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Undeveloped/Developed land not converting

Started by scottrasmussen, February 25, 2019, 07:43:52 AM

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Any cells noted as either "Undeveloped" or "Developed" are not converting after a simulation. Protection scenarios are set to "Don't Protect". I'm expecting these to change most likely to transitional salt marsh but it's as if these cells aren't involved in the habitat switching parameters at all. All other habitats are converting as would be expected.

Thank you.

Jonathan S. Clough

This category is usually changed as a function of the "salt elevation" parameter which has units of meters above MTL.  Make sure that parameter is properly set within the "Site Parameters" screen.  It is often approximately 133% to 140% of MHHW (relative to MTL). 

To examine the distribution of dry-land cell elevations you can go through "elevation analysis" (you must go through the "set map attributes" button first to load all cells and elevations for analysis.)  Select run elevation analysis and you can view statistics and histograms about each land-classes elevation.  There's more information about this screen in the users manual (context sensitive help).

I hope this gives you a hint as to how to proceed, otherwise please post again!


Thank you Jonathan, that WAS insightful.

This leads me to my next question; how are you deriving 133-140% of MHHW? I've read through similar SLAMM forum posts regarding this topic and found (% of inundation x GT)/2) in addition to searching the web (nothing there). I'm downloading 30 day data from the NOAA gauge at Newport, RI and coming up with a percentage of inundation above the accepted MHHW datum at Newport and am only coming up with ~ 57%. I must be missing something.

Thank you.

Jonathan S. Clough

Hi Scott:

First of all, please note that there is a difference in datum used for the two parameters (which is probably not an ideal design.)   GT is expressed as meters between MLLW and MHHW.  The salt elevation is expressed as height above MTL (the mid point between MLLW and MHHW), so is a lower value than the GT generally.

As you have likely seen in some of our reports, this is based on "frequency of elevation" analysis from observed-data analysis so that it takes into account wind tides as well as astronomical tide cycle data.  I can point you at one of these analyses at some point if you'd like.   If you calculate a daily high water level using NOAA data for several years and then calculate the 0.967 percentile of those data that pretty much will get you there.

Best!  -- Jonathan