NPV negative values for Carbon sequestration


Can somebody explain me why the outcome of the carbon model is giving me negative values in the net present value (NPV)? why is this ocurring? 

Thank you in advance


  • RichRich Administrator, NatCap Staff
    Is it possible your discount rate is negative?  If not, could you post your log here?
  • RGriffRGriff Member
    This is an expected model output if you have net carbon emission (versus sequestration) over your study area. Is that your case?  
  • CastaCasta Member
    The discount rate is not negative.

    I also do not have emission vs sequestration. I attached the log for you to see it, I will be pending on your answer.
  • RichRich Administrator, NatCap Staff
    Okay, don't see anything odd in the log.  Can you dropbox me your data to and I'll see if I can recreate your issue on my end? 
  • CastaCasta Member
    Dear Rich,

    I just shared with you the data by dropbox, I appreciate if you can answer me as soon as you can, thanks.
  • CastaCasta Member
    Dear Rich,

    Please check your e-mail I sent you the data I worked with for you to check, thanks.
  • RichRich Administrator, NatCap Staff
    Sorry, I was on vacation Monday and Tuesday.

    I just ran the model with your data and got a positive NPV.  See below for the report.  I don't know what's happening otherwise on your end.  Could you paste your report and see what's different?

    InVEST Carbon Model Results

    This document summarizes the results from running the InVEST carbon model with the following data.

    Report generated at 2017-08-16 13:44

    arg idarg value
    lulc_fut_pathE:/Dropbox/Rich InVEST/CLC12_ws100_OCModel_NewCodesSLM_etrs89.img
    lulc_cur_pathE:/Dropbox/Rich InVEST/CLC12_ws100_etrs89.img
    carbon_pools_pathE:/Dropbox/Rich InVEST/Carbonpools_SLM25x100_1mdepth_OK_csv.csv

    Aggregate Results

    DescriptionValueUnitsRaw File
    Total cur214174100.00Mg of CC:\Users\rpsharp/Documents/carbon_workspace\tot_c_cur.tif
    Total fut228860632.00Mg of CC:\Users\rpsharp/Documents/carbon_workspace\tot_c_fut.tif
    Change in C for fut14686504.25Mg of CC:\Users\rpsharp/Documents/carbon_workspace\delta_cur_fut.tif
    Net present value from cur to fut109032332.00currency unitsC:\Users\rpsharp/Documents/carbon_workspace\npv_fut.tif
  • CastaCasta Member
    Dear Rich,

    thank you very much for your reply. In fact the outcome you showed me is positive. However, I have a couple things to add:

    1. I just realilsed one of the files I sent you is wrong (I am sorry).
    2. I am working at sub-watershed level, therefore I want to know NPV values per sub-watershed (I add the shapefile sub-watersheds to the folder)

    I just ran the model with the new data and extracted the data from the raster, even when the total NPV is positive, some of the sub-watersheds are presenting negative values (I added excel file to the folder). Could you please take a look of the files and if possible explain me why the values are negative? taking into account that the cathcment is around 17.000km2 dont you think the total NPV (53713,47) is low?

    I am sorry for the inconveniences, thank you in advance
  • RichRich Administrator, NatCap Staff
    Hi, I spot checked the npv raster and clicked through on your landcover map for some regions which show a negative return.  In one case the base landcover was "coniferous forest" with a total carbon stock density of 183.91, and future landcover was "natural grasslands" with a stock of 104.77.  You would expect a negative NPV in this case since you've got an emission there.

    If you're unsure about the subwatersheds that are negative, you might load the npv raster, present landcover, future landcover, in a GIS tool and click through a couple of pixel stacks on the negative NPV side to see if they are corresponding to an emissions land change.  If you're seeing something else, please follow up here again and we can work more on it.

    As for the total amounts of carbon seeming low, I'm not sure what's reasonable in your case.  It doesn't seem that there's a software bug, but I'm happy to follow up further if you need.
  • CastaCasta Member
    Dear Rich,

    Thank you very much for your cooperation, I did what you said about cheking raster in detail and indeed is happening what you are saying, emissions. I appreciate your supoprt, thanks again.

    I will let you know if I have further questions, have a nice day.

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