I am trying to create a polygon (and eventually a raster) surface of river deposits that have since been eroded away. We know that at maximum, deposits got up to 600 ft above the present river. Given that a river slopes as it goes down hill, the answer is not as easy as a raster calculation, or determining X ft above sea level + 600 ft. How does one make a sloping surface as constant elevation above certain points in the river to determine the previous geographic extent of these deposits?

Using ArcGIS 10.5.

  • 3
    What software you are using?
    – Moh
    Jun 25, 2018 at 23:12
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    – PolyGeo
    Jun 25, 2018 at 23:20
  • 1
    What data do you have?
    – user2856
    Jun 25, 2018 at 23:47

1 Answer 1


You need to create a HAND (Height Above Nearest Drainage) raster. See this paper. You can use ArcHydro tools or TauDEM to create the D-infinity Down and intermediate layers.

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