Nitrate calibration using inverse modelling

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Brijesh
Posts: 3
Joined: Wed May 08, 2019 7:09 am
Location: India

Nitrate calibration using inverse modelling

Post by Brijesh » Thu Nov 21, 2019 2:15 pm

Dear Jirka,
I am doing work on spatiotemporal distribution of nitrate using Hydrus-2D model under different tillage practices. I successfully simulated soil water balance and its component’s. Now, I am facing nitrate simulation questions as following:
(1) The parameters will be optimized using the inverse approach during nitrate calibration?
(2) Many constants, such as µa, µn and µv have been described in many literatures but the model does not display such constants . It displays like Sinkwater1, sinksoild1, sinkgas1, sinkwater’1, sinksolid’1, sinkgas’1, sinksolid0, sinkwater0, sinkgas0 and alpha.
(3) Still, I am confused about initial condition? Whether, I have to mention dose of fertilizer or concentration of nitrate (mg/lit) on first day of simulation as initial condition. If dose of fertilizer has to be mentioned than how to convert into mg/lit.

Sir, please help me and I shall be ever grateful to you.

Thanking You Sir

Jirka
Posts: 4982
Joined: Sat Mar 16, 2002 3:47 pm
Location: USA
Location: Riverside, CA

Re: Nitrate calibration using inverse modelling

Post by Jirka » Thu Nov 21, 2019 2:49 pm

1. That's up to you whether you run HYDRUS in the direct mode or calibrate the model against your experimental data. I think that it is always better to start with the direct mode and then adjust the parameters in the inverse mode.
2. Note that all these parameters are very clearly described in the Help. You only need to click on the Help button or press F1 when in this dialog.
help.png
help.png (197.29 KiB) Viewed 1053 times
3. Initial conditions describe the initial state of the system. If fertilizer is applied during the simulation, it is a boundary condition. Note that HYDRUS considers only liquid fluxes and thus you need to apply fertilizer with water and give a correct concentration so that you get the right solute mass in the profile.

Best regards,

Jirka

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