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).

So glad you solved the problem!  I will make a note for the next version to override the Windows settings so that a decimal point is used in either case, so this does not pose a problem in future versions.  Thanks -- Jonathan

Thank you so much for the very helpful reply!

Hello,
I have two technical questions on how the lateral marsh erosion is implemented in SLAMM 6.7.
1)Let's say the rate of marsh erosion is 2 m/yr. How are the cells actually updated?
I assume the cells are updated every time step, maybe every year.
How do you implement the erosion of 2 m in a cell that is likely much larger than 2 m?
Do you implement a sort of partial cell erosion?

2)Also, when you erode a cell marsh by lateral erosion, what elevation do you impose to the update cell? A fixed elevation of the tidal flat?

Thanks,
Giulio

1. Yes, this replaces the default 9km.  It will not use the 9km default if 0 is used, therefore if you wish to use that default, please input 9.0.

2. Leaving these as zero should not have an impact on your simulation. 

3. These can be left at zero.  Please see the latest model application documents for some information about how we have set this parameter in the past.

https://www.nyserda.ny.gov/-/media/Files/Publications/Research/Environmental/18-04-Integrating-SLAMM-Results-Marsh-Adaptation-Strategies.pdf

http://warrenpinnacle.com/prof/SLAMM/NROC/SLAMM_NROC_Report_Final_Corrected.pdf


Sorry about the long delay in response!  -- Jonathan

Hi Jonathan,

I have found the solution to this problem. It was a simple default setting that needed to be changed on my computer. My Windows 10 machine was set up with US English as the default language, with a comma to be used as a decimal point instead of a full stop. This prevented the ASCII files from being loaded because the decimals were being read as commas, even if the original files were correctly formatted.

All is working smoothly now.

Thanks,

Jackie

Hello,
I would like some clarity with some of the new input parameters in SLAMM 6.7.

1) The Marsh Erosion Fetch (km) -  is this a maximum value to input instead of the default 9km that was previously in the other versions? If this is left "0", will it use the 9km default, or do I need to input a max value?

2) H1-H5 inundation Parameters - since these relate to infrustructure, if I am not including roads etc., then can I leave these inputs as "0" ?

3) Irreg-Flood Collapse and Reg-Flood Collapse (m) - do these parameters need to be put in for SLAMM to run correctly? I'm not sure how to calculate these values, or if there are default values that can be used here. Any references or material on how to calculate these would be great.

Many thanks!
Tessa

I guess we've never run with just an 010 and not also a 100 year storm.  I think it's fair to say that this portion of the model has only been utilized by our team and is not deeply user friendly.  I'll look into the code to understand the requirements.

Yes, if you have no correction factor for NAVD88 then using the MTL datum would be correct.  This is because, while the model will try to convert data from NAVD88 (which has been the format we generally received data in) it would use the zero conversion factor, so there would be no change.

Sorry about the deficiency in documentation.  This is from some metadata we created when running the model:

Inundation maps were created by running SLAMM for 5 different inundation elevations (H1-H5 in the subsite parameters)

Raster values are: 0 (zero) - open water, 1 - inundated at H1 level (we often set this to the 30-day inundation level), 2 - inundated at H2 (we have used 60 days), 3 - inundated at H3 (90 days) 4 - inundated by H4 (we often set this to the 10 years storm), 5 - inundated at H5 (100 years storm), 6 - above H5,  7 - below H5 but not connected, 8 - protected by dikes, -99 no data/blank