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I have a problem where I need to, for each cell, calculate the distance to the nearest flow channel. This is likely a complex problem due to the fact that I need the nearest flow channel while considering topography (flow direction). A simple Euclidean distance does not suffice due to this. I cannot even think of terminology to use to google a little deeper. Anyone with any experience they would like to bestow on to me?

ArcGIS 10.3, all license levels

So, I have looked at both path distance and flow length and, correct me if I am wrong, neither work for my current scenario. The path distance tool does not look like it incorporates flow direction and the flow length tool only calculates distance to the last cell in the drainage watershed. I am looking for the least cost path sum of distance for each cell to the nearest source point considering flow direction. Am I missing something in either method?

I have now been looking at what @dru87 pointed to and am making progress. The method of subtracting the dem from 0 and computing flow accumulation upon this raster is almost what I need. There is just one further step that I need to address; the fact that I have defined a classification of the FA to represent stream channels and I need the distance from this classified layer. I feel this necessity might limit this method as editing of the FD layer would likely be required. Thoughts?

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  • Have you tried path distance?
    – Fezter
    Commented Oct 18, 2016 at 22:37
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    I just found this question about calculating flowpaths downstream. It seems to me that it might be related to your problem. There are some good hints on there that you may be able to use. If you don't have access to qgis, try the proposed inverse upstream channel network.
    – dru87
    Commented Oct 19, 2016 at 15:52
  • You could have a look at SAGA GIS which has functions for vertical and overland distance to channel.
    – Jae
    Commented Oct 19, 2016 at 20:24

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Try the flow length tool in Spatial Analyst - http://pro.arcgis.com/en/pro-app/tool-reference/spatial-analyst/flow-length.htm .

If you are interested in vertical height above the water surface try Topography Tools, which has two algorithms HAND and HAR for estimating height above the water surface.

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