Characterizing The Contribution Of Groudwater In The Water Budgets Of Wetlands Using GIS Groundwater Modeling And The Field Measurement Of Water Quality

Wetlands provide many benefits to society, including flood attenuation, groundwater recharge, water quality improvement, and habitat for wildlife. Because their structure and function are sensitive to changes in hydrology, characterizing the water budgets of wetlands is crucial to effective management and conservation. The groundwater component of a budget, which often controls resiliency and water quality, is particularly difficult to estimate and can be costly, time-consuming, and invasive. This study used a GIS approach using a digital elevation model (DEM) and the elevations of lakes, wetlands, streams, and hydric soils to produce a water-table surface raster for a portion of the Itasca Moraine. The water-table surface was used to delineate groundwatersheds and groundwater flow paths for lakes and wetlands and map recharge and discharge rates across the landscape. pH and specific conductance, which depend on the hydrological processes that dominate a wetlands water budget, were measured in the field to verify this modeling technique. While the pH of surface waters varied in the study area, specific conductance increased from 16.7 to 357.5 μS/cm down gradient along modeled groundwater flow paths which revealed increased groundwater interaction. These results indicate that GIS tools and public-domain elevation datasets can be used to map and characterize the contribution of groundwater in the water budgets of lakes and wetlands in the Itasca Moraine. Applied elsewhere, this cost-efficient and less invasive modeling technique should be of use to natural resource managers who need to access the vulnerability of lakes and wetlands to changes in land use, groundwater development, and climate change