Changes in land-use and climate perturb the balance of hydrologic fluxes in catchments around the world. In poorly drained basins, imbalances between precipitation and evapotranspiration are less likely to be compensated for by changes in surface runoff and are therefore more likely to lead to changes in groundwater storage. In South Central WI, within internally drained basins created in the hummocky terrain near the terminus of the Wisconsinan Glaciation, the balance of these changes has led to GW recharge and flooding which has caused loss of farmland and permanent inundation of homes.
Keywords: Groundwater Flooding, Historical Land Use Land Cover Change, Climate change
Check out a research highlight below!
Our Team:
- Eric Kastelic, Graduate Student in Geological Engineering Program
- Melina Dennis, Undergraduate Student supported by Freshwater@UW SROP
Questions:
- Where does groundwater flooding occur in WI?
- What are the drivers of groundwater flooding ?
- What is the impact of the individual driver?
- Would biomanipulation have impact on groundwater / lake levels?
Approach:
- Field Methods: Monitoring groundwater levels and soil moisture.
- Analysis: Time Series analysis of lake levels, groundwater levels, precipitation, and remotely sensed evapotranspiration and mapping of historical surface water extent.
- Modeling: Numerical simulation of 1-D vadose zone processes.
Funding:
- The University of Wisconsin System in support of the Wisconsin Groundwater Research and Monitoring Program.
- North Temperate Lakes Long-Term Ecological Research Program.
Findings
Historical analysis of aerial photography and lake stage data has shown that Fish Lake water levels have predominantly increased since the 1930s. As these are seepage lakes, during periods of drought lake levels have decreased but experience a general upwards trend. Due to differences in magnitude and duration of evapotranspiration, agricultural row crops experience a lesser amount of evapotranspiration and a greater amount of groundwater recharge compared to historical mixed forest ecosystems. Land use and climate change are key drivers of groundwater flooding, but have been the dominant driver at different times. Prior to the 1980s, land use change was the main driver of groundwater flooding. Without historical land use change to agricultural row crops in the basin, lake levels may have seldomly increased until precipitation significantly increased with the onset of climate change. Groundwater flow to the Wisconsin River is the second greatest flow of water from the basin. The gradient in hydraulic head between the two allows for removal of a certain amount of groundwater recharge from the basin before lake levels would increase, which we have determined and named the “Critical Recharge Value”. Investigating the impact of biomanipulation methods revealed that while using cover crops and increasing forested area increased evapotranspiration and decreased recharge would occur. However, this would only slow current lake level increase and not lead to a significant decrease in lake levels, especially with the increase in precipitation due to climate change.
Publications for this work:
- WRI Final Report (Coming Soon)
- Paper in Hydrologic Processes (Coming Soon)