Is it possible to calibrate or feed NDR and SDR models using SWAT model outputs?

Software Support
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Hello everyone,

I recently came across the Colombian study “Assessing the Effectiveness of the Use of the InVEST Annual Water Yield Model for the Rivers of Colombia: A Case Study of the Meta River Basin” (https://doi.org/10.3390/w15081617). The authors state that the InVEST-AWY model can be calibrated using outputs from the SWAT (Soil and Water Assessment Tool) model.

I would like to ask the community if this same approach—calibrating or using SWAT outputs as a “proxy” —is methodologically sound for the Nutrient Delivery Ratio (NDR) and Sediment Delivery Ratio (SDR) models. I have seen some studies where SWAT runoff estimates are used as the Nutrient Runoff Proxy in NDR to increase accuracy in regions with limited weather station data.

Are there any recommended protocols for performing this “soft calibration” between SWAT and InVEST for sediments and nutrients while maintaining model integrity?

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Can someone please answer me?

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Hi @Fernbg77 -

I haven’t done this myself, but i do recall a project (i forget which one now, it was a while back) where we compared SWAT HRU results with InVEST freshwater results aggregated to the same HRUs. Because it was model-to-model comparison and not actual observed data, we focused on the agreement with the patterns of high to low, instead of the absolute values of water flow or sediment export. Of course, you need to make sure that you’re comparing the specific SWAT results that correspond with the InVEST model outputs. And i think this is a valid way to do perhaps more of a sanity check than an actual calibration, for NDR and SDR too.

If anyone else has done this sort of comparison between SWAT and InVEST outputs, please chime in!

~ Stacie