[GRASS-user] How can I remove step artefacts in digital elevation model? Re: how to calculate volume of water stored in water storage with r.sim.water?

bonushenricus bonushenricus76 at gmail.com
Sun Aug 6 03:08:50 PDT 2023 

Hello again.
I continue with my process of "How to calculare volume of water stored
in water storage" but with a change in object.
I was able to improve my final dem again, by improving the ditch
profile, through a script based on this
discussion https://www.mail-archive.com/grass-user@lists.osgeo.org/msg40844.html
But still the simulation with hmax=1 poses problems for the dem I
built. I didn't have that many points in the survey. Ponds form in the
simulation with water_depths up to almost 1m, along the ditches.
I attach a pdf of a profile of 7 metres.
In red is the ditch I managed to obtain with the script based on the
discussion above linked, much better than the old ditch in blue.
The problem is the dem on which this ditch interacts.
The dem is built with
"v.surf.rst --overwrite input=point_survey zcolumn=z elevation=dem
mask=MASK tension=36. smooth_column=rms segmax=500 npmin=600 dmin=0.5
dmax=5"
Tension 36. is taken from a validation script.
To smooth it I tried to reconstruct it with r.surf.contour, after
creating a contour with resolution 0.05, level at 0.1.
I tried to make from this an r.resample.rst with tension 50.
The result, however, is not good. What can I do to remove the steps?

Thanks

-- 
-- 
Perito agrario Enrico Gabrielli
progetto F.A.R.M. www.farm-agroecologia.it
Tessera n. 633 Collegio Periti agrari prov. Di Modena
Biblioteca agricoltura: https://www.zotero.org/groups/aplomb/
https://www.inaturalist.org/observations/bonushenricus

Il giorno dom, 06/08/2023 alle 07.09 +0200, bonushenricus ha scritto:
> Hello
> I made two better digital elevation models for my tests,
> here https://cubeatic.com/index.php/s/dYzjRdLGD7wksQt attached.
> There are two designs, each with a pond about 1 metre deep, the same
> position on the slope, and two ditches reaching the pond.
> One design has a pond with a surface area of 63m², and the other has
> a surface area of 131m², with a depth of about 1 metre, with a volume
> of 52m³ and 118m³, respectively.
> I expect that having the same slope and ditches upstream, the two
> ponds will be filled with a similar volume of water.
> Seen infil_rast for make waterproof the ponds doesn't run, I tried
> using flow_control, and it work.
> And I tried with hmax=1
> Here the "script" (after import geotiff attached)
> > r.lake --overwrite elevation=dem_pondB water_level=480.7 lake=pondB
> > coordinates=687064.2576117209,4910526.453118301
> > #results 118m³ 131m²
> > r.lake --overwrite elevation=dem_pondA water_level=480.9 lake=pondA
> > coordinates=687064.2576117209,4910526.453118301
> > #results 52m³ 63m²
> > r.mapcalc expression="flow_control_pondA = if(pondA,0)" --overwrite
> > r.mapcalc expression="flow_control_pondB = if(pondB,0)" --overwrite
> > r.slope.aspect --overwrite elevation=dem_pondB dx=dx_pondB
> > dy=dy_pondB
> > r.slope.aspect --overwrite elevation=dem_pondA dx=dx_pondA
> > dy=dy_pondA
> > r.mask raster=dem_pondA
> > r.sim.water --overwrite -t elevation=dem_pondB dx=dx_pondB
> > dy=dy_pondB rain_value=40 infil_value=15 man=manning
> > flow_control=flow_control_pondB hmax=1
> > depth=water_depth_pondB_40x30mm discharge=discharge_pondB_40x30mm
> > niterations=30 output_step=5 random_seed=42 nprocs=8
> > r.sim.water --overwrite -t elevation=dem_pondA dx=dx_pondA
> > dy=dy_pondA rain_value=40 infil_value=15 man=manning
> > flow_control=flow_control_pondA hmax=1
> > depth=water_depth_pondA_40x30mm discharge=discharge_pondA_40x30mm
> > niterations=30 output_step=5 random_seed=42 nprocs=8
> The results are:
> - water_depth approximately 0.38 meters for pondB (about 49m³) , 0.61
> meters for pondA (about 32m³)
> - discharge of the watershed: pondB 48m³, pondA 51m³
> But I am not sure that the spread of water in the slope, and
> especially in the ditches, is correct in this way, with hmax=1.
> 
> Openfluid I find difficult to install, also for small watersheds with
> the design of ditches, possibly not topologically connected.
> 
> Could this route, with hmax=depth of the pond, be correct?
> 
> Thanks
> -- 
> -- 
> Perito agrario Enrico Gabrielli
> progetto F.A.R.M. www.farm-agroecologia.it
> Tessera n. 633 Collegio Periti agrari prov. Di Modena
> Biblioteca agricoltura: https://www.zotero.org/groups/aplomb/
> https://www.inaturalist.org/observations/bonushenricus
> 
> 
> Il giorno ven, 04/08/2023 alle 08.26 +0200, bonushenricus ha scritto:
> > Thanks Micha
> > What a mistake with Manning's coefficient! I took off a zero!
> > For infil: the soil is sandy. The 24.1 mm/h is taken from the soil
> > map with published regional data. There are two reference sites in
> > the area of soil delineation: 48% sand and 22% clay: 7.7 mm/h; 52%
> > sand, 14% clay: 24.1 mm/h. If I can, I will go and measure on the
> > ground. But for now, maybe 15 might be good.
> > The result, however, still doesn't convince me.
> > If I try the simulation on "invaso6", with the same parameters as
> > "invaso2", it ends after 10 minutes with a result of 30 cm.
> > 
> > Il giorno mer, 02/08/2023 alle 00.45 +0300, Micha Silver ha
> > scritto:
> > > Hello Enrico:
> > > 
> > > Anna knows this subject better than I do, but I noticed a few
> > > problems with your command, so here are some comments that might
> > > help to get a better result.
> > > 
> > > First, your man_value is way too high. You probably want
> > > something like 0.03
> > > Second, you are using the '-t' flag but no `output_step`, If you
> > > add output_step of a few minutes, then you should get multiple
> > > output rasters at each time step.
> > > Third, you have 40 mm/hr rain_rate and 24.1 mm/hr infiltration
> > > rate. Is that correct? That means that 60% of the rain is
> > > infiltrating throughout the 30 minute storm. This might happen in
> > > very dry and sandy soil. Is that your situation?
> > > 
> > > Here's what I tried (changing the above 3 parameters):
> > > 
> > > r.external ./reservoir_farm_granello/dem_invaso2.tif output=dem_2
> > > g.region -ap rast=dem_2
> > > r.slope.aspect elevation=dem_2 dx=dx_2 dy=dy_2
> > > r.sim.water -t elevation=dem_2 dx=dx_2 dy=dy_2 rain_value=40
> > > infil_value=15 man_value=0.0368 depth=water_depth_invaso2_40x30mm
> > > discharge=discharge_invaso2_40x30mm niterations=30 output_step=5
> > > random_seed=42 nprocs=8 --overwrite
> > > 
> > > This resulted in 5 depth (and 5 discharge) rasters. For example:
> > > 
> > > r.univar water_depth_invaso2_40x30mm.05 
> > > 100% 
> > > total null and non-null cells: 1197120 
> > > total null cells: 667811 
> > > 
> > > Of the non-null cells: 
> > > ---------------------- 
> > > n: 529309 
> > > minimum: 4.25896e-05 
> > > maximum: 0.313524 
> > > range: 0.313481 
> > > mean: 0.00323487 
> > > mean of absolute values: 0.00323487 
> > > standard deviation: 0.0125372 
> > > variance: 0.000157182 
> > > variation coefficient: 387.565 % 
> > > sum: 1712.24596255017 
> > > micha at RMS:bonuschenricus$ r.univar water_depth_invaso2_40x30mm.25
> > > 100% 
> > > total null and non-null cells: 1197120 
> > > total null cells: 667811 
> > > 
> > > Of the non-null cells: 
> > > ---------------------- 
> > > n: 529309 
> > > minimum: 4.25896e-05 
> > > maximum: 0.406802 
> > > range: 0.406759 
> > > mean: 0.00358821 
> > > mean of absolute values: 0.00358821 
> > > standard deviation: 0.0176433 
> > > variance: 0.000311286 
> > > variation coefficient: 491.702 % 
> > > sum: 1899.27293131027
> > > 
> > > r.univar discharge_invaso2_40x30mm.05 
> > > 100% 
> > > total null and non-null cells: 1197120 
> > > total null cells: 667811 
> > > 
> > > Of the non-null cells: 
> > > ---------------------- 
> > > n: 529309 
> > > minimum: 0 
> > > maximum: 0.595495 
> > > range: 0.595495 
> > > mean: 0.000783053 
> > > mean of absolute values: 0.000783053 
> > > standard deviation: 0.0121067 
> > > variance: 0.000146571 
> > > variation coefficient: 1546.08 % 
> > > sum: 414.477138618156 
> > > micha at RMS:bonuschenricus$ r.univar discharge_invaso2_40x30mm.30 
> > > 100% 
> > > total null and non-null cells: 1197120 
> > > total null cells: 667811 
> > > 
> > > Of the non-null cells: 
> > > ---------------------- 
> > > n: 529309 
> > > minimum: 0 
> > > maximum: 0.595495 
> > > range: 0.595495 
> > > mean: 0.000857986 
> > > mean of absolute values: 0.000857986 
> > > standard deviation: 0.0125651 
> > > variance: 0.000157882 
> > > variation coefficient: 1464.49 % 
> > > sum: 454.13982509354
> > > 
> > > 
> > > Attached is the final depth map (after 30 minutes).  You might
> > > try a longer run time (higher niternations)
> > > One other note: Your region resolution is 0.2 meters (from the
> > > original DEM) so each pixel is 0.04 sq meters.  The sum of values
> > > of all non-null cells in the final depth map is about 1900 (from
> > > the r.univar result). So the total discharge should be about 76
> > > m³. Does that sound reasonable?
> > > 
> > > HTH
> > > Micha
> > > 
> > > On 01/08/2023 21:35, bonushenricus wrote:
> > >  
> > > > 
> > > > Thank you Anna.
> > > > I will try to attach the two geotiffs in a compressed folder,
> > > > with the simplest example of a single ditch, for both
> > > > reservoirs. EPSG:32632.
> > > > The ditch is not exactly the same for the two reservoirs, they
> > > > change a little bit in the final part of the mouth of the
> > > > reservoir, but it is very similar.
> > > > Sorry I didn't use a sample vector of points, I did it later
> > > > with temporal.
> > > >  
> > > > > r.slope.aspect elevation=dem_invaso2 dx=dx_invaso2
> > > > > dy=dy_invaso2
> > > >  
> > > > > r.sim.water -t elevation=dem_invaso2 dx=dx_invaso2
> > > > > dy=dy_invaso2 rain_value=40 infil_value=24.1 man_value=0.368
> > > > > depth=water_depth_invaso2_40x30mm
> > > > > discharge=discharge_invaso2_40x30mm niterations=30 --
> > > > > overwrite
> > > >  
> > > > > r.slope.aspect elevation=dem_invaso6 dx=dx_invaso6
> > > > > dy=dy_invaso6
> > > >  
> > > > > r.sim.water -t elevation=dem_invaso6 dx=dx_invaso6
> > > > > dy=dy_invaso6 rain_value=40 infil_value=24.1 man_value=0.368
> > > > > depth=water_depth_invaso6_40x30mm
> > > > > discharge=discharge_invaso6_40x30mm niterations=30 --
> > > > > overwrite
> > > > Thank you very much
> > > > I am sure there is some mistake on my part!
> > > > 
> > > > -- 
> > > > -- 
> > > > Perito agrario Enrico Gabrielli
> > > > progetto F.A.R.M. www.farm-agroecologia.it
> > > > Tessera n. 633 Collegio Periti agrari prov. Di Modena
> > > > Biblioteca agricoltura: https://www.zotero.org/groups/aplomb/
> > > > https://www.inaturalist.org/observations/bonushenricus
> > > > 
> > > > Il giorno mar, 01/08/2023 alle 13.17 -0400, Anna Petrášová ha
> > > > scritto:
> > > >  
> > > > > 
> > > > >  
> > > > > On Tue, Aug 1, 2023 at 10:23 AM bonushenricus
> > > > > <bonushenricus76 at gmail.com> wrote:
> > > > >  
> > > > > > Thank you, Anna.
> > > > > > r.sim.water finishes the simulation not at the end of the
> > > > > > rainfall event, in my case at 30 minutes, but at an earlier
> > > > > > time. In my case, in the smaller reservoir at 16 minutes,
> > > > > > in the case of the more extensive reservoir at 24 minutes.
> > > > > > But the water keeps coming even after that. I imagined that
> > > > > > the calculation ends when it reaches the steady state of
> > > > > > the water blade.
> > > > > > But it's not so. Then I don't understand why it ends at 16
> > > > > > or 24 minutes. Doesn't the water continue to arrive after
> > > > > > that? Shouldn't it increase?
> > > > > > I cannot understand it. In the reservoirs, the discharge is
> > > > > > very low, as I expect. But if the discharge does not
> > > > > > increase and the precipitation continues, I expect the
> > > > > > water depth to rise again.
> > > > > > And it is not understandable that two reservoirs, one twice
> > > > > > the volume of the other, contain the same depth of 30 cm at
> > > > > > the end of the rainfall.
> > > > > > To understand how this works, I would apply waterproofing
> > > > > > to the reservoirs. The ksat, or infil_value, is the only
> > > > > > variable that can explain this: the larger reservoir loses
> > > > > > more water.
> > > > > > If both reservoirs were waterproof, I would have removed
> > > > > > this variable. Unfortunately r.sim.water infil=raster where
> > > > > > I have marked value 0 in the reservoirs does not work.
> > > > > > There is perhaps a bug that I have reported. So I haven't
> > > > > > had a chance to test this.
> > > > > > I don't know how to do it; I can't trust the 30 cm as a
> > > > > > value to calculate the water volume in the two reservoirs.
> > > > > > I will have to use another model.
> > > > > > I will try to use a distributed model. Since I have the
> > > > > > data in GRASS, I will try using the old geomhydas, hoping
> > > > > > the modules will work in GRASS8, and then use the Mhydas
> > > > > > models in OpenFluid. I have no other chance unless someone
> > > > > > can help me find a solution.
> > > > > >  
> > > > > 
> > > > > 
> > > > > Unfortunately I haven't had time to look at the reported
> > > > > issue. Perhaps you could share your data and provide exact
> > > > > commands and pictures, explaining very clearly what's wrong. 
> > > > >  
> > > > >  
> > > > > 
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