The researchers used a computer model to estimate how easily water flows through the ground and riverbed near the Susquehanna River in New York. They found that the sand and gravel in the area allow water to move quickly horizontally, but not as fast vertically. The riverbed itself lets water pass through slowly. By refining their calculations, they determined that the upper part of the aquifer has a high horizontal flow rate compared to the lower part. The study also showed that the model was most sensitive to changes in the aquifer's horizontal conductivity and anisotropy.