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Negative N_export value

As suggested by my committee members, I used 5 foot DEM, re-sampled to 10m*10m and changed the biophysical table also. This time I get negative N export values. The lowest being -0.98 and the highest is +0.45. I would be grateful if I get an explanation for this.


  • RichRich Administrator, NatCap Staff
    Hi @KumariGurung, is it possible you introduced hydrological pits in your DEM when you resampled it? Or maybe there were hydrological pits to begin with that weren't filled? You might get some insight if you look at some of the intermediate files like the flow accumulation raster. A sign of a bad dem is broken flows across the landscape where one that drains will have nice continuous flows to the drain.

    If this is your issue you'll need to fill your DEM first. I use SAGA's Wang & Liu algorithm, but I think ArcHydro also has some methods. And let us know more if this is not your issue.
  • Dear Richard,

    Thank you for getting back real quick. The DEM was filled in Arc Map using the tool "Fill". I apologize I could not attach the DEM filled tiff file here. So I am going to email you. Please have a look if your time permits. 

    Kumari Gurung
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