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Classic dike layer not protecting land from change

Started by rodlammers, May 15, 2019, 12:24:51 PM

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I'm running some simulations of SLAMM with and without the classic dike layer (specifying land protected by dikes). Aren't these dikes supposed to keep land cover from changing? Per the technical guide: "In the traditional model, if a cell is defined as protected by a dike or levee it is not permitted to change."

When I run the simulations, land cover is changing even in cells protected by dikes. If I compare this diked-scenario with the same simulation but with dikes turned off, the only differences between the two results are in areas "protected" by dikes. So clearly the dikes are having some effect on land cover change, but not the effect I expected. I thought they would completely prevent any land cover change in the diked area.

Am I incorrect in my interpretation of how the dike layer works? I'm using the most recent version of SLAMM (6.7 beta).

Jonathan S. Clough

You are correct.  However, soil saturation is not affected by dikes which could be causing the differences you are seeing.   Try turning soil saturation off.

Are you rendering the dike layer in "Set map attributes" to ensure that the software is interpreting your data layer correctly?  

And I think you get this, but you define the entire area protected by dikes using "classic" mode rather than the location of the dike itself.  

If none of these answer your question, feel free to post or email me some screen caps showing what you are seeing.

Thanks!  -- Jonathan


Thanks for the reply. I have soil saturation turned off, the dike layer is correctly rendering in the "Set map attributes", and I'm defining the entire area protected by dikes.

I've sent you an email with some screen shots showing my execution options, the dike layer rendering, and the output showing land cover change even in the diked areas.

A potential work around to this problem is changing the diked areas to "Developed Dry Land" and running the simulation with the "Protect Developed Dry Land" option. This takes some additional pre-processing and post-processing of the rasters but it does work.