What does the Output vri_sum represent

Software Support
1

Hello goodnight!!

In the attributes table of the water production model, the following output appears “vri_sum” but the user documentation does not talk about this variable, only Vri_[Suffix].tifam both refer to recharge values?

2

Hello! This represents total recharge contribution, (positive or negative) within the watershed. The sum of Vri_[Suffix].tif pixel values within the watershed. I’ve just added this to the user’s guide. Thanks for letting us know that this was missing!

James

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3

Hello @jdouglass ,

I would like a little bit more details please.

  1. When you say “total recharge contribution (positive or negative)” what does it exactly means?
    Is the total recharge equal to:
    baseflow + quickflow - evapotranspiration?

  2. and then, a negative total recharge contribution would mean that evapotranspiration is higher than baseflow and quickflow together?

Thanks in advance! :slight_smile:

4

Hi @Olivier , I’m so sorry about the delay here!

The “total recharge” is equal to the sum of all recharge (Vri.tif) pixels within the watershed. The equation describing how vri.tif is calculated is given at this portion of the user’s guide chapter, under “Attribution of Recharge”: Seasonal Water Yield — InVEST® documentation

I believe this is correct, yes, at least when looking at the whole watershed.

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