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Dienstag, 4. März 2014

Mountain hay meadows - a case for EU-DEM and Corine landcover? - part 2

While reading chapter 9 Landforms and Landform Elements in "Geomorphometry - Concepts, Software, Applications" (Hengl, T., Reuter, H.I., eds. 2009: Developments in Soil Science - Volume 33, Elsevier) an idea for a further refinement of the first blog's results came around.

Footslopes are areas characterized by colluvial (nutrient) redeposition from upslope. As species rich Mountain hay meadows (habitat 6520) are mesophile, nutrient-rich colluvial footslopes may be excluded from a potential range.

But how to calculate footslopes by GIS means?

There is an interesting GRASS GIS 7svn-addon:

r.geomorphon - Calculate geomorphons (terrain forms) and associated geometry using machine vision approach.

Geomorphon is a new concept of presentation and analysis of terrain forms:
  • Stepinski, T., Jasiewicz, J., 2011. Geomorphons - a new approach to classification of landform, in : Eds: Hengl, T., Evans, I.S., Wilson, J.P., and Gould, M., Proceedings of Geomorphometry, 109-112.
  • Jasiewicz, J., Stepinski, T., 2013. Geomorphons - a pattern recognition approach to classification and mapping of landforms. Geomorphology, vol. 182, 147-156.
Let's install the addon in GRASS GIS 7svn
g.extension extension=r.geomorphon svnurl=
and do a default run of the addon
r.geomorphon --verbose dem=eudem_austria forms=mostcommongeomorph search=3 skip=0 flat=1 dist=0
and a run with an increased search window
r.geomorphon dem=eudem_austria forms=mostcommongeomorph_search6 search=6 skip=0 flat=1 dist=0
Calculated terrain forms (geomorphons) are:
r.category map=mostcommongeomorph                                           
1    flat
2    summit
3    ridge
4    shoulder
5    spur
6    slope
7    hollow
8    footslope
9    valley
10   depression
A quick visual comparison shows that footslopes seem to be already excluded by the calculations mentioned in the earlier blog.

 Shaded EU-DEM with potential range of habitat 6520 (yellow):

Shaded EU-DEM with potential range of habitat 6520 (yellow) and footslopes (search window =3; red) by r.geomorphon:
Shaded EU-DEM with potential range of habitat 6520 (yellow) and footslopes (search window =6; blue) by r.geomorphon:
More investigations are needed. But r.geomorphon is an interesting GIS tool for calculating/defining landforms and landform elements.