Water Yield Model - factor Z
I am using InVEST 3.3.0 x86 in a small watershed in Brazil. I had no big troubles to find and to calculate the parameters required to run the model, no errors. However, since I have observed data, I am trying to calibrate the factor Z to compare with my data.
I have data from 2003 to 2015 and when I first run the model, I used different Z values for each year, in a way I could match or get closer to my real data.
Based on what is the user´s guide " The model is an annual average time step simulation tool", someone told me that I could use different Z values for, let´s say, the years from 2003 to 2008 and get an average of these years, and try it on the other years, but I don´t know how accurate this is. I tried to do that, and the results were not what I expected.
I have been reading a lot about how to calibrate this parameter and how to validate it... I realize that: higher Z values, the response is often a reduction in water yield and by doing some tests Z value is very sensitive to precipitation.
My question is if the analysis can be doing accounting a time series database (using an average or something) or if the calibration should be done year by year, different Z values for each year. ( as the user´s guide says: "The biophysical models do not consider surface – ground water interactions or the temporal dimension of water supply.").
And if it´s that the case, how can I use this value when I change my land use scenario? I mean, after the calibration of the model, I would like to predict the water yield in a different land use cover situation, considering reforestation for example.
Sorry for the long post
Post edited by unbmaite on