” which provide estimates for the heights of high tide along the Australian coast. The technical level for the high tide used in CRA is the highest astronomical tides (HAT). The HAT values along the Australian coast have been computed from the CANUTE tide model relative to mean sea level. The CANUTE model has been developed by the Antarctic Climate and Ecosystems Cooperative Research Centre (ACE CRC) and provides estimates for 12,000 ‘virtual tide gauges’ spaced approximately every 2.5km around the coast. Aligning the Tides to the DEMs Whilst the tide is modelled relative to mean sea level (MSL), the DEMs are modelled relative to the Australian height datum (AHD). AHD was established using MSL values for 1966-1968 for 30 tide gauges around the coast of Australia. Since the establishment of AHD MSL has increased by approximately 3-4cm around the Australian coast. Whilst there is variation locally around the coast, a national average has been added into the scenarios to account for this historical increase. Digital Elevation Models (DEMs) The DEMs are 3D models of the land which are used to compute the low-lying areas susceptible to inundation. The DEMs have been mapped in great detail using airborne LiDAR technology. The DEMs used in CRA have a resolution of 5m, or in other words, a height value for every 5m along the Australian coast. To get access to the Australian Coastal DEM or find out more about LiDAR technology go to Further Information under the Useful Links on CRA.
It’s great that you're keen on seeing what the Australian coast may look like in 2100. Here is some information on how to get the most out of Coastal Risk Australia BETA (CRA). This BETA version has been opened for public consultation, therefore if you experience any issues, or wish to provide feedback please submit a comment using the feedback link provided. If you enjoy the experience, feel free to like us with Twitter or LinkedIn by clicking the icons in the top right of your screen. For more information on any of the terminology or concepts in this guide go to the Background section of CRA. Quick and Easy Click on one of the well-known places on the front page, accept the conditions of use and you're away. Pan and zoom to your places of interest to see the high tide flood extent for today (dark blue) and the high sea level rise scenario for 2100 (light blue). Type in a location in the top left Google Search once you're in the map and you can go to any coastal location around Australia where there is data. Using the 2100 Sea Level Rise Scenarios provided by the IPCC In the top left corner of the map screen you can see the predicted scenarios. You are able to select either the high, medium or low sea level rise scenarios to look at how the 2100 high tide inundation changes with each scenario. Go to the Background section to read about the details of each scenario. These are based on the Intergovernmental Panel on Climate Change Fifth Assessment Report scenarios. Seeing More or Less Information You can click either of the two "Current Day Highest Tide" or "2100 | + X.XXm Highest Tide" buttons to turn off the flood extents. You can also go to the Layers panel on the left hand side to reveal the Flood, DEM and Tide Gauges buttons. Click any of these boxes to turn them on and off. The Flood box turns on and off the flood extents. The DEM box turns on and off the underlying data which shows the heights of the land. The DEM is used to calculate which are the low-lying areas that get flooded. The Tide Gauges turn on and off the virtual tide gauge network which is used to compute the highest tide level for locations around the coast. Manually Setting Your Inundation In the top left you can select either Predicted or Manual. Click on Manual and then use the slider to set the inundation level to whatever you like. The level you set will be the height above current day mean sea level. Controlling the High Tide Level Under the Layers tab you can select the Tide Gauges. If you select this option, you can control the high tide level for the local area by selecting one of the Virtual Tide Gauges. The Virtual Tide Gauges appear as red dots around the coast. When you click on one of these gauges the high tide value will appear in the information box along with the tide gauge number. The tide gauge you selected will also be highlighted in green. If you pan away from this area a warning will appear on the left hand side of the screen noting that you're no longer in the local area near the chosen tide gauge. To go back to the default setting which uses the mean value of the tide gauges that appear in your view, turn off the Tide Gauges box.
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