Terrain derivatives

1. Terrain derivatives Derived from the 1 second resolution SRTM DEM-S and DEM-H John Gallant and Jenet Austin | Terrain Analysis Team, CSIRO Land and Water 7th November 2012 Sustainable agriculture flagship

2. Data Source • Terrain derivatives all based on the national SRTM-derived 1 second DEM-S or DEM-H • Australia wide coverage • Consistency • Users working from the same version • Accuracy • Best practice methods • DEM geometry properly addressed Terrain derivatives | John Gallant and Jenet Austin

3. Available Datasets • Aspect • MrVBF • Plan and profile curvature • Slope (percent and degrees) • Median slope over 300 m radius circle • Relief (elevation range) over 300 m and 1000 m radius circle • Slope-relief classification • Topographic position index • Contributing area • Topographic wetness index • Cell area (varies with latitude due to geographic projection) Terrain derivatives | John Gallant and Jenet Austin

4. Location of example datasets • North-central Tasmania • Some flat areas and some hilly areas for contrast Terrain derivatives | John Gallant and Jenet Austin

5. Slope (%) Relief (300 m radius) Terrain derivatives | John Gallant and Jenet Austin

6. Slope-relief Class Topographic Position Index Terrain derivatives | John Gallant and Jenet Austin

7. MrVBF Topographic Wetness Index Terrain derivatives | John Gallant and Jenet Austin

8. Resolutions and Coordinate System • Terrain derivatives are available at two resolutions • 1 second – approximately 30 m • 3 second – approximately 90 m • The 3 second versions have been aggregated from the 1 second versions using methods that suit the characteristics of each dataset • Geographic coordinate system • Datum WGS84 • Derivatives can be projected to other coordinate systems at a comparable cell size • 9 second resolution versions do not currently exist • Not suitable for some derivatives (e.g. TWI, aspect) • If genuinely required, contact John Gallant to discuss an appropriate method of aggregation Terrain derivatives | John Gallant and Jenet Austin

9. Data Format • Terrain derivatives are in ESRI grid format • 1 second resolution datasets are available only as 1x1 degree tiles • 3 second datasets are available as 1x1 degree tiles and as an Australia-wide mosaic in an ESRI file geodatabase Terrain derivatives | John Gallant and Jenet Austin

10. Data Access Portal • Terrain derivatives will be available via the Data Access Portal • https://data.csiro.au/dap • 3 second resolution mosaic • Some metadata publicly viewable now • Public download of large datasets in next release of DAP (early November) • Currently waiting on confirmation of CC-BY licence before all terrain derivative datasets will be approved and available through the DAP • Link from the TERN Data Discovery Portal • http://portal.tern.org.au • Soil and Landscape Facility • 1 second resolution datasets – size constraints • Available within CSIRO • Most have been distributed to a number of agencies via external hard drive Terrain derivatives | John Gallant and Jenet Austin

11. January Future Datasets • Solar radiation surfaces • SRAD model, accounts for topography and climate • 1 second resolution • Monthly averages • Testing complete for Tasmania • Estimated completion date for Australia – March 2013 • Prescott Index • Requires radiation surfaces as input July Terrain derivatives | John Gallant and Jenet Austin

12. CSIRO Land and Water David JacquierIn charge of toilet paper and other consumables t +61 2 6246 5916 edavid.jacquier@csiro.au wwww.csiro.au/people/david.jacquier CSIRO Land and Water John GallantTerrain Analysis Team Leader t +61 2 6246 5734 ejohn.gallant@csiro.au wwww.csiro.au/people/John.Gallant CSIRO Land and Water Jenet AustinSpatial Analyst t +61 2 6246 5707 ejenet.austin@csiro.au wwww.csiro.au/science/Soil-and-Landscape-Science Sustainable agriculture flagship