Advice on Modelling Lake Impact on Groundwater Heads

[KAED MORSKAD]

Dear all,

I hope you are doing well.

I am currently working on a simplified groundwater model and would appreciate your input on the best approach for the following situation:

I have an existing condition model where the hydraulic head distribution is known before the creation of a lake. Now, I would like to assess how the introduction of a lake affects the groundwater head distribution.

My main question is:
What would be the most appropriate modelling approach and boundary conditions to represent this scenario in a simplified way?

More specifically:

• Would it be better to represent the lake as a constant head boundary (CHD), or to use something like a river/lake package with conductance?

• How should the external boundaries be treated (e.g., fixed heads vs. general head boundaries)?

• Are there key processes (e.g., recharge, leakage, interaction terms) that should not be neglected, even in a simplified model?

The goal is not to build a highly detailed model, but rather to capture the main effect of the lake on the groundwater system in a reasonable and physically consistent way.

I would really appreciate any suggestions, references, or examples you might have.

Thank you in advance for your help!

Best regards,
Kaed