SDR updates: is legacy "sediment deposition" output incorrect?

[rdejesuscrespo]

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InVEST version

3.12.0

Dear Nat Cap,

I just downloaded the new Invest and realized the changes to the SDR model. I am in the process of writting a manuscript with values derived from the previous version, where sediment deposition was the recommended output. However, now this output has been replaced with avoided erosion and avoided exports. Is it still correct to use sediment deposition from the previous model version? Can you provide details as to why sediment deposition is no longer the recommended output?
Thanks!

[jdouglass]

Hi @rdejesuscrespo ,

With the recent modifications to InVEST 3.12.0, the SDR model still produces a raster of sediment deposition, although the calculations of deposition and flux have both been changed slightly to avoid a form of double-counting. This is described in the User’s Guide under “Recent Changes to the SDR Model”.

The other outputs you mention, avoided erosion and avoided export have been added, but they do not replace sediment deposition. In fact, deposition/“trapping” is one of the inputs to the avoided export raster. These new outputs are intended to more clearly indicate services provided by the ecosystems. These are more fully described in the corresponding User’s Guide section.

More directly addressing your questions:

Is it still correct to use sediment deposition from the previous model version?

The former deposition output (before InVEST 3.12.0) double-counted the role of vegetation, and so the newer InVEST version will be more conceptually consistent.

Can you provide details as to why sediment deposition is no longer the recommended output?

A description of why we changed the model in the ways that we did is outlined in the user’s guide at https://storage.googleapis.com/releases.naturalcapitalproject.org/invest-userguide/latest/sdr.html#recent-changes-to-the-sdr-model.

Please let us know if you have any further questions!

James

[rdejesuscrespo]

Thank you! Very helpful response.