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How is the lateral erosion implemented?

Started by giuliomariotti, May 09, 2019, 11:27:53 AM

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giuliomariotti

Hello,
I have two technical questions on how the lateral marsh erosion is implemented in SLAMM 6.7.
1)Let's say the rate of marsh erosion is 2 m/yr. How are the cells actually updated?
I assume the cells are updated every time step, maybe every year.
How do you implement the erosion of 2 m in a cell that is likely much larger than 2 m?
Do you implement a sort of partial cell erosion?

2)Also, when you erode a cell marsh by lateral erosion, what elevation do you impose to the update cell? A fixed elevation of the tidal flat?

Thanks,
Giulio

Jonathan S. Clough

The cells are updated every time step, correct.

SLAMM actually tracks partial conversions of cells over time -- it was originally created many years ago when computers were much less powerful and cell sizes were therefore much larger (150-500meter).  For this reason it has always tracked multiple land types in each cell.  For this reason the tables of output are not always precisely what you would get when adding up the area of the raster maps.  After erosion to tidal flat, the elevation of the cell would be set to the elevation of the flat or MTL if there is no adjacent flat. 

In some of our older runs we found that the flat itself, became protective against further erosion at the marsh-to-open-water interface.  For this reason marshes erode directly to open water.   https://github.com/WarrenPinnacle/SLAMM6.7/blob/master/PROGRAM/Categories.pas ; line 627

-- Jonathan


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