Defining General Head Boundary (GHB) for my model

[behnazk]

Hello.

I have a MODFLOW model developed using GMS. The model domain is like a rectangle rotated about 30degree clockwise. the north and south boundaries are no-flow boundary. But, the east and west boundaries are defined as general head boundary (GHB). The flow direction in the domain is always from northwest to southeast. I want to run the model as steady-state, I have quarterly measurements of water levels in couple wells inside model domain. My question is where should I get the head, and conductance to set-up my GHBs in the west and east boundaries? Is there any general rule that I should follow?

Thanks,

bk

[Michael Kennard]

A regional-to-local model approach is a common way to do this, where you start with a regional model that is bigger and extends to natural boundaries and then create your smaller, local model using the heads and flows from the regional model as the boundaries of the local model. There are a few different ways to do this, and we have a few tutorials in the learning center about it.