One of the challenges in groundwater modeling is the prediction of hydraulic head related to local stress fluctuations with a regional scale model. Typical applications of numerical models require extensive field information for input data and for calibration. If we can model the change directly, we may not have to know all the modeling parameters because sometimes the changes only depend on fewer parameters. In this article, we present an improved methodology for groundwater modeling related to local stress fluctuations using a perturbation approach. Our results demonstrate that this approach is capable of matching an exact solution for drawdown in both confined and unconfined aquifers. The results suggest that this perturbation method can provide an accurate representation of head in a large-scale hydrogeological system.