Imbalances in Great Lake water inputs and outputs cause Great Lake Water Levels (GLWLs) to fluctuate with an observed range of ~2m for Lake Michigan since 1860. These GLWL changes cause groundwater (GW) fluctuations in coastal aquifers that can propagate 10s of km inland depending on the magnitude of fluctuation, the time scale of the oscillation, and the hydraulic properties of the aquifers and interact in complex ways with local, intermediate, and regional GW flow systems.
Coastal ridge and swale ecosystems offer an ideal opportunity to study the effects of climate induced GLWL fluctuations on coastal GW systems and terrestrial ecosystems. The overarching goal of this project is to quantify the impact of changing GLWLs on GW storage, GW flow patterns, lake-GW interactions, evapotranspiration and forest productivity to better understand spatial variability in vulnerability to GLWL fluctuations both within and among Wisconsin’s ridge and swale ecosystems along the Lake Michigan coast.
Keywords: Groundwater, Ridge & Swale Ecosystems, Great Lakes Water Levels, Coastal Forests.
Our Team:
- Eric Kastelic, Graduate Student in Geological Engineering Program
- Ben Runzheimer, Undergraduate Student supported by Water@UW Flow Project 2025
- Ella Flattum, Undergraduate Student supported by Freshwater@UW SROP 2024
- Dr. Evan Larson, Faculty at UW – Platteville
- Dr. Dominick Ciruzzi, Faculty at William & Mary
Questions:
- What impacts do Great Lake water levels have on groundwater movement and storage in coastal ridge and swale systems?
- How do trees respond to fluctuating water levels in these systems?
- What impact does landscape position have on tree growth?
Approach:
- Field Methods: Monitoring groundwater levels and collection of tree core data.
- Analysis: Time Series analysis of groundwater levels, lake levels, and precipitation and tree core analysis of ring width and growth patterns.
- Modeling: Flow paths of groundwater through ridge and swale system.
Funding:
- The University of Wisconsin System in support of the Wisconsin Groundwater Research and Monitoring Program.
- The Anna Grant Birge Memorial Scholarship
Findings:
This work is in the preliminary stages. We have found that tree growth varies based on location within individual ridges. Groundwater levels measured on differing ridges experience differing responses to precipitation events despite close proximity.
