Hi @Fernbg77,
The Annual Water Yield model was made to represent long-term annual average water production. This thread contains a discussion of the precipitation, ET0, and LULC rasters that you may find helpful, and this thread goes into additional detail regarding the 10-year recommendation.
You may also find the User’s Guide sections on calibration, precipitation, and evapotranspiration helpful, if you haven’t yet seen them.