Flow direction values of 1 - 255. Why is this happening?

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04-12-2017 07:20 PM
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AnanG
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New Contributor II

I am using a practice data set to practice the delineation of watersheds. I have been following the manual and so far everything is going well. However, when using the "Flow Direction" tool, the output has values ranging from 1 to 255. 

The values show that they extend from 1 to 255 but they go on to expand even more until 254Although it shows the value between 1 - 255, should I be worried? Why is it showing so many values?

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DanPatterson_Retired
MVP Emeritus

That is what would be expected... see How flowdirection works

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JayantaPoddar
MVP Esteemed Contributor

Adding to Dan, There are eight valid values of flow direction (1,2,4,8,16,32,64,128) depending on the direction a water can flow from a particular pixel.

Direction Code

If a cell's (or spatially connected cells') flow direction cannot be assigned one of these eight values in a flow direction raster, it becomes a Sink.



Think Location
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