simulation of soil water content in surface drip irrigation

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madhukarthick
Posts: 12
Joined: Wed Aug 02, 2017 9:38 am
Location: India

simulation of soil water content in surface drip irrigation

Post by madhukarthick » Tue Oct 03, 2017 9:26 am

Hello Sir,
i am doing research on simulation of soil water content by HYDRUS-2D. In that research i need to find wetting dimension with different irrigation amount. In geometry information 2D axisymmetrical vertical plane was checked. boundary conditions of system geometry was enclosed.
1) How to find wetting dimension with different irrigation amount?
Attachments
boundary conditions.jpg
boundary conditions.jpg (45.82 KiB) Viewed 1803 times
Last edited by madhukarthick on Mon Jun 25, 2018 7:20 pm, edited 1 time in total.

Jirka
Posts: 4688
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Location: USA
Location: Riverside, CA

Re: simulation of soil water content in surface drip irrigat

Post by Jirka » Tue Oct 03, 2017 11:58 am

Water contents are related to pressure heads by retention curve. Various analytical models (e.g., van Genuchten, Brooks & Corey, etc) are used to define retention curves various porous materials. J.

madhukarthick
Posts: 12
Joined: Wed Aug 02, 2017 9:38 am
Location: India

Re: simulation of soil water content in surface drip irrigat

Post by madhukarthick » Wed Oct 04, 2017 4:16 am

Thank you sir.

madhukarthick
Posts: 12
Joined: Wed Aug 02, 2017 9:38 am
Location: India

Re: simulation of soil water content in surface drip irrigat

Post by madhukarthick » Wed Mar 21, 2018 5:39 pm

hello sir,
Initially i did simulation of soil water content by using hydrus 1d. In this simulation i was used 40cm vertical profile, time variable boundary conditions,flux (38.21cm/day), top and bottom pressure head was -2213--1455cm. And also i was used 0.001 and 0.0001day minimum and maximum time step. Finally i was run the model screen output showed that ''Numerical solution has been stopped s ... ime step''. How to solve these problem sir?

Jirka
Posts: 4688
Joined: Sat Mar 16, 2002 3:47 pm
Location: USA
Location: Riverside, CA

Re: simulation of soil water content in surface drip irrigat

Post by Jirka » Thu Mar 22, 2018 7:40 am

Make sure that you have the correct signs for boundary fluxes (negative for inflow/irrigation and positive for outflow/drainage). Note that we have posted several examples dealing with drip irrigation on the HYDRUS website, which should give you some guidance on how to set up correctly such project. J.

madhukarthick
Posts: 12
Joined: Wed Aug 02, 2017 9:38 am
Location: India

Re: simulation of soil water content in surface drip irrigat

Post by madhukarthick » Thu Mar 22, 2018 10:46 am

Thank you sir

madhukarthick
Posts: 12
Joined: Wed Aug 02, 2017 9:38 am
Location: India

Re: simulation of soil water content in surface drip irrigat

Post by madhukarthick » Sat Mar 24, 2018 7:07 am

hello sir,
Simulation was done. In that simulation i was used irrigation flux, initial top and bottom pressure head. i was used time variable flux, during the day times evaporation also occur in the top 15cm soil profile. In that irrigation flux part of water could be evaporated. It is also be a one of the parameter to affect the soil moisture distribution in the top layer. So i have to give evaporation as input parameter for hydrus 1d.
How to give a soil evaporation for a input of hydrus 1d?
Output file showed that graphical representation only, how to convert graphical into text format?
I was enclosed time variable boundary conditions and observation nodes.
Attachments
variable boundary conditions.PNG
time variable boundary conditions data
variable boundary conditions.PNG (12.6 KiB) Viewed 2557 times
VtChart_ Print.pdf
soil water retention curve
(44.42 KiB) Downloaded 78 times

Jirka
Posts: 4688
Joined: Sat Mar 16, 2002 3:47 pm
Location: USA
Location: Riverside, CA

Re: simulation of soil water content in surface drip irrigat

Post by Jirka » Sat Mar 24, 2018 5:59 pm

I think that you should first try to understand how HYDRUS works, before posting such trivial questions. There are such things as technical manual, help, tutorials, online examples, etc.

Clearly, evaporation is associated with the atmospheric BCs. J.

madhukarthick
Posts: 12
Joined: Wed Aug 02, 2017 9:38 am
Location: India

Re: simulation of soil water content in surface drip irrigat

Post by madhukarthick » Sun Mar 25, 2018 4:12 pm

Thank you sir and sorry to asked that question because first time i am using hydrus software. Really i don't know how hydrus software works. I will try to Learn sir.

Jirka
Posts: 4688
Joined: Sat Mar 16, 2002 3:47 pm
Location: USA
Location: Riverside, CA

Re: simulation of soil water content in surface drip irrigat

Post by Jirka » Sun Mar 25, 2018 6:09 pm

I do enjoy helping HYDRUS users to successfully use our code. However, I do expect them to first do their homework and read the technical manual and online help before asking questions in the discussion forum. Without doing it (consulting the manual and help), it is a waste of time for everyone and discouraging me to look at the forum at all and helping other HYDRUS users. J.

madhukarthick
Posts: 12
Joined: Wed Aug 02, 2017 9:38 am
Location: India

Re: parameter optimization through inverse modelling

Post by madhukarthick » Sun Jul 01, 2018 3:07 pm

hi sir,
For parameter optimization, the observed cumulative infiltration data was used. Three type of soil material i was used, except pore connectivity parameter i need to optimize(fifteen soil hydraulic parameters). Zero iteration only simulation was done, i increased the iteration 0 to 2 the problem is not converged.
How to optimize the three set of soil hydraulic parameters?

Jirka
Posts: 4688
Joined: Sat Mar 16, 2002 3:47 pm
Location: USA
Location: Riverside, CA

Re: simulation of soil water content in surface drip irrigation

Post by Jirka » Sun Jul 01, 2018 3:36 pm

I do not think that you can optimize more than two parameters from the cumulative infiltration data. See, for example:

Šimůnek, J., and M. Th. van Genuchten, Estimating unsaturated soil hydraulic properties from tension disc infiltrometer data by numerical inversion, Water Resources Research, 32(9), 2683-2696, 1996.

J.

madhukarthick
Posts: 12
Joined: Wed Aug 02, 2017 9:38 am
Location: India

Re: simulation of soil water content in surface drip irrigation

Post by madhukarthick » Sun Jul 01, 2018 3:57 pm

Thank you sir.

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