I'm simulating a long-term fallow irrigation, so the upper boundary should represents irrigation for 4 short periods and 'atmosphere' conditions in-between these periods and in the following months.
Variable flux could suite, but then, it seems i loose the evaporation component ??
I don't know whether it will work with Hydrus, but theoretically it is right to set a changing or constant water potential at the soil surface (RT*lnψ) during periods of absence of irrigation, and either constant flux or constant head during periods of irrigation, depending on its sort.
You can use variable flux, open boundary condition options and check: treat as atmospheric boundary.
In variable boundary conditions parameters (table) give the potential evaporation (positive numbers) for the times you are not irrigating, and add irrigation amounts (negative numbers) for times that you are irrigating. The potential is only the max, the real evaporation will be limited according to water availability and some threshold for minimum pressure at the surface (hCritA)
should be straight forward :-)
Hi,
I think atmospheric boundary conditions is good for your upper boundary, because it simulates soil surface interaction with atmosphere. Set evaporation to zero. Just give irrigation values when you irrigate and set remaining at zero I think atmospheric boundary is better than variable flux for this condition.
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