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Messages - Elena V

Using SLAMM / Re: Output files
September 25, 2013, 10:59:11 AM
Hi Caroline,
Thanks for posting this - I've had the same challenges. It would be great if you could import the same symbology to multiple rasters at once, but I guess that's a question for the ArcGIS forums...

I also wonder whether future versions of SLAMM would let you specify the format of the output name. I am also trying to batch rename my files because the names are far too long and complicated to do subsequent batch processing in Arc (most of which requires converting the ASCII to raster first). You get a slurry of errors due to spaces in the names and the length of the names. I'm currently looking for python scripts to batch rename my files.

Just as an example, I'd like to rename a file of this format:
Run3-37_output, 2080, 1.664 meters _GIS.ASC

To something like this:
R3372080n.ASC  (where n stands for not protected)
I recently noticed that accretion is not occurring as expected in areas defined as "freshwater influenced."

I first ran my model with an inverse linear relationship between accretion and elevation (low = 2 mm/year, high = 6 mm/year) in a region that was "freshwater influenced". All categories without the empirical relationship were assigned accretion of 3 mm/year.

Then I ran the same model, but with 2x the accretion rates and found no difference between the model outputs within the region of freshwater influence. There were differences outside the freshwater region.

To confirm, I ran the low/high accretion scenarios without freshwater influence and saw a major difference.

Am I implementing the freshwater influence module incorrectly? Or is it just a bug since this option is still relatively new in SLAMM?
Hi again,
Based on my understanding, the Elevation Analysis only uses global water level parameters to assess the vegetation/elevation relationship. Are there plans for future SLAMM versions to run this analysis using spatially varying MTL-NAVD, Salt Elev, and GDTR? This would be helpful in systems where there is tidal damping.

I know a lot of WPC's studies have used spatially varying tide ranges - how did you assess the compatibility of your changing tide ranges with the topography? It would be neat to be able to run the Elevation Analysis on a specific sub-site where the parameters are being modified from the global value.

Hi Jonathan,
That was really helpful - the paper gave me some confidence in how I'm selecting my erosion rates. I also played around with a little spreadsheet model and that definitely showed that the model is not so sensitive to the accretion elevation feedback (or even the accretion rates themselves, within reason). I've attached an example output...

I'm surprised that the transitional marsh doesn't have an accretion rate - it seems like this would creep up the edges of dry land as sea level rises. I'll post a follow up on a recent connectivity thread since it's more relevant there.

Anyways, thanks for your help as always!
I've been looking at my results a little closer and it does seem like all these habitats still have the same lower elevations because from my input map to my t=0 map to a map one year later the habitats switch 3 times (Swamp --> Tidal Swamp --> Tidal Fresh Marsh --> Rarely flooded marsh).

Is it possible to change the lower elevations for these habitats? What was the thought behind the new habitat switching function if they have the same lower elevation?

Thanks! I realize this is a new option in SLAMM - just want to make sure I understand what the model is doing :)
The Tech Doc (6.2) says the following habitat-switching function is implemented when an area of freshwater influence is specified:

Swamp --> Tidal Swamp --> Tidal Fresh Marsh --> Irregularly Flooded Marsh

However, according to the Tech Doc the default lower elevation of the first three habitats is the salt elevation. Are the defaults different when freshwater influence is specified? Or do they simply switch once per timestep?

And a sidenote - if I do want to change the lower elevation, can this be done in the user interface or should I run SLAMM from the command line? Is editing the value in the Elevation Analysis window sufficient to change the minimum elevation for model runs?

thanks once again!
A few questions about implementing accretion feedback curves:

1. Timestep: I was expecting to run at a much smaller timestep because of the feedback between two variables, but when I ran the same model with 10- and 5-year timesteps I saw only very slight differences. Is SLAMM tracking elevation/accretion between timesteps? Or am I running the model incorrectly? If "Use Model" is set to True, this overrides the constant accretion rate specified above, correct? I'd expect that with a large timestep, a low-lying wetland cell would accrete very rapidly for the long timestep, overshooting and reaching a much higher elevation by the next timestep.

2. Wetland Types: Is there a reason this model is only available for four habitat types (Irreg Flood, Reg FloodTidal Flat, Tidal Fresh)? Are those categories actually generalized and include multiple SLAMM habitats? Seems like you would want to have the option for Transitional Salt Marsh and maybe Swamp/Tidal Swamp/Mangrove?

3. Are there any published examples of this model being implemented? I am selecting a reasonable low and high value and assuming an inverse linear relation between elevation and accretion.

I'm using SLAMM 6.2 beta.
Using SLAMM / Re: Save a copy of model inputs
August 05, 2013, 04:04:36 PM
Thanks Jonathan - this is helpful to know. Once in a while I forget to save the simulation immediately before or after running it, so when I save-as a new simulation and make changes for the next run I lose the exact inputs that were used for the first run. Not a big deal - I was just wondering if these inputs could be automatically saved as a text file along along with the output upon hitting "Execute".
Using SLAMM / Save a copy of model inputs
August 05, 2013, 03:10:52 PM
Is there a capability in SLAMM that automatically saves a copy of the inputs (not the source files themselves, but the file paths), site parameters, and execution options?
I am having this problem too - turning off soil saturation removes some of the linear features, but many remain (mainly the sandy beach category). Was this question resolved?
Using SLAMM / Re: Salinity Raster
June 04, 2013, 06:37:14 PM
Hi Jonathan,
Is the Georgia SLAMM report publicly available? I'd be interested to read about how the salinity module was implemented and calibrated there. Are there any updates on the salinity documentation?

Also, do the SLAMM salinity maps show surface salinities, since that's what most vegetation comes in contact with? Or is it some water column average value?

I will follow up with a new thread about applicability of the salinity module.
Thank you!
I just ran the elevation analysis again and it seems that this is only a problem when using NAVD88 as the "Zero". This does not seem to be a problem when I use MLLW, MHW, MTL as the Zero.
Thanks for the response -- I did install the latest 64-bit version of v6.2 and checked that the no data elevation is equal to -9999. I used the exact same inputs in v6.1 and v6.2, but in v6.2 the statistics are slightly different for all habitat types, and the statistics for dry land categories includes -9999 in the statistics. This did not appear to be a problem in v6.1.
Hi again,
I'm using SLAMM version 6.2 (which has some really neat new features!). I just ran an elevation analysis on the same input data as I was using in version 6.1 and it looks like the value corresponding to "no data" (-9999 in this case) might now be included in the elevation analysis. This mainly shows up in the results for the dry land categories (the mean elevation is ~ -6000 m NAVD) since these areas are at the edges of my study area where I don't have topo data.

Just wanted to confirm that this is what's happening because I want to be aware of any skew it might be introducing to the other veg categories (where there are fewer "no data" points so it might not be as obvious).
Great, thanks Jonathan! Just wanted to make sure it wasn't a problem with my input topo/habitat map. I'll download the most recent version and give it a shot. I'll probably just display those two water categories with the same color.