[GRASS-user] how to calculate volume of water stored in water storage with r.sim.water?

Tue Aug 1 11:35:29 PDT 2023

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. 
>  
> > -- 
> > -- 
> > 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 09.23 -0400, Anna Petrášová ha
> > scritto:
> > > 
> > > 
> > > On Mon, Jul 31, 2023 at 11:42 PM bonushenricus
> > > <bonushenricus76 at gmail.com> wrote:
> > > > Hi Anna
> > > > I too immediately thought it was enough to compute it for the
> > > > final step of the simulation,
> > > > but I noticed that the same slope, same ditches, same rainfall,
> > > > for two reservoirs at the same location, same length along a
> > > > contour, but different width and depth, at the final step of
> > > > the simulation the water depth was always 30 cm, I went to read
> > > > the article 
> > > > Mitasova, Helena, Chris Thaxton, Jaroslav Hofierka, Richard
> > > > McLaughlin, Amber Moore, e Lubos Mitas. «Path Sampling Method
> > > > for Modeling Overland Water Flow, Sediment Transport, and Short
> > > > Term Terrain Evolution in Open Source GIS». In Developments in
> > > > Water Science, 55:1479–90. Elsevier, 2004.
> > > > https://doi.org/10.1016/S0167-5648(04)80159-X
> > > > where I read the Saint-Venant equation. I am an agricultural
> > > > technician and geographer unfortunately ignorant of
> > > > hydrological calculations and serious mathematics, and I
> > > > understood, looking at the equation, that the water depth is
> > > > the depth of overland flow = rainfall exces - water flow.
> > > > So the final 30 cm should not be understood as accumulated
> > > > water, but as the blade of water that was added at that precise
> > > > moment.
> > > > Isn't my interpretation right?
> > > > 
> > > 
> > > 
> > > No, it should be actual water depth.  I didn't understand the
> > > discrepancy you are describing?
> > > > 
> > > > -- 
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