About the average annual rainfall data in the Water Yield module

Hello, I am a person who recently started learning the Invest model, I have a confusion, I would like to ask whether the annual average rainfall raster data in the water yield module uses the rainfall of the current year, or the average of the rainfall in the past ten years ?

Hi @Ray and welcome!

The annual average rainfall raster is the average rainfall in the past ten (or more) years, since the model science is built around long-term averages.

~ Stacie


It was so, thank you very much for your answer, and wish you a happy life.

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Hi Stacie,I have another question, if I want to calculate the water production in 2000, 2010 and 2020 separately, can I use the average annual rainfall for 30 years? Or do I need to use the average annual rainfall for different time periods (every decade)?

Well, optimally you’d have a 10 year rainfall average that falls around each of those decades, for example, average annual rainfall between 1995-2005 to calculate water production in 2000. It’s not often that we have that kind of data though, and I don’t know exactly what you have access to. Are you also using different land cover maps for each of those years?

~ Stacie

Yes, I use different land cover maps for every decades, and thank you for your answer.

If you use different land cover maps for each decade, with the same precipitation/ET for all of them, then your results will specifically highlight the differences due to land cover change, which of course can be very useful, depending on the purpose of your analysis.

~ Stacie

I see, I’ll think about it carefully, thanks for the advice.

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