Water initial conditions

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epelde.ane@gmail.com
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Water initial conditions

Postby epelde.ane@gmail.com » Thu Jan 19, 2012 15:01

Hi all,
I´m looking to the different parameters (or keywords) related to the initial water conditions of a porous media.
For the one hand, we have a file created with Mohid tools (this would be the one used in <beginwaterlevel>). on the other, there are Theta property and START_WITH_FIELD keyword.
I know that if I write a "1" in Start with field, then, Theta property is not used. So I guess that if I set it to "0", it is.
Can anyone give me further explanation about this please? And what is theta property used for? as it is set in each soil id (Theta saturated and residual)...

Best regards,
ane

frank.maretec@ist.utl.pt
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Re: Water initial conditions

Postby frank.maretec@ist.utl.pt » Thu Jan 26, 2012 14:44

Dear Ane, all,

if you active the START_WITH_FIELD option (which I advise), the model will calculate in the beginning, independent of the Theta Value you provide, the theta values in a way that the soil water content is in equilibrium conditions above the water table. Equilibrium = balance between soil suctions and gravity force.

So, cell which are below the initial water table are fully saturated. Cells above will are gradually be less wet. I recommend that you set up a 1D case which shows this physical behaviour of soils, in an entire catchment it is much more complicate to understand these processes...

So:
START_WITH_FIELD : 1 => Model will calculate initial Theta values from WaterLevel (recommended option)
START_WITH_FIELD : 0 => Model will use initial Theta values provided in the <beginproperty> Theta... block

Hope this helps,


PS: Do you remember the 1D test case we did during the course...? It's explained there.
In order to understand recursivity you must first understand recursivity.

epelde.ane@gmail.com
MOHID Advanced user
Posts: 172
Joined: Thu Jan 01, 1970 00:00

Re: Water initial conditions

Postby epelde.ane@gmail.com » Fri Jan 27, 2012 13:45

Thank you a lot Frank :)


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