Recently I'm trying to build an simple model for rainfall filtration in vadose zone with EOS3. According to TOUGH2 training material, it seems that to set up an atmospheric boundary condition with evaporation needs the following steps:
1) specify an single atmospheric element with large volume and small nodal distance at land surface.
2) Use single phase gas model to simulate atmospheric boundary with less than 100% RH.
3) Use ICP (1) in EOS3 in atmospheric element in which a very strong Pc is estimated based on Kelvin's law.
4) Specify evaporation and infiltration rate in row of elements below the atmospheric boundary element using the GENER Block.
When I follow these steps to set up an atmosphere BC and try to simulate the filtration into vadose zone for one year with annual climate data, I met the following problems:
1. How to give an reasonable daily evaporation rate in the model according to the climate data? Use the net filtration rate as injection (rainfall-evaporation) or Put rainfall as injection and evaporation as production separately?
2. When I use single phase gas model for atmosphere boundary, the model doesn't work. Instead if I use two phase model at the atmosphere boundary with an extreme large porosity and low water saturation, then it works.
3. If I need to simulate the filtration in a long term (50 years for example) by assuming every year has the same annual climate data, how could I give an reasonable rainfall and evaporation rate?
So Any ideas? I also attached my climate data and sim file for reference.