INTEGRATED HYDROLOGIC MODELING OF A RECENTLY RESTORED FLOODPLAIN WETLAND FOR REDUCING NUTRIENTS

More than 180 wetlands have been or are planned to be restored or created by the Ohio Department of Natural Resources (ODNR) under the H2Ohio Initiative to improve water quality in Lake Erie and Ohio’s inland lakes. To evaluate if these wetland projects could effectively function in terms of removing nutrients (i.e., nitrogen and phosphorus), it is important to understand the hydrologic dynamics and nutrient transport mechanisms of these newly built wetlands. This study, supported by ODNR’s Wetland Monitoring Program (WMP), developed an integrated 3-D hydrologic model for one of the H2Ohio wetlands, i.e., the Forder Bridge Floodplain Reconnection, to assist the assessment of the wetland’s nutrient-reduction function. Located in NW Ohio in the Maumee River Watershed, the 54-acre Forder Bridge wetland site was restored on active and retired farmlands and is now featured as a flow-through system consisting of a series of wetland pools connected by small stream channels that eventually drain to the Maumee River and two sets of isolated pools as well as a floodplain wetland area. The model, built based on HydroGeoSphere, simulates both surface-water and groundwater flow as well as solute (i.e., dissolved reactive phosphorus or DRP) transport across the wetland site. Our preliminary simulation results demonstrate that the model was capable of routing the water and solute from the source (a culvert on CR 424) to the Maumee floodplain. In addition, the 3-D model also provided detail information on some complex hydrologic processes and responses occurring in the wetland system, such as climate-driven variations in water depth and inundation of surface-water bodies as well as their interactions with groundwater (i.e., exchanging fluxes). Once calibrated and validated, the model will be used with the physical and chemical data collected by the WMP monitoring crew to estimate how efficiently the wetland reduces nutrient transport and to elucidate how intricately this wetland functions.