Length of the main stem in a river by summarizing line segments

[Anonymous User]

Original User: ossi88

Hello,

I have a problem with calculating the length of the main river in a network of rivers. I am only interested in the main stem length. Problem is that the river only consists of line segments and many side-rivers I am not interested in. Do I have to calculate this manually by using the "Identify" tool or are there easier options? I am going to use this on many different rivers so I hope there are more efficient ways to sort this out. If so, can you give me a little guide or point me in the right direction?

Help will be appriciated
Thanks

�?ystein

[DanPatterson_Retired]

At least by using the Strahler method of stream ordering and other tools

http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#//009z000000z3000000.htm
http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#//009z00000057000000.htm
http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#/Stream_to_Feature/009z00000058000000/

it will simplify what you consider to the the main stream channel then you can select the segments and get their length

[DuncanHornby]

The tool RivEX can help with this problem as long as your river network is vector and not a raster network.

If you define the main river as starting at the mouth of the network then RivEX has the Add Main Channel.

If you are starting at some random point within a catchment is the main channel the route to source? If so you could use the Find source of site tool.

If your definition of main river from some random starting point is the route to source and route to network mouth then you could use the Create site centred reach and set the distances to a very large value to ensure searching reaches the source and mouth, an example is shown below.