SIMULATING HYDROLOGIC COMPLEXITIES OF A NUTRIENT-REDUCTION WETLAND IN THE MIDWEST OF THE UNITED STATES

With the main goal of reducing excess nutrient export to Lake Erie to ameliorate its harmful algal bloom (HAB) problems, over 110 wetlands are being constructed or restored by the Ohio Department of Natural Resources as part of the H2Ohio Initiative. To evaluate how efficient these restored wetlands can improve water quality concerning phosphorus and nitrogen, however, it is imperative to have a full understanding of the hydrologic dynamics and nutrient transport in and out of the wetlands. Using HydroGeoSphere and in-situ data collected by the H2Ohio Wetland Monitoring Program, this study creates a novel 3-D hydrologic model to simulate flow and mass transport across surface water and groundwater in a representative H2Ohio wetland site in NW Ohio - the Oakwoods Nature Preserve that is featured with tens of depressional ponds dotted on the land surface. Our preliminary simulation result shows that, driven by weather data, the model can capture the complex hydrologic dynamics occurring in the wetland site, including surface-water and groundwater interaction, as well as coalescence and separation of the depressional wetlands as they respond to wetter and drier climatic conditions, respectively. Next, we will collect water quality data from ponds and monitoring wells within the site and use the data to calibrate and validate the model. It is expected that the results and findings of this study would inform managers and policymakers about the effectiveness of the wetland in nutrient removal and contribute new knowledge of how wetland systems work.