Authors / CoAuthors
Unknown
Abstract
The 1 second SRTM derived DEM-H Version 1.0 is a 1 arc second (~30m) gridded digital elevation model (DEM). The DEM-H captures flow paths based on SRTM elevations and mapped stream lines, and supports delineation of catchments and related hydrological attributes. The dataset was derived from the 1 second smoothed Digital Elevation Model (DEM-S; ANZCW0703014016) by enforcing hydrological connectivity with the ANUDEM software, using selected AusHydro V1.6 (February 2010) 1:250,000 scale watercourse lines (ANZCW0503900101) and lines derived from DEM-S to define the watercourses. The drainage enforcement has produced a consistent representation of hydrological connectivity with some elevation artefacts resulting from the drainage enforcement. A full description of the methods is in preparation (Dowling et al., in prep). This product is the last of the series derived from the 1 second SRTM (DSM, DEM, DEM-S and DEM-H) and provides a DEM suitable for use in hydrological analysis such as catchment definition and flow routing.
Product Type
dataset
eCat Id
77232
Contact for the resource
Custodian
Point of contact
Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
Canberra
ACT
2601
Australia
Keywords
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- GIS Dataset
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Earth Sciences
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- Published_Internal
Publication Date
2013-08-21T00:00:00
Creation Date
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Maintenance Information
asNeeded
Topic Category
geoscientificInformation
Series Information
Lineage
Drainage enforcement The 1 second Hydrological Digital Elevation Model (DEM-H) was derived from the 1 second Smoothed Digital Elevation Model (DEM-S) using the ANUDEM software (Hutchinson, 1988, 1989, 2009), version 5.2.5, dated 1 December 2010. This version of ANUDEM was modified to work effectively on the SRTM data, as briefly described in Hutchinson et al. (2009). ANUDEM uses a spline interpolation method that smooths the surface, enforces continuous descent along supplied drainage lines and removes sinks consistent with the accuracy of the source elevation data (DEM-S). The 1:250,000 scale stream line data used to produce the GEODATA 9 second DEM Version 3 was chosen as the source of drainage line data as it was the only available source of cleaned and correctly oriented drainage lines and it covered the entire continent. This 1:250,000 scale data, with a spatial accuracy of about 200 metres, was significantly coarser than the 1 second DEM-S that is accurate to 50 metres or better. In low relief landscapes the spatial error of the 1:250,000 stream lines is not a significant problem but in steeper areas the spatial offsets result in drainage lines being incised into hillslopes rather than valley floors. To prevent this, the mapped stream lines were used only where slope in DEM-S was less than 10 degrees. The excised segments were replaced with infilling stream lines derived from DEM-S using a version of the AT search algorithm (Ehlschlaeger, 1989; known primarily as its implementation in GRASS as r.watershed) method that constructs flow lines through depressions without first filling the depressions to the outlet level. The ANUDEM software cannot process the entire continent, or entire drainage basins at the 1 second resolution in a single pass. Drainage enforcement was therefore performed separately for each 1-1 degree tile using ½ degree overlaps on each side. The resulting 2-2 degree tiles were trimmed to a 100 cell overlap, mosaicked with adjacent trimmed tiles then clipped to the 1-1 degree tile. The mosaicking process does not guarantee the preservation of continuous descent along drainage lines so a final descent enforcement step was applied using the CheckStreamDescent program written for that purpose. CheckStreamDescent processes all tiles as a single data set so continuous descent of all stream lines to their termination points was ensured. As a final step, the ocean areas were set to 'no data'. Other water bodies have not been altered after drainage enforcement and most water bodies include a drainage line through them reflecting the connectors in the AusHydro data. Note that this is in contrast to the finishing of the DSM, DEM and DEM-S that all contain flattened water bodies and used the SRTM edit rules to ensure that land adjacent to water bodies is at a higher elevation than the water.
Parent Information
Extents
[-44.0, -10.0, 113.0, 154.0]
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