Amount of Leachate Water at observation points

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astrid
Posts: 2
Joined: Mon Nov 15, 2021 6:48 pm
Location: Germany

Amount of Leachate Water at observation points

Dear all,
I am simulating a soil colume (3m depth) for a one year periode in HYDRUS 1D with root water uptake modul and I want to know how much leachate water appears at different observation points (50cm and 1m). I check the Obs_Node.out for the negative fluxes. When I ran the same modul without root water uptake I get less leachate at my observation points. How can that be? I thougt it will be definitly more since no plants are reducing the leachate water amount.
Do I understand it right, that the negative fluxes in the Obs_Node.out are leachate values and no Darcian velocities?

Jirka
Posts: 5343
Joined: Sat Mar 16, 2002 3:47 pm
Location: USA
Location: Riverside, CA

Re: Amount of Leachate Water at observation points

When HYDRUS prints (Darcian) fluxes for observation nodes, negative values indicate downward fluxes and positive values upward fluxes. J.

astrid
Posts: 2
Joined: Mon Nov 15, 2021 6:48 pm
Location: Germany

Re: Amount of Leachate Water at observation points

Thank you. How can I then calculate the amount of leachate water, when the fluxes in Obs_Node.out are Darcian fluxes? Concerning my other question: How can the (Darcian) fluxes be greater, when the root water uptake modul is applies for the same model setting as without the root water uptake modul? In general plants are taking water from the soil so it should be less in my understanding.

Jirka
Posts: 5343
Joined: Sat Mar 16, 2002 3:47 pm
Location: USA
Location: Riverside, CA

Re: Amount of Leachate Water at observation points

I do not know what the difference between Darcy’s flux and leachate. How do you define the latter?

Why the fluxes decrease when roots are present? Likely, because you do something wrong.

J.