Problem with Pond seepage

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RonRainmaple
Posts: 7
Joined: Thu Aug 13, 2015 6:11 pm
Location: USA

Problem with Pond seepage

Post by RonRainmaple » Fri Jan 22, 2021 6:00 am

Hi HYDRUS experts,

I am trying to build a two ponds system for seepage (vertical and horizontal) calculation.
I have setup the frame but not sure what boundary condition should be used for the bottom of the domain.
In field measurement, the water level of a well close to the pond is about 2m lower the surface water in the pond.

Should I use variable head, seepage face or free drainage for the domain bottom?

Thank you so much!
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Jirka
Posts: 5268
Joined: Sat Mar 16, 2002 3:47 pm
Location: USA
Location: Riverside, CA

Re: Problem with Pond seepage

Post by Jirka » Fri Jan 22, 2021 6:57 pm

You need to choose from the options that HYDRUS offers you and that best reflect your conditions.
1. You can select “no flow” BC and then the water table will fluctuates based on what happens at the surface (furrow, ET, etc).
2. If you measure a time series of GWT position, you can use the “Time-variable Pressure Head” BC. In this case, you should use the special option with linear interpolation between specified values, so that you do not get sudden jumps in the GTW position.
3. You can also use the “Deep Drainage” BC and then you can prescribe a recharge flux at the bottom in response to the GWT position.
4. You cannot choose the “Free Drainage” BC. That BC cannot be used if you have a saturated zone at the bottom.

J.

RonRainmaple
Posts: 7
Joined: Thu Aug 13, 2015 6:11 pm
Location: USA

Re: Problem with Pond seepage

Post by RonRainmaple » Mon Jan 25, 2021 12:06 am

Dear Jirka,

Thank you for the quick and detailed reply!

Based on some measurements, the water table is like the picture below.
So I could choose "no flux" BC for the bottom, correct?

Thanks!
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Jirka
Posts: 5268
Joined: Sat Mar 16, 2002 3:47 pm
Location: USA
Location: Riverside, CA

Re: Problem with Pond seepage

Post by Jirka » Mon Jan 25, 2021 12:42 am

This is something you will have to decide. J.

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