If you are using a dike layer I would turn that off as a test.
Next thing to do is look at the elevation analysis -- Set Map Attributes, Elevation Analysis button towards middle of Analysis Tools tab. Then "Run Elevation Analysis (This Site) Double click on the category names to sort, sorting by n cells can be useful. The 5th percentile for wetland classes should be around the minimum elevation.
See the help file text for more information on interpreting the matrix on that page. Also you can see this reference:
Last post by Hartney - February 12, 2018, 08:50:42 AM
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.
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
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.
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).
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?