How to assign correct flow direction to stream network polylines?

Question

I would like to create a map showing the results of watershed analysis as well as the resulting stream network with flow direction.

I have a stream network which has been created from the flow accumulation raster. I also have a stream link raster which was created from the resulting stream network raster and the flow direction raster.

Once I convert the stream network or the stream links to vector polylines the resulting feature class does not retain the correct directions of the various segments.

What is the approach?

I have ArcGIS 10.2.1 Standard, Spatial Analyst, 3D Analyst

Red lines on the below example show the network I would like to show the map along with arrows indicating direction of flow:

Answer 1

I can think of a few ways to do this:

• Symbolize the lines so they have direction indicated, and manually Flip those in the wrong direction.
• Use an attribute if available or a calculation (such as end z > start z) to select segments going the wrong direction and Flip (GP) them.
• Create a geometric network of the lines and use the Flow Direction tools, setting appropriate sinks and sources.

However the best solution might be not having to do it at all. Using the Stream to Feature tool should allow you to use both your stream network raster and your flow direction raster as inputs so that the vector stream lines that are output have the correct direction to start with.