Addition to SDR: water regime

Dear NatCap InVEST developers, I have a question on the SDR model. Would it be possible, and how would you suggest doing so, to include data on river water regimes (wettest and driest seasons) in the SDR model?
We would like to develop a scenario changing the LULC and placing about 10 Km2 of retention basin nearby, but we’d also like to develop a scenario that includes the river water yield into the SDR model. Would it be possible? I would really appreciate any tips on how to get around this issue. Thanks!


Hi @luisagalgani -

I’m not quite sure what you’re wanting to do here. SDR does not model erosion within river channels, but if you happen to know how much is produced within the channels, you can add it to the SDR results and have a more complete picture of erosion, since you’ll have both overland and channel (but not landslides or gulley.)

SDR also is really made for annual average inputs and outputs, and it’s not made for seasonal calculations. That said, we have estimated monthly erosion from SDR’s annual results using monthly precipitation data, by multiplying the annual sed_export.tif by the monthly fraction of (monthly_precipitation.tif / annual_precipitation.tif). This is very simplified and not precise quantitatively, but it can give an idea of seasonal differences.

Apologies for not understanding more clearly. If neither of these address what you want to do, please let me know, and describe how you expect “river water yield” to impact erosion.

~ Stacie

Dear Stacie,
I understand. I was trying to model erosion within the river channels actually. Now I understand. I’ll try to estimate monthly erosion as you suggested. Many thanks!

Just a note, so I may be able to determine annual erosion as well by multiplying sed_exp by annual precipitation, right?

Hi Luisa -

SDR outputs annual average values, so the default results are annual already. It is only if you want to break it down into seasonal or monthly that you’d need to adjust by precipitation.

~ Stacie

Thank you! It is clear now. If I wanted to calculae in-stream processes (erosion within river channels), do you have any suggestions? It does not have to be with the SDR model, but I was just wondering whether there are other models or ways to calculate it. Thanks for your help!

I don’t have any experience modeling in-stream processes, but perhaps @RafaSchmitt might have a suggestion?

~ Stacie

Hi Luisa, for modeling instream processes of sediment deposition or erosin you could look into CASCADE (Schmitt, R.J.P., Bizzi, S., Castelletti, A., 2016. Tracking multiple sediment cascades at the river network scale identifies controls and emerging patterns of sediment connectivity. Water Resour. Res. 3941–3965. or similar (e.g., Czuba, J.A., 2018. A Lagrangian framework for exploring complexities of mixed-size sediment transport in gravel-bedded river networks. Geomorphology 321, 146–152.

Both modeling frameworks are open source.

Those frameworks are good if you are interested in entire river networks. If you are more interested in deposition/erosion for a smaller channel section, you can look for example into BASEMENT(



Thank you Rafael and Stacie for following up on this and for your suggestions. I’ll have a look. Thanks again and have a great day!