Abstract
The sources of water and corresponding delivery mechanisms to groundwater-fed fens are not well understood due to the multi-scale geo-morphologic variability of the glacial landscape in which they occur. This lack of understanding limits the ability to effectively conserve these systems and the ecosystem services they provide, including biodiversity and water provisioning. While fens tend to occur in clusters around regional groundwater mounds, Ives Road Fen in southern Michigan is an example of a geographically-isolated fen. In this paper, we apply a multi-scale groundwater modeling approach to understand the groundwater sources for Ives Road fen. We apply Transition Probability geo-statistics on more than 3000 well logs from a state-wide water well database to characterize the complex geology using conditional simulations. We subsequently implement a 3-dimensional reverse particle tracking to delineate groundwater contribution areas to the fen. The fen receives water from multiple sources: local recharge, regional recharge from an extensive till plain, a regional groundwater mound, and a nearby pond. The regional sources deliver water through a tortuous, 3-dimensional “pipeline” consisting of a confined aquifer lying beneath an extensive clay layer. Water in this pipeline reaches the fen by upwelling through openings in the clay layer. The pipeline connects the geographically-isolated fen to the same regional mound that provides water to other fen clusters in southern Michigan. The major implication of these findings is that fen conservation efforts must be expanded from focusing on individual fens and their immediate surroundings, to studying the much larger and inter-connected hydrologic network that sustains multiple fens.
Highlights
Fens are groundwater-fed wetlands that support the existence of a disproportionately large number of plant and animal species [1], [2]
It was found that the hydraulic heads at the calibration locations were not very sensitive to the hydraulic conductivity values assigned to the lithologic materials ‘MAQ’ and ‘PCM’
The calibrated hydraulic conductivity for ‘AQ’ of 30.5 md-1 was within the expected range of values for these aquifer materials ranging from 10−1–104 md-1 [51]
Summary
Fens are groundwater-fed wetlands that support the existence of a disproportionately large number of plant and animal species [1], [2]. Fens influence downstream water quantity and quality in headwater streams and wetlands [3] and buffer water temperatures as they provide. Fens are known to remain saturated throughout the year but are never inundated for significant lengths of time [1], which indicates the importance of groundwater to fen hydrology. In terms of their location on the landscape, most fens tend to be located near headwater streams [1]. Another distinguishing feature of fens is that they are known to occur in regions where the bedrock consists of limestone, dolostone and marble [1]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
