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I have a DEM with values that range from 0 to 1040. I'd like to create a layer with the flow directions by means of the Flow Direction tool in the Hydrology section of the ArcToolbox. However, when I try to do so, it creates a raster with only one value: zero. I'd like to have a raster with the values 1, 2, 4, 8, 16, 32, 64, and 128.

Does anyone know what I'm doing wrong, and how my mistakes can be repaired? Here are some screenshots of what I tried:

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  • Was there any warnings in the geoprocessing results?
    – Liam G
    Aug 4 '20 at 12:36
  • @LiamG I don't think so. I do see the following: "output drop raster: <empty>"
    – Max Muller
    Aug 4 '20 at 13:11
  • Normally you would run the dem through the fill sink tool and feed that into the flow direction tool. Also make sure you do not have any extent properties set.
    – Hornbydd
    Aug 10 '20 at 12:45
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What @Hornbydd mention is most often the case for seeing an empty (0) value raster. When you are running the tool, go to Environments -> Processing Extent. 'Default' should work in this instance or you can test out other extent options.

You could also try in a fresh MXD were no settings have been set.

Also confirm that there is a coordinate reference system assigned to your DEM. Sometimes if there is no CRS assigned or it is bad, there can be a mismatch between the units of the extent and the actual raster. In this case you will also see the same issue.

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