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General questions

Started by magdeline, April 22, 2014, 11:36:49 AM

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magdeline

1. We are curious about salinity in the model when the salinity model is not used.  We are seeing salt marshes in all of our output files.We would like to restrict salt outputs to the areas where they would realistically occur.  Is it possible to restrict salt outputs to certain extents?

3)  We noticed a lot of irregularly flooded marsh in our output, some of which didn't make sense to us.  There are many examples of tidal swamp or tidal fresh marsh becoming irregularly flooded marsh.  This might be related to salinity above, but we would like to better understand the model behavior that causes this particular transition.

Jonathan S. Clough

Unfortunately modeling well up a river is pushing your domain to or beyond the edge of what the SLAMM model can be expected to do without explicitly accounting for salinity and model artifacts are to be expected.  More thoughts below:


QuoteWe are seeing salt marshes in the output files up and down the river.  We would like to restrict salt outputs anywhere north of where they would realistically occur.  Is it possible to break up the geographic component models at a designated point and only allow salt outputs in the southern extents? note:we did not use the salinity model in the first SLAMM run.


I'm afraid this is not possible without code changes.  You can designate a zone as Freshwater influenced which changes the decision tree.  However, once marshes get to a certain elevation and are regularly tidally flooded they will be assumed to be converted to regularly flooded marshes (note part of the reason this is not called "salt marsh" in the model is that we usually are not explicitly accounting for the salinity of the water the marsh is "regularly flooded" with.) 

2)      We noticed a lot of irregularly flooded marsh in the output, some of which didn't make sense to us.  There are many examples of tidal swamp or tidal fresh marsh becoming irregularly flooded marsh.  This might be related to salinity above, but we would like to better understand the model behavior that causes this particular transition.

The SLAMM freshwater model is based primarily on succession of marshes seen in classic large estuaries like in Georgia where there is a secession, based on salinity of tidal swamp (least saline) followed by tidal-fresh marsh, followed by brackish marsh (irreg. flooded) followed by salt marsh (reg. flooded and most saline).  In the absence of a salinity model, in a freshwater influenced zone, we must take frequency of inundation as the best surrogate for salinity that we have.  Therefore tidal fresh marshes convert to irregularly flooded marshes. 

We have in a proposal for SLAMM 7 that will produce a more flexible decision tree, enabling the decision tree to be editable and more applicable to special cases such as yours.  Unfortunately it won't be available for several years, even if funded...

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