does specifc head change with time ?

[ahmedp...@gmail.com]

I am modeling a model of an aquifer with a specific head on the north and west boundary. The aquifer I am modeling has an aquifer next to it ( western limits ) which acts as a drain for the boundary I am modeling. My model consists of a transit model from 1990 to 2016 and a prediction scenario in 2030. my question is 

Can I change the specific head points along time in my western side to simulate the extraction and the drainage it does to my model ?