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Messages - cpapiez

Hi Jonathan,

I recently received interest from our wetland folks in the connectivity function of SLAMM.  Has there been any updates to this function to make it a spatial file with attributes?  Please let us know if you've updated this function or if there are plans to do so over the next year.


Using SLAMM / Time step and time zero
November 12, 2010, 01:04:26 PM
Hi Jonathan,

What is the best time step to run for NWI dates that are primarily in the 1980's?  We are running SLAMM by county so should we adjust the timestep based on the time zero/NWI date?  When we compared a 25 year and 10 year time steps for Dorchester County (NWI 1991) we saw significantly different results for tidal flats (15532 vs. 4603), Regularly flooded marsh (13013 vs. 3906), Transitional Salt Marsh (7738 vs. 2748), and Estuarine Open Water (106751 vs. 131923).

We are primarily interested at 2050 and 2100 results.  Any advice would be really appreciated.  As of right now, we have run all Maryland coastal counties with a 25 year time step but I'm concerned about the potential difference if we would have run it with a 10-year time step.  What are most people using for large scale projects like this?

Thank you!

I am wondering about the model parameters when I run salinity Connectivity function.  Should I keep all the model parameters the same assuming they all affect the connectivity output, i.e. Include dikes, no-data elevs loaded as blanks, use soil saturation, and protected developed.  Would more salinity intrusion occur if I did not include dikes?

When I run the connectivity function I ask the model to pause with examination tools, but I've run into some error with this.  I have found that I need to uncheck the IPCC scenarios when running connectivity for a custom scenario otherwise the connectivity will only run the IPCC scenario and give me an error when I ask it to give me the next scenario.

Is there any way to have the connectivity saved as a GIS output instead of pausing the model run and taking a screen print (jpeg)?

Model Formulation & Parameters / NWI photo date
September 21, 2010, 02:27:11 PM
How does the NWI photo date effect the model?  Does the model set that date as the initial and then calculate the parameters from it for each timestep?  So if we put in 1991 but it was really a 1981 photo date would we see different results similar to those found when you change the timestep?

Model Formulation & Parameters / Saturation
September 15, 2010, 02:40:47 PM
If saturation is turned off then is there less conversion of uplands to coastal swamps and fresh marshes?  I know turning it off makes the output less streaky but I'm afraid of lossing some of the key wetland movement/corridors.  Please let me know what the caveats are of not having it turned on are.  We are primarily interested in wetland corridors.

Thanks for your technical support!
Model Formulation & Parameters / Re: Salt Elevation
September 08, 2010, 01:48:14 PM
Ok Great!  Thanks!
Model Formulation & Parameters / Re: Salt Elevation
September 08, 2010, 01:33:20 PM
The wetland classification is in the National Wildlife Federations SLAMM report for the Chesapeake Bay.  We used the same NWI breakout as them and I just want to know what the "Riverine Tidal" class is.  I believe Jonathan ran the model for NWF so maybe he knows what "Riverine Tidal" is.  It may not be a wetland type but rather a form of water body.  Here's the link to the report:

Model Formulation & Parameters / Re: Salt Elevation
September 07, 2010, 02:00:07 PM
Thanks for clarifying Evan.  I have one additional question about the NWI breakout for the NWF study.  What is the description of Riverine Tidal wetlands?  It's listed in the final wetland conversion chart but I can't find a description for it.  We used the same NWI breakout so a description would be super helpful.


Model Formulation & Parameters / Salt Elevation
September 07, 2010, 11:32:16 AM

How do you calculate the salt elevation parameter?  Is it MHW or MHHW minus the MTL?  So far the model outputs are looking good with the LiDAR and new accretion calculation...its great to have a comparison (Maryland NWF study) to see the differences you've made to the model.



I noticed that the wetland accretion parameters were renamed from SLAMM v5 (salt marsh, brackish marsh, and tidal fresh) to the current parameters of regular flooded, irregular flooded and tidal marsh.  Is the regular flooded refering to salt marsh and irregularly to brackish marsh?  We have accretion data based on the wetland type and I'm not sure where to put brackish accretion rates.  Please let me know if my thinking is correct.


Model Formulation & Parameters / Sedimentation
July 29, 2010, 12:44:39 PM
We are reviewing the data inputs from the previous SLAMM study and noticed that 0.5 mm/yr was used as the beach sedimentation rate throughout the Chesapeake and Delaware Bays.  I could not find any information on this choice and was wondering if it was a default setting or based on previous accretion or sediment studies. 

Any help on this would be greatly appreciated!

Model Formulation & Parameters / Chesapeake Bay prj
July 09, 2010, 02:18:23 PM

As you know we are working on running SLAMM6 for Maryland's Chesapeake Bay and we've been analzying the previous model run by NWF.  We have a few questions listed below.  Any help is greatly appreciated.  Thanks!

We are working on refining our diked data from the NWI classifications.  I've been talking to our wetland ecologist about the function SLAMM uses to address diked wetlands, but I'm not exactly sure how it works.  Diked wetlands are not allowed to accrete even after over 2 meters of rise over tops them, is this correct?  Why are all dikes considered to be 2-meters high, can this be adjusted? 

Time step
Are sea-level rise, accretion and other parameters, with a value per year added only at each time step or are they added every year?  i.e. if we choose 25 year time step does the accretion value only get added every 25 years?

Great Diurnal Tide Range(m)
We noticed that the input for SLAMM 5 included Tide Range Ocean, Tide Range Inland, Mean High Water Spring, MHSW Inland and Water Depth but the latest version only has Great Diurnal Tide Range (m).  How do we figure out what that is for each subsite?  Is this NOAA tidal stations data?

What is the reasoning to use and not use overwash?  NWF study had an overwash of 25 years for all subsites but it wasn't clear why this number was chosen or why overwash should be included for the Bay vs. outer coast.