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Setting Manning's Roughness

  • Sep 24 2020
  • prabhathromitha

Hi all,
I am modeling a vegetation patch. I need to assign roughness values separately for the bed and vegetation. When preparing the grid by multifunction grid generator, I assigned the roughness of the bed as 0.012. Then I add a polygon group for the vegetation patch and gave the roughness as 0.05. Once I execute the attributes mapping, the bed roughness automatically changes from my initial value (0.03). Why? Can anyone guide me on this? Thanks!


Manning`s n.png
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  1. iRIC admin says:

    You should make a polygon which covers all of your calculation domain and specify its value as “0.012”, at first.
    Then make polygons which cover the place where you want to speify the special roughness value.
    The order of polygon data in object browser that is located at the left side in your iRIC window, means priority of mapping into grid attribution. Upper one has more priority.

    Please try it again!


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