digital elevation data
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The Harvey 2008 LiDAR data was captured over the Harvey region during February, 2008. The data was acquired by AAMHatch (now AAMGroup) and Fugro Spatial Solutions through a number of separate missions as part of the larger Swan Coast LiDAR Survey that covers the regions of Perth, Peel, Harvey, Bunbury and Busselton. The project was funded by Department of Water, WA for the purposes of coastal inundation modelling and a range of local and regional planning. The data are made available under licence for use by Commonwealth, State and Local Government. The data was captured with point density of 1 point per square metre and overall vertical accuracy has been confirmed at <15cm (68% confidence). The data are available as a number of products including mass point files (ASCII, LAS) and ESRI GRID files with 1m grid spacing. A 2m posting hydrologically enforced digital elevation model (HDEM) and inundation contours has also been derived for low lying coastal areas.
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<p>Note: Geoscience Australia no longer supports users' external hard drives. The data can either be downloaded from the ELVIS Portal or from the Related links. The 1 second Shuttle Radar Topography Mission (SRTM) Digital Elevation Models Version 1.0 package comprises three surface models: the Digital Elevation Model (DEM), the Smoothed Digital Elevation Model (DEM-S) and the Hydrologically Enforced Digital Elevation Model (DEM-H). The DEMs were derived from the SRTM data acquired by NASA in February 2000 and were publicly released under Creative Commons licensing from November 2011 in ESRI Grid format. <p>DEM represents ground surface topography, with vegetation features removed using an automatic process supported by several vegetation maps. This provides substantial improvements in the quality and consistency of the data relative to the original SRTM data, but is not free from artefacts. Man-made structures such as urban areas and power line towers have not been treated. The removal of vegetation effects has produced satisfactory results over most of the continent and areas with defects identified in supplementary layers distributed with the data, and described in the User Guide. <p>DEM-S represents ground surface topography, excluding vegetation features, and has been smoothed to reduce noise and improve the representation of surface shape. An adaptive smoothing process applied more smoothing in flatter areas than hilly areas, and more smoothing in noisier areas than in less noisy areas. This DEM-S supports calculation of local terrain shape attributes such as slope, aspect and curvature that could not be reliably derived from the unsmoothed 1 second DEM because of noise. <p>DEM-H is a hydrologically enforced version of the smoothed DEM-S. 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) by enforcing hydrological connectivity with the ANUDEM software, using selected AusHydro V1.6 (February 2010) 1:250,000 scale watercourse lines 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. <p>Further information can be found in the supplementary layers supplied with the data and in the User Guide.
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To be completed
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The 1 second Shuttle Radar Topographic Mission (SRTM) derived smoothed Digital Elevation Model (DEM-S) Version 1.0 is a 1 arc second (~30m) gridded smoothed version of the DEM (ANZCW0703013355). The DEM-S represents ground surface topography, excluding vegetation features, and has been smoothed to reduce noise and improve the representation of surface shape. The dataset was derived from the 1 second Digital Elevation Model Version 1.0 (DSM; ANZCW0703013336) by an adaptive smoothing process that applies more smoothing in flatter areas than hilly areas, and more smoothing in noisier areas than in less noisy areas. This DEM-S supports calculation of local terrain shape attributes such as slope, aspect and curvatures that could not be reliably derived from the unsmoothed DEM because of noise. A full description of the methods is in progress (Gallant et al., in prep) and in the User Guide (Geoscience Australia & CSIRO, 2010).
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The Australian tidal error model is the first attempt to define uncertainties in Mean Sea Level (MSL) around the Australian coastline between tide gauges. Tide gauge observations for the Australian coast span from less than 1 month to greater than 100yrs of observations. The high quality, decade and longer observation tide gauges are used in the production of the frequency dependant error surface. The observed hourly data are analysed using the National Tidal Centre TANS analysis package, resulting in harmonic constituents (used for prediction), a MSL determination, a fitted linear trend and a residual. The power spectrum of the residual is then separated into a predefined set of frequency bins, representing the noise levels of the sea surface proportional to frequency. The longer span observations fill more of this predefined spectrum, specifically the lower frequency errors, which contribute a significant proportion of error. Spatial interpolation around Australia is performed individually for each frequency bin. Using this method allow regions with shorter span observations to have lower frequency error added, creating a synthetic spectrum at the interpolation point. The synthetic spectrums are then used to determine confidence intervals of MSL around the coastline of Australia. The understanding of these errors is an important step for combining bathymetry and topography datasets ultimately creating a seamless national digital elevation model.
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The 3 second (~90m) Smoothed Digital Elevation Model (DEM-S) Version 1.0 was derived from resampling the 1 second SRTM derived DEM-S (gridded smoothed digital elevation model; ANZCW0703014016). The DEM represents ground surface topography, excluding vegetation features, and has been smoothed to reduce noise and improve the representation of surface shape. The DEM-S was derived from the 1 second Digital Surface Model (DSM; ANZCW0703013336) and the Digital Elevation Model Version 1.0 (DEM; ANZCW0703013355) by an adaptive smoothing process that applies more smoothing in flatter areas than hilly areas, and more smoothing in noisier areas than in less noisy areas. This DEM-S supports calculation of local terrain shape attributes such as slope, aspect and curvatures that could not be reliably derived from the unsmoothed 1 second DEM because of noise. A full description of the methods is in progress (Gallant et al., in prep) and in the 1 second User Guide. The 3 second DEM was produced for use by government and the public under Creative Commons attribution. The 1 second DSM and DEM that forms the basis of the product are also available as 3 second products (DSM; ANZCW0703014216, DEM; ANZCW0703014182, DEM-S; ANZCW0703014217). <strong>Please note that all 1 second products are available for GOVERNMENT USERS ONLY.</strong>
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SRTM Documentation (best viewed with mono-spaced font, such as courier) 1.0 Introduction The SRTM data sets result from a collaborative effort by the National Aeronautics and Space Administration (NASA) and the National Imagery and Mapping Agency (NIMA), as well as the participation of the German and Italian space agencies, to generate a near-global digital elevation model (DEM) of the Earth using radar interferometry. The SRTM instrument consisted of the Spaceborne Imaging Radar-C (SIR-C) hardware set modified with a Space Station-derived mast and additional antennae to form an interferometer with a 60 meter long baseline. A description of the SRTM mission, can be found in Farr and Kobrick (2000). Synthetic aperture radars are side-looking instruments and acquire data along continuous swaths. The SRTM swaths extended from about 30 degrees off-nadir to about 58 degrees off-nadir from an altitude of 233 km, and thus were about 225 km wide. During the data flight the instrument was operated at all times the orbiter was over land and about 1000 individual swaths were acquired over the ten days of mapping operations. Length of the acquired swaths range from a few hundred to several thousand km. Each individual data acquisition is referred to as a "data take." SRTM was the primary (and pretty much only) payload on the STS-99 mission of the Space Shuttle Endeavour, which launched February 11, 2000 and flew for 11 days. Following several hours for instrument deployment, activation and checkout, systematic interferometric data were collected for 222.4 consecutive hours. The instrument operated virtually flawlessly and imaged 99.96% of the targeted landmass at least one time, 94.59% at least twice and about 50% at least three or more times. The goal was to image each terrain segment at least twice from different angles (on ascending, or north-going, and descending orbit passes) to fill in areas shadowed from the radar beam by terrain. This 'targeted landmass' consisted of all land between 56 degrees south and 60 degrees north latitude, which comprises almost exactly 80% of the total landmass.
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The Swan Coast hydrologically enforced digital elevation model (HDEM) was produced in 2010 as part of the Urban DEM project managed by the CRC for Spatial Information and Geoscience Australia. The HDEM was created from a combination of the following surveys; Perth, Peel, Harvey, Bunbury and Busselton LiDAR The Swan Coast 2008 LiDAR data was captured over the Swan Coast region during February, 2008. The data was acquired by AAMHatch (now AAMGroup) and Fugro Spatial Solutions through a number of separate missions as part of the larger Swan Coast LiDAR Survey that covers the regions of Perth, Peel, Harvey, Bunbury and Busselton. The project was funded by Department of Water, WA for the purposes of coastal inundation modelling and a range of local and regional planning. The data are made available under licence for use by Commonwealth, State and Local Government. The HDEM was produced by SKM using the ANUDEM program. The HDEM ensures that primary stream/channel flow, and water flow across the land surface are accurately represented. The hydrologically enforced HDEM depicts water bodies as being flat, and water courses depict consistent downward flow of water unimpeded by vegetation or man-made structures such as bridges and major culverts. Drainage enforcement was limited to watercourse lines depicted on 1:25,000 topographic mapping and to the intersection of the water course layer and transport layer. For the purposes of inundation modelling, inundation contours have been developed using the HDEM. The inundation extents were extracted at 0.2m intervals below 2m AHD and 1m intervals up to 10m. The inundation contours are available as polylines. The inundation contours have also been flagged as to whether the area connects directly to the sea. he data was captured with point density of 1 point per square metre and overall vertical accuracy has been confirmed at <15cm (68% confidence). The data are available as a number of products including mass point files (ASCII, LAS) and ESRI GRID files with 1m grid spacing.
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The Lapstone Structural Complex (LSC) comprises a series of north-trending faults and monoclinal flexures forming the eastern margin of the Blue Mountains Plateau, ~50 km west of the Sydney CBD. The LSC is considered a potential source of large earthquakes, however its evolution, and in particular its tectonic history is not well constrained. The LSC is bounded to the west by the Kurrajong Fault System (KFS), a series of <i>en echelon </i>reverse faults downthrown to the west. Streams crossing the LSC oversteepen by about 2-5 times over these faults. This study aims, through longitudinal profile analysis of 18 streams crossing the LSC coupled with field observation, to determine whether the oversteepening can be attributed to a lithological change at the faults, or tectonically-induced disequilibrium. Two approaches are used. Firstly, plots of log slope versus log distance (DS plots) are produced for each of the streams. As a result of noise in the topographic data, these results are inconclusive in demonstrating either situation. Secondly, an area-slope relationship, defined by <i>A<sup>0.4</sup>S</i> (where A = area and S = slope), is plotted against downstream distance. This factor is derived from the stream incision law, <i>dz/dt </i>= <i>KA<sup>m</sup>S<sup>n</sup></i>, where <i>K</i> is assumed to be constant, and <i>m</i> and<i> n</i> are positive constants relating to erosional processes, and basin hydrologic and geometric factors. The analysis shows that in all but two streams, values for <i>A<sup>0.4</sup>S</i> are at a maximum over the LSC. Peak <i>A<sup>0.4</sup>S</i> values of about 0.2 are estimated to be equivalent to vertical incision rates of about 70 m/Ma. <i>A<sup>0.4</sup>S</i> varies with lithology; however the lithological effect is demonstrated to be of similar magnitude or smaller than the apparent structural control exerted by the LSC. All streams with catchment areas less than 100 km<sup>2</sup> have developed swamps upstream of faults on the LSC. Sediment accumulated in these swamps is generally 0.5-4 m thick, but reaches 14 m in Burralow Swamp. In Blue Gum Creek and Burralow Swamps, the sedimentary sequence includes an organic clay layer indicative of low-energy depositional conditions. Previous radiocarbon dating and pollen analysis suggests the sediment is of Pleistocene age. The elevation of the clay layer is similar to that of bedrock downstream of the faults, consistent with damming related to from tectonically induced uplift.
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The 3 second (~90m) Shuttle Radar Topographic Mission (SRTM) Digital Elevation Model (DEM) version 1.0 was derived from resampling the 1 arc second (~30m) gridded DEM (ANZCW0703013355). The DEM represents ground surface topography, and excludes vegetation features. The dataset was derived from the 1 second Digital Surface Model (DSM; ANZCW0703013336) by automatically removing vegetation offsets identified using several vegetation maps and directly from the DSM. The 1 second product provides substantial improvements in the quality and consistency of the data relative to the original SRTM data, but is not free from artefacts. Man-made structures such as urban areas and power line towers have not been treated. The removal of vegetation effects has produced satisfactory results over most of the continent and areas with defects are identified in the quality assessment layers distributed with the data and described in the User Guide (Geoscience Australia and CSIRO Land & Water, 2010). A full description of the methods is in progress (Read et al., in prep; Gallant et al., in prep). The 3 second DEM was produced for use by government and the public under Creative Commons attribution.