Root uptake Parameters

A discussion forum for users of the new HYDRUS 2D/3D. HYDRUS is a software package for simulating water, heat and solute movement in two- and three-dimensional variably saturated media. Happy Posting!
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Tausifilyas
Posts: 8
Joined: Mon Sep 23, 2019 6:57 pm
Location: Pakistan

Root uptake Parameters

Post by Tausifilyas » Thu Oct 24, 2019 9:07 am

I have to model/simulate root water uptake using Hydrous-2D. In fedes model, there are lot of parameters related to transpiration are given. Do you guide me , how to determine them for my case? Any Methodology?

Jirka
Posts: 4798
Joined: Sat Mar 16, 2002 3:47 pm
Location: USA
Location: Riverside, CA

Re: Root uptake Parameters

Post by Jirka » Thu Oct 24, 2019 2:22 pm

A database of suggested values for different plants for the Feddes et al. [1978] model is provided in HYDRUS based on studies by Wesseling [1991] and Taylor and Ashcroft [1972]. For methodology, you can look into the original references:

Feddes, R. A., P. J. Kowalik, and H. Zaradny, Simulation of Field Water Use and Crop Yield, John Wiley & Sons, New York, NY, 1978.
Maas, E. V., Crop salt tolerance. In K. K. Tanji (ed.), Agricultural Salinity Assessment and Management, ASCE Manuals and Reports on Engineering practice, No. 71, NY, 1990.
Taylor, S. A. and G. M. Ashcroft, Physical Edaphology. Freeman and Co., San Francisco, California, p. 434-435, 1972.
Wesseling, J. G., J. A. Elbers, P. Kabat, and B. J. van den Broek, SWATRE: instructions for input, Internal Note, Winand Staring Centre, Wageningen, the Netherlands, 1991.

J.

Tausifilyas
Posts: 8
Joined: Mon Sep 23, 2019 6:57 pm
Location: Pakistan

Re: Root uptake Parameters

Post by Tausifilyas » Sun Oct 27, 2019 10:29 am

Thanks Jirka!
I have gone through these publications and find difficult to assess the input parameters regarding root water uptake.
I have potential ET data measured by weather station, could i use that value instead of above mentioned parameters to encounter root water uptake?

Jirka
Posts: 4798
Joined: Sat Mar 16, 2002 3:47 pm
Location: USA
Location: Riverside, CA

Re: Root uptake Parameters

Post by Jirka » Sun Oct 27, 2019 3:53 pm

You really need to first understand how the model works overall. Your questions suggest that you don’t'. The manual gives the main details. The full description is in:

Šimůnek, J., and J. W. Hopmans, Modeling compensated root water and nutrient uptake, Ecological Modeling, 220(4), 505-521, doi: 10.1016/j.ecolmodel.2008.11.004, 2009.

J.

Tausifilyas
Posts: 8
Joined: Mon Sep 23, 2019 6:57 pm
Location: Pakistan

Re: Root uptake Parameters

Post by Tausifilyas » Tue Oct 29, 2019 5:35 am

Thanks jirka!
I have gone through this document. I have learnt a lot about the mechanism of root water uptake.
There is an issue regarding determination of inputs required to put in HYDRUS simulation i.e. h values to see variations in stress function (alpha).
Can you guide me how do we determine these inputs?
Tausif

Jirka
Posts: 4798
Joined: Sat Mar 16, 2002 3:47 pm
Location: USA
Location: Riverside, CA

Re: Root uptake Parameters

Post by Jirka » Tue Oct 29, 2019 11:22 am

I do not have any other guidance beyond that provided in the above- mentioned paper and in the HYDRUS texts (manuals, help). J.

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