I have a problem with the Flow Direction tool ArcGIS 10.2.2. After running the tool on a digital elevation model in .tif format 16 bit unsigned integer. However the result is an image of 8 bit unsigned integer without flow values. See figure. enter image description here

Can someone help me?

  • 1
    That's right. The directions are between 1 and 255 (0 is flat or no flow), see this old doc that shows how it works webhelp.esri.com/arcgisdesktop/9.2/… Feb 12, 2015 at 23:29
  • Ok. The output contains integer values that range from 1 to 255, but these values should not be ordered: 1-2-4-8-16-32-64-128. The field Value not this this way. Thanks for help Feb 13, 2015 at 1:20
  • Please include an example of your flow direction raster. If you export a small part to Esri ASCII (resources.arcgis.com/en/help/main/10.1/index.html#//…) you can open in notepad(++) and select a few values. Feb 13, 2015 at 1:28
  • Sometimes the algorithm cannot make up its mind; it determines that two or more directions are likely. In those cases it sums the codes for all the directions. You will therefore find very large counts for the codes that correspond to definite flow directions--1, 2, 4, ..., 128--together with smaller counts at other values corresponding to these problematic points. Typically, the fewer ones there are in the binary expansion of the value, the more counts it will have. For instance, 48=32+16=00110000B will have a higher count than 47=00101111B. This pattern is visible in the table you marked.
    – whuber
    Feb 13, 2015 at 15:08

1 Answer 1


I have the same problem, but I solve in this way:

1- Mask the raster 2- Use hydrology/fill 3- use Flow direction


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