Annual Water Yield Hydropower - energy units & valuation timespan

Hi!
I’m working with the annual water yield model at the moment and i’m trying to get the hydropower evaluation to run. I have some questions regarding that:

  1. In which unit is the output value hp_energy? The user guide states that it should be kW/timespan, since kW is a unit for power not for energy i’m guessing this is a typo and it should be kWh, is that correct?
    2.I tried to run the model twice with the same input data except for time span, where i used one time one and one time thirty years. For hp_energy it gives me the same value, but from how i understand the user guide it should be thirty times as high for the 30 year time span. Is hp_energy just the annual energy production or is it the production across the overall time span?
    I would be grateful for answers to these questions.
    Thanks in advance and best regards
    Felix

Hi @Felix , thanks for posting your questions,

Yes, it should be kWh.

It looks like hp_energy is meant to be the annual energy production, not total over the whole timespan. That is described in this section of the User Guide before equation 4 Annual Water Yield — InVEST documentation

And it is described incorrectly later in the “Interpreting Results” section.

Then, NPV is calculated with respect to the timespan (equation 4) and this is hp_val in the model results. The equations in the User Guide after equation 4 don’t actually appear anywhere in the model. I’m not sure if they used to be calculated, but we should probably remove those equations from the User Guide.

Thanks for bringing this to our attention, we’ll make corrections to the documentation.

Hi Dave,
thank you very much for your answer!
Best Regards
Felix

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