Computes the horizontal distance to stream for each grid cell, moving downslope according to the D8 flow model, until a stream grid cell is encountered.
This value acts as threshold on the Stream Raster Grid to determine the location of streams. Cells with a Stream Raster Grid value greater than or equal to the Threshold value are interpreted as streams.
Default: 50
processing.runalg('taudem:d8distancetostreams', -p, -src, -thresh, -dist)