Help Needed: Deriving Monthly Seasonal Water Yield Raster from InVEST Outputs (Baseflow + Quickflow)

Science, Research & Data
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Hi @abir -

We have been discussing these same issues in your other thread here.

In that thread, I listed two options for deriving monthly baseflow:

  1. Divide annual Baseflow equally 12 ways for each month
    All you need to do is calculate (annual baseflow / 12) and use that raster for all monthly calculations.This is most simple, and might be more appropriate in places where the rainfall is not highly seasonal.

  2. Divide annual Baseflow proportionally, based on each month’s rainfall depth
    For this, you need to add up all of the monthly rainfall rasters to get a total annual value, then calculate the proportion of each month’s rainfall with (monthly rainfall proportion = (monthly rainfall / annual rainfall)) then use the result to calculate (monthly rainfall proportion x annual baseflow). This takes an extra couple of calculations, but might be better for places with highly seasonal rainfall, like monsoons.

While the model was not made for calculating monthly baseflow, we do use it that way occasionally, being very clear in our reporting that the baseflow values are very approximate, and describing exactly how we calculated them.

~ Stacie

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