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.
Although it shows the value between 1 - 255, should I be worried? Why is it showing so many values?
That is what would be expected... see How flowdirection works
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.
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.