NDR - load_subsurface parameter = 0 ?

edited March 2018 in General

I am using InVEST's NDR model : for N and P, input of load, proportion_subsurface and load_subsurface is required (at least according to model sample's biophysical_table)Until now, I have been able to find parameter values for load and proportion_subsurface. But I'm not sure to understand how the "load_subsurface" parameter works. 

According to online documentation's figure 2, load_subsurface is equal to load_surface * proportion_subsurface. This is confirmed by equations (2) and (3). Then, why would I need to define a "load_subsurface" by myself ?
Moreover, the documentation specifies : "In case no information is available on the partitioning between [surface and subsurface], the recommended default value of load_subsurface is 0". Wouldn't this automatically lead to a null value of all subsurface exports (which is not what I want) ? If yes, then how to find value for this parameter ?

Finally, according to online documentation, additional parameters should be added, such as "Subsurface_retention_efficiency" and "Subsurface_crit_len". However, none of those are in the model sample's biophysical_table, which still allows to run the model. Why is that ?

Thanks a lot !

Post edited by Emmanuel_Faure on
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