I am trying to process a DTM by using r.watershed in QGIS 2.14.3, with the GRASS GIS toolbox. It should be the file named: "Number of cells that drain through each cell".
I get some negative values, even if the shape of drainage line seems very correct. I think that the problem might be the number format (like float or integer).
I am working on a .tiff dem, but it was extracted by clipping from a .asc bigger dem.
How can I solve this?