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

[bonushenricus]

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.
-- 
-- 
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?
> > 
> > -- 
> > -- 
> > 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 lun, 31/07/2023 alle 14.34 -0400, Anna Petrášová ha
> > scritto:
> > > 
> > > 
> > > On Sun, Jul 30, 2023 at 6:01 AM bonushenricus
> > > <bonushenricus76 at gmail.com> wrote:
> > > > Hi
> > > > From r.sim.water, how can I calculate the volume of water
> > > > stored in
> > > > small water storages placed along a relief and connected to
> > > > ditches?
> > > > In this article https://doi.org/10.1016/j.agwat.2023.108398
> > > > these
> > > > Italian researchers with r.sim.water manage did this
> > > > calculation, but I
> > > > do not understand how. With a calculation at different times on
> > > > discharge at the entrance to the water storage?
> > > > I tried to contact them, but they did not reply.
> > > > Thanks!
> > > > 
> > > 
> > > 
> > > Hi,
> > > 
> > > volume would be simple depth times cell size squared for a
> > > certain selected area. I would compute it for the final step of
> > > the simulation, I am not sure what is the purpose of summing
> > > it for different time steps. Perhaps you could clarify a little
> > > bit?
> > > 
> > > Anna
> > >  
> > > > 
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