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I followed the instructions how to build a dam by whuber (How to build an artificial 'dam' across a river?)

  1. "draw a line segment"

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  1. "compute the Euclidean distance to this line segment"

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  1. "divide that by 5" for the correct slope (no picture here, looks like the result of step before divided by 5...)

  2. "subtract that from the elevation of the top of the dam" (I want my dam to be 2 m high)

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  1. "combine it with the original DEM"

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  1. My result (damdtm)

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It is correct for the top of the dam:

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But incorrect for the rest of the processing extent:

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Shouldn't there be a step before step 5 where you cut the dams footprint from the raster before combining it with the original DEM?

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Simon
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    I believe you might have confused the height of the dam (2 m) with its elevation (which would be different than 2 m unless its base is at sea level). – whuber Dec 18 '15 at 18:15
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    that could be a serious dam problem ;) – ed.hank Dec 18 '15 at 18:24
  • @whuber: Yes, you're right, thanks! But changing this value wouldn't change anything at the situation, that the area outside the dams footprint is modified. – Simon Dec 19 '15 at 16:39
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    That's because you're not performing the required combination: "combine it with the original DEM simply by taking the larger of the dam elevation and the natural elevation, cell by cell." That requires a local maximum operation. – whuber Dec 19 '15 at 17:39
  • I used the Cell Statistics tool and set Overlay statistics to MAXIMUM, the result looks great, thanks! – Simon Dec 21 '15 at 09:28

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