convergence error groundwater recharge

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bobtom059
Posts: 1
Joined: Wed Sep 16, 2020 8:59 am
Location: Australia

convergence error groundwater recharge

Post by bobtom059 » Wed Sep 16, 2020 10:26 am

I have been attempting to model groundwater recharge, using Hydrus 1D, but I encounter a convergence error at day 284 out of 933 day period, with root water uptake and root growth selected. I have run the model only considering water flow and it has come out successful. I am using the Hargraves Formula, with boundary conditions selected; upper boundary condition = atmosphere BC with surface run off and lower boundary condition = free drainage. My root water uptake model uses the Feddes water uptake reduction model and have selected my crop data to be constant (crop being sugarcane). I have my 400cm soil profile containing three different soil materials. I have attached a picture of my soil profile where red = clay loam, blue = sandy clay loam and green = sandy loam

I have tried the following to solve the error:
- Increase minimum time steps
- Increase water content toleration
- Select “with air-entry value of -2cm”
- Increased node density close to the surface
- Increased maximum number of iterations
- varied the lower limit of the tension interval
- have looked through tutorials and the discussion page for solutions
Although some of these have helped to extend the time to 284 days, I am still yet to run a successful model. I suspect the abrupt changes of the soil materials may be affecting the model as through your tutorials with a uniform soil body, the model seems to run fine. Any suggestions would be much appreciated.
Thanks,
Asitha
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soil profile.png
soil profile
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