dear Jrika

I'm working with Hydrus 2D/3D version and I'm little confused about the scale of the root water uptake in the domain properties that means the density of roots or what exactly ?

In my case I'm trying to calibrate the water flow under sub-surface drip irrigation with the inverse method and then I will calibrate the solute transport seperatly and I'm confused here if I should take into account the solute stress in the calibration of water flow or not (the irrigation water is 4dS/m). what is your reommendation in this point .?

Thank you for your help in advance

## Root distribution /root water uptake

### Re: Root distribution /root water uptake

Root water and solute uptake model: You should look either at the technical manual or at the Simunek and Hopmans (2009) paper, where we give all information about this model.

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.

To consider the salinity stress: That depends on the considered crop and its tolerance to salinity. Note the HYDRUS GUI gives you parameters for the salinity stress response function for multiple different crops.

Jirka

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.

To consider the salinity stress: That depends on the considered crop and its tolerance to salinity. Note the HYDRUS GUI gives you parameters for the salinity stress response function for multiple different crops.

Jirka

### Re: Root distribution /root water uptake

dear Jirka

thank you for your reply

in fact, I work on data-palm trees; and in the hydrus database for the solute stress model, I can not find it; even I can not find the deciduous fruit.

so it is correct to calibrate the water flow with inverse model (with out considering the solute stress model I consider only water stress model) and then once I get the van-gunechten parameters I calibrate the solute transport always with the inverse model and at this part I take into-account the solute stress. . ,?

please Exuse me if I ask very simple questions I just start working with hydrus 2d and the inverse model

thank you for your reply

in fact, I work on data-palm trees; and in the hydrus database for the solute stress model, I can not find it; even I can not find the deciduous fruit.

so it is correct to calibrate the water flow with inverse model (with out considering the solute stress model I consider only water stress model) and then once I get the van-gunechten parameters I calibrate the solute transport always with the inverse model and at this part I take into-account the solute stress. . ,?

please Exuse me if I ask very simple questions I just start working with hydrus 2d and the inverse model

### Re: Root distribution /root water uptake

If you cannot find a particular crop in the HYDRUS database, you need to look into literature (and HYDRUS references). I believe that I have seen several manuscripts in which HYDRUS has been used for problems associated with palm trees.

If the salinity stress is an important factor, then you should consider it during model calibration (inverse problem). If you neglect an important factor, the calibrated parameters will have to somehow account for this factor and will be unrealistic.

J.

If the salinity stress is an important factor, then you should consider it during model calibration (inverse problem). If you neglect an important factor, the calibrated parameters will have to somehow account for this factor and will be unrealistic.

J.

### Re: Root distribution /root water uptake

ok thank you for your reply

### Re: Root distribution /root water uptake

Dear professorJirka wrote: ↑Tue Feb 26, 2019 5:26 pmIf you cannot find a particular crop in the HYDRUS database, you need to look into literature (and HYDRUS references). I believe that I have seen several manuscripts in which HYDRUS has been used for problems associated with palm trees.

If the salinity stress is an important factor, then you should consider it during model calibration (inverse problem). If you neglect an important factor, the calibrated parameters will have to somehow account for this factor and will be unrealistic.

J.

I have the same question, please. Are we required to consider root water uptake while calibration for hydraulic parameters? when I want to use inverse modeling while considering root water uptake I don't get the final result.

my second question is when I want to calibrate my model for 120 days cropping season for a plant I must use all 120*24 hours data(hourly data sampling) for inverse modeling? considering I have several observation points and daily irrigation.

### Re: Root distribution /root water uptake

I do not have an answer on the first question.

It is up to you what data selection you use. You can use all data or make some intelligent selection. J.

It is up to you what data selection you use. You can use all data or make some intelligent selection. J.