NDR output mostly nodata values

ndr
#1

Dear NatCappers,

The 3.6.0 NDR model ran to a close and generated output that includes some double-digit values but is mostly nodata. The nodata does not correspond to any of the LULC classes.Log file is attached. Any insight would be most welcome.

Thanks,
David

InVEST-Nutrient-Delivery-Ratio-Model-(NDR)-log-2019-05-02–00_24_22.txt (8.5 KB)

#2

Hi David -

Thanks for posting the logfile, and it looks like we’d need to see your inputs and outputs to understand what’s going on. I do have to wonder about using an .asc file for the DEM, I’ve never tried that and don’t know if/how coordinate systems etc are handled. My first hunch would be to turn that into a TIFF with the same coordinate system as the rest of the spatial inputs and rerun.

The next thing to look at is the stream.tif output. If streams are not produced, then there will be no n_export/p_export generated, because they rely on nutrient ending up at a stream. This could be caused by the DEM format not being handled correctly, or a value for threshold flow accumulation that’s too high. Take a look at the other files in the Intermediate folder as well, they might help explain where things are going wrong.

~ Stacie

#3

Hi Stacie,

Many thanks for the constructive reply. The DEM was indeed the culprit but not due to the .asc format. I had neglected to fill the sinks in it causing a lousy stream.tif output. Now the NDR output is much more complete. The remaining curiosity is small areas of nodata pixels on the edge of the landscape. I fortunately included a buffer in the analysis area that compensates for this.

All best,
David