Impacts of Hydraulic Variables on Groundwater Model Calibration for Long Island, New York

Groundwater is the largest source of readily available freshwater on our planet. Aquifers are vulnerable to climate change and require new groundwater management plans to account for changing precipitation patterns and sea level rise, among other factors. Building a three dimensional groundwater model as framework for evaluating these changes is fundamental. Ultimately this model will be coupled with the output from several Global Circulation Models and used as a predictive model to determine the impact of climate change on Long Island, New York. This research looks at the process of modeling the physical elements of the groundwater hydrology of Long Island, New York. The model accounts for the unconfined and confined aquifers, as well as the confining zones. Calibration of the model includes visual comparisons with HA-709, a groundwater model built by the USGS in 1989, to illustrate similarities in the model foundation. The model is then calibrated by calculating the root mean square error between historic USGS groundwater data to the models simulated groundwater heads. Looking at how changes in the model impact the calibration process provides insight into model accuracy and modelers' choices. In this research we show how various combinations of model cell sizes, horizontal hydraulic conductivity, recharge, and drains impact model calibration, and ultimately the model that will be used during the research process.