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Model Formulation & Parameters / Model runs but shows change in...
Last post by Hartney - February 12, 2018, 08:50:42 AM
Hi all,

I have been running a model for the Pearl River LA/MS region.  The model runs smoothly but there is never any wetland change, even with 6m of SLR and no accretion values.  I have been able to run other models with parameters based on journal studies, including Pascagoula, and those models do show wetland change.  Some things I have double checked (based on answers to similar posts on this forum) include elevation data units, DEM/NWI date, and the NAVD88 to MTL conversion (based on the Bay Waveland Yacht Club, MS tidal station: https://tidesandcurrents.noaa.gov/datums.html?units=1&epoch=0&id=8747437&name=Bay+Waveland+Yacht+Club&state=MS ).  My accretion values are based on Louisiana's Coastwide Reference Monitoring System (CRMS).  What other parameters should I be looking at to fix the issue? At this point, it feels like I'm missing something obvious so I'm hoping for an extra set of eyes to help me brainstorm what the issue may be. 

Thank you!
I ran multiple tests and, for my study files, when there is no dike input raster map, the maps produced have been identical whether "use dikes" is checked or not.  Are you willing to share your input files so that I can look into this further?   Regards -- Jonathan
Model Formulation & Parameters / Re: Differences between Includ...
Last post by maryramirez - November 13, 2017, 10:57:45 AM
Using the most recent version available (SLAMM 6.7 beta).
If you do not have a dike file specified, the results should be identical.  Please let me know which version you are using and I'll run a test and ensure there is not a software bug causing this problem.
Using SLAMM / Re: Data Set
Last post by Jonathan S. Clough - November 10, 2017, 02:14:58 PM
As you know, NRow and NCol and "lower left corner attributes" must match precisely.

In the QGIS world we use GDAL WARP to ensure that this is the case.

It is best to set the attributes precisely when converting from NWI polygons into a raster because re-projecting or moving raster files can result in data loss.

I cannot speak to the ESRI world -- anyone else?

Best regards -- Jonathan
Using SLAMM / Data Set
Last post by EmmaBremp - November 10, 2017, 09:22:50 AM
My Slope and DEM data have equal Number of Rows and Columns but my NWI data is not having equally rows and columns how do i solve that issue
Model Formulation & Parameters / Differences between Include Di...
Last post by maryramirez - November 07, 2017, 02:30:27 PM
I am running SLAMM without a dikes raster layer. When I check 'include dikes' on the execute screen, the results for Time 0 are very different than when I don't check 'include dikes'. Checking 'include dikes' results in a T=0 that is nearly identical to initial conditions, which is good (not the case when 'include dikes' is not checked). However, I don't see certain conversions that I would expect over time and that do occur when 'dikes' are not checked (specifically reg. flooded marsh converting to tidal flat). Neither run actually includes a dike layer, so I'm wondering what is causing the difference. Thanks!
I think the problem is that the ASCII DEM is treating 1.17e-38 as its NODATA value.  The GIS software is then not recognizing this NODATA value.  Try specifying a NODATA value of -9999 prior to conversion and this may solve the problem. 

Also, look at the header in the first lines of the ASCII DEM to see if that helps understand the problem (the NODATA value is defined there.)  The best way to do this is convert the file type to a TXT file and look at it in the Windows Explorer Preview pane (not Internet Explorer, just the Windows Explorer file manager).

Hope this is useful.
Model Formulation & Parameters / DEM to ASCII conversion issue
Last post by Hartney - October 20, 2017, 03:29:43 PM

I am having an issue when I convert my study area dem to ascii.  The elevation range/values are different following the conversion (see image You cannot see attachments on this board.).  dem_censustract is my original dem while dem_asc is the new file after conversion. I found one person mention a similar issue on another gis forum but the question was unanswered. Has anyone else encountered this issue? Is there a work around?

Thank you!
Using SLAMM / Re: Editing cells in the Set M...
Last post by marco.propato - October 11, 2017, 08:10:16 AM
It may depend on which SLAMM version you are using. However, in general you click edit cells, make your edits using draw/fill cells, and when done you may simply close the window and you will be asked if you want to overwrite the raster (the raster will have same name as the original one but with the edits) or click "Save As ..." and save the raster and project with different names. Hope this solves your problems.
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