Dear @swolny
I’m sorry to reactivate this old thread, but while reviewing the discussion on estimating the Z parameter, a question related to AWC arose.
I used the ISRIC AWC raster, recommended by the InVEST User Guide, as input for PAWC. Is this correct? Is it valid to use the ISRIC AWC to estimate the Z parameter? Also, if so, would any pretreatment be required before using it?
Thank you in advance for your time and guidance.
Best regards.
Hi @bmnoz_2001 -
I have moved this post to a new topic, since the previous one was quite old.
The units do get confusing with AWC/PAWC, and the short answer is that yes, there is some pretreatment required before you can use the raw AWC 2017 layers from ISRIC.
ISRIC’s AWC rasters have units of volumetric percent.
Regarding calculating the Z parameter, the InVEST User Guide says that “AWC es el contenido volumétrico (mm) de agua disponible para las plantas.” (“AWC is the volumetric (mm) plant available water content.”)
So the raw ISRIC data should be converted from units of percent to units of millimeters.
The User Guide assumes that you have a PAWC layer created for use in the model, which has units of fraction. If you have followed the User Guide’s instructions for creating that PAWC layer from ISRIC’s AWC layers, then you can use the equation given in the Data Sources Z Parameter section to calculate AWC (in mm) from PAWC (fraction).
~ Stacie
Hi @swolny!!
I really appreciate your clarification and explanation.
I hope you’re doing well!