Soil erodibility - convert to standard units before using?

Science, Research & Data
1

Hi all,

I am currently using the SDR model in two regions of the United States and have a question about the soil erosivity input. I found a 30 m resolution soil erosivity dataset for the U.S. (please see here; ArcGIS ) and wanted to confirm: do I need to convert the values to any standard units before using them in the model?

Thank you for your guidance.

Hazhir

2

Hello @hkarimi -

The model does require specific metric units for soil erodibility, as noted in the User Guide Data Needs section.

The ArcGIS layer description says “The values are in units of Micrometers per second (μm/s)”, which is a bit surprising to me, since I have in the past used the SSURGO data to create soil erodibility data (using one of the USDA’s soil data tools) and recall it having values that were more in line with what’s required for the USLE equation (and InVEST). They might have had US units that just needed a conversion factor applied (as is also discussed in the Data Sources section of the User Guide). But the ESRI layer may be using a different method, and I don’t know how to convert micrometers per second to the units required by USLE/InVEST.

~ Stacie

3

Hi Stacie,

Thank you so much for your quick reply. Can you please introduce any website or link to directly get soil erodibility layer?

Bests,

Hazhir

4

Hi @hkarimi ,

Have you read the User Guide, specifically the section Stacie linked?

You’ll also find previous posts about erodibility by searching this forum, for instance:

Now, you can download two different global soil erodibility layers from the NatCap Data Hub and clip them to your study area.

-Jesse

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Hi Jesse,

Thank you for your reply. Yes I read the User guidline. I think SSURGO GIS toolbox can be only used by ArcGIS dektpo, not ArcGIS pro. I do not have ArcGIS desktop unortunately. And the NAtCap data for soil are too coarse. Actually, I am looking for finer sclae for the US.

Hazhir

6

At the end of the Data Sources section on Soil erodibility, it mentions a new toolbox that you can try:

Another option is SSURGO Portal (https://www.nrcs.usda.gov/resources/data-and-reports/ssurgo-portal), which is a new (beta) application independent from ArcGIS.

~ Stacie

1 Like
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Thank you so much. Appreciuated it,

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Hi Stacie,

I have run the model with global soil data and here is the result for US Southeast. Can you please take a quick look at this map and tell if this values make sense for you?

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Hazhir

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Here is the better visualization of the output SDR.

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