I would like to make a map of sinkholes. I have a DTM ARC/INFO ASCII GRID of Asiago Plateau and and I'm using grass gis. Does anyone know what is the correct form in grass gis?

  • Please take a look at this page why sink filling is not needed in GRASS GIS: grasswiki.osgeo.org/wiki/…
    – markusN
    Nov 18 '14 at 9:36
  • Thanks, I read. I understood that it was necessary to consider the areas highlighted as a fault. I was not happy with the result and so looking at the DEM I saw that large sinkholes could be seen by eye. The area that I have analyzed is not large and karst features are well developed. From a DEM with cells to 5 meters I could not expect much more.
    – Filippo
    Nov 18 '14 at 21:09
  • Fortunately I'm a caver and I can make out the sinkholes from rough terrain.
    – Filippo
    Nov 18 '14 at 21:18

In general, to create a map of sinkholes using a DEM, you would first fill the topographic depressions (sinkholes) then difference the original DEM from the filled DEM. This gives you 'depth in sink' but if you simply want a Boolean sink map, reclass the depth map such that 1 is assigned to all values greater than 0. The tool in GRASS GIS to fill depressions is called r.fill.dir. As an aside, in ArcGIS there is a convenient tool that maps sinks in one step by using the Sink tool and in the open-source GIS Whitebox GAT, for which I am a developer, you can use the similarly named Sink tool to achieve the same result.

  • @Filippo That's great. I'm glad you got solved. Nov 14 '14 at 14:50

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