I want to determine which villages lie upstream and which villages lie downstream big cities built on the side of rivers in Indonesia. I have the .shp file of villages and cities, the .shp file of all rivers in the country and some .tif files showing elevation (standard SRTM rasters, although I cannot find the exact resolution right now). I know how to identify villages located close to rivers (using spatial join with the rivers .shp file). However, I do not know how to determine the direction of the rivers. Should I discard my rivers .shp file and try to create a Digital Elevation Model from the SRTM .tif data? Using the .tif data I just did: FLOW DIRECTION + FLOW ACCUMULATION, but the computer is stuck since 40 minutes ago and even if it works I would not know how to continue..
Any suggestion? Thank you. /michele