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Specifying accretion as a function of elevation

Started by slammdunk, October 01, 2019, 04:19:42 AM

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slammdunk

Hello Jonathon and Marco,

I am new to SLAMM and have had some difficulties understanding how to vary accretion rates as a function of cell elevation for different NWI wetland codes. I am hoping you can provide some more guidance on how to go about this.

I would like to use surface elevation change data from SETs that were placed in marsh and mangrove regions. Rather than breaking up the dataset for subsites around each SET, I would like to have accretion rates vary with elevation and tidal range for marsh and mangroves. I'm not certain about how to input this data into SLAMM though. Could you provide a step by step overview?

I have read through the user manual and technical guides, and have tried playing with the Excel SLAMM6_Accretion file included with the download. However, I'm still confused about how to go forward.  ???  Could you also provide an overview of the SLAMM6_Accretion file- bit of an introduction on how to utilize the spreadsheet?

Thank you ahead of time for all your help!   :)

Jonathan S. Clough

October 07, 2019, 08:33:52 AM #1 Last Edit: October 07, 2019, 01:51:43 PM by Jonathan S. Clough
First calculate the longest term average elevation-change rate for your SET tables that you have available.

Then calculate the elevation of the SET table relative to MTL in "half-tide units."  As a reminder, half-tide units are "elevation-in-meters / (0.5 * GTU-in-meters )"

Then, plot these data on a graph so you can understand the relationship between SET elevation and measured elevation changes.   

A line using the accretion spreadsheet data can then be fit through the data to the best of your capability.

e.g. Fig 4 from https://www.sciencedirect.com/science/article/pii/S1364815216302705#fig4

Often SET tables are not set at elevations throughout the tidal range and are focused up around MHW so you would need to estimate the other portions of the range or use a model such as MEM3 to help fill out the relationship between marsh platform elevation and predicted accretion rates.

This is a quick birds-eye view of the procedure, please ask specific questions about the spreadsheet and we will answer them ASAP.

Love the user name BTW.

Regards!  - -Jonathan

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