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1 second SRTM derived water bodies mask

Abstract

This dataset and its metadata statement were supplied to the Bioregional Assessment Programme by a third party and are presented here as originally supplied.

The dataset defines water bodies across the Australian continent. See 'UserGuideforSRTM-DerivedDEMs.pdf' stored with dataset for more detailed information.

Purpose

The water bodies mask should be used to determine whether any cell belongs to the land or a water body, rather than relying on elevation values above or below zero. The water bodies mask is 1 for all water bodies (including the ocean) and NODATA for land cells. These masks have been derived from the SRTM Water Body Data (SWBD), which identifies water bodies as ocean, lake or river with relatively arbitrary boundaries between river and ocean in estuaries.

Dataset History

The original SRTM elevation data was prepared using 'edit rules', which specified (amongst other things) that land areas adjacent to water bodies are at least 1 m above the water level; note that the original SRTM data was in integer form so the 1 m increment was the smallest possible. Any land elevations that were equal to or lower than the adjacent water elevations were raised to 1 m above the water elevation. Land cells immediately adjacent to the coast were therefore at least 1 m in elevation, although cells further inland can have lower elevations.

The modifications to the SRTM elevations to remove stripes, remove offsets due to trees, reduce noise and enforce drainage have induced changes to elevations that may result in lower elevations, raising the possibility of logically inconsistent land elevations lower than the adjacent water elevations. The DSM and DEM have had a modified version of the edit rules applied to ensure that land areas adjacent to coast are at least 0.01 m. Note again that the edit rules only apply to cells immediately adjacent to the coast, so cells further inland can have negative elevations. In some cases this is due to over-estimation of vegetation heights, in other cases it is due to the original SRTM data.

The edit rules were not applied after the adaptive smoothing to produce DEM-S so there are some areas where land elevations adjacent to water bodies (including the ocean) are lower than the adjacent water elevations.

In DEM-H, ocean areas have been set to 'NODATA', water bodies have not been re-flattened and the edit rules have not been applied to avoid corrupting the hydrological enforcement. As a result, there are some areas immediately adjacent to the coast with elevations below zero.

Dataset Citation

Geoscience Australia (2011) 1 second SRTM derived water bodies mask. Bioregional Assessment Source Dataset. Viewed 29 September 2017, http://data.bioregionalassessments.gov.au/dataset/31c15f1e-b598-4f8c-a4c0-da392ff14204.

Data and Resources

Additional Info

Field Value
Title 1 second SRTM derived water bodies mask
Type Dataset
Language eng
Licence Creative Commons Attribution 3.0 Australia, http://creativecommons.org/licenses/by/3.0/au/, (c) Commonwealth of Australia (Geoscience Australia)
Data Status completed
Update Frequency unknown
Landing Page https://data.gov.au/data/dataset/806f5248-9c3e-42e0-9c2d-2d18cf8ff265
Date Published 2016-04-08
Date Updated 2019-11-19
Contact Point
Bioregional Assessment Program
bioregionalassessments@environment.gov.au
Temporal Coverage N/A - N/A
Geospatial Coverage POLYGON ((154 -44, 154 -10, 113 -10, 113 -44, 154 -44))
Jurisdiction Australia
Data Portal data.gov.au
Publisher/Agency Bioregional Assessment Program