Slope Units Delineation-OLD

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Details: The software r.slopeunits requires a DEM, an optional raster layer showing alluvial plains, and the following user-defined parameters:
  • the initial flow accumulation area threshold (t in square meters);

  • the reduction factor r (integer, >1), that is used to calculate, iteratively, new values for the flow accumulation area threshold (t = t-t/r). Values larger than 5 are recommended;

  • the minimum surface area for the slope units (a in square meters);

  • the minimum circular variance of terrain aspect within a slope units (c, varies between 0 and 1, where 0 means no variance, i.e. cells dip in the same direction, and 1 means maximum variance);

  • the maximum surface area for the slope units (maxarea, in square meters, optional);

  • threshold area value for the cleaning procedures (cleansize, in square meters, used to remove very small slope units that may occur give some geomorphological conditions).







Data (ready-to-use maps)

Italy: regional maps

  1. Abruzzo
  2. Basilicata
  3. Calabria
  4. Campania
  5. Emilia-Romagna
  6. Friuli-Venezia Giulia
  7. Lazio
  8. Liguria
  9. Lombardia
  10. Marche
  11. Molise
  12. Piemonte
  13. Puglia
  14. Sardegna
  15. Sicilia
  16. Trentino-Alto Adige
  17. Toscana
  18. Umbria
  19. Valle D'Aosta
  20. Veneto

Italy: national map

Himalaya (mostly Nepal)



Requirements, installation and run

The software have been tested starting on Ubuntu 14.04 LTS server but
      should run on a generic GNU/Linux machine.
      Requirements: our software require GRASS GIS 7.*, Python, Bash.
      The two files contained in the tar.gz archives (one python script, one bash script) must be copied
      in the “scripts” folder of the GRASS GIS installation directory. They must be executable (see below).
      A typical approach, for the installation, is (replace grass78 for previous versions):
      # open a bash shell
      # change working directory to the download folder, e.g.:
      cd /home/$USER/Downloads
      # move the files into the scripts folder of the grass installation, e.g.:

      mv r.slopeunits /usr/lib/grass78/scripts

      mv /usr/lib/grass78/scripts
      # give execution rights
      chmod ugo+x /usr/lib/grass78/scripts/r.slopeunits
      chmod ugo+x /usr/lib/grass78/scripts/
      # run GRASS GIS in the location containing the digital elevation model type and:
      r.slopeunits --help
      # to see the options. The minimal command line to obtain a slope units delineation is
      r.slopeunits demmap=[dem] slumap=[output_SU_map] thresh=[t, square meters] circularvariance=[c] areamin=[a, square meters] reductionfactor=[r, r>2] maxiteration=[max number of iterations]
      # see: M. Alvioli, I. Marchesini, P. Reichenbach, M. Rossi, F. Fiorucci, F. Ardizzone, F. Guzzetti ( 
      # and: M. Alvioli, F. Guzzetti, I.Marchesini (
      # and references therein for explanations, examples and additional options.
      # please address comments, questions and bug fixes rquests either to: 
      # ivan.marchesini[AT];
      # massimiliano.alvioli[AT]




  • Alvioli M., Guzzetti F., Marchesini I., (2020).
    Parameter-free delineation of slope units and terrain subdivision of Italy.
    Geomorphology 258, 107124.

  • Alvioli M., Marchesini I., Reichenbach P., Rossi M., Ardizzone F., Fiorucci F., Guzzetti F. (2016).
    Automatic delineation of geomorphological slope units with r.slopeunits v1.0 and their optimization for landslide susceptibility modeling.
    Geoscientific Model Development 9, 3975-3991.

  • Alvioli M., Marchesini I., Pokharel B., Gnywali K.R., Lim S. (2021).
    A geomorphological slope unit map of the Himalayas.
    Under review;

    Pokharel B., Alvioli M., Lim S. (2021).
    Assessment of earthquake-induced landslide inventories and susceptibility maps using slope unit-based logistic regression and geospatial statistics.
    Scientific Reports 11, 21333.

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published on 2021/12/20 15:59:53 GMT+2 last modified 2021-12-20T17:30:15+02:00