I have to apply uncertainty principle to computing flow accumulation using Monte Carlo method. I generate raster with random numbers which represents mistakes in creating DEM. Then I apply those rasters on DEM in iterations. For each DEM with added random numbers raster I compute flow accumulation. In each iteration it generates slightly different lines of flow accumulation. At the end of process I merge these lines into one raster. It looks like this: multiple flow lines

What I have to do is extract most probable flow line from this data. I use ArcGIS10 but it does not matter which software should be used. In ArcGIS I tried to use thin function or extract by attributes which gives me pretty good results. I also converted every line into polyline, merged them and applied buffer. Then I used thin function on buffer. This gives me also very good result.

I want to ask if you can help me with finding another solutions for extracting most probable line?


use newraster = con(Flowaccum > X, Y) . for example x =100 y=1 . the result is streams of your watershed .but if you want to extract most probable flow you should change x and y value . use this expression in map algebra or raster calculator .

  • Thanks, it works good. But I have problem with extracting line in flat terrain. With applied mistakes to DEM, differences between flow lines are bigger than in mountainious terrain. I tried to work with only 2 lines at a time, add them together, apply thin on them and then add another line to result. It gives me different results but they arent still good. I also tried to use flow direction raster. I used cell statistics with majority parameter on flow direction raster from DEMs with applied mistakes and then did flow accumulation. Do you have some solution with lines in flat terain? Thanks. – Jakub Dec 3 '12 at 11:34
  • could you please describe more clearly and upload an image of your result? – BBG_GIS Dec 3 '12 at 15:45

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