Calculating percentage (or length) of stream network that is multiple channel streams using ArcGIS Desktop?

Question

I have a polyline stream network of all channels within a drainage basin (which is 1.1 million square km) A number of the rivers in the basin alternate between single thread and multichannel (i.e. anabranching or braiding).

Is there a way using argis for me to calculate the length or percentage of total which are either multi or single thread, without simply measuring the along line distances?

The ideal end product would be two values:

1. percentage (or total length) multichannel
2. percentage (or total length) single channel

Answer 1

If I understand well, all your multiple channels create "islands" (portions of land surrounded by water, maybe it has a specific name) between them. Therefore you can identify the multichannels as being the river segment which intersect one of your islands.

In practice (if you have a standard licence)

1) use "feature to polygon" to create the "islands"

2) Planarize your lines to split them at each intersection (editor > more editing tools > advanced editing tools)

3) Select the river segments that share a line segment with you island

4) use the statistics on the length field to compute the total length.

Answer 2

Have a look at RivEX it has a tool that does exactly what you want, identifies multi-threaded sections and tags them with an ID, then you could count the number of loops as well as work out sum the lengths.