Biomanipulation of Groundwater Flooding

Changes in land-use/land management and climate perturb the balance of hydrologic fluxes in catchments around the world. In extremely flat, internally or poorly-drained landscapes, 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 (GW) storage. In South Central WI, within internally drained basins created in the hummocky, the balance of these changes has led to GW recharge and flooding which has caused loss of farmland and permanent inundation of homes. Yet, the primary cause of GW flooding in the region is unknown and solutions are illusive.
The objectives of this project are to 1) document the occurrence and extent of GW flooding from 1936-2022 2) identify the dominant drivers of GW flooding and characterize their role in GW flooding through time and 3) evaluate the effectiveness of biomanipulation (particularly strategic tree planting) at decreasing the extent of GW flooding and creating a more resilient landscape. First, aerial photography from the 1930s and satellite data from the 1980s will be used to quantify changes in surface water coverage and the appearance of new water features in the study area. Secondly, COMSOL, a general-purpose and flexible finite-element software environment will be used to simulate the two-way ecohydrologic coupling between surface and subsurface processes to isolate the independent effects of changing climatic and land use/management practices over the past 100 years. Finally, we will perform scenario testing through numerical modeling experiments to determine whether GW flooding can be curbed through various degrees of strategic tree planting. This study would evaluate biomanipulation of the water budget as a novel solution which may provide other ecosystem services including habitat provisioning, carbon accumulation, and water quality benefits under the prevailing climatic conditions in WI.