NDR measured runoff and Application rate in Biophysical Table

Software Support
1

Hello InVEST Community…

I just want to understand the Load Data types used in the InVEST User Document (Given below)

"These two types of loading values are denoted application-rate and measured-runoff, respectively, in the biophysical table. Since the model equations require measured runoff values, if you supply application rate values, the model will adjust for the nutrient retention provided on the pixel itself, using the application rate and retention efficiency value (eff_n or eff_p) for that land cover type:

𝑙⁢𝑜⁢𝑎⁢𝑑⁢𝑖⁢𝑛⁢𝑔 =𝑎⁢𝑝⁢𝑝⁢𝑙⁢𝑖⁢𝑐⁢𝑎⁢𝑡⁢𝑖⁢𝑜⁢𝑛⁢𝑟⁢𝑎⁢𝑡⁢𝑒 ∗(1 −𝑟⁢𝑒⁢𝑡⁢𝑒⁢𝑛⁢𝑡⁢𝑖⁢𝑜⁢𝑛⁢𝑒⁢𝑓⁡𝑓⁡𝑖⁢𝑐⁢𝑖⁢𝑒⁢𝑛⁢𝑐⁢𝑦)

using the specific biophysical table fields for nitrogen:

𝑙⁢𝑜⁢𝑎⁢𝑑⁢𝑖⁢𝑛⁢𝑔 =𝑙⁢𝑜⁢𝑎⁢𝑑_𝑛 ∗(1 −𝑒⁢𝑓⁡𝑓_𝑛)

Note that you can provide a mix of measured-runoff and application-rate values, and the model will only adjust the application-rate values as described; measured-runoff values do not need to be adjusted."

Yes. For some agriculture class I am using a measured runoff value, whereas for other classes, I am using application rate (mostly compiled from published papers). My doubt is if I use measured runoff value, should also mention retention efficiency for that particular class?

I have attached a screenshot of my Biophysical table below;

image
image524×197 5.65 KB

Thanks and Regards

G. K

2

Yes, you should include the retention efficiency values for all classes, whether or not you are using application-rate or measured-runoff. The efficiency values are not only used to adjust the application rates, they are also used to calculate the effective retention along the flow path (see eff_LULC_i in Equation 50 of the user guide). That calculation applies to nutrients flowing down from upslope sources (as opposed to a nutrient load being introduced on the pixel), so it is independent of the load_type, and values for every LULC class are used.