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?
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.