I'm trying to make a model of surface runoff of rain water. I'm using GRASS GIS function r.flow, which generates nice smooth lines of runoff. What I need is edit these flowlines some way to avoid crossing between lines (see picture). As a input data, I'm using DEM in 5 meters resolution, which is smoothed by circle filter 9 x 9 cells.

Do you have some ideas how to automatically adjust lines? I can use ArcGIS, GRASS GIS, QGIS or SAGA GIS. I can even write some in Python. But I do not know how to solve it.

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1 Answer 1


Not a real solution ... but you may use r.carve first to burn the main flowline into the DEM. Then re-run r.flow on that. In order to find the main flowline, some v.net.* modules may help (shortest path perhaps). In essence, using a dual-step approach.

  • 1
    Nice idea, I will try it in few days and I will let you know about result!
    – david_p
    Jul 31, 2015 at 13:41

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