Geologic-Scale Erosion

Submitted by dylan on Thu, 2005-08-11 00:10.
erosion_image_1

Initial Landform
erosion_image_2

10 Iterations

100 iterations of mass removal based on preferential flow of water as calculated by r.topidx in GRASS. Notice how landform is cutdown most in stream channels, least at the ridges. The basins between ridges appear to "fill" with sediment near the 50th iteration as the entire landform is lowered to sea level (0m). Absolute change in elevation is visble in the elevation profiles below. Example GRASS commands below. Here is a link to a movie, containing all 100 iterations.

erosion_image_3
50 Iterations
erosion_image_4
100 Iterations

Note that this is *not* a direct measure of sediment removal, mearly one means of visualizing the qualitative effects of sediment removal. Actual sediment flow values could possibly be calculated with r.terraflow and some expert knowledge of the area. In addition, sediment transport models such as RUSLE, USPED, and SIMWE will provide a quantitative erosion AND deposition estimate. Details here:

Geologic Erosion: Elevation Profiles

Elevation profiles for selected time steps.


r.topidx in=elev_meters out=ti
#
for x in `seq 0 1 100`
  do r.mapcalc "e = if( float(elev_meters - float($x*ti)) > 0.0 ,float(elev_meters - float($x*ti) ), 0.0 )"
 r.shaded.relief map=e shade=s1
 d.rast s1
 d.barscale at=0,0
 d.out.png out=e_$x res=1
 d.erase
done
convert `ls *.png | sort -n -k2 -t"_"` movie.mpg

#make an elevation profile
r.profile in=e100 profile=663451.38153808,4038227.40942676,663719.16510544,4041226.58538121 > e100.profile




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