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I have the z-values of the contours (physical contours) of a watershed in AutoCAD civil, but I may use them in ArcGIS 10.2 and I have already created a DEM. I need to extract the z-values for the stream, in order to create the AgreeDem and to continue with the fill and flow accumulation process in ArcGIS.

  • Could you please expand upon your question. What software are you using? When you say you have the Z values of the contours, do you physically have a contour layer or do you have an existing DEM / Raster Surface. You can edit your question to include this information, it will assist you in getting the answer you want quicker. The follwoing link is helpful in describing how best to ask a question on SE. gis.stackexchange.com/tour – Keagan Allan Feb 14 '18 at 13:54
  • In what formats are your layers? There are different spatial join processes depending on format (vector vs raster) and geometry. – mikeLdub Feb 14 '18 at 16:34
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An option would be to take your stream network and convert it to a 3D feature using the 3D Analyst in ArcMap. The Tool you are looking for is:

Interpolate Shape

This is located under - 3D Analyst -> Functional Surface -> Interpolate Shape Here is the help file if you want to read further into how the tool works: ESRI - Interpolate Shape

Select the DEM as your Input Surface and your 2D River Layer as the Input Feature Class.

This should be what you need to run the AGREE_DEM.

  • thank you for your help, i tried with two ways, the first one with add surface information, and the second one with interpolation shape, the results were the same about the z-values of the stream, but when i try to do agree DEM with the raster and the new stream, i cannot do it. the Dem recognition failed – Anida Feb 15 '18 at 14:29
  • It might be the DEM. How did you create it originally? – Keagan Allan Feb 15 '18 at 14:51
  • i took from aster gdem with the coordinates i needed, after i applied the mosaic to new raster, and i got the last raster that i am using. while the river that i had without z values, i used add surface information once, and after i tried with interpolation shape to verify the results. and now i cant do the Agreedem – Anida Feb 16 '18 at 9:30
  • I am not familair with the formats of the ASTER GDEM. It may be that the format of this raster may not be supported in the ArcHydro Toolbox. You could try to use the contours to create an elevation surface, and then use that for for the rest of the processes. – Keagan Allan Feb 16 '18 at 9:53
  • I Tried that too, a made a raster and after taking the z values with interpolation shape or add surface information, but running the Dem agree, fill, flow direction and flow accumulation, and after the other steps to get the delineation of the watershed, the river was divided, and wasn't present in some parts, and the drainage points weren't ok – Anida Feb 16 '18 at 9:56

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