A collegue here has a problem I cannot help with. She has the surface (as raster) of a landslide release area (from AFTER the slide) and wants to calculate the calculate the theoretical/approximate volume of the release surface. Is there a funtion in ArcGIS or GRASS GIS 7 that fills the slide relesease area? The problem is that we do not have the pre-release surface, so cut/fill does not work here.

  • Can you identify both the release area and the accumulation area, or do you have just the post-release elevations? (Showing us an image of the DEM would help.)
    – whuber
    Oct 24, 2013 at 21:32

2 Answers 2


You can perfectly use the stable GRASS GIS 6.4.x (7 is not necessary):

  • depression areas can be filled with r.fill.dir (filters and generates a depressionless elevation map and a flow direction map from a given elevation layer)

  • and resulting volume can be calculated by r.volume or r.lake

  • This most likely is not a depression in the sense of areas that would fill with water. Even if it were to have such a shape, the amount of fill surely would grossly underestimate the landslide volume, because the fill would level out the depression but landslides never occur on level ground!
    – whuber
    Oct 24, 2013 at 21:29
  • Thank you! She has not gotten back to me, but seems to have solved the issue with a tool in ArcGIS. For my part, I find the GRASS GIS solution offered more interesting and will use this for my work in the future.
    – Peter
    Dec 13, 2013 at 7:51

Do the cell values of the raster represent release volume or is the raster simply imagery (e.g. aerial/satellite)? Do you have a polygon (vector) representing the slide region?

If the raster does represent volume, and you have a polygon for the slide region, then you should be able to run zonal statistics tool from ArcGIS Spatial Analyst and get the descriptive statistics for the area.


  • Could you explain how this would solve the problem? In particular, rasters rarely represent "volume": the relevant one in this case would be a DEM which, by construction, represents height. Regardless, descriptive statistics would only tell you what is currently there, not what was lost during the landslide!
    – whuber
    Oct 24, 2013 at 21:31

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