About the GHB

[riad arefin]

Dear Friends and Modflow Team,

I am developing the modflow model using GMS modflow. I am getting confusion for assigning the General Head Boundary (GHB). My study area contains 5 layers. Where, 5th layer is the aquifer, has well screen and giving the General Head Boundary (GHB) information. Well screen depth 50 to 60 m. 5th layer thickness is 20m. And 5th Aquifer top and bottom depth 45m to 65m. Where, water table depth about 3m. Which is existing to the first layer. And all mentioned depths are from ground surface. 

I am not understanding which layer should I need to assign for the General Head Boundary, first or 5th or all layers?

Thanks in advance.

Regards

Riad

[Richard Winston]

What physical feature does the GHB represent? GHB is not typically used to represent wells. Layer 1 is the top layer. Layer 5 is the bottom layer. 

--
This group was created in 2004 by Mr. C. P. Kumar, Former Scientist 'G', National Institute of Hydrology, Roorkee. Please visit his webpage at https://www.angelfire.com/nh/cpkumar/
---
You received this message because you are subscribed to the Google Groups "MODFLOW Users Group" group.
To unsubscribe from this group and stop receiving emails from it, send an email to modflow+u...@googlegroups.com.
To view this discussion visit https://groups.google.com/d/msgid/modflow/a210ff9d-d49f-4d93-aaa3-879124a0d710n%40googlegroups.com.

[franklin]

Hello

If your wells are installed in the 5th layer, then you should assign the GHB to only the 5th layer. However, if the water level extends to maybe the 3rd layer, then you should assign your GHB from layer 3 to layer 5.

I hope this helps

Regards.

To view this discussion visit https://groups.google.com/d/msgid/modflow/CAMVFkVdGeCbnRWX%3DedCYrw6AL%3DK%3DcL-83DcFUc%2BWAVOTcgNyEw%40mail.gmail.com.

[Jakab Andras - Gmail]

Assigning GHB or any other lateral boundary condition to low permeability units is not required if one can assume predominantly vertical flows within these units.

To view this discussion visit https://groups.google.com/d/msgid/modflow/CANHLNVOoA%2Bxj1Z5rQ2cpJjkCHFCY5DY%2BPc4Z%2BdNWaPYw%3DPRLcw%40mail.gmail.com.