I’m still getting to grips with hydrological modelling in InVEST. After running the seasonal water yield model, I am getting some strange results for the quickflow and stream.tif validation file (the latter is shown below), along with a land cover map for context.
As you can see, the model is predicting large jagged areas of streams in various places. These often seem to be around where lakes exist in real life (see the land cover map for comparison), but go beyond the lake areas too. What could I do to fix this? Is it something to do with the flow accumulation threshold? So far I have just been keeping this around the recommended starting value of 1000. This seems to match the real stream distribution pretty well, until one gets to those large jagged ‘blobs’.
A whole bunch of LZW decode warning appeared as the model was running, however it still completed fine to my surprise. I am also attaching a second log file from a previous run conducted in the same region of the world but for a smaller area. This showed the same issue with the quickflow/stream.tif layers, so it doesn’t seem to be related to the LZW decode issues. The reason I’m adding its log file is because it doesn’t have hundreds of lines with LZW decode warnings, so might be easier to look through!
InVEST-Seasonal-Water-Yield-log-2020-07-27–14_02_23.txt (63.4 KB)
Any pointers would be much appreciated.