Hydrologic Modeling of a Small Wetland Complex to Inform Estimates of Phosphorus Retention

Isabelle Augustin

University of Vermont

Co-Authors: Adrian Wiegman, Eric Roy, Kristen Underwood, William Bowden

Phosphorus (P) is an important nutrient in ecosystems and is often limiting in freshwater systems and the human application of P in agriculture has made P management a priority to maintain freshwater ecosystem health. Previous studies suggest that small wetlands play a disproportionately large role in landscape-scale nutrient processing. Modeling watershed P dynamics requires estimates of water budgets within the areas of interest. The objective of this work is to model the inflow, outflow, stage, and storage relationships of a small wetland with an active beaver dam in the Prindle Brook floodplain in Addison, VT using HydroCAD. This model will be coupled with a P model to understand P dynamics in restored riparian wetlands on former agricultural land during flood events. These results will be important for recommendations to the state and non-profit agencies about how to best prioritize potential restoration sites. Testing of the HydroCAD model of the Prindle Brook wetland complex is still ongoing. A sensitivity analysis is being performed to assess how various parameters, such as curve number, antecedent moisture condition, and the length of storms affect results. Sensitivity analysis will also be performed by changing the modeled outlet structure representing an active beaver dam. Limited research has been published with guidance for modeling a beaver dam in HydroCAD.