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SDR and NDR flow direction error

Hello all,

I am encountering an error running the SDR and NDR models. There are points that are not found to have a flow direction. The rasters do not have exactly the same spatial extent and there exists some pixels in spaces where there is not a DEM, was wondering if that is what would be causing this problem. 

Thank you for your time,
Thomas Price


  • swolnyswolny Member, NatCap Staff
    Hi Thomas -

    I suspect that those warnings are for pixels that are on the very edge of your DEM, and the model is calculating flow direction that would actually go off the map, where there is no data. You probably don't need to worry about those warnings, but I do suggest checking on two things. First, make sure that your DEM covers the whole watershed that you are analyzing, even extending a bit beyond the borders. Theoretically, if you have included the whole watershed, all pixels should be draining within the map and have a flow direction. Second, check the stream.tif raster that the model outputs, and make sure that your streams look ok. It is also possible that if no flow direction is found for pixels along the stream, you might have a discontinuous stream network (or, there just might be sinks that need to be filled that are causing the discontinuity.)

    ~ Stacie
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