Actual RWU equals Potential RWU

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mpleasan
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Joined: Mon Aug 22, 2016 5:06 pm
Location: USA

Actual RWU equals Potential RWU

Post by mpleasan » Wed Mar 22, 2017 12:02 am

Hi All,

I am modeling a hillslope with root water uptake enabled. I have supplied Hydrus with Tpot, Surface length associated with Transpiration, and the root distribution function (beta). The water uptake reduction model is set to Feddes. Feddes' parameters are to PO=-10 cm, POpt=-25 cm P2H=-600 cm, P2L=-1200 cm, P3=-15000 cm.

After running Hydrus, the Actual Root Water Uptake is equal to the Potential Root Water Uptake despite the rooting zone pressure head often lying outside the "optimal" RWU pressure head range and falling below the wilting point at times. This result does not seem correct to me. The reduction model never seems to have no influence on root water uptake and Hydrus is only using the supplied Tpot to define root water uptake. Has anyone run into this before? Maybe I am missing something obvious?

Thanks,
Mark

Jirka
Posts: 4712
Joined: Sat Mar 16, 2002 3:47 pm
Location: USA
Location: Riverside, CA

Re: Actual RWU equals Potential RWU

Post by Jirka » Wed Mar 22, 2017 9:43 am

That’s not possible unless you use the compensated root water uptake (a critical stress index smaller than 1). Then, it is exactly what should happen. J.

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