I am trying to generate flow direction from DEM. However I am getting some vales as 80 and 129, though it should be only from 1, 2, 4, 8,16, 32, 64, 128
What could be the reason for this error? How to resolve it?
Edit: Original DEM is at 90m resolution, whereas I am generating fdr at 0.25 degree spatial resolution by setting the cell size as 0.25 degree in raster analysis.