Point source runoff

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Niels88
Posts: 2
Joined: Mon Aug 20, 2018 7:36 pm
Location: USA

Point source runoff

Post by Niels88 » Mon Aug 20, 2018 7:45 pm

Hi,

I am trying to model runoff from a point source, which I would model as a very small area at the surface with constant flux (or positive pressure if that is more stable). These conditions should mimic flood irrigation with irrigation pipes.
I thought the overland flow module would be suited for this, as I went through the examples presented there of which one is described as an example where a continuous inflow of water is occuring from uphill (hs=0.5 cm or 1.0 cm). However, when I look into the input files of these examples, the complete surface is set as an atmospheric boundary and all over the surface, a boundary condition of 0.5 or 1.0 cm seems to be applied. Is there a way to limit the 0.5 cm or 1.0 cm to a specific area of the surface and have runoff taking place which in turn infiltrate further down the profile? Is there a way to specify this in the input files?

Thanks,

Niels

Jirka
Posts: 4726
Joined: Sat Mar 16, 2002 3:47 pm
Location: USA
Location: Riverside, CA

Re: Point source runoff

Post by Jirka » Tue Aug 21, 2018 6:02 am

The standard HYDRUS (2D/3D) software does not consider surface runoff. It assumes that all excess water is instantaneously removed from the system (presumably by surface runoff).

The specialized optional 2D “Overland” addon module (https://www.pc-progress.com/en/Default. ... d-overland), which consider surface runoff (not a part of the standard software; but downloadable from the HYDRUS website), allows surface runoff only on the atmospheric boundary and nowhere else. I do not recall that any of the examples would deal with inflow from uphill (or that this module would even have such capability). To my best recollection, this module can only deal with the atmospheric BC and fluxes such as precipitation and evaporation, i.e., overland flow is generated on the atmospheric boundary as a result of precipitation being larger than the infiltration capacity.

J.

Jirka
Posts: 4726
Joined: Sat Mar 16, 2002 3:47 pm
Location: USA
Location: Riverside, CA

Re: Point source runoff

Post by Jirka » Tue Aug 21, 2018 6:07 am

You may want to look at the special boundary condition (Boundary Conditions Options), which simulates Surface Drip Irrigation with Dynamic Wetting. This BC allows water spreading over the soil surface from a point application. J.

Niels88
Posts: 2
Joined: Mon Aug 20, 2018 7:36 pm
Location: USA

Re: Point source runoff

Post by Niels88 » Tue Aug 21, 2018 4:35 pm

Hi Jirka,

Thanks for the suggestion.

Niels

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