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

<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.

<b>This record has been superseded by eCat 149403</b> The National Intertidal Digital Elevation Model (NIDEM) product is a continental-scale elevation dataset for Australia's exposed intertidal zone. NIDEM provides the first three-dimensional representation of Australia's intertidal zone (excluding off-shore Territories and intertidal mangroves) at 25 m spatial resolution, addressing a key gap between the availability of sub-tidal bathymetry and terrestrial elevation data. NIDEM was generated by combining global tidal modelling with a 30-year time series archive of spatially and spectrally calibrated Landsat satellite data managed within the Digital Earth Australia (DEA) platform. NIDEM complements existing intertidal extent products, and provides data to support a new suite of use cases that require a more detailed understanding of the three-dimensional topography of the intertidal zone, such as hydrodynamic modelling, coastal risk management and ecological habitat mapping.

<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.

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).

<div>Intertidal environments contain many important ecological habitats such as sandy beaches, tidal flats, rocky shores, and reefs. These environments also provide many valuable benefits such as storm surge protection, carbon storage, and natural resources.&nbsp;</div><div>&nbsp;</div><div>Intertidal zones are being increasingly faced with threats including coastal erosion, land reclamation (e.g. port construction), and sea level rise. These regions are often highly dynamic, and accurate, up-to-date elevation data describing the changing topography and extent of these environments is needed. However, this data is expensive and challenging to map across the entire intertidal zone of a continent the size of Australia. &nbsp;</div><div>&nbsp;</div><div>The intertidal zone also forms a critical habitat and foraging ground for migratory shore birds and other species. An improved characterisation of the exposure patterns of these dynamic environments is important to support conservation efforts and to gain a better understanding of migratory species pathways. &nbsp;</div><div>&nbsp;</div><div>The <strong>DEA Intertidal </strong>product suite (https://knowledge.dea.ga.gov.au/data/product/dea-intertidal) provides annual continental -scale elevation and exposure products for Australia’s intertidal zone, mapped at a 10m resolution, from Digital Earth Australia’s archive of open-source Landsat and Sentinel-2 satellite data. These intertidal products enable users to better monitor and understand some of the most dynamic regions of Australia’s coastlines.</div><div><br></div><div><strong>Applications</strong></div><div><br></div><div> - Integration with existing topographic and bathymetric data to seamlessly map the elevation of the coastal zone.&nbsp;</div><div>&nbsp;</div><div> - Providing baseline elevation data for predicting the impact of coastal hazards such as storm surges, tsunami inundation, or future sea-level rise.&nbsp;</div><div>&nbsp;</div><div> - Investigating coastal erosion and sediment transport processes.&nbsp;</div><div>&nbsp;</div><div> - Supporting habitat mapping and modelling for coastal ecosystems extending across the terrestrial to marine boundary.&nbsp;</div><div>&nbsp;</div><div> - Characterisation of the spatio-temporal exposure patterns of the intertidal zone to support migratory species studies and applications.&nbsp;</div><div><br></div><div><br></div><div><br></div>