Terrain derivativesDerived from the 1 second resolution SRTM DEM-S and DEM-H

SUSTAINABLE AGRICULTURE FLAGSHIP

John Gallant and Jenet Austin | Terrain Analysis Team, CSIRO Land and Water7th November 2012

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 Austin2 |

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 Austin3 |

Location of example datasets

• North-central Tasmania• Some flat areas and some hilly

areas for contrast

Terrain derivatives | John Gallant and Jenet Austin4 |

Terrain derivatives | John Gallant and Jenet Austin5 |

Slope(%)

Relief(300 m radius)

Terrain derivatives | John Gallant and Jenet Austin6 |

Slope-reliefClass

TopographicPosition Index

Terrain derivatives | John Gallant and Jenet Austin7 |

MrVBF TopographicWetness Index

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 Austin8 |

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 Austin9 |

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 Austin10 |

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

Terrain derivatives | John Gallant and Jenet Austin11 |

January

July

CSIRO Land and WaterDavid JacquierIn charge of toilet paper and other consumablest +61 2 6246 5916e david.jacquier@csiro.auw www.csiro.au/people/david.jacquier

CSIRO Land and WaterJohn GallantTerrain Analysis Team Leadert +61 2 6246 5734e john.gallant@csiro.auw www.csiro.au/people/John.Gallant

CSIRO Land and WaterJenet AustinSpatial Analystt +61 2 6246 5707e jenet.austin@csiro.auw www.csiro.au/science/Soil-and-

Landscape-Science

SUSTAINABLE AGRICULTURE FLAGSHIP