Calculate stream order with Trace Network

[Anonymous User]

It would be great if the Trace Network ribbon had an option to calculate stream order (using vector layers, instead of running the Stream Order tool on stream and flow direction rasters). The current tools, such as Downstream and Upstream, are helpful, but there is much potential for expanding Trace Network functionality. 

For context, I created a trace network using an NHD stream layer, which already has flow direction in the attribute table. I would like to identify all first-order streams (example streams highlighted in yellow in image). I need to use the regular NHD dataset, not NHDPlus (NHDPlus contains stream order data, but it is calculated differently than I want to). 

[curtvprice]

There are many stream order schemes. The Spatial Analyst Stream Order tool supports Strahler and Shreve. NHDPlus uses Strahler.  Can you be more specific about how NHDPlus stream ordering is not what you want? 

[Anonymous User]

Hi curtvprice, thanks for prompting the clarification!

- The Spatial Analyst Stream Order tool requires a stream raster and flow direction raster. If I am using just NHD vector data without a good DEM, this tool is not appropriate (unless I am misunderstanding something?). I would like to be able to calculate stream order (Strahler or Shreve) with just the NHD lines and the flow direction field. 

- I don't want to use NHDPlus for 2 reasons:

1) I prefer the quality of the regular NHD for my study area.

2) When I symbolize NHDPlus streams based on stream order, the streams with a value of 1 (uppermost tributaries) don't make sense to me. I joined the NHDPlus VAA table to the NHDPlus Flowline feature class using the shared NHDPlusID field, so unless something went wrong in that step, I cannot use the NHDPlus stream order to identify first-order streams. In the screenshot below, the thick green NHDPlus lines are StreamOrder=1. Some of these make sense to me as first-order streams (black check mark), but why is the main river, which has many tributaries, labeled as a first-order stream (black question mark)?

[curtvprice]

The NHDPlus I was referring to is the NHDPlusHR which is built on the full resolution data, not the 1:100K scale features. Are the data you were looking at NHDPlusHR or NHDPlus v21? There certainly could be some errors in there, or an issue with your join, I'm not sure.

There is attribution within the NHDPlus VAA (STARTFLAG) that identifies all headwater flowlines if that's what you are looking for.

I certainly endorse this idea though, it would be a great thing to have available, especially since elevation derived hydro is all the rage.

[Anonymous User]

I was looking at NHDPlusHR, and I figured out the issue with joining the VAA to the NHDPlusHR features - I had indexing turned on, which I think messed with the join. I redownloaded the data and ran join without indexing, so stream order looks accurate now. 

It would be great if stream order could be easily calculated with the regular NHD, which is more accurate in my project area. In parts of Oregon, the Bureau of Land Management is adding certain attributes to the regular NHD, including stream order (by HUC12 units, status of data release here). This is what I would like to see for NHD across the U.S. 

[TamikoStone1]

Hi,  if you have access to Arc Hydro Tools Pro, in the analysis tools, there is an Assign River Order tool that calculates stream order.  You have to do a bit of preprocessing to get it to work.