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Ocean beach to open water subtidal rather than open ocean

Started by Elena V, February 05, 2013, 01:03:28 PM

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Elena V

According to my understanding, Ocean Beach (12) converts to Open Water Subtidal (17) if the elevation drops below MLW, which should then convert to Open Ocean (19) if connected to the ocean in the offshore direction and within 500 meters of the ocean. The offshore direction is set as South. I've attached an example of a (very initial) input/output habitat layer at one my sites (the mouth of the Ventura River in Ventura, CA) as well as the input topography.

Why do some cells clearly connected to the ocean convert to Open Water Subtidal while others convert to Open Ocean? I see this in my other sites as well.

Other comments:
- I am using v6.1 beta
- Bruun erosion is disabled for Ocean Beach erosion
- Using a 10 year time step
- All erosion parameters are set to 0.2 m/yr and accretion to 1 mm/yr
- Overwash is disabled

Please disregard the names of the habitats in the legend -- they don't match directly with the official SLAMM names as we've adapted them to our habitats.

Thanks!
Elena

Jonathan S. Clough

I'll be honest.  We haven't spent much time differentiating between "Estuarine Open Water" and "Open Ocean."  Within the source data (NWI), the line between these classes is usually drawn at the mouth of the estuary.  SLAMM doesn't redraw that line as the mouth of the estuary evolves.  For most of our clients, "open water" is "open water" so the precise designation hasn't been important.  The code, for the most part, tries to predict new open ocean cells adjacent to existing open ocean cells and estuarine open water adjacent to other estuarine water.

I will acknowledge that it can sometimes make maps look strange if the model guesses "wrong" and these two water categories are plotted with different colors.  We recently noticed that our ocean beach when eroded with the "non-Bruun rule" formulation (recommended) would convert to estuarine open water and we changed that code accordingly.  I'm pretty sure that's what's happening in your verison.

This is fixed in our version 6.2 (64-bit) which is available upon request pending review of our technical documentation.  I'll send you information about downloading that in a separate email.

Best regards -- Jonathan


Elena V

Great, thanks Jonathan! Just wanted to make sure it wasn't a problem with my input topo/habitat map. I'll download the most recent version and give it a shot. I'll probably just display those two water categories with the same color.

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