DESCRIPTION

r.width.funct produces the Width Function of a basin. The Width Function W(x) gives the number of the cells in a basin at a flow distance x from the outlet (it is also referred as distance-area function). It is important to underline the fact that the distance is not the euclidean one, but it is measured along the flowpath towards the outlet.

Input

Distance to outlet map: Input map, required. It is obtained by r.stream.distance (with the option: distance to outlet, flag -o).

Output plot: Path and name of the plot.

Output

It provides the quantiles of the area - distance distribution and the plot of the Width Function. In x axis is reported the distance and in y axis is the area.

EXAMPLE

North Carolina sample dataset example:

g.region raster=elevation -p

# Calculate flow direction
r.stream.extract elevation=elevation threshold=1000 \
direction=direction 

# Create outlet point 
echo "637304.924954,218617.100523" | v.in.ascii input=- sep=',' out=outlet

# Convert outlet point to raster
v.to.rast input=outlet type=point output=outlet use=cat

# Calculate distance to outlet map
r.stream.distance -o stream_rast=outlet \
direction=direction distance=dist2out

# Calculate width function
r.width.funct map=dist2out image=/tmp/my_basin

Dependencies

Matplotlib

REFERENCES

Rodriguez-Iturbe I., Rinaldo A. — Fractal River Basins, Chance and Self-Organization. Cambridge Press (2001)
In Italian: Di Leo M., Di Stefano M., Claps P., Sole A. — Caratterizzazione morfometrica del bacino idrografico in GRASS GIS (Morphometric characterization of the catchment in GRASS GIS environment), Geomatics Workbooks, n. 9 (2010)

AUTHORS

Margherita Di Leo (grass-dev AT lists DOT osgeo DOT org), Massimo Di Stefano, Francesco Di Stefano

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