Dynamic ice formation in channels as a driver for stream-aquifer interactions

This research introduces and provides evidence of a novel mechanism of stream-aquifer exchange caused by dynamic ice formation on streams. At a stream site in southwestern Wisconsin, we document a significant fluctuation in stream depth and the potentiometric surface in the adjacent aquifer during periods of ice formation, suggesting that stream-aquifer interactions may be influenced by these transient events. Four years of winter stream data document that dynamic ice formation (1) causes an average increase in stream depth of 106%, (2) affects stream depth on 20% of days from December through February, and (3) substantially alters stream-aquifer interactions by reducing the hydraulic gradient toward the channel during ice formation events. Dynamic ice formation represents a potentially widespread mechanism for altering stream-aquifer interactions and associated biogeochemical transformations. The sensitivity of this process to air temperature indicates a need for further research on the impacts of climate warming.