I have a stream network and outlets as shown below.

It is overlapped with outlet cells raster which I can use to get sub-watersheds but when I add an outlet (red color cell in current example) then I have to divide stream segment in order to have correct "From Node" to "To Node" relationships with use of Stream to Feature (Spatial Analyst) tool in ArcGIS 10.1

Any suggestions on how to correctly divide stream segment to have correct topological relationships?



On the topology toolbar is the tool Planarize Lines which can be used in Standard and Advanced license levels and then Explode Multipart features on the Advanced Editing Toolbar, the lines do not need to participate in a topology to be subject to this tool.

Start editing, select all and activate the tool, enter a suitable tolerance and done! Don't forget to save your edits.

A tool that also may help is Multipart to Single Part which will break the lines down to single part features, which is probably what the tool is having issues with: each feature should be a single part geometry.

If you are in a situation where one line is continuous and the other terminates without an intersection you can use Feature Vertices to Point on the lines with an option of both ends to generate end points. Use the generated end points and original lines in Split Line at Point tool which will break the continuous line allowing for a true topological intersection. Follow that with an Integrate to ensure ends are confluent, then Repair Geometry with delete empty to remove very short segments and then just to be sure Multipart to Single Part.

  • I am doing it all using arcpy and wondering how it can be achieved using Multipart to Single Part? – Ibe Jun 23 '14 at 2:40
  • Try it, it is probable that for some reason there are multi part features (clip will do this) in your data. They will probably all be split at the intersections already. I don't know of a planarize in geoprocessing, so if this doesn't work I'm out of ideas. – Michael Stimson Jun 23 '14 at 2:45
  • I have found a solution. Multiplied stream link with flow direction and then used that new stream link raster to get watershed layer (used all outlets). It gave me updated stream link raster. – Ibe Jun 25 '14 at 1:58
  • That's good Ibe, may I suggest that you answer your own question in case someone has a similar problem. – Michael Stimson Jun 25 '14 at 3:00

I have found a solution. Following are the steps:

1] Use stream link raster and multiply it with flow direction grid. It will give updated stream link raster. 2] Use updated stream link raster and outlets (all) in watershed delineation tool. It will give watershed layer for over streams area only and rest is NoData. It will show updated streams based on all outlets.

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