The project area -- in farmland -- is small (< 20 ha) and essentially
flat with elevation differences less than 1 meter. The LiDAR raster cells
(imported from ARC Grid format) have a cell size of 3x3 international feet;
elevation resolution is 0.013 feet.
While r.slope.aspect generates an aspect map, the slope map is blank. The
maps for dx, dy, and relief display variations.
While I have some soil data, it's sparse and I haven't (yet) found
infiltration rates; the rainfall data is very low and from a station several
miles away. I probably do not have all required input data for r.sim.water
or r.watershed.
Based on your much more extensive experiences applying GRASS to limited
areas please suggest approaches that might be appropriate for this project.
It might be that all I can do is create detailed contour maps of the area
and describe the situation qualitatively without robust quantitative
analyses.
For the infiltration, if you can determine the soil texture, then you
could estimate the Green-Ampt parameters using [1]
What do you want to do in that area? Perform hydrological/overland
flow analysis?
If it is the case, you might give Itzï a try: https://www.itzi.org/
Some of the parameters could be estimated (like friction coefficient).
Regards,
Laurent
[1] Rawls, W., Brakensiek, D., and Miller, N. (1983). "Green‐ampt
Infiltration Parameters from Soils Data." J. Hydraul. Eng.,
10.1061/(ASCE)0733-9429(1983)109:1(62), 62-70.
The project area -- in farmland -- is small (< 20 ha) and essentially
flat with elevation differences less than 1 meter. The LiDAR raster cells
(imported from ARC Grid format) have a cell size of 3x3 international feet;
elevation resolution is 0.013 feet.
While r.slope.aspect generates an aspect map, the slope map is blank. The
maps for dx, dy, and relief display variations.
While I have some soil data, it's sparse and I haven't (yet) found
infiltration rates; the rainfall data is very low and from a station several
miles away. I probably do not have all required input data for r.sim.water
or r.watershed.
Based on your much more extensive experiences applying GRASS to limited
areas please suggest approaches that might be appropriate for this project.
It might be that all I can do is create detailed contour maps of the area
and describe the situation qualitatively without robust quantitative
analyses.
The project area – in farmland – is small (< 20 ha) and essentially
flat with elevation differences less than 1 meter. The LiDAR raster cells
(imported from ARC Grid format) have a cell size of 3x3 international feet;
elevation resolution is 0.013 feet.
While r.slope.aspect generates an aspect map, the slope map is blank. The
maps for dx, dy, and relief display variations.
While I have some soil data, it’s sparse and I haven’t (yet) found
infiltration rates; the rainfall data is very low and from a station several
miles away. I probably do not have all required input data for r.sim.water
or r.watershed.
Based on your much more extensive experiences applying GRASS to limited
areas please suggest approaches that might be appropriate for this project.
It might be that all I can do is create detailed contour maps of the area
and describe the situation qualitatively without robust quantitative
analyses.
I had previously started playing with Itzï but reported problems; now, it seems to work to a point. I have followed your tutorial here: https://www.itzi.org/user-manual/ but when I do this I get:
GRASS 7.0.3 (nc_spm_08_grass7):/media/teaiii/development/grass > itzi run param.file.txt
ERROR: Unable to execute sql statement. There is no temporal database
connection defined for mapset
Traceback (most recent call last):
File “/home/teaiii/.local/bin/itzi”, line 11, in
sys.exit(main())
File “/home/teaiii/.local/lib/python2.7/site-packages/itzi/itzi.py”, line 40, in main
args.func(args)
File “/home/teaiii/.local/lib/python2.7/site-packages/itzi/itzi.py”, line 93, in itzi_run
sim_param=conf.sim_param)
File “/home/teaiii/.local/lib/python2.7/site-packages/itzi/simulation.py”, line 75, in init
self.gis.read(self.in_map_names)
File “/home/teaiii/.local/lib/python2.7/site-packages/itzi/gis.py”, line 189, in read
elif self.name_is_stds(self.format_id(map_name)):
File “/home/teaiii/.local/lib/python2.7/site-packages/itzi/gis.py”, line 138, in name_is_stds
if tgis.SpaceTimeRasterDataset(name).is_in_db():
File “/usr/local/grass-7.0.3/etc/python/grass/temporal/abstract_dataset.py”, line 370, in is_in_db
return self.base.is_in_db(dbif)
File “/usr/local/grass-7.0.3/etc/python/grass/temporal/base.py”, line 314, in is_in_db
dbif.execute(sql, mapset=self.mapset)
File “/usr/local/grass-7.0.3/etc/python/grass/temporal/core.py”, line 956, in execute
“mapset <%(mapset)s>” % {“mapset”: mapset}))
File “/usr/local/grass-7.0.3/etc/python/grass/pygrass/messages/init.py”, line 269, in fatal
raise FatalError(message)
grass.exceptions.FatalError: Unable to execute sql statement. There is no temporal database connection defined for mapset
[Raster MASK present]
I’m using GRASS 7.0.3 and Itzï 16.8
Any thoughts?
Regards,
Tom
···
On Thu, Sep 22, 2016 at 2:27 PM, Laurent C. <lrntct@gmail.com> wrote:
Hello Rich,
For the infiltration, if you can determine the soil texture, then you
could estimate the Green-Ampt parameters using [1]
What do you want to do in that area? Perform hydrological/overland
flow analysis?
If it is the case, you might give Itzï a try: https://www.itzi.org/
Some of the parameters could be estimated (like friction coefficient).
Regards,
Laurent
[1] Rawls, W., Brakensiek, D., and Miller, N. (1983). “Green‐ampt
Infiltration Parameters from Soils Data.” J. Hydraul. Eng.,
10.1061/(ASCE)0733-9429(1983)109:1(62), 62-70.
The project area – in farmland – is small (< 20 ha) and essentially
flat with elevation differences less than 1 meter. The LiDAR raster cells
(imported from ARC Grid format) have a cell size of 3x3 international feet;
elevation resolution is 0.013 feet.
While r.slope.aspect generates an aspect map, the slope map is blank. The
maps for dx, dy, and relief display variations.
While I have some soil data, it’s sparse and I haven’t (yet) found
infiltration rates; the rainfall data is very low and from a station several
miles away. I probably do not have all required input data for r.sim.water
or r.watershed.
Based on your much more extensive experiences applying GRASS to limited
areas please suggest approaches that might be appropriate for this project.
It might be that all I can do is create detailed contour maps of the area
and describe the situation qualitatively without robust quantitative
analyses.
The coordinates are those of a culvert inflow (easting, northing) in
international feet. Do I need to create a new location to convert these
value to meters or have I done something else incorrectly?
Could you check that the point you want to set as outlet is inside your Region? Please check your Region extend.
For the units, as long as the location is not in lat-long, Itzï will run. But it expects SI units, so using feet might gives you unexpected results. I would suggest to work with the units given in the manual.
The coordinates are those of a culvert inflow (easting, northing) in
international feet. Do I need to create a new location to convert these
value to meters or have I done something else incorrectly?
Could you check that the point you want to set as outlet is inside your
Region? Please check your Region extend.
For the units, as long as the location is not in lat-long, Itzï will run.
But it expects SI units, so using feet might gives you unexpected results.
I would suggest to work with the units given in the manual.
Laurent,
Yes, that point is well within the region. The region is set to the
analytical boundary which incorporates that point. That's what puzzled me
about the error message.
I'll convert feet to meters and try again tomorrow morning.