Coordinate system - UTM zone 17, NAD_O, meters

Format ESRI ascii grid

The streams and basins are the results of r.watershed
applied to the IFSARE DEM without any pre- or post- processing.
So the results need to be verified using an independent source
of stream information before they are used for an application where
high accuracy is required. The streams fit within 50m of most
GPS points, some points are not on the stream but those may be errors
in the GPS measurements or data input.

Raster map layers

10m 25m and 50m resolution

- sub-basins (50m: 2 Chagres, 0 outside)
- stream network with stream directions (-9999 no stream, 0 outside stream, 1-8 stream)

Sub-basins are around 100000 cells, so the smallest are for 10m resolution,
the 50m resolution gives the entire Chagres basin
Stream network is defined as flow accumulation larger than 100 units
Directions are defined as follows

0 streams outside Chagres green
1 NE cyan
2 N aqua
3 NW blue
4 W purple blue
5 SW violet
6 S magenta
7 SE soft red
8 E red 

The results are not masked so streams and basins outside Chagres are included
but they have category 0 while the streams within Chagres basin have category
representing their direction - see table above.

The following commands were used:

r.watershed el=chagdem.n th=100000 accum=accum.10m drain=dir.10m basin=bas.10m stream=stream.10m
r.mapcalc dirstr.10="if(abs(accum.10m)>100,dir.10m,null())"

r.watershed el=chagdem.n th=100000 accum=accum.25m drain=dir.25m basin=bas.25m stream=stream.25m
r.mapcalc dirstr.25=if(abs(accum.25m)>100,dir.25m,null())

r.watershed el=chagdem.n th=100000 accum=accum.50mn drain=dir.50m basin=bas.50m stream=stream.50mr.mapcalc dirstr.50="if(abs(accum.50mn)>100,dir.50m,null())"