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Messages - Evan Larson

As Jonathan noted, the VDatum correction input file needs to be in the same format as other input files for SLAMM.  SLAMM then reads in the correction values from the raster on a cell-by-cell basis according to equation one in Dean's post.

You must then convert this into a raster using some sort of processing techniquie but we do not currently support this process.
Model Formulation & Parameters / Re: LiDAR-defined Dikes
November 12, 2010, 09:29:50 AM
The Connectivity section in the technical documentation (page 31) will give you a more in depth explanation of connectivity than I did.

Using SLAMM / Re: Mangrove threshold
November 12, 2010, 09:25:12 AM
Page 39 in the technical documentation says if more than 0.5% of the wetland input data is comprised of mangrove then the site is considered tropical. 

The SLAMM mangrove model is somewhat rudimentary and assumes rapid growth without taking into account growth-stunting hard freezes.

I should clarify that the initial condition is the input wetland data and the time zero is the input wetland data after elevation boundary processing.  The model has certain assumptions about wetland elevation boundaries and the time zero reflects these assumptions, changing a land type if it falls below the assumed lower boundary. 

With the preprocessor turned on, wetland elevations are forced to fit these boundaries, creating rising planes (ramps) that face the offshore direction.  Preprocessing should only be used if your elevation data is extremely poor (like 20 foot contour USGS topographic data).

You can customize these elevation boundaries so they fit the habitat you're modeling.  To do this, perform an elevation analysis in Set Map Attributes.  For the land categories that are changing the most in time zero, the elevation analysis probably reveals that the 5th percentile is much different (lower) than the minimum half tide unit (min HTU).  Try lowering the minimum elevation of the land categories and see if that changes the time zero results.

Model Formulation & Parameters / Re: LiDAR-defined Dikes
November 11, 2010, 09:32:12 AM
As far as I know, dry land is the only land category that can block inundation in the connectivity algorithm.  If the high elevations surrounding the mosquito impoundments are anything but dry land the impoundments will be flooded.

I recommend using a separate dike file and filling in the mosquito impoundments manually with Set Map Attributes.

Hope this helps,
The connectivity feature is an attempt to make the inundation for each time step more realistic, but it is unrelated (as far as I know) to our salinity model.  With the feature turned off, the model works by inundating every cell that lies below a certain elevation value, regardless of land features which might prevent such inundation (high walls, dikes not designated as dikes in the dike file, etc.).

With the feature turned on, a search is performed at each cell to determine whether or not it could be inundated based on surrounding cells' elevations.  The cell determines whether it is below the current sea level, and if so tests whether or not it is ultimately "connected" (hence the name) to a cell that is flooded.

Using connectivity with dikes turned off may be a fun (although not necessarily scientifically defensible) way to test the efficacy of the dikes, assuming you are working with a high resolution elevation map that accurately represents the dike wall.  One little breach in the dike wall -- or more likely an error in the elevation data -- will lead to inundation. 

Note that more memory is required to run the connectivity feature.

What is the language of the error you receive and what are the exact steps leading up to it?

There is currently no way to save the connectivity raster as an asci file.

Hope this helps,
Model Formulation & Parameters / Re: Saturation
September 16, 2010, 12:17:26 PM
The water table is assumed to be the maximum elevation of freshwater wetlands within a particular SLAMM simulation.  With saturation turned off, the water table does not rise with sea level rise, so drylands/uplands do not convert to swamps, fresh marshes or other fresh water categories.  Unfortunately I cannot answer how turning saturation off affects wetland corridors in particular.

Hope that helps.
Model Formulation & Parameters / Re: Salt Elevation
September 08, 2010, 01:44:43 PM
We treat Riverine Tidal as open water.  Jonathan may be able to further clarify our definition.

Model Formulation & Parameters / Re: Salt Elevation
September 07, 2010, 11:49:38 AM
We typically multiply the GT by the percentage of MHHW where water reaches at least once every 30 days, and divide by 2.  So, for the Chesapeake Bay region -- where this percentage is around 133% -- the calculation would be (GT)(1.33)/2.

I hope that answers you question.

Using SLAMM / Re: Range Check Errors in 6.0.1
August 19, 2010, 07:56:26 AM
I couldn't reproduce the error in 64-bit Windows 7.  In 32-bit Windows XP I was able to produce an "out of memory" error during SLAMM execution, but not the "range check" error you're receiving.

Using SLAMM / Re: Batch File for SLAMM 5
January 04, 2010, 09:00:57 AM
Hi Keil,

The following text is from one of our SLAMM 5 batch files:

Format:  Input File, OutputDir, LastYear, INCLUDE Dikes, Note, put largest file first for optimal memory management.
------------2 HEADER LINES UP HERE ------------------------------------------------

The following text is from one of our SLAMM 6 batch files:

cd "\Shared work\SLAMM\SLAMM6"
SLAMM6.exe "..\Root\Data\USFWS\December 09\Plum Tree Island and Nansemond\VA.SLAMM6.txt"
SLAMM6.exe "..\Root\Data\USFWS\December 09\Supawna Meadows and John Heinz\NJ.SLAMM6.txt"


The SLAMM 6 batch file is a standalone MSDOS batch file because version 6 does not have built-in batch runs, yet.  Hope this helps!

- Evan