I have to make a Model in the Model Builder which will select the areas with slope bigger than 10° and which are facing to the south. It should be used for environmentalist who will just insert a DEM and the model will automatically display only these wanted areas.

How do I do that?

I already used tools Slope to and Aspect, but I don't know how to select only that values which I want to display and make a Model for that.

  • 1
    Did you try adding a raster calculator step with Con() function? – aldo_tapia Aug 17 '17 at 10:55
  • Not yet, I don't know how exactly this expression works. I'll try to find explanation somewhere. – daky Aug 17 '17 at 11:40
  • Sounds like you want to expose your model parameters, it's all in the help file here. – Hornbydd Aug 17 '17 at 11:41
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    The reclassify tool would work here. It would allow you to group all cells >10 and <10 into two categories. desktop.arcgis.com/en/arcmap/10.3/tools/spatial-analyst-toolbox/… – Map Man Aug 17 '17 at 13:22
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    @Map man : you should put it into an answer :) – gisnside Aug 18 '17 at 13:43

Here is the workflow I would recommend:

  1. Bring in your DEM
  2. Run the Slope tool
  3. Run the Reclassify tool, so that cell values >=10 = 1, and <10 = 0
  4. Separately, run the Aspect tool on the original DEM
  5. Run the Reclassify tool, so that cell values within your aspect range (however you define South) = 100, and all other degrees = 0

Now you have two raster layers

  1. Run the Raster Calculator tool, and add the two raster layers together

Now you have a bunch of cells that are valued 0,10,100, and 110. The 110 value are the cells that meet your criteria (south and with slope).

  1. Finally, run the Reclassify tool again so that cells that equal 110 = 1, and all other values = 0

Now you have a layer with cells in two values (those that meet your criteria, and those that don't.)

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