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Topics - Dean

Model Formulation & Parameters / slamm 5 vs 6
February 23, 2011, 10:38:04 AM

Has anyone else noticed some major differences b/t slamm 5.0.2 and 6.0.1 outputs, especially regarding conversion to open water vs estuarine beach?  I seem to be having much more estuarine beach in ver. 6 compared with open water for ver. 5. I'm wondering if this is an error in the code or if something is new in slamm 6 that would be affecting this part of the decision tree. All input parameters were essentially the same. Is there some switch that is set to a different default, like erosion, in ver. 6?  Some of the areas that convert from reg. flooded marsh to estuarine beach start out at 0m of elevation, so I know something's not processing correctly.  

You can see the attached screenshots of the initial condition compared with slamm 5 and 6 ouputs. The only changes b/t the inputs b/t versions relate to using the MTL correction grid, instead of a global site value and some minor modifications (for the better) of the DEM.

Thoughts and suggestions welcome!

Model Formulation & Parameters / Model Uncertainty
December 07, 2010, 02:45:08 PM
One major criticism I keep hearing from people is that SLAMM does not model any uncertainty in its forecasts. Of course, one can spatially show some uncertainty by modeling various SLR scenarios (e.g. 1m, A1B, etc) and showing a range of options. However, is there a way to show an "envelope" or range of possibilities around one particular scenario (such as 1m)?

I have seen uncertainty modeled for bathtub type models in a recent publication, assessed against Geodetic benchmarks.

I was wondering what the effect of running the 1m scenario with the MTL changed to both MHW and MLW (and correspondingly changing the MHW and MLW by equal amoints in similar directions) for independent runs would do? Would this work, and potentially show a range of possibilities or uncertainty in the model?

Any feedback on these thoughts from folks working with SLAMM, especially regarding how to show model uncertainty would be great!

Model Formulation & Parameters / protection scenarios
November 30, 2009, 11:21:58 AM
Is there an effect on the surrounding land cover class outputs between the protect development and "don't protect development" scenarios? I don't see one when visually inspecting the outputs. It seems though, that if an armored shoreline were in place to protect development, the displacement of the water from SLR would cause different scenarios to play out in the habitats surrounding these areas, right?

Based on my visual inspection, does the model essentially run the same with the protected option checked as with not checked, except that it visually preserves those developed areas in the final output?

This technical note may note matter much for the 30m NED runs, but for lidar elevation data, I would think the differences caused by local seawall displacements and the like would be significant.

Something to consider.

Model Formulation & Parameters / SLR scenarios
November 24, 2009, 09:14:39 AM
I've noticed when running the one meter fixed scenario to 2100 (25yr timestep), that in the excel output file the "SLR (main)" column for the final year is 1.1275. I assume this column is showing the elevation change in meters for MTL (ie predicted sea level) for each respective year. Does the most recent NWI photo date or some other input date or datum adjustment have an impact on the model's 1m fixed rate by 2100 computation?

Model Formulation & Parameters / subsites
November 16, 2009, 01:51:30 PM
Is there a better, more accurate way to define the subsites by creating subsites from polygons,etc?  For example, using a USGS quad as the delineating lines for the different NWI dates and NED dates would be much more accurate than hand drawing approximate boundaries.  Am I missing something about how to do this in slamm 5?  Will slamm 6 have the capability to handle imported polygons for these subsites (or at least a grid file with the correct dates)? I did notice in the site file that there's some reference to this grid-derived date file, but did I overlook the technical notes on how to do it?

Thanks for the help!
General Discussion / Examples
November 04, 2009, 11:52:34 AM
Here's a link to our first year's outputs for the Georgia coast.  We'll be working in Glynn Co., using LiDAR and more stakeholder involvement for year two.


Using SLAMM / protection and nwi photo data options
August 31, 2009, 11:18:25 AM

It seems that unchecking these in the model does not effect the outputs.  Every run I've completed models the NWI photo date (unchecked or not) and always protects developed, regardless of what's checked.  I've tried with both "Don't Protect" and "Protect Developed..." checked and then with just "Don't Protect" checked, with the same results for all three outputs (the developed is protected).  Any ideas/suggestions?

Using SLAMM / salinity model and map attributes
August 26, 2009, 08:16:22 AM
Hi Jonathan (or anyone who can help),

I'm having trouble understanding the inputs for the map attributes. I want to set the estuary boundaries so the salinity model is used, but can't discern what all the inputs in the model inidicate after reading the Tech. Doc from Oct. '08.  Do you have this written up with more detail?  If not, any assistance would be greatly appreciated. (FYI, I'm not wanting to use subsites, as I'm modeling a relatively small area as it is.)

Things I don't understand include:
1. Define Origin, Mouth (is this like the vectors in Fig. 9 of the Tech Doc or something completely different?)
2. Define Boundary (is this also like Fig. 9, but the polygon?)
3. Max Elev T.S. (Tall Spartina?)

Finally, when I create an attribute file with just one or two estuaries defined, I'm getting the following error message when I try to Calibrate FracFresh:

"Access violation at address 00479DC8 in module 'slamm5.0.2.exe' Write of address 00000008"

Again, any help would be greatly appreciated.

Using SLAMM / impervious data and dryland class
August 24, 2009, 03:09:11 PM
I understand that the impervious input is used to define developed (>25%) vs undeveloped dryland (<25%).  However, I can't tell if this is happening from the model outputs, b/c there are no statistics in the Excel output for changes in these.  I would expect some undeveloped dryland (2) to be lost.  I am running the model with Protect Developed checked ON.

Do I understand it correctly that the NWI input file should have no category 1 or 2, but that they are derived from the imp.txt file?  How can I be sure this is working?  I'm using impervious data from the Georgia Land Use Trends, b/c it's from 2005. My cell size matches the DEM, and is in integer form (though I've tried floating point and integer). 

Does the file name matter?  I've tried both filename_imp.txt and filenameimp.txt?

Any suggestions or hints would be great.

Using SLAMM / model input files
August 21, 2009, 12:36:18 PM
I'm trying to run the model for the first time with my own data, but an error is being returned.

It states: "Data File "C:\.../nwi.txt" Does Not Correspond to DEM Data File."

I've double-checked everything I know to check, and I know that the model runs with the Puget Sound sample data.

I'm using a county boundary to delineate my input .txt files.  Polygons are alright in v.5.0.2 though, right?  Also, my data inputs are huge, ~150-200MB each. I'm going to try clipping everything to a smaller area and to a rectangle, to check those two ideas out.

If anyone has any other ideas, please let me know.

Using SLAMM / NWI to SLAMM land cover classes
August 18, 2009, 04:05:01 PM
I am using the VLOOKUP function in Excel to reclassify the NWI land cover to the SLAMM5 categories as shown in the Tech. Doc. from October 2008.  I am having trouble understanding Table 5 in this Tech Doc and discerning exactly which NWI classes are being changed.  It appears as though some NWI classes are double counted, ie appearing twice in the new SLAMM5 categories.

For example, SLAMM5 class 6 (TidalFreshMarsh) shows that it is derived from NWI classes R1EM and PEM ["K"-"U"]. However, SLAMM5 class 23 appears to overlap, showing NWI classes PSS, PFO"K"-"V"/EM1 "K"-"V".  To me, it looks as though PEM1K - PEM1U are doubly represented.  Am I missing something here.  An explanation of shorthand of the NWI classes may help.

On another note, is there an explanation somewhere why the modifier "K" was chosen to be included with tidal, in most if not all cases of reclassification?

Is there a way to perform this process in ArcMap, or perhaps using AML code?