Intertidal Extents Model Confidence Layer

Brief description

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).

Lineage

Maintenance and Update Frequency: asNeeded

Statement: 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.

Notes

Purpose
The purpose of the ITEM v1.0 product is to assist in understanding the extent and elevation profile of the Australian intertidal zone. Examples of where this knowledge can contribute include environmental monitoring applications for migratory bird species, habitat mapping in coastal regions, hydrodynamic modelling, and geomorphology studies of features in the intertidal zone. Through attribution of the LOT and HOT values modelled for each cell, the extents model can be used to derive an elevation profile of the observed intertidal zone extent on a cell by cell basis. The method employed can be tailored based on user requirements. For example, by dividing the observed tidal range for a cell (HOT-LOT) into 10% interval values, contours can be assigned to the section of the Intertidal Extents Model contained in that cell. These can then be used as a standalone elevation data source, or interpolated to create a continuous intertidal digital elevation model for the cell. The ability to create an elevation model relative to MSL enables the data to be integrated as a complimentary data source, linking shallow water bathymetry and terrestrial elevation models.