InVEST SDR sediment export overestimation

Hi,

I am currently using InVEST SDR to estimate the sediment export of some watersheds in France. I am using a 25 meters mesh and a 100 meters mesh. The results are pretty close between these two meshes but I overestimate my validation data by 10 each time.

I have compared InVEST SDR with a manual way to compute sediment export and it’s doing good compare to my validation data. The only difference between the two methods is that the LS factor is really high compare to the one I am manually computing with QGIS (Desmet and Govers 1996 equation).

I would to know if someone has met the same issue and if the LS factor could be the only reason of the overestimation of my sediment export estimation.

Thank you and cheers from France.

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Hi @TheoMzr,

Welcome to the forum and thanks for writing in about your experience with SDR results.

Is the model overestimating your validation data by 10 times?

Recently, one of our hydrologists (@RafaSchmitt) began investigating a potential issue with the LS-factor cap in this model. It is currently hardcoded at a value of β€œ333”. It has been observed that the model may significantly overestimate export in very large watersheds. We are now testing a developmental build where we can manually vary the LS-factor cap and have been considering β€œ122” instead of β€œ333”. So this definitely could be the sole cause of your overestimation.

I apologize that you ran into this problem. Perhaps Rafa can offer more details.

-Jesse

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