• Is It ‘Deduction’ or ‘Induction’, My Dear Watson?

    Sherlock Holmes often talks about ‘deductive reasoning’, but was he really using deduction or induction. Although by definition these two approaches appear to be opposites, in practice, the differences between the two can be subtle.

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  • Relief Analysis Toolbox

    The central purpose of this toolbox is to provide ArcGIS users a convenient way to calculate hillslope position from elevation grids. However, the Relief Analysis Toolbox also includes some other ArcGIS models that may be of interest to anyone working with landscape and landform segmentation. The main features of this toolbox are:

    • hillslope position (calibrated to the U.S. Soil Survey),
    • relative elevation (a moving-window approach as described in Miller, 2014; middle elevation used for reference),
    • topographic position index (modified from Weiss, 2001; mean elevation used for reference),
      • TPI slope position,
      • TPI landform class,
    • plus a couple of data classification tools that might come in handy.
    Download the Relief Analysis Toolbox (405.1 KB)
    Includes instructions and a suggested color scheme for displaying hillslope position.

    More about the Digital Classification of Hillslope Position

    Hillslope Position

    Classification of hillslope position has a long history in soil geomorphology. However, its roots in tacit field knowledge has prevented its use in GIS. The model provided here has been calibrated and validated on soil scientists’ observations in the field. The resulting maps of hillslope position represent base maps that can be used to (1) improve research on toposequences by providing explicit definitions of each hillslope element’s location, (2) facilitate the disaggregation of soils currently mapped as complexes, and (3) identify map unit inclusions that exist due to subtle topographic variation. The base maps developed by the model can also help identify areas of possible mismapping, especially where soil boundaries cross topographic breaks. This information can enable the mapper to redefine many existing soil map unit boundaries, placing them more correctly at locations where defendable landscape breaks exist.

    Supplemental Materials
    References

    Development of the hillslope position classification tool is documented in the following publications and dissertation, and should be used for citation as appropriate:

    Miller, B.A. and R.J. Schaetzl, 2015. Digital classification of hillslope position. Soil Science Society of America Journal 79(1):132-145. doi:10.2136/sssaj2014.07.0287.

    Miller, B.A., 2014. Semantic calibration of digital terrain analysis. Cartography and Geographic Information Science Journal 41:166-176. doi:10.1080/15230406.2014.883488.

    Miller, B.A. 2013. Incorporating tacit knowledge of soil-landscape relationships for digital soil and landscape mapping applications. Dissertation, Department of Geography, Michigan State University, USA.