Actually I am new to GIS, so I don't know much about technical terminology.

I have extracted a river network but now have a problem in distinguishing the branch order of stream (from order 1 to 2, 2 to 3; side branches, not the main ones [say 1 to 1, 2 to 2]) according to the Strahler scheme. It is displaying only one column of stream order. Can anybody tell me how can I extract a separate column for side branch streams as I mentioned above?

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Here is a Strahler ordering scheme. In the strahler order method, all links with no tributaries are assigned an order of one and are referred to as first order. When two first-order links intersect, the downslope link is assigned an order of two. When two second-order links intersect, the downslope link is assigned an order of three, and so on. When two links of a different order (say 1 to 2) intersect, the downslope link is assigned the order of the maximum of these two. My query is, can we make a separate field for the same order branch (1 to 1, 2 to 2) and different order branch (1 to 2, 2 to 3)?

I have added two tables. In first table we can see that all stream orders (Grid_code) are given in one column. I want to know how many streams of 1st order are joining with other 1st order, 2nd order, 3rd order, etc. Similarly, how many streams of 2nd order are joining with 2nd order, 3rd order, etc.

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For example, in this table there are 12 '1st' order streams. I have to know that out of 12, how many are joining with another 1st order (1 to 1)? How many are joining with a 2nd order (1 to 2)? How many are joining with a 3rd order (1 to 3)? And so on.

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  • 2
    I'm not sure I follow. Stream order is a property of all segments/branches. Common properties are stored in a single field ("column"). It doesn't matter if a 2 meets a 3 at the end or in the middle, it's still a 2. If you want a new attribute that distinguishes those two kinds of 2s, you'd have to create a new field and calculate the values after doing some selections. Can you provide a screenshot of what you're after?
    – Chris W
    Jul 17, 2015 at 22:16
  • I'm fairly sure that ArcHydro will generate Strahler stream order gis.stackexchange.com/questions/138530/generate-strahler-number, Arc Hydro tools are free to download from Esri resources.arcgis.com/en/communities/hydro/… As @ChrisW said please provide a picture of what you're after from what you have. Jul 17, 2015 at 22:18
  • @MichaelMiles-Stimson I don't think there is any need to download the ArcHydro tool-set as most of the ArcHydro feature have been incorporated into ArcGis 10+ under the name "Hydrology toolset". As long as you have the Spatial Analyst extension, you should be good to go.
    – TsvGis
    Jul 18, 2015 at 2:08
  • 1
    While you've explained the Strahler order well, I think most of us watching this particular question are familiar with it. I'm still not clear what you're wanting the attribute table to look like (what this new attribute would show) - perhaps you can provide a mock-up example table that corresponds to the diagram you have above? You have no 1 to 1 that are not also 1 to 2 (and so on). Are you looking for some kind of flag attribute that says a particular segment has only lower order segments feeding it?
    – Chris W
    Jul 18, 2015 at 17:46
  • 1
    I'm not familiar with hydrology tools or network analysis, so there may be one or a name for the analysis you want to do out there. But I can think of a brute force method to get the summary you want. First you'd need to split your file up by stream order. All ones into a feature class, all twos into another, and so on. Then you'd start at your highest order and select them all, following by selecting all from the next lowest order that intersect them. Repeat. It'd be easier to do this with start/end extractions as points, but I can't give a full outline to that process right now.
    – Chris W
    Jul 22, 2015 at 0:05


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