Stream Order (Strahler) and Flow Direction

[PeterWilson]

I have generated a terrain dataset for South Africa from 20m contours and SPOT shots. In order to eliminate errors in the terrain where there isn't enough data especially low lying areas. I would like to make use of river centerlines to enforce the drainage within the terrain dataset. My proposed methodology is to intersect the river centerlines with the contours and extract the Z values of the contours into the river centerlines. I would then use the polyline Z river centerlines as hard break lines within the terrain dataset.

The problem that I have is that I need to ensure that the flow direction of the existing river centerlines that I wish to use is correct and secondly need to assign a stream order (Strahler) to the river centerline segments.

I've attached a screen shot of the river centerlines to help explain the problem that I have with the currently available river centerline dataset. There are numerous segments that should be tributaries but do not extended enough to link up with the main river. I'm looking for advice in how I can make use of the available river centerlines to embed into my terrain. Do I eliminate the segments that are not connected to the main river centerlines.

What is the most efficient methodology to rectify the river centerlines to a point that they won't add additional error to my terrain dataset, which I then would like to use to generate a river centerline network to build up an hydro data model. Any assistance will be appreciated.

[AslamHanief]

Hi,

I'm unable to locate the Assign River Order toolset under the Attribute Tools. Has it been removed in ArcHydro 2?

[AslamHanief]

Got it. Thanks.

[SandeepMahajan1]

Hi Aslam can you please let me know how you solved your problem? because I also want to generate drainage order on a digitized drainage network?

Thanks & Regards

Sandeep Mahajan

[NicoleCarlozo]

Mark - I see the SA tool, but it requires a flow direction raster and a stream raster. I don't see a "Flow Direction with Streams" tool. There is a "Flow Direction Tool" that requires a hydro DEM, but I only have a stream polyline/shapefile.

Zye - The "Create Drainage Line Structures" tool requires a Raw DEM. Do you have any more information about the DEM specifics? Does resolution matter?

[ZichuanYe]

the Create Drainage Line Structures function needs a DEM for it's cellsize and as a snapgrid.
In that sense, any DEM that provide correct cellsize and coordinate snapping will work.

[DuncanHornby]

There is a more efficient Strahler ordering algorithm created by Gleyzer et al 2004 which is implemented in an ESRI 10.1 AddIn tool called RivEX, worth a look?

[NicoleCarlozo]

After attempting to create stream order attributes via Lidar processing using the Hydrology Toolbox, I have circled back to this. Due to low coastal elevations and landuse changes, the lidar output isn't lining up with the stream polyline data that I already have.

I have a stream polyline, but I need stream order attributes. I have lidar, which I have used to create flow direction and flow accumulation grids. I attempted to use the "Create Drainage Line Structures" tool, however I received an error due to missing HydroIDs. I used the Assign HydroID tool within the Attribute Toolbox and tried again. It is still failing to execute. Am I missing something? Should I be using the lidar data as the raw DEM instead of the flow direction or flow accumulation grids? Do I need to specify file type?

If anyone has any experience with identifying stream order using known streams and lidar, I would really appreciate the help.

Thanks,
Nicole

[MarkBoucher]

Should I be using the lidar data as the raw DEM instead of the flow direction or flow accumulation grids? Do I need to specify file type?

The LiDAR data (points, I assume) must be converted to raster data. The rawdem is a raster file not a point file.

My experience is most polyline data fails to always follow the creek/river/stream (stream) idenditified via raster DEMs. This is because they are likely created by tracing over old maps that inaccuratly depict the streams or over ariel photos where the stream is hidden by trees.  So, I use the raster with Arc Hydro to determine where the creeks are w/o the streams layer. Then I correct that where there stream is vauge in the DEM and where there are bridges/culverts, etc. that "mask" the creeks. This is where I burn in stream with the DEM reconditioning.

I suppose if you wanted to keep your stream polyline layer, you could do the Arc Hydro process create the stream order field inthe drainage layer and then transfer the stream order to your stream polyline layer.

[NicoleCarlozo]

Thanks Mark,

The lidar is in a raster format. I am having problems with the lidar results due to the ditching/artifical paths that are abundant in my study site. The Hydrology Toolbox first output "streams" in the middle of ag fields. I changed the CON value to produce an output more in line with my polyline file, but I still had the same problem. Now I am circling back to assigning stream order values to the polyline file I already have. If my study area was at a smaller scale, I think the lidar method could be used. But I am looking at county-wide data.

Does any initial processing need to be performed before running the "Create Drainage Line Structures" or "Assign River Order" tools? I feel like I'm missing something, but I haven't located any documentation that steps me through the process.

[MarkBoucher]

I normally use Arc Hydro that has several handy tools. You can use the Spatial Analyst (SA) tools but the process is not as well set up for someone doing it just once. This is a good link to review if you are using the SA tools. http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#/Understanding_drainage_systems/009z000...

This link http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#/Deriving_runoff_characteristics/009z00... is a sub-section of the one above and shows a good flow chart of the process.

You can force the drainage lines to be at our polylines by "burning" them into the DEM (raster). You can do this by converting the polylines to a raster with a very low number (say -1000). Then add the DEM to the stream raster. The result is a DEM with the streams obviously below the surrounding terrain. Then you can run the fill tool and then the flow direction tool and this will set you up to create the stream features to which you can add the stream order because our flow direction grid will match the streams.

Arc Hydro adds a "buffer" the stream burning to ensure that the cells near the burned stream are lowered and you don't get parallel streams right next to the stream defined by your stream polyline based raster. This can happen if the polyline does not line up with the stream in the DEM. I'm sure you could figure out a way to lower the cells around the stream. Possibly you could create a small buffer around your stream polylines and then convert that to a raster with a smaller low number (-100). Then add the buffer based raster to the DEM and THEN the polyline based raster to that resulting DEM. This would take care of some parallel streams.

Some of this process will be influenced by the size of your DEM raster cells. If they are large, I don't think you will have many parallel streams. If the grid is small, you could have more.

Hope this isn't to confusing.

Best,