Abstract
A simulation model is developed for a coastal wetland of Lake Erie, one of the North American Laurentian Great Lakes, to determine the fate and retention of phosphorus in the wetland as water flows from an agricultural watershed through the wetland and into Lake Erie. Phosphorus retention in the wetland is a desirable to prevent eutrophication of Lake Erie. The model is developed with sub-models for hydrology, productivity, and phosphorus and a simulated barrier beach that can be opened or closed to Lake Erie. A simulation based on 1988 data is calibrated in step-wise fashion. Resuspension is a necessary inclusion in the model to predict phosphorus concentrations in the wetland's water column. Subsequent simulations are made for various combinations of increased flow from the watershed and changing Lake Erie water levels. Phosphorus retention varies from 17 to 52% with highest retention when high inflows are coupled with high lake levels. A nutrient budget constructed from the model for 1988 conditions showed marked differences with budgets developed from empirical models or field data. The model results suggest a near balance between inorganic sedimentation and resuspension but an active plankton sedimentation that results in a net phosphorus retention rate of 2.9 mg P m
−2 day
−1.