[GRASS-user] Terrain Modeling on Small Areas

What I'd really like to know, actually, is how to do terrain modelling and waterflow analysis on a small area. I have a .csv file with xyz coordinates. My approach has been:

1. Import this using v.in.ascii -z input=C:some_file.csv output=vector_xyz format=point fs=, skip=0 x=2 y=3 z=5 cat=1

2. Create an interpolated raster surface with v.surf.idw from the imported vector map.

3. R.contour for a contour map from the output of v.surf.idw

4. R.flow to determine flow lines of water on the map surface

Do you all think this is a good approach? My area is very small, about 10 acres. I'm not quite sure about the quality of my outputs. If somebody is willing to give some tips here, would much appreciate it.

Frank Aragona

There are a lot of great hydro tools in GRASS. I would recommend at a minimum, some of these below.

On Wed, Jan 28, 2009 at 2:08 PM, Frank Aragona <frank@agroinnovations.com> wrote:

What I’d really like to know, actually, is how to do terrain modelling and waterflow analysis on a small area. I have a .csv file with xyz coordinates. My approach has been:

  1. Import this using v.in.ascii -z input=C:some_file.csv output=vector_xyz format=point fs=, skip=0 x=2 y=3 z=5 cat=1

Try using r.in.xyz http://grass.itc.it/grass62/manuals/html62_user/r.in.xyz.html to process the data, look at voids, use statistics to determine an appropriate cell size, etc.

  1. Create an interpolated raster surface with v.surf.idw from the imported vector map.

try too http://grass.ibiblio.org/gdp/html_grass63/v.surf.rst.html

  1. R.contour for a contour map from the output of v.surf.idw

  2. R.flow to determine flow lines of water on the map surface

  1. r.terraflow for flow accumulation and dispersion
    6 r.watershed and it’s outputs.

How good is your input data? Meaning what is rough horizontal spacing?

Have Fun.
Mark

Do you all think this is a good approach? My area is very small, about 10 acres. I’m not quite sure about the quality of my outputs. If somebody is willing to give some tips here, would much appreciate it.

Frank Aragona


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